How to Scratch-Build a Vintage Amp, Part 7: Chassis Finishing and Point-to-Point Wiring

In this Part 7 video, the chassis is painted, lettered, and clear-coated. The components and transformers are all attached to the chassis and the point-to-point wiring is begun. The majority of circuit wiring, including primary AC, power transformer outputs, output transformer, reverb transformer, input jacks, etc. are carefully explained, and there are brief discussions on safety, grounding, soldering technique, shielded cables, and different types of solder.
Here is the schematic link. You can scroll for detailed diagrams of each sub-circuit and the chassis: www.mediafire.... I believe this will be the final version of the schematic. The Layout Diagram is included in this link.
If you enjoy clear, basic videos on subjects such as vintage electronics, old jukeboxes, and unusual electro-mechanical devices, then please subscribe to my channel and gain immediate access to over 120 related videos.

[@TheJstewart2010]

Those rub-on letters really bring back memories. My Dad used them for all of his electronics builds and he had sheets and sheets of them in the shop. When I started graduate school in chemistry, we had analogous rub-ons for chemical bonds, element abbreviations, etc. It could take me most of a morning to build up a single chemical diagram. In the mid-80's a Macintosh program called ChemDraw was introduced that allowed you to make all the diagrams on a computer rather than using rub-ons. It reduced those hours of work to minutes and everyone tossed their rub-on sheets into a file drawer for good.

[@UncleDoug]

The rub-on sheets used to be fairly expensive, as I recall, and I would dread having to buy entire sheets just to get the right numbers and letters for a project. Then, as you said, the sheet went into a drawer for eternity.

[@dwightjt]

Cats are pretty smart They know where water can be found When its on. Jack in the bathtub was thirsty Put water in His waterbowl or Christle goblet And he will stay out of the tub nice kitty. That is a nice professionally made Home built Amp Good work.

[@UncleDoug]

Thanks, Dwight. Jack actually considers the bath tub to be like a playpen. He takes toys in with him, to play with.

[@ReFretted]

If there was a hall at the Louvre for electronic beauty, this wiring would be in there - beautiful.

[@UncleDoug]

Wow.....thanks so much, ReF :)

[@ianforfun1]

That workmanship is exquisite and you explain each section extremely well. The exterior finish is stunning and the gold will match the cabinet. One-click away from Part 8. It's really good of you to mention the safety angle at the end of this. A long time ago when I was a teenager with spots I took a shock from a capacitor while building an EL84 record player amp while it was unplugged from the wall socket and almost threw me across my Dads garage! Lesson learned I'm amazed why nobody has to best of my knowledge manufactured a wand to discharge caps?

[@UncleDoug]

Thanks for your very kind words, Ian. I'm glad you are enjoying the series and appreciate the need for safety precautions.

[@curtislucka9954]

Dear Uncle, I am very familiar with most of your best practices around the electronics parts but there is always more to learn, especially with the metal and wood working. This is quite ambitious but you are a master of many things. Thanks for the education. It means a lot!

[@UncleDoug]

You're welcome, Curtis. I appreciate your very nice comments and wish you the best with all your projects.

[@MrMac5150]

You do such a nice clean job with that wiring, nice job. Be sure to say hi to Rusty and Jack for me. I would like to see more of them.

[@UncleDoug]

+MrMac5150 Thanks, Mr. M. Neatness is all part of the challenge to make it look and work well. I'll convey your greeting to them :)

[@budandbean1]

Hey Uncle Doug, I just wanted to let you know again how much I am enjoying your build, it looks wonderful and it's so nice to have a real professional like you doing the building. I'd also like to throw out a big "Thank You" to the person that drew up your schematic. That is so nice of them and it will be great to have when you get the amplifier finished. You sure find a lot of real nice people hanging around the Uncle Doug channel...

[@UncleDoug]

+Buddy Martin You're quite welcome, Buddy. Comments like yours make it all worthwhile :) Also, I completely agree with your assessment of our channel's audience. When I watch other videos on YT, there are often all sorts of mean, vulgar comments....but thankfully on this one (at least so far) everyone is respectful, helpful, and kind. To be honest, if the atmosphere were not so pleasant, I would have lost interest long ago. PS, thanks also for recognizing the great work by Tommy, preparing all the schematics.

[@budandbean1]

+Uncle Doug Thank you Uncle Doug, and thank you Tommy for going that extra mile to help out, it very nice of you!

[@UncleDoug]

You're welcome, Buddy.....it was our pleasure.

[@BurtonBoyz715]

+Uncle Doug .I concur...even though your circuit is subject to revision until the build is done....The schematic "link" is a great plus and very useful. A big thanks to your helpful subscriber .... Tommy....Bill ;D)

[@UncleDoug]

I hope he reads these comments, Buddy and Bill; but if not, I'll let him know how much you appreciate his very skillful work.

[@David-rc8us]

Hi Uncle Doug ! What a brilliant piece of absolute exceptional workmanship ,your soldering is first class, just how I was taught too, a mechanical joint with a covering of solder and still being able to see the wire profile . This is going to be one magnificent good-looking amp . Doug this amp is a work of art you should have it on display .Looking forward to the next show . Regards to Rusty and the rest of the crew . It is a privilege to watch you in action. Just one word dazzling ,outstanding oh !!!! that was two. Best wishes from David UK

[@UncleDoug]

+David dave Wow, what a kind appraisal, Double-D. Rusty and I really appreciate your kind words and sincerely hope that our projects lives up to your expectations. Thanks for much for watching and making us feel so good with your comments.

[@johncunningham5435]

A superb construction job Doug; The craftsmanship is astounding, the careful placement of tube sockets, transformers and other parts will make sure that with the extra shielding hum should be at a minimum or possibly eliminated.

[@UncleDoug]

+John Cunningham Thanks, John. This one did turn out virtually hum-free. After building a bunch of amps, you gradually develop techniques that enable this type of result.

[@johngeddes7894]

Impressive catch to me on the error in the schematic. Equally impressive is your point to point wiring job. The amp is one place where art and science converge!

[@UncleDoug]

Thanks so much, John. We strive to please :)

[@seasonedtoker]

yep, the gratitude at making something from scratch is immense. I am only able to make a simple booster pedal with a single transistor, but when finish the PCB/stripboard and I drill the enclosure to start test fitting everything, it starts to make much more sense than before, when you had an empty stripboard, a bunch of components and a plain aluminium brick box

[@UncleDoug]

There is no better way to learn about electronics than to actually construct circuits and components.

[@irusman62]

Uncle Doug, thank you for the link to the schematic, and of course to the viewer who drew it all out, its super helpful.

[@UncleDoug]

You're welcome, Russell.

[@irusman62]

@@UncleDoug are you using 14 awg solid wire for the B+ high voltage?

[@irusman62]

@@UncleDoug do you use ceramic tube bases here in this build?

[@irusman62]

@@UncleDoug hi UD im going over the schematic for this build. my question is about the capacitors. there are 2 symbols for non polarized capacitors being used according to a symbols sheet I have, -| (- -I I- do you use these to differentiate capacitors in your circuit? and which ones are the electrolytics, Mallorys etc. please I know im not the only one asking you questions. I can probably figure it by watching the videos.

