6BQ5 Amp Kit Part 3 - Mods & Test

[@1959Berre]

Tony, you are absolutely right. Do not give in, do not make your video's shorter. After a rough day in the field, I like to relax and hear you elaborate in every possible direction. Those who don't like it have the unlimited freedom to stop watching.

[@bugdrvr]

I can't believe there are people out there who complain that your videos are too long. Seriously? He's taking a pile of his time to produce excellent content that he releases for free. If you want electronic repair vines then start your own videos.

[@solidstate90]

i second that, this is my fav KZbin channel the longer the better, I wish people would stop complaining about other peoples content , if it upsets you that much make your own damn content

[@ianmedium]

I third that, the longer the better as far as I am concerned. I’m a detail freak and love all of the minutiae that is covered. I forget sometimes we live in a sound bite instant gratification world where detail and depth of knowledge is less important than an immediate fix without care as to how one gets to that fix. It’s the problem solving that I love in anything, even more than the end result sometimes. Yesterday I spent an hour getting a Raymond Weil quartz Chronograph hands to line up. I found out it was not like a normal quartz Chronograph for hand setting as instead of pulling the crown out then pushing the chrono pushers this has a sunken button one has to press in a particular order. It’s an old watch, no manuals so I just spent an hour going through all the permutations till I figured it out. Now I have learned something new, a bit esoteric and it gave me great satisfaction in getting my friends watch to work properly. This channel reminds me of that mentality and the world would be a better place if folks could learn this so to those who moan amount length think about the content you have and the potential for you to learn new things!

[@jonka1]

Life is a journey not a destination. Keep it up Tony.

[@williammcmanus7522]

Bought this kit on the bay some time back and assembled using the information in these excellent videos. Mine is the updated kit with no loudness switch and probably the better for it. No hiss and no hum. I have replaced all the original Chinese power tubes over time when they started popping with Russian ex military tubes. Seem fine with no audible difference to my ears. Also recently replaced the 6N1 tubes with mullard ecc85 and this has made a very big improvement to the sound quality. Haven't needed to make any component or connection changes so far.

[@Waltkat]

You do what you do and ignore the short attention span haters. I for one enjoy hearing what you have to say and possibly learning something new. I am an electronics tech by trade and have been working on both solid state and vacuum tube electronics since the sixties but like the old saying goes, I don't know everything and like picking up new ideas and knowledge. Thanks.

[@johnreel8944]

Tony... you conversational style of talking is as a group of like minded friends and the length is not of concern. it is the company and the learning of new ideas/views and human nature of groups.

[@derkmolenkamp9173]

Again, very nice video's! They are absolutely not too long. Thank you very much Tony.

[@bulwinkle]

Thanks for all of your video output. They are all he perfect length, fitting exactly between the intro and the outro. 😀

[@williamsquires3070]

The 1 Megohm resistor and the 680 pF cap form a 1st-order high-pass filter. If you (mentally) short the cap and remove the resistor, you’re left with a 1st-order low-pass filter consisting of the 15 kilohm resistor and the .1 uF cap (and a 3 kilohm resistor). Together, they make a 2nd-order bandpass filter. If it weren’t for the high-end of the volume pot, then no DC could get through due to the 680 pF cap, so the response is attenuated at low frequencies. At high frequencies, the 3 kilohm resistor and .1 uF cap shunt those to ground, so the high end is attenuated; overall, this leaves a pass-band of frequencies that get through when the volume pot is “below” the tap. I applaud you for redrawing the schematic to make it easier to understand; it was kind of a mess as originally drawn, with the switches and everything! 😎

[@gregorysands2388]

You speak of your video length. I for one appreciate your detailed presentation and if it takes 2 hours it is OK in my opinion. I simply pause at a convenient spot for me and continue when I can. I would appreciate a video on an el84 push pull design from start to finish. I am very interested in constructing one.

[@jked7463]

I have to say, you are great at explaining electronics, better than most anybody i have ever heard. Thx.

[@leohobbleohobb3781]

keep videos long.All useful content.They are great..

[@erikjohansson1814]

Why would anybody complain? These videos are perfect. Good content, nice length and good quality.

[@lelandclayton5462]

Today's generation has a low attention span. If it isn't some one playing a video game spouting off random crap for eight minutes then they complain. That is at least what I have seen from my kids and heard from friends with their kids.

[@erikjohansson1814]

Leland Clayton Correct, those are called millennials and known to be the dumbest generation to date and a lost generation.

[@jonka1]

@@lelandclayton5462 I agree and I am concerned how the world will be when these attention span deficient generations are adults and our pre digital lot are gone.

