HiFi Tube Pre-amp: Final Three Shootout!

[@ceylonmooney]

geez, even for a newbie who knows nothing the layout of and build quality of yours is superior. funny it LOOKS so much better.

[@mikeday62]

Glad I watched this. For awhile I was thinking about trying that Nobsound Marantz 7 china-clone...not anymore. Thank you.

[@josejasper]

thank you for the info on the 7 clone, i think you just saved me some $$$

[@XeroBritt]

Very good work here! Thanks for your thoughtful evaluation of these amps.

[@andreas3896]

Nice little pre-amp 👌! In Germany we say "Weniger ist mehr" (less is more).

[@jsg1469]

I own your loser amp and it sounds very good. I updated the 12ax7 to 6sL7 and it really opens the soundstage. I upgraded the rectifier to an American 6x5. Also on pointing out the transformer weighing in at 110 volts. That's a Chinese thing. I've owned several chifi amps and they all have 110 printed on them but seem to hold up well. I own one that is around 8 years old, and barely runs warm

[@allenwalters8812]

Instead of going DC on the heaters could you put it a terminal strip and run twisted wire directly to the heater pins on the tubes bypassing the circuit board?

[@SkunkieDesignsElectronics]

That might be the easy solution to try and just cut the board traces. I think I will try that first.

[@crimsonghost6454]

I would love to see a clone build of the 6SN7 preamp. With better parts and point to point i think that would do it for me. I have a ton of nos 6SN7,5Y3,and5U4 tubes. This shoot out was very good. Thanks

[@coldfinger459sub0]

I use the DarkVoice 336SE headphone amplifier as a preamp it uses the 6SN7. And there’s a lot of following on this little budget Chinese amplifier and people have done a lot of modifications to improve it. I accidentally came across new old stock from World War II all the way up to the 1960s 6SN7 tubes brand new in the box. And 6AS7 tubes I got a selection of 30+ of each tube type from every manufacture they were given to me for free I did not know what to do with them. This was years ago and I knew nothing about tubes. So I researched and googled tube amplifiers that use these combination of these two tubes and the DarkVoice 336 SE seem to dominate the market with reviews. Which has pre-outs that bypass to serve as a preamp. It was the best investment I’ve ever made by accident.

[@bootstrapjesse]

That is so weird, because I have the looser, X2 units. I run them with two Dynaco ST-70s with a pair of Klipsch RP600Ms and Sony SSCS5s. One for the top and one for the bottom. I think the sound is fantastic, and I have several preamps to compare to. I run them on an AmpManiac variac and keep them at 110-112v to protect the 110v transformer. They sound absolutely amazing to my ears. I do have Genalex Gold lion tubes in them, but they sounded great with the stock Chineseium PSVane tubes as well. The point to point wiring is top notch IMO, and the chassis is solid. À chacun ses goûts I guess. I love your channel and watch at least weekly. Keep 'em comin'!

[@SkunkieDesignsElectronics]

As with all audio gear, "how does it sound?" is very subjective. It lost my shootout for safety, parts quality and design reasons, plus to me the other pre-amps sounded better and actually produced a usable amount of gain. As always YMMV, if you enjoy them, keep enjoying them.

[@grhaggerty]

I recently bought the #2 Nobsound and it sounds awesome,I also also got 4 genalax gold lions. I don;t know what the other two sound like but I sure they are good I am also getting a couple of rectifing tubes in the mail today, Here's to tweaking and upgrades.

[@artsabound7627]

Very well explained comparison , thank you ! Can you post a link for the 6sn7 kit or complete ? I find a 110v version but not 120. thanks.

[@jonsays3762]

Such a great breakdown! Reminds me of watching my dad working on two way radios as a kid!

[@EskWIRED]

I would love to try building some of these projects, but you always promise to make them sound better in the future. I would try some of the completed projects, but the new ones are always increasingly interesting. Please keep doing exactly what you are doing. 🙂

[@scaryperson27]

You could build it and just update it to the final version once it is completed if you like.

[@larryboles629]

Enjoyed your knowledge of the subject, you are truly a gem.

[@ceylonmooney]

"skunk gives this one an F for effing awful" HAHAHA! nice one!

[@SkunkieDesignsElectronics]

😁

[@warp2600]

I was looking forward to this shoot-out and enjoyed it a lot. Good idea to copy and improve a bit on the 6SN7 PRE.

[@sethjohnson1590]

Now I'm listening! Just what I wanted to hear. Fat tube pre. and make it pure. This is the one I want to build. I have a lot of old tubes for it. First I head about the CV 181 treasures. Nice! Thanks for doing what you do.

[@tacutacu]

glad I found your channel, Skunkie! Great vid. I've just subscribed.

[@SkunkieDesignsElectronics]

Welcome aboard!

[@astroporpoise7802]

The pre-amp that you built looks great--very clean layout. Nice work! And thanks so much for your explanations, I learned a lot! Subbed :)

[@SkunkieDesignsElectronics]

Glad it was helpful!

[@andyfritchen6409]

Fantastic video. I'm learning a heck of a lot from your videos. I built a couple nobsound amps that look just like the loser preamp. My hearing must not be too discerning because I think the push pull amp with 6u8a and 6p1 tubes sounds great. I'm not experienced enough to be able to tell and possibly since I'm a retired diesel mechanic so my hearing is not so good. As you mentioned these kits come with a schematic and that is it. No other guidance at all so I had to figure a bunch of stuff out on my own which in turn I learned a heck of lot from those builds too. Can't wait to build the little preamp you mentioned putting together. Being a vintage radio guy the little wooden chassis is appealing to me but I imagine that would be hard to find.

[@mikelebron3807]

Really enjoyed this one! Keep up the great content

[@SkunkieDesignsElectronics]

Glad you enjoyed it!

[@dtg474]

Skunkie I'm with Crimson Ghost. A 6SN7 clone on a hammond chassis to match your 300B, EL34, etc etc. I'd love to see it in cathode follower and not. So, imagine a 6SN7 preamp matching 300B monoblocks. I'd love to see that build and see performance shootout. Keep up the great work. I'm learning and loving this channel