[@UncleDoug]

@@irusman62 I don't recall, Russell. Can you tell from watching the video ?

[@JustSomeGuy1967]

Uncle Doug, you make this deceptively easy... watching your videos and others that are good at their trade make things very understandable. It's when someone like me who has always been very interested in electronics dives in and tries it on their own. I have been working on old tube radios and find myself stumped at every turn...watch a few videos and finally someone says something that clicks. Anyways, what I'm saying is you have produced excellent videos that make sense to those of us starting out...heck, I wait for your videos about as excitedly as I do for the next season of Gold Rush!!! Thanks for taking the time!

[@UncleDoug]

+Mark Jordan You're welcome, Mark, and thanks for the very kind appraisal. Rusty and I really try to produce videos that will appeal to a very broad audience, and comments like yours make us feel that it's all worthwhile.

[@brentstewart59]

Very nice work here Uncle Doug and nice to see it coming together. I'd really love to see you build a Ken Fischer circuit like the Express or Liverpool as your style of explaining things is second to none

[@UncleDoug]

Thanks so much, Brent. I'll keep your suggestion in mind.

[@rongay81276]

Awe inspiring work Uncle Doug!.....now I have some ideas and a fire extinquisher just in case!

[@UncleDoug]

+Ron Gay Thanks, Ron. Don't get confused and grab the acetylene tank by mistake :)))

[@td7456]

Top notch work, as per usual! Man, I hear Rusty is getting so snooty that he's demanding any misshapen cookies be removed from his dressing room..Jeez...

[@UncleDoug]

+Tim Dockery Thanks, Tim. Yes, as Rusty's fame steadily grows, he has become increasingly persnickety :)

[@audiotechlabs4650]

I had a few good things to say, but after reading your viewer comments, they have all been said. This series is the most complete and informative amp built there is, period! I think you have the best YT tube channel. I am so blessed to be a part of it and the community you have created. The lovely birds were merely stunned at the opportunity to pitch hit for Rusty and Jack. Thankz

[@rongay81276]

^what he said!

[@UncleDoug]

+Audio Tech Labs Wow, thanks so much ATL. Viewers ask me why I try to respond to every comment, and the reason is that just about every one of them seems like a note from a friend. I see all sorts of insults and childishness in the Comment sections of many other channels, but none of that nonsense occurs here. I think this is the way YT was meant to be. I'm really glad to be a part of it.

[@UncleDoug]

+Ron Gay Thanks, Ron :)

[@audiotechlabs4650]

+Uncle Doug, You make these videos feel like the viewer is looking over your shoulder. I have a degree in electronics and a 1st Phone in broadcasting, and I still learn something new from every one of your videos. Your love of animals is great. Your humor makes the learning fun. Like others, I can't wait for the next video or series to be posted so I first watch, then try and duplicate what I have seen. Thank you and please as long as you can, share with us your vast knowledge. Thankz

[@UncleDoug]

You're welcome, ATL.....and again, thanks so much. Kind comments like yours make it all worthwhile.

[@fredcockerhamfan]

I am scratch building a vibro champ clone right now and this video series is helping me a ton. Thank you for all your knowledge and help!

[@UncleDoug]

+Hillbilly Hula You're welcome, HH. I'm glad to hear that you're able to apply the principles in this video to your own project. That was my initial intention. Good techniques are universally applicable.

[@AndyWragg]

And the light bulb goes on! I've just realised how the filter caps work (low pass filter to eliminate 50Hz ripple) thanks to your once again excellent narration. I don't know why but it never twigged before. Awesome build Doug. I've got my first 'customer' amp repair job going on right now. I'm replacing the main power tube board in a Marshall JCM2000 DSL100 for a friend of a friend. Got my 'Uncle Doug' dim bulb tester and cap draining gizmo all sorted out too.

[@UncleDoug]

+Andy Wragg You're welcome, Andy. It's great to hear that my abstract mumblings are actually being absorbed and applied in a constructive way. Congratulations on your first paid repair job. I hope it goes well and is only the first of many. Best of luck to you in all your projects and pursuits.

[@rollofthedice]

Fantastic video. For an amp builder noob, it's nice to see how you translate from schem to chassis planning, layout and all.

[@UncleDoug]

Thanks, LV. We're glad to hear that the videos are clear and helpful :)

[@BurtonBoyz715]

Uncle Doug and Rusty.....Meticulously Planned.. Beautifully executed...crystal clear...incredibly informative......and as always artfully illuminating.... (great cable-form too). You'd like to think that everything built had this much care and thought put into it. Thanks. Bill.

[@UncleDoug]

+William Earney Dang it, Bill, you're making me blush :) Thanks so much for your kind words. Receiving such a response definitely makes it all worthwhile. You're quite welcome :)

[@tectalabyss]

Hello Doug. A very professional job !! to say the least. I have watched many channels here on youtube over the years and you Sir have a gift. Not only in your well thought explanations,but you make us the viewers feel a part of each and every video. one doesn't feel talked down to,but made to feel as though a dear friend was explaining what they were doing. That is a rare and wonderful feeling. Much Respect Doug. Give Rusty and Jack A pat for me. All my best. Bobby

[@UncleDoug]

+Bobby Tectalabyss Wow, Bobby, thanks for the extremely kind words. Rusty and I try to do exactly what you described, not so much as a teaching maneuver, but simply because we really respect and appreciate our viewers. And, when we receive a nice comment like yours, it makes us feel like we're not only achieving our goal.....but all the work and time are very well spent.

[@tectalabyss]

+Uncle Doug You are most welcome Doug. Thank you for the time it took to reply to me. Very much looking forward to your next video.. All my best. Bobby

[@wreckoningday]

I'm slow on commenting on this one as I was held up by unforseen surgery but I see I'm only behind 1 vid! Can't thank you enough for the great vids, I kept wanting to get to my phone so I could see if a new vid was up the while time I was recovering. The chassis is looking real nice UD, looking forward to the next installment. Rusty left u hanging this vid but I have a feeling he's saving up for the final unveiling. Cheers

[@UncleDoug]

+wreckoningday You're welcome, WD. I hope you recover quickly from the surgery. You're right about Rusty......he's been working night and day on Part 8. Hopefully it will be posted tomorrow (Thursday). Thanks for watching and best of luck :)

[@cassvirgillo3395]

Hey Uncle Doug & Crew, I hope your all doing good. You need to remind Rusty he is still under contract. Your craftsmanship is awesome, cleaner looking work I'm sure you will not find, and, with your schematic revisions, based on years of experience, will sound great! I really am enjoying the series. Take care, be good. See ya, Cass

[@UncleDoug]

+Cass Virgillo Thanks, Cass. I hope you're right about the revisions working out. It's always a bit of a crapshoot, and I may have to do some slight modifications after it's up and running......but they can't help but improve the tone and versatility.

[@GregsGarage]

The payoff is starting! Looks fantastic. Thanks for explaining the layout and thoughts behind the schematic / circuit design & modification.