[@carlfudger4528]

Just keep doing what you are doing Tony. You are providing an invaluable service to many willing to receive the gift. Our world is lacking people with respect for others and some have to put their worthless 2 cents into everything. Thank you for the knowledge youv'e shared! GOD Bless!

[@Chrissy4605]

I really appreciate your statement on your content and those who watch your hobby because they find you interesting!!!

[@dogbucket]

Just another vote FOR the longer videos. Pretty tempting to buy one of those kits; I haven't messed about with tubes since I was a kid. Thanks for all the videos.

[@dantx4545]

Thank you for the time that you take to make these videos for us I appreciate what you do make them as long as you wish it's your show!

[@kendavis8046]

I just found your channel the other day. The length of them is NOT an issue for me. I'll probably never build a tube amp, but as a recovering guitar player (kidding!) I have always loved the sound of tube amps and enjoy several channels dealing specifically with those (Uncle Doug, Guitologist, D-Lab.) Anyway, thanks for your content, and thumbs up for all I have seen so far.

[@papageorgiola]

Half the stuff you talk about i just nod and say yup, or ah I see. Makes me look smart in front of wife. But honestly I’m learning lots. Thx for real quality videos.

[@nunovieira905]

Love your videos and great explanation of your work. No way they are too long. They're always very educational and interesting. Greetings from Portugal

[@alancordwell9759]

Hi Tony, I like the longer videos and really appreciate the work that you must put in to make and edit them. As an old tube amp fan I also appreciate the level of detail that you cover regarding the design and components. My initial gut feeling watching part 1 was why on earth didn't they just use a 12AX7 like anybody else, and surely an ECC85 belongs in the front end of an FM receiver! But I accept all of the points you make in this excellent video particularly that the 6N1 doesn't have an exact equivalent and should be judged on it's own merit. Hey, times change!! Anyway, best wishes from the UK and stay safe :)

[@ptronix]

Your videos are great as they are, the longer the better for me, far better than what's on tv!

[@tongordebeke1355]

People have to complain. Please make more of this long and in depth video,s. I enjoy them and learn from it. Ton (The Nederlands)

[@mfr58]

Hi Tony, thanks for your vids. Keep making them as you like. Ignore the nay sayers. The log pot has a similar contour to the human ear's sensitivity to loudness, that's why they use them for volume controls. Thanks for the explanation about the grid stopper volume control issues. I learned something important there.

[@kane100574]

Love your videos man! You do a great job and I enjoy the in depth long vids...

[@lelandclayton5462]

Tony, your videos have helped me quite a bit. I work for a Security/Audio/Visual company, a lot of times I have to troubleshoot an Audio Amplifier at a site and your tips have helped me greatly.

[@AaronProctor-ed3jl]

Many thanks for these 3 very enjoyable videos. They contain essential information for building the kit I now fully intend to buy. I notice the kit is now available without the loudness function!

[@69mercurycyclone44]

Tony a great video! Ignor the winers. You've forgotten more than they will ever know!

[@exogarwinoputt4257]

Tony; Thanks. Very much appreciate the update on this kit.

[@noelj62]

The experience and the information your present in your videos is quite valuable, thanks. For people who find your videos long, use the speed control in the KZbin player. 125% faster works for me.

[@jutukka]

Very enjoyable set of videos indeed. Some comments: I cannot see any problem with grounding the grid of a cathode resistor biased triode stage with a potentiometer wiper. The grid virtually is at ground potential whether the grid leak resistor is 50k or 500k and if the tube is not gassy, in which case it tries to develop positive voltage across the grid resistor especially if the resistor value is too large. And normally there is a maximum allowed grid resistor value for every tube type if cathode biased. If it was grid leak biased (and in that situation cathode is normally directly grounded without any cathode resistor), then it (shorting grid to ground) really is a problem and that's why a grid leak biased stage needs a blocking cap. What comes to led pinout and long and short legs of it, I have been messing around with leds from late 70's and the polarity has never ever been a problem because if you can see inside it, as you normally can, the structure inside the led is still the same; the wider, often clearly a bit bowl shaped electrode is cathode. What comes to "happiness" of a cathode biased two tube output stage with a common cathode resistor, I do not find it happy at all. Because two tubes which are not perfectly matched can quite well work as a pair if they have cathode resistors of their own, so not sharing the same cathode resistors. But if they are put to use same cathode resistor, they are forced by laws of electronics to set themselves in unbalance (however, a pretty stable unbalance still) if they are not a matched pair. And if a pair is matched now, it probably won't be after 6 months. Normally this won't be a fatal problem but however, if for some understandable reason those tubes are intentionally biased to run very hot, the quite small unbalance can after some time period be fatal to the tube that runs hotter of that pair. In addition, unbalance causes unwanted dc current to the primary of PP OT and does not make sound quality any better either unless you don't mind, or even particularly like to hear unbalanced, i.e. distorted output signal. (Well, some people like, I have heard, or do not care.)