[@UncleDoug]

+Greg's Garage You're welcome, Greg. I hope this video answers a lot of the questions that viewers have been asking about design, wiring, fabrication, etc.

[@bullthrush]

Looking good, the parakeets could strip wire ends for you, Jack has the cold water ready for the obligatory soldering iron burn, and Rusty's camera work is still top notch.

[@UncleDoug]

+bullthrush Thanks, Andrew. Those pesky parakeets are eating me out of house and home......hopefully, they'll develop some skills to earn their keep. I've given up on Jack. Rusty is still a big help, but he's getting a little rheumatism in his camera paw.

[@MrPodvig]

I'm grooving on these videos. Thanks for existing.

[@UncleDoug]

The pleasure is all ours, Richard :)

[@tremelo68]

I love your humor. I nearly spit out my tea when you offered up the "steampunk rivets" joke. Thanks

[@UncleDoug]

+tremelo68 You're welcome, Trem. A little humor breaks up the monotony of some crazy old guy droning on and on about circuits, sockets, and such.

[@stanleychytla3786]

Hello UD. Thanks for all of the construction tips and demonstrations of how to achieve a really high quality build. I plan to incorporate your methodology on my next (second) tube amp build. my first build works fine but is not nearly as neat and clean as your wiring. I did encounter some problems with a tremolo ckt that ended up being due to component placement and lead length. Your methodology will avoid any similar issues. The timing for this video series is perfect since I had just finished the cabinet but had not started the chassis construction. As others have said, you have a gift for teaching and I appreciate all of the effort that you put into making these videos for our benefit. Thanks again.

[@UncleDoug]

+Stanley Chytla You are quite welcome, Stanley. It's great to hear that the videos are helpful and appreciated. Amp building is a rather complex art, and, like any challenging task, requires a lot of concentration, foresight, and practice. I have no doubt that your skills will increase appreciably as you gain experience. As my old granny used to say: "If it was easy, it wouldn't be nearly as rewarding". Best of luck with all your projects.

[@stanleychytla3786]

+Uncle Doug Hello again. I noticed on the schematic that the second half of V4 for the tremolo circuit does not have a plate resistor but is connected directly to point B3 which has the 10uf cap. Is that an error?Also I have a general question about plate voltages on guitar amp output tubes. It seems that guitar amplifiers routinely show plate voltages that exceed the maximum ratings found in the manufacturer's datasheets. Why is that the case and does that harm the output tubes? Finally just a comment about amp design... In my research about standby switches I have learned that amps that use solid state rectifiers need the standby switch so that the tube filaments have a chance to warm up before the high plate voltage starts stripping electrons from the cathode. This seems less important with tube rectifiers since the B+ comes on more gradually along with the other tubes heating at the same time.

[@UncleDoug]

I'll try to address each of your questions. The lack of a plate resistor on V4b is because it is a cathode follower.....the output is from the cathode, not the plate. Yes, guitar amp output tubes often run plate voltages way above the stated max value, particularly 6V6's in Fender amps (in my experience). The value that really seems to determine tube life, however, is plate dissipation (the product of PV x PC). If the PV is high, the PC should be low to compensate, resulting in a normal PD. As long as the PD is within proper boundaries, the tube should be OK. I agree that Standby switches are of use only with SS rectifiers. I do not include them in any of my tube-rectified amp builds....IMHO, they cause more harm than good. According to The Valve Wizard, cathode stripping does not occur at the voltages seen in guitar amplifier tubes: www.valvewizard.co.uk/standby.html

[@Echo_III]

Sir, you make youtube worth to watch :)

[@gmjones2001]

He does. So do a lot of folks. Just found Uncle Doug though. Really good teacher. Got some parts on order to start my own amp building. I am an ex electronics tech though ... know how to solder (was Mil spec 2000 qualified at one point, soldered under a stereo microscope ...chip components)... have learned a ton from Uncle Dough about tube amps.

[@UncleDoug]

Thanks, Echo :)

[@TheRevClyde]

I have a modest request of you. these are a most excellent series of videos and are highly enjoyable. I'm in the process of building my own modified clone amp and would like to know ( and possibly see) how you made the rub off lettering for your control panel. a video on that would be most awesome, entertaining and educational for all of us. please keep up the work, I'll be watching.

[@UncleDoug]

+TheRevClyde Thanks, RC. Several people have asked about the rub-on letters, so I just may make a short video about the process. Meanwhile, have you watched my video on how to make your own lettering and logos for amps? Check my video list. It's how I did the logo and name on this control panel (but not the individual control labels).

[@jeffm8122]

Hello Uncle Doug, Another well built Dani-Sonic is taking shape. You are showing great patience in building this amp, particularly now. Mount the terminal strips, stop & video; paint the chassis, stop & video; do the lettering, stop & video; mount the transformers, stop & video; etc, then you finally get to solder a resistor in place. The temptation to do it in bigger chunks must be hard to resist but I know the object of the exercise is to explain and show every step required and this you have achieved perfectly. One point on the wiring. I think you may have potentially created a small chance for a hum loop. It is the green wire that runs from the ground lug at the negative end of the two 20/450 caps to the 'safety' ground lug. The wire forms a parallel current path with chassis which may cause a hum problem. If the negative ends of the caps could be changed to one of the adjacent vacant terminals and the green wire then connected to the ground lug of the B+, all of the B+ current would then have a single direct path to your filter stage. If the two caps could swap positions I think their leads would be long enough. The integrity of the safety grounding of the chassis is maintained. I hope you don't mind this suggestion as I know what it's like undoing work that was carried out so carefully and then some guy looks over your shoulder and says, "Hey, what about....". Love the cameos by the two stars, my daughters cat jumps into the bath at the slightest chance. Thanks again Doug.

[@UncleDoug]

+Jeff M You're welcome, Jeff, and thanks for your very detailed input. Here's my take on it. The negative leads of the filter caps are all soldered to a terminal that is riveted to the chassis. I believe this would be the least-resistance pathway for any residual AC to reach the safety ground. I added the auxiliary green grounding wire strictly as a failsafe, should corrosion every occur between the riveted terminal and the chassis. Also, I cannot picture any spurious AC taking an upstream voyage to the input or pre-amp end of the chassis, when the ground it seeks is nearby and located at the opposite end. Does this make sense ?

[@jeffm8122]

+Uncle Doug Thanks for the quick response. It's just gone 5 in the afternoon here I only expected to hear back tomorrow. Yes it does and I take your point regarding corrosion and spurious AC, it is a very short wire after all. My thought was that if the negative ends of the filter caps were wired & soldered directly to the P/T secondary centre tap lug it eliminates any need for the B+ current to travel through the chassis even though it's such a short distance. I had made the assumption you would be having a star ground system as in your Vibro-Champ clone. Sorry, I should have worded my original comment better. I also forgot to say what a great job your friend did on the circuit diagram with black for original and red for changes. I wish I could do as good.

[@UncleDoug]

You're welcome, Jeff. I considered a star ground, but the chassis dimensions would have required much longer leads. I am going more for the short-lead, uncluttered approach in this one....with solid grounding for the rather remote primary AC and power supply. Yes, Tommy is doing a wonderful job....and he never complains when I burden him with revision diagrams. He's definitely a helpful, generous member of our channel community.

[@stevenwilliamdewitt]

I am really excited about this amp. I have been building higher wattage amps for a while and really want to build a low watt amp with tremolo and reverb. My wife can't wait for a quit amp. As if there was such a thing! Great job as always. It is the electronics class I never had.

[@UncleDoug]

+Steve Dewitt Thanks, Steve. Low-wattage amps do indeed have their place, especially in my house (and yours, it seems).....where blasting the wall boards loose would not be conducive to marital bliss. Thanks also for taking the time to watch and comment.

[@philr6865]

Beautiful job Doug. FWIW I agree about lead solder. All the big manufacturers are ROHS-compliant, the number of home-built jobs that would appear at recycling plants is negligible so for as long as "proper" solder is available, I say Use It!

[@UncleDoug]

Agreed, Phil. Stifling rules that intrude on our personal lives and preferences are intolerable to me. To be honest, I would use lead solder even if it didn't work better......just to spite them.

[@bucyruserie1211]

Hi Uncle Doug, Yours is the 1st channel that I have officially subscribed to. Although I have seen all your video's (most multiple times) and think their all great, I just had to subscribe and leave a comment about this series. I have always been fascinated by tube amps and intimidated by them as well. I truly appreciate all the time and hard work you put into making these video's. You have a knack for making the complex seem understandable. I have just purchased an unused hammond AO-43 and am going to try and convert it into a guitar amp, and do so safely. So this series in particular is just what I needed to see, to know the correct way to place and route everything. Can't wait to see the next one. Keep up the great work! Rusty too!

[@UncleDoug]

+Bucyrus Erie12 Thanks so much, BE. Rusty and I are quite flattered that you subscribed to our channel and really appreciate your interest and input. We hope the videos are helpful. Welcome aboard :)

[@freak55beat]

sheer joy uncle doug, loving it

[@UncleDoug]

+freak55beat That's great news, Jon. Thanks for watching :)

[@danielcgomez]

I'll watch this later tonight ...can't wait!

[@UncleDoug]

+Daniel Gomez I hope you enjoy it, Daniel :)

[@HarpinJScott]

Thank you Uncle Doug! Your work always makes my day, Rusty and Jack make me laugh out loud, and the work you produce brings a tear to my eye and music to my ear. You are one of my personal heroes. I know that you have not yet completed this series, but I am going to make a very humble request: could you, please, make a video describing the details of point-to-point wiring? Pretty please?!? The tag board thing is cool and all but your point-to-point approach is the very essence of simplicity. Thank you in advance and please give that Rusty a nice rub on the noggin from a faithful viewer!

[@UncleDoug]

+Harpin' J.Scott You're quite welcome, HJ. It's great to hear that our videos are helpful and entertaining.....mostly thanks to my crazy assistants :) Re the point-to-point wiring, I am trying to provide as much detail as possible within a reasonably timed video......soldering techniques, chassis layout, shielded cables, terminal strips, proper grounding, transformer and power cord wiring, etc. If, at the end of this series, you feel that I left anything out, please let me know and I'll address it in a future video. Thanks so much for watching, and I will indeed give Rusty your regards :)

[@MotorWiz]

Hello uncle Doug. I've just started watching your channel about a couple weeks ago. For years I have wanted someone to show me how tube amp circuitry works. FINALLY I am beginning to understand and can not thank you enough for sharing your wealth of knowledge on this topic with all of us tuned in. I will probably go back and watch them all over again after I get through them all. I have truly enjoyed all the fine details that you take the time to point out. Thank you again so very much.

[@UncleDoug]

+Motor Wiz Welcome aboard the Rusty Express, MW. It's great to have you join our YT family. Best of luck with your pursuit of knowledge.....we all started off the same way, and are here to help you.

[@peterphilbrook5887]

Another excellent production! - A comment on filter caps @9:24 - The Fender Tweed Princeton 5F2A has this set up as well with (2) 16uF in parallel equaling 32 uF as the first filter cap, and it also uses a 5Y3 rectifier, so I don't think the original schematic is in error, they most likely made it that way. Would be fun to find an original and prove our theories. I continue to revert back to all your excellent videos for tips on my own amp builds. Thanks!

[@UncleDoug]

+Peter Philbrook You're welcome, Peter. I'm glad the videos are helpful. You're right about the 5F2A Princeton circuit and I guess it could have been done this way in the Supro....although it does look strange on the schematic :) I'm really pleased with the modified power supply rail......it's absolutely dead quiet, without the stress of the 32uf first cap.

[@davidsigglekow1349]

Wow ! What a build sir! B.E.A.utiful!!!!!!

[@UncleDoug]

Thanks, David :)

[@300poundbassman]

Grounded cord Yes thats my first item Downloaded the schematic. thanks for the help. thank you

[@300poundbassman]

I'm capt nemo.Lol

[@UncleDoug]

You're welcome. Good luck.

[@tremolux13]

My but it looks gorgeous... I can't wait to start on my own build as I am a big SE amp fanatic as well... Thank you Uncle Doug, say hello to Rusty and Jack... Beautiful golden amp...

[@UncleDoug]

+Jesus Cervantes You're welcome, Jesus, and thanks for the kind words. Best of luck with your amp project :)

[@chrisdavis9872]

I thoroughly appreciate this video series (so far). Not only is it highly informative, but I find it to be incredibly entertaining. Excellence typifies every aspect of the content of these videos. Uncle Doug, you have the heart of a teacher. I'm looking forward to the remaining installment(s).

[@UncleDoug]

+Chris Davis Wow!! Thanks for the very kind appraisal, Chris. People ask me why I read and respond to every comment.....it's because I don't want to miss one as nice as yours. I'm glad your part of our YT community.

[@lionelberthelon6658]

Oh Boy, this suspense is killing me Uncle Doug. Thats incredible, following a Layout is one thing but point to point scares the hell out of me. Keep up the great work and thank you for all of this

[@UncleDoug]

+Lionel Berthelon You're welcome, Lionel. Relying on a layout drawing is like using training wheels on your bike. They perform a valuable service at first...... I used them too.....but eventually, it's a good idea to at least try it without them.

[@marcohermans3207]

You're explaining things with so much ease and with not too much technical stuff. It's awesome and very educational. It's like Bob Ross was explaining his paintings while making them in the past. I learn a lot from you and wanna thank you for that. I think that your channel is the best if you wanna know more about tube amplification without going in too much mathematical detail. Thanks. Gretigst from Holland!

[@UncleDoug]

+Marco Hermans You're welcome, Marco. I try to explain concepts in basic terms that most viewers can easily understand. People who cloak their discussions in overly complex terminology are generally wasting the viewers time.....and their own.

[@wardcheryldarcie]

CANT WAIT TO HEAR HOW IT SOUNDS!!!!!!!!