[@charlescartwright6367]

If I am having to pay for the privilege of watching your videos then maybe I can complain!!!! I personally enjoy them as is, remember this is YOUR channel not ours, I say this because there is a positive side to your viewers as well as the negative side, some folks feel they need to criticize what ever they are involved in. Thank you for your time and efforts in providing this information to us. I know it would be faster and easier to do it without including us. Keep up the good work and Mahalo for your time and efforts.

[@bucketlistbeginner]

Great show keep the shows long and full of content. I watch to learn I have enough commercials on tv lol I would enjoy seeing the actual hook up of the test equipment when you do tests. Thanks for a great channel

[@VK2UAL]

I love the length of your videos as I want to learn and understand how and why, so keep up the great subject all your time and effort is greatly appreciated by most of us. Regards Richard vk2ual

[@arcorob]

DONT EVER BE SORRY FOR HOW LONG THE VIDEO IS !!!!

[@kadosas]

Keep up the good work. The longer the better!

[@cainzach1]

Impressed with your videos very comprehensive, I like your approach to kit Design. Do like your explanations and knowledge of tube amplifiers.

[@stephenbobby6715]

I like longer videos. I think maybe you should include a time stamped index in the description if they are an hour long. This was a great series.

[@mikeburch2998]

You did a really nice clean job building that kit. It looks great. Thanks for the upload and greetings from Arizona.

[@JohnMartin-vc5dj]

You are the best for this greenie .look in Toronto for a senior class to learn soldering and tube Amplifier My amps are Scott 99B Mono blocks and Casta c speaker. Love watching your diagram work. Love tubes for 60 years

[@pa5ca]

Tony, thank you so much for these excellent video's. I have build just de preamp and phase splitter and used ECC83 tubes, I can tell you this brings a whole lot of dynamic in to the Amp. The bare tone response in comparison to the ECC85 / ECC88 is IMHO mutch better with the ECC83. The annoying thing, you have to change the way ff is applied to the tubes. pin 4 an d 5 need to be shorten en the ff is applied to both pin 4 and 5 and pin 9. I'm not sure if pin 9 on the circuitboard is connected to the ground, in that case you have a challenge. (I have build it in a point to point way) My output stage I converted to the Ultra linear option, the output transformers have this option so I used it. I have measured the linearity and output clipping, linearity is excellent and the output goes up to 13...14V before clipping. The EL84 fixed resistor is still the 150E 5W version. Going from 20Hz low distortion up to 35kHz practically no distortion. These chinees transformers are good quality ones. I'm using a 500K Log potentiometer, need to remover the 470K and replace with the 10M and adding the 360E grid stopper resistors. But as it is like now, the amp has a very high volume output and starts to clip at 13...14V RMS Anyway I have gained a great bunch of very useful information. Tony, thanks a lot.

[@xraytonyb]

Thanks for the comment! There is a lot you can do with these kits. I didn't go too far with this one as I just wanted to see how it worked as is. There were a few things the I felt were necessary, however, such as the loudness circuit and lack of grid stoppers. I went a bit further on the JABOP amp project. I was happy with how both projects turned out.

[@moodyga40]

Love your videos as a technician I still like to watch theses videos. Great video

[@harrothepilot]

Thankyou for posting this series. It was fun to watch and inspiring also. Makes a person think seriously about tackling this project. I have built a little 6L6GC SE Elekit amp, and put a couple of thousand hours on it. Also have an old Silsonic EL34 PP amp, and a genuine Line Magnetic PP KT88 amp. Would be nice to build a PP amp from a kit.

[@cameronkrause4712]

your videos are not too long-very good work.

[@dhpbear2]

I would re-purpose the V1, V4 sockets as preamp stages between the input and the control board. It'd give you more gain and isolate the volume pot from the input.

[@chrisboylan4599]

I like the pace that u went thru this series and I have saved them for reference, cause I too like to modify circuits to try to get better sound. Thx much Tony!

[@jheyar10]

nice series of video. thumbs up to this project.

[@peterarsenault2671]

Excellent video. l think l may buy the same kit. Thanks for your time and effort.