[@UncleDoug]

+wardcheryldarcie Me too, Ward. The suspense is killing me.

[@OptomodMix]

That is looking Super Neat Doug :)

[@UncleDoug]

+Optomod Thanks, Opto. Glad you like it :)

[@ChickenStripped]

Excellent work once again Uncle Doug. Your video producing team gets better with every video. Thanks to all of you.

[@UncleDoug]

+KT88 You're welcome, KT. Rusty, Jack, Tommy, and I really appreciate your kind appraisal.

[@chakathewolf]

Ah, we're getting to the good part! I like the heat shrink on the un-grounded end of the coax. Keeps it out of trouble and looks nice, too.

[@AdmiralQuality]

+Chaka Wolf I scored a point for myself when I said "ground loop" 30 seconds before Uncle Doug did. (I'm more familiar with that problem in external patching, but I have made enough ground lifted patch cords to solve it that I immediately recognized why this was a good idea inside as well as outside the chassis.)

[@UncleDoug]

+Chaka Wolf Thanks, CW. Sometimes the small details can make a big difference :)

[@UncleDoug]

+Admiral Quality The elusive ground loop has caused a lot of grief over the years. They are easier to prevent than they are to detect :)

[@300poundbassman]

Hey happy 4th of July, I just now got to watch this amazing series. I bought a Electron-O amp that was a ac-dc line operated amp Im going to try and make a 5 watt single ended amp out of it And I am going to use that name as my logo. It had 3 octal tubes and 2 teeny transformers I chucked all of the insides kept the nameplate and pilot jewel. Anyway its a long term project Hope to send you some photos Your videos are a godsend thanks again William

[@UncleDoug]

Best of luck with your new project, William. Be sure the chassis is properly grounded.

[@PrinceOfBodom]

It is very nice to see the success. The progress that you did in the short time between the episodes is quite impressive. I can't wait for Rusty showing us some Licks on the the finished amplifier!

[@UncleDoug]

+PrinceOfBodom Thanks so much, PB. Rusty hasn't been practicing at all lately, so you might be stuck with my feeble efforts :)

[@MrOldnslofly]

Man oh man this is getting better every step of the way. On a side note but still related.... all your videos on how an amp works and how each part does its job are incredible. Thank you for all your fine effort!!!!!!!

[@UncleDoug]

+MrOldnslofly You're quite welcome, Mr. O, and thanks for the very kind appraisal :)

[@chrisbarnes4222]

Looking great can't wait to see the next one

[@UncleDoug]

+Chris Barnes Thanks, Chris :)

[@Slugg-O]

I eagerly await your next video. Although I'm not building the same amp, so much of what you share can by used in other builds that I continue to get more ideas with each new release. Now I need to buy more tools for my 5F2a build.

[@UncleDoug]

+Slugg0matic That was my intention, Randy. I know that the amp I'm making might not appeal to everyone, but the steps I take with it can be applied to any tube amp. Best of luck with your projects.

[@dhpbear2]

I remember that Tektronix REQUIRED use of silver-solder (8:13) in their old tube 'scopes (with the ceramic terminal strips). I few of inches of this solder was actually provided with the unit, wrapped around a spool in the interior of the cabinet!

[@UncleDoug]

An interesting insight, David. Thanks.

[@bdemski]

Hi Uncle Doug! Thank you so much for all your videos. I got hooked on this amp build and have been trying to watch all your other videos. You are a very good teacher and I appreciate you sharing your knowledge with all your subscribers. I was wondering if you could do a video showing some of the techniques and tools you use for soldering the components and wires. This video touches on some of the issues but I would like to see what you recommend as far as a soldering iron, and how you go about attaching the components. I've never seen solder paste before so I'd like to see how you use it. Thanks again for all your great videos that are entertaining and educational at the same time. I love Jack and Rusty, too! Please give them some extra treats from me!

[@joedonlan2979]

Thanks again for putting out these videos Uncle Doug. I may not be quite ready to build one from scratch yet but each one of your videos and referencing Dave Hunter's "The Guitar Amp Handbook" really has been a great learning experience. Keep those videos coming!

[@UncleDoug]

You're welcome, Joe. Glad you enjoy the videos :)

[@joramkalfa4038]

Wow, that was quick. Thanks for that very prompt reply. That’s my mistake. The Champ has only one output tube. But I understand what you’re getting at. I’d probably have to use a more robust speaker as well. Maybe not worth the trouble or I could actually learn something. Anyway, thanks for the info and try and get Rusty to do a little more work around the house. Joe

[@UncleDoug]

You're welcome, Joram. Good luck.

[@lpspecial1985]

I gutted the chassis of sears 40XL solid state, and built a corsica circuit in it which looks to be the same. the cabinet held a 12" spkr which was nice.This is a classic circuit that has great harmonics. If anyone was to build a amp, this is the one to build.

[@UncleDoug]

I'm not familiar with a corsica circuit, Craig, but if it's like the Supro T-V, then it must be a good one to build.

[@mixolydian2010]

Thanks a lot Doug Everything is looking very neat now and its going to look great and sound great too i cant wait. All the best to you all. Colin

[@UncleDoug]

+mixolydian2010 You're welcome, Colin. Boy, I hope you're right :) Our best to you too......

[@sa230e]

Hi, Uncle Doug. I'm looking at the Oct 15 schematic you linked in the description and I'd strongly recommend adding the 1MEG and 2.2MEG series resistors back to the tremolo circuit. Those resistors and the 250k pot form a voltage divider that reduces the sine wave from the oscillator to a suitable level (about 7% of the original voltage). Without the top half of that divider the full voltage signal (probably in the ball park of 200v p-p) appears at the grid of the cathode follower making for a very overpowering tremolo! It would probably also drive the cathode follower hard into grid current limiting, clipping and distorting the tremolo signal. Also, without those resistors the 250k pot will be a heavy load for a 12AX7 in common cathode when you turn it way down, which might drag down the gain of the circuit enough to cause the oscillations to stop. Also, I'd recommend having the footswitch ground the input of the cathode follower so it doesn't effect the feedback path of the oscillator because, in the current position, when you close the switch (grounding the feedback) and open it again it might take a second for the oscillator to ring up again. Alternatively you can keep the footswitch there and connect the adjacent 1MEG resistor to the cathode of the 12AX7 which will shock the circuit back into oscillation when the switch is opened. www.valvewizard.co.uk/trem1.html

[@UncleDoug]

+sa230e Thanks for these excellent suggestions, SA. I understand your points and your conclusions. One of the best features of YT is interaction with knowledgeable viewers who often provide valuable insights, much like peer review of scientific journal articles. I was emulating the trem circuit in the Fender Vibro-Champ, in which the plate of the oscillator tube feeds directly into the grid of the cathode follower, without any series resistance. I am tempted to install a variable resistor in place of the 1M and 2.2M resistors, dial in an optimum signal input, then replace it with a fixed resistor. I will amend the linked schematic to reflect the footswitch relocation, and will eventually post the optimum resistance (experimentally determined) between the plate and cathode follower grid. Thanks again for your helpful input and lucid explanation.

[@sa230e]

+Uncle Doug I see. It's your amp and you can do what you please but if this amplifier's tremolo is a nice as you say I'd be trying to preserve the originality of the circuit as much as possible.

[@UncleDoug]

I experimented today and found that, as you recommended, 3Meg of resistance was necessary to prevent over-driving V4b. Thanks again for your very helpful input.

[@ElPasoTubeAmps]

That is a beauty, Doug. I really admire that you can work with steel chassis also. I seem to always cut myself with working with steel.

[@UncleDoug]

Thanks, David. I managed to turn my youthful indiscretions with a hammer into something far more creative.....but every bit as noisy :)

[@GuteisFinger]

Watching this work progress with your clear explanations and steady hand was so enjoyable I've watched it twice already. Thank you. I do think Fellini would have had Jack and the birds in the same scene, but this is just a minor quibble. Wonderful work.

[@AdmiralQuality]

+Carl M Varady Perhaps, but Fellini would have had them bark and chirp nonsense only to dub it in later, as he hadn't completed the script yet.

[@UncleDoug]

+Carl M Varady Greetings, Carl, and thanks so much for your very kind appraisal. I shudder to think how David Lynch would have directed the scene......the birds would probably be eating the cat :(

[@UncleDoug]

+Admiral Quality From what little I understand about old FF.....that would have been par for the course. Then they would all have gone skinny dipping in a public fountain.

[@AdmiralQuality]

+Uncle Doug For sure! (I'm still recovering from 4 years of film school almost a quarter century ago. Where, oddly, I taught myself image processing programming on computers after I had transferred out of electrical engineering to go there. Go figure...)

[@jeffwinick8859]

Hey Uncle Doug, Thank you so much for these videos! They are so informative and really enjoyable to watch. I've learned a lot from you and you really do inspire me to try my hand at amp building. Please keep up the great work!

[@UncleDoug]

+Jeff Winick You're quite welcome, Jeff. Rusty and I are glad the videos are helpful. Thanks for watching :)

[@5barkerstreet]

nice work I've learned a lot from you. thanks for your video's and your time!!!

[@UncleDoug]

+paul c You're welcome, Paul. Glad you enjoy the videos :)

[@Relicsun]

Can't wait to hear your beautiful amp Uncle Doug , I'm sure it'll sound fantastic! Take care.

[@UncleDoug]

+relicsun Boy, do I hope you're right, RS. Thanks so much for the good wishes :)

[@Ratchet2]

Great video series. Has anyone ever told you that you sound like Dr. Ronald Nash? Awesome.

[@UncleDoug]

Thanks, TS. No, you're the first to do so.

[@kevinking2468]

Thanks for the excellent instruction, this video was so so helpful - You're the best Uncle Doug!

[@UncleDoug]

+Kevin King Thanks so much, Kevin. Rusty and I really appreciate your kind comments :)

[@SiliconSet]

Very impressive work Doug!!! Many thanks for sharing the making of such a great amplifier Always enhanced by cameos from Jack and Rusty.

[@UncleDoug]

You're welcome, SS :)

[@PeterWalkerHP16c]

LOL Love the art-deco 𝕋𝕣𝕖𝕞𝕠-𝕍𝕖𝕣𝕓

[@utahprepper8925]

I've done this a bunch of times. After watching your videos I learn new cool things to make better amps. For instance, I never even dreamed of using pop rivets to hold in my tag strips. Speaking of which, I've always done point-to-point literally - from one component to the other, using tag strips only for the power supply filters and the grounding (where I don't use a ground bus). Now, I'm going to start using the tag strips more. They make for a much neater circuit. My amps sound good and are very quiet, but look like a rat's nest with all the components stretched all over the place in the chassis. This video changed all that. Thanks for that! I still don't think I'm ready to hand-forge my own chassis though! :-) Nice work there too!

[@UncleDoug]

You're welcome, Dave. I prefer the terminal strips because they securely anchor all the components and prevent them from moving around while the amp is transported.....and they look very neat. Rusty and I are glad the videos are helpful and informative :)

[@skycarl]

Man that's looking good. Thanks again UD.......Carl

[@UncleDoug]

+skycarl You're welcome, Carl, and thanks :)

[@yrulooknatme]

Your work is wonderful. I hope I get the chance to build one. Thanks for sharing your knowledge.

[@UncleDoug]

+yrulooknatme Thanks so much, YRU. I think you'll get a kick out of Part 8. Best of luck if you do choose to build one :)

[@chanchopancho]

Hi Uncle Doug! I wanted to thank you for the videos, they are fun and very helpful. I followed your intructions on the video you posted about the tolex, and ended up with a great looking cabinet. I'm enjoying this video series and looking forward for the next part (parts?). Regards to rusty and keep up with the contract :D

[@UncleDoug]

+chanchopancho You're welcome, CP, and thanks for the kind words. It's great to hear that your Tolexing project went well. Rusty says "arf".....which means "Thanks for remembering me" :)

[@fredimachadonet]

Awesome series Uncle Doug! It's very informative and easy to follow.

[@UncleDoug]

+Fredi Machado Thanks so much, Fredi. We're really glad you enjoy our videos :)

[@farmerwayne1404]

Uncle Doug: Birds let go to work! Birds: You said line up at feeding bowl, right?

[@UncleDoug]

I guess......it's been a long time, Wayne.

[@farmerwayne1404]

@@UncleDoug ohhhh! Sorry...

[@sketchstuffs]

I was following everything well up until this video lol. I don't know why but circuitry just eludes my understanding. I'll get it though. Awesome series!!

[@UncleDoug]

Thanks, David. Stick with it and circuitry will become increasingly understandable. It's like a new language that takes a while to master.

[@tiki_trash]

Lookin' good Uncle Doug! The maximum value of the first filter cap after a rectifier is not set in stone. It depends on the impedance of the power transformer. The values given on data sheets are just examples of typical operating conditions. If you look they will usually list a value of the plate supply impedance for that particular example. Measure the secondary's resistance and use the chart on the 5Y3 datasheet to determine if the capacitance is within a safe range. Not all datasheets have this chart, you need to look around on the net to find one. (an RCA tube manual probably has it somewhere) If the secondary's resistance is very low and the capacitance is very high, resistors can be placed in series between the secondary and the plates of the 5Y3. You can actually run quite high capacitance on the first filter cap this way. Of course, this series resistance leads to increased sag which will counteract the high capacitance. Usually the higher the current capability of the transformer the lower it's impedance will be. With the transformer you have chosen and the fact that class A amps have a relatively constant current draw, 40uF is probably just fine. Look at the data sheet for your transformer It may list it's secondary resistance or impedance then look at the MINIMUM plate supply impedance on the data sheet. Since resistance is usually the more reactive element of a given impedance you should be safe to go by that value. Hope that makes some sort of sense and I haven't just rambled on too much. I'm just a hobbyist so better to look this stuff up than go strictly by my word. I think Merlin Blencowe at The Valve Wizard site has something on this if I remember correctly.