[@michaelwolak3098]

Have really enjoyed your videos of the whole build Mike (England)

[@williamsquires3070]

Another way to think of the tap on the volume control is like a switch: when your input (shaft position) is above the tap, the high end is your direct-feed input signal, and the low end is the attenuated signal, but when you turn the pot (shaft position) below the tap, now the top end (of the voltage divider) is the attenuated signal, and the low end is ground. So, it’s almost like having two pots and a selector switch (per channel), but without the added complexity or cost! HTH! 😎

[@telosfd]

I really like what you do. But I would love to see how soldering the components to PCB , the mounting of the vaccum tube bases, their power supply, and generally the amplifier assembly. Thanks a lot.

[@JelckedeBoer]

Love the detailed videos.

[@epos79]

Good stuff buddy, nice series, gonna build one myself as well, thanks appreciated for the extensive comments and tips

[@Scott-K7sce]

tube amps are king, modern transistor just can't compare.. This amp sounds great !

[@jansen2810]

Please go on and do the videos the way you always do. Don't get distracted by other people!

[@lupus7194]

On Ali Express, the kit is currently $291 or you can get it fully assembled for $317. For most of us, there doesn't seem much point is doing the assembly. Douk seem to have a lot of good stuff but without any reviews for most items, who knows what is any good.

[@SuperFredAZ]

You should add a time delay to the B+ supply, so the tubes can come up to proper voltage around the same time as the filaments.

[@brucewinterstine9582]

I want to buy one of these kits after watching ALL 3 of your videos and reading through the comments. Thank you for taking the time to be thorough ... a rare quality today. ONE QUESTION: is it possible to add a headphone output so the amp can also be used to power a high impedance headphone? Maybe repurpose the loudness switch to disconnect the speaker grounds and at the same time connect in a pair 20w resistors to between the 8 ohm + and ground? Connect left and right 8ohm + to stereo headphone socket using a pair of 100 ohm resistors?

[@chrisdado]

Do what you enjoy for as long as you like Tony. Don't get hung up on catering to other people, it'll make it like work, and we'll get less vids. :)

[@HammyTechnoid]

This amp is quite intriguing. I'm hoping it has real good performance.

[@russellhltn1396]

I think the 10Mohm resistor was to help the caps find their DC equilibrium so you don't get a loud pop when switching the loudness control on.

[@jked7463]

As paul klipsch used to say, all he needed was a high quality 5 watt amp for his corner horns

[@walt3223]

First, in the circuit shown the bias for the tubes is set by the current flow through the cathode resistors, and that will make the cathode more negative then the control so if the cathode is placed to ground level, so what. Two, there is a way to change a linear pot to an audio tapper pot by placing a larger (10X) resistor across the output and ground posts of the linear pot. 50K in parallel with 500,K should do the trick.

[@christopherredfern6472]

Hi - so much thanks for the 3 superb videos - I have 1 question though , I would actually like to keep the loudness circuit in place - but before I start my build what volume pot would you think I can use for a simple direct replacement ? as like you I do not like stepped pots much thanks in advance Chris

[@jimdawes7261]

Long video or short I enjoy them all. If it's long I watch in parts or skip ahead like you said. So Tony what is the input voltage with the pre-amp? Or was the 1 volt already with the pre-amp?

[@xraytonyb]

The test was with 1Vrms directly into the amp. The demo songs at the end were with an Adcom GTP-500 preamp driving the amplifier. I was using an MP3 player as a source.

[@dhpbear2]

27:38 - I guess they changed the standard for poteniometers when I wasn't looking :)

[@robertcalkjr.8325]

Nice lesson, thanks!

[@russellhltn1396]

To deal with long videos, I speed them up. I recommend Video Speed Controller (a free Chrome add-on). You can set the speed in 0.1x steps. I zipped though this video in about half an hour.

[@taichisifu734]

Great video - learn a lot from you .....

[@guntagrant7405]

Taichi SiFu d

[@rickg8015]

Great vid.. That loudness circuit wouldn’t be needed for the most part with good budget DACs that have healthy outputs these days.. What value grid leak R would you reccomend if a 100k pot or series stepped attenuator is in use in the amp’s input?

[@1835dueber]

the loudness circuit is needed if you have human ears.

[@andymouse]

great work...cheers.

[@tongxu721]

Emmm. In china about 80s we began use FM radios, usually they were made by semiconductor. And because of semiconductor more and more people can buy a radio.So many people call radio “BanDaoTi‘’（The semiconductor）. In 60s 70s 80s our AM radio use 6A2(RF AMP and OSC ) ,6K4 (6BA6,IF AMP),6N2（ECC83,audio amp），6P1 or 6P14(EL84,in this video),6Z4(6X4)and 6E2（in video）. At that time although many factory use semiconductor to make radios, a radio（CHUN LEI 101{means “spring thunder ”101}） made by valve Tube. Although maybe it was very hot and loss more power ,its Audio is very loud. So we have 6N3(GE5670) 6N4（12ax7）....They are very expensive then the other Tube which were Made in China(Now). They were Used in radio of military and Scientific instruments (I guess). 6K4 6A2 ..are very cheap about 2 yuan（0.3 dollar） ,beacause They means “no use”--in audio amplifier.

[@dhpbear2]

34:00 - I thought it was best for those grid stop resistors to be as close to the tube socket as possible. (?)

[@alfredneumann4692]

The human ear hears ascending volume logarithmic. Thats the reason for the log pot.

[@fredflintstone8048]

Regarding xraytonyb's long video's as well as other youtube videos that might seem long. I watch most youtube videos at 2x speed. His voice is very good for this, good enunciation, clarity of speaking. I hope this helps, and I just wanted to add, I like his video work and always learn something from it.

[@bnghjtyu767]

So what would a store-bought amp cost in order to equal this performance?

[@tomdewey9907]

I think the age old "spec" for driving an audio power amp to full power was 0.5V RMS line level out from a pre-amp/etc if memory serves me correctly.

[@sc0or]

Did you still have R2-C2 with Fc about 530Hz on the board in parallel to the volume control potenciometer? 10 MOhms resistors add enormous thermal noise right to a grid. PS Did I hear a double bass on the track #2 or just an elephant? )

[@johnsweda2999]

How would it be if you made it a parallel mono or bridgeable like to see something on this any chance?

[@jamesmdeluca]

Greetings: What is the resistance between the tap and gnd end of the pot out of circuit? Why do resist using the stable input signal as your scope trigger source; your choice makes it hard to focus on your explanation. You do not need to even display the trigger signa that gets in the way as you increase the signal toward clipping.

[@dzee9481]

Tony where did you buy the nice set of surface mounts with that case? Is that something you can buy with all of the values you showed?

[@xraytonyb]

www.aidetek.com

[@wntu4]

Truly, video length problems lie with the watcher, not the author.

[@RobertKohut]

Nice!!

[@ms01rci]

What is the input voltage to properly drive the amplifier? I couldn’t find this spec online...

[@xraytonyb]

I don't recall the specific input level, but it can be driven to full output from the headphone jack of most smartphones.

[@ms01rci]

@@xraytonyb That's perfect. Was asking because I built a tube phono preamp and the output is no more than 500mV. I was planning to restore a vintage tube amplifier but from what I saw for sale they need at least 1V to drive them so that's a no go unless I build one more stage or something...

[@caspianwendell]

Does anyone out there have any information on a FCS1676 transistor? Need to replace one and can’t find anything on it.

[@BobWiersema]

These should work. www.ebay.com/itm/1854-0022-NSC-5961-00-917-0660-NTE128-ECG128-Silicon-NPN-Transistor-Audio-Output/302996055429?hash=item468bf8e585:g:JCkAAOSweX5cEz7i:rk:1:pf:1&frcectupt=true

[@harelshachar7711]

Where do you find these kit amps? are there any for sale? thanks

[@RapperBC]

Here's a timestamped link to the point in his previous video where he lets us know where to find them. Basically, eBay or Ali Express: kzbin.info/www/bejne/nHWbZIKfa8x2i9U

[@moodyga40]

About $600 to get the amplifier here to Australia

[@anekparntong8718]

I'm

[@russellesimonetta3835]

Hey educational videos are long in lenth!!! If your looking for entertainment you don,t need to watch!!

[@geraldovaras7678]

Muy fome y antiguo.

[@johnsenchakinternetnetwork2025]

Long video 333 ads and trackers blocked on this video

[@erikjohansson1814]

John Senchak / Internet & Network Security Disconnect from the Internet, crawl back under the bed sheet and hide.

[@69mercurycyclone44]

Why are you here johnny? Nobody forced you to watch so keep the comments to yourself and go away. We like Tony's videos the way they are.

[@coldfinger459sub0]

Much appreciated gives us the chance to get a decent performing amp at a relatively acceptable price range with minor modifications. Just like my first tube headphone amplifier DarkVoice 336 SE did some modifications turned a $199.headphone amplifier to sound like a $1,000 headphone amplifier.

[@jdmccorful]

Hi Tony, I am a new watcher. Really enjoyed all three videos on this amp. Liked it enough to buy one from Ebay, along with a kit on Phono amp. I was wondering if I could get the same info you got online for build with pics and such. I would be willing to make it worth it for you . Thanx again. JDM.