[@UncleDoug]

+tiki torch I looked through quite a few schematics, TT, and couldn't find a single one that had more than 20uf as the first cap after a 5Y3. I believe what you are telling me, but still feel better splitting up the 1K into two 500's. I guess I'm just old fashioned, but I tend to take the conservative approach......especially when it's rather easy and can cause no inadvertent harm. Thanks for your detailed and informative input.

[@tiki_trash]

+Uncle Doug I hope you didn't think I was trying to say you were doing it wrong or anything. I was just trying to point out the relationship between rectifiers, transformer impedance and capacitance. But, like I said, this stuff is just a hobby for me. I'm not an expert and have no "formal" schooling in this. I would have done it just the same as you did anyway. Or I might have fed the OT from the second node...whatever. Your amp is looking great and I'm watching this series with great interest. Vintage Valco amps rock!

[@UncleDoug]

Thanks, TT. I truly appreciate any informative input, and yours definitely was. I will keep it in mind for future study. I'm glad you agree with my solution to the problem. Another viewer asked if the second 20uf cap might not have been the typo. I tend to think that even if it were, having an extra low pass filter in the power supply can't help but make the DC a little more ripple-free. Again, your input is always welcome and appreciated.

[@RafaelSampaio1]

I can't wait to hear it! Although I wish you took a little time with the lettering, I have no idea how to do something like that. In any case, this series is awesome Doug, thanks for all the knowledge you're sharing.

[@krang07]

+Rafael Sampaio Making the lettering would be fairly easy with a printer and some specialized paper like a transparent front and sticky backing thing. What I think would be awesome for the lettering would be to use a CNC machine that would physically etch the lettering onto the metal itself and you`d never have to worry about losing the lettering to the elements. But, ya, once a good clear coat is sprayed over the sticker-type lettering it should hold up fine.

[@UncleDoug]

+Rafael Sampaio You're welcome, Rafael. The letters are the rub-on type they sell at art supply stores. They are available in hundreds of sizes and fonts. It takes a little practice, but they can produce some very nice results.

[@UncleDoug]

+Krang Gangs That's exactly how the logo and amp name were done, KG. I made a video about it a while back. The rub-ons are covered with several coats of acrylic spray. I agree that laser etching or something of the sort would be fabulous.

[@aleksej79novosibirsk]

Wow, this looks nice! :) The right stuff for spending time at home...

[@UncleDoug]

Thanks, Alek. Yes it is :)

[@mechmusicman]

Uncle Doug, I see everyone is putting their two cents here. I hope you don't mind me tossing mine in. I'd really like to see some big blobs of solder on the chassis, in this case perhaps silver solder or tix, or what ever will adhere to bare sheet metal. 30 years from now, when all the corrosion between your terminal strips and ground tabs forms, this amp will still work just fine. I worked on antique radars for 20 years and those rivets get loose from the stuff that forms under them and between the layers of metal. I've seen some crazy stuff happen. I admit, these monsters were on ships and exposed to salt spray.

[@UncleDoug]

+mechmusicman Thanks for the input, MM. I live in the desert, so corrosion is not a big issue, but I understand what you are saying.

[@mechmusicman]

What I found mostly wasn't corrosion but electrolysis due to dissimilar metals riveted together. Especially aluminum. Even tinned against steel.

[@UncleDoug]

I understand, MM. The terminal strips, ground lugs, and chassis are all steel, so electrolysis shouldn't be a major issue, since the metals in direct contact (and involved in ground connections) are all the same.

[@ThomasHafemann]

Nice serie of videos Uncle Doug! I copied the supro 1660t/Gretsch 6150t and your videos with voltage reading were very useful! I tried to make the faceplate as similar as possible. I used thermal transfer on bare aluminum chassis (toner print using glossy paper and flatiron) and clearcoat.

[@UncleDoug]

+Thomas Hafemann Thanks, Thomas. We're glad the videos were helpful. How did that thermal transfer process turn out? From how I visualize your description of it, I would think the lettering would come out backwards.

[@ThomasHafemann]

+Uncle Doug I mirrored everything before printing. The thermal transfer took me almost an hour, as the chassis was big enough to dissipate the heat. There were some small flaws that I managed to correct with a pen. After the clear coat everything looked better. s1303.photobucket.com/user/Thomas_Eduardt_Hafemann/media/DSC_0927_zpszkdf5xnl.jpg.html

[@UncleDoug]

Beautiful work, Thomas. The black lines are a nice design touch, making it look professional rather than homemade.

[@nusior]

Oh Yeah, part 7: post-breakfast treat for me!

[@UncleDoug]

+nusior Be sure not to choke on your Wheaties, Nusior :)

[@nusior]

+Uncle Doug I'm ok. My buddy "Rambo" aka "Jack's twin from the other hemisphere" takes care of me :) drive.google.com/file/d/0B16LIiIaNEylZVl0bDlMMlVOU1J3ZGRVSUNCTTdEOVVCdklF/view?usp=sharing

[@UncleDoug]

Wow, there is a definite resemblance. A viewer informed us that Jack is a recognized breed of cat called a Bombay Black.....specially bred to resemble a miniature panther, which he does. I guess Rambo is one too :)

[@nusior]

+Uncle Doug I guess he is. Hence the very "combat" name :)

[@georgekrabs6948]

Su-perb work unc.Just a couple of tips, I know it's a bit late but I'm a recent subscriber, the grid stopper should be wired directly onto the 12AX7 grid lug. I also was using rub on letters nearly 30 years ago but it's much easier to use printable adhesive clear and use 2nd piece over print to protect it.Some water with a drop of detergent is used to easily slide it in place.I know why we never see you loading the components and soldering.....because Rusty is the genius behind it all.Sorry the truth hurts.

[@UncleDoug]

Greetings, George, and thanks for the input. You're right about Rusty.....he's "the man".

[@TheStuffMade]

Beautiful build, thanks for sharing.

[@UncleDoug]

+TheStuffMade You're welcome, TSM. Glad you like it :)

[@pablitoron938]

amazing video!

[@UncleDoug]

+Pablito Ron Thanks, Ron :)

[@davethompson2881]

Hi again Uncle Doug. As usual you've produced an excellent video to keep us entertained and educated. I'm pleased to see you added the rider about safety and good building practices as it really can't be stressed enough that bad wiring habits can make even the best-thought-out amp sound terrible, and those same bad habits can result in a bad shock, or even worse if we aren't ever-vigilant and treat these amps with deep respect. One thing I'd like to ask you about is your opinion about the methods of connecting flying leads of components to terminal strips. I've been critised in the past for looping capacitor and resistor leads through terminals before soldering (as you appear to do) because of the fact they are much harder to remove in case of component replacement. My feeling is that while it does create a bit of extra work if they do need replacing, it is better to have a physically sound joint over any ease-of-removal concerns. As you point out, solder is not there to add physical strength to a joint; of course, the very nature of how it electrically binds the component lead means solder does add some strength but this is secondary to the aim of soldering for electrical soundness. While it may seem obvious that using one of the softest metals for its strength is not very feasible, in my experience as an avionics engineer and serviceman, many people rely on solder to hold things together, making for some interesting outcomes. I'm looking forward to part 8 and hearing how this beauty sounds; hopefully your predictions about burning the house down don't come to pass! Regards, Dave T.

[@UncleDoug]

+D-tone Amps and Guitars Greetings, Dave. I agree with your opinion that leads should be looped and compressed against terminals prior to soldering. Yes, it's harder to undo the solder joint, but the attitude that solder joints should be compromised to facilitate disassembly makes as much sense as leaving the lug nuts loose on your car wheels to facilitate replacing a flat tire. Perhaps if solder joints were secure, repairs and replacement would not be required as often......or at all.

[@irusman62]

I only use the non leaded for plumbing when needed, I use PEX tubing and fittings mostly. I use the led zep solder for electrical 😀

[@UncleDoug]

Thanks for sharing, IM.

[@DeadKoby]

It's interesting to see your style of wiring vs. mine. There's a few good ways, and tons of bad ways. I almost always do my heaters in a daisy chain... I've not seen them done your method. The smell of solder rosin makes for a happy day. My guess for the cathode resistor for the 6L6 would be 300-600 ohms 10 Watts. 500'd be the first I'd try... This is based on looking at the completed work of others.

[@UncleDoug]

+DeadKoby I used to do the daisy chain too, DK, but am trying a different method in this circuit. I always found it difficult to solder two separate wires to each tiny little 12AX7 pin with the dc method. This way there is only one wire per pin to solder and only two AC wires come near the tube base, rather than 4. It may work out great.....or not. We'll see. I'll experiment with the 6L6 bias once I get it powered up, and post my findings. Your guess sounds pretty good to me.

[@snorrevonflake]

cool that you explain some of the wiring, still i cant understand how you can design such a layout in rather a "rats nest" style, there is so much to consider and so many things can be done wrong even in a conventional way using eyelet boards, grounding, placing of components to avoid hum or interferences especially with that more complex amp with tremolo and reverb - really awesome this one. wish i could do that.

[@UncleDoug]

Rusty and I only build in point-to-point ("rats nest") style, SF. It may look confusing, but in reality it's not, since you are following a schematic and building the circuit stage by stage.

[@cmguitar50]

Great work! Ordering and reordering - like the mounting screws I don't have? lol

[@UncleDoug]

Reordering is always step 2.....and inevitable.

[@moodyga40]

love the gold paint i too use gold

[@UncleDoug]

+ian “valve doctor” forster Glad you like it, Ian :)

[@DANGUmustDIE]

You could have added another mod using that extra tap of the output transformer to make the tube work in UltraLinear configuration. Just to hear the tonal difference though. Implementing via switch or relay adds a bit more complexity to the circuit, because u need to swap B+ wireing and secondary windings too to reflect rougly the correct impedence on the primay. Just my thought, and great video by the way

[@UncleDoug]

Thanks for the suggestion, Dang. Glad you enjoyed the series.

[@randyboen6016]

Simply outstanding! I built my first tube amplifier back in 1960, based on the Olson Electronics amplifier kit. They put out an honest 12 watts RMS and sold for $19.95. all parts included. The tube line-up was 2 12AX7's, 2 6V6's and a 5U4 rectifier. Also Baxandall tone controls and even the 60/40 Kester solder was thrown in for free. Now a simple output transformer can cost $100.00 or more. One question, what's up with the sound? Some of the episodes had as much as a 40Db scene to scene difference in volume levels. (As measured with a Simpson 260.) BTW, I'm an old fart, 72 years old as of Jan. 2019. Vinyl sounds better than CD's and tube amplifiers sound way better than solid state. How about a tube amplifier project for High-Fidelity? (Maybe stereo High- Fidelity?) Thank you, Uncle Doug. This series rated ***** 5 stars for me.::::::::::::::::::::::::Milwaukee Randy

[@randyboen6016]

I forgot to mention, the amp that I built had 2 6SL7's, 2 6V6 outputs and an 80 rectifier. Yup, an 80. (Remember the real old 4 pin base tubes? All the parts came out of "Grandpa Schmidt's" parts bin. I still have it and use it along with a Shure M95 phono cartridge wired for mono. The quality of the sound is beyond comparison. Also, you might want to check out PartsExpress.com. Lots of tube stuff there at reasonable prices. And Celestion guitar speakers too.

[@UncleDoug]

Thanks, Randy. They don't make kits like they used to, I guess, especially at that price :) It sounds like a great amp. I'm sorry if the volume levels were not balanced. I was not aware of the problem......you're the first person to comment on it. I do remember the 80 rectifiers as well as the 5Z3's. Thanks for your nice comments and suggestions.

[@charris939]

Hi Uncle Doug, My wife recently had a dream about an Aunty Doug website in which the lady travelled around in a caravan and made videos of crafting:)

[@UncleDoug]

+charris939 By (great) coincidence, Colin, my wife is an artist and deeply involved in crafting. Her paintings have won several awards and I really wish she would start a website or YT channel to share her talents with the world. But meanwhile, she's stuck putting up with me, Rusty, and Jack. Poor lady :))

[@tubical71]

Wow....just Wow....:) :) :) You may do a special part regarding to safety...i usually get a little bit overconcerned regarding my DIY-HighVoltage Suff...i put some extra insulation on B+ leads and extra clearance to components carrying the B+ to avoid any arcing or may intermitened contacts...whatever..and add some bleeding resistors to the filtercaps....As it´s always better to be/stay save than sorry ;)

[@UncleDoug]

+TubiCal Thanks, TC. I too spend a lot of time arranging wires and contacts to eliminate any chance of arcing or accidental contact. Amps are subject to a lot of vibration, and care must be taken to prevent it from causing circuit mayhem :)

[@alvagoldbook2]

Very nice construction so far! One problem I ran into on my latest build is that I used a fairly tall turret board, and many of the resistors I ordered from Mouser just didn't have leads that were long enough to reach from turret to turret. It seems as time goes on, components makers are getting skimpy on their leads!

[@UncleDoug]

+Alva Goldbook Thanks, Alva. I guess if they can save .00001 cent on each resistor, it will add up over time.....much like McDonald's shorting each customer one french fry :))

[@alvagoldbook2]

+Uncle Doug I had a heck of time with this! I even ordered resistors with long enough leads based on their data sheet, and some of them were still too short. So frustrating!

[@UncleDoug]

I ordered a Fender-style footswitch a year ago and it arrived with the usual RCA plugs, but the contact pins in the center of the plugs were less than a half-inch long (overall).....they barely protruded beyond the outer shields and couldn't reach the contact in the jacks.

[@freakflagjo]

awesome as usual!!!

[@jozzef1990]

Greetings +Uncle Doug The amp looks fantastic, what a beautiful cabinet. Have you ever considered building a British style Marshall/Vox amplifier. I think it would make for an interesting project!

[@UncleDoug]

+jozzef1990 Thanks, Joz. I am definitely considering a British-style circuit for a future build. It won't be right away, but in a few months. Thanks for your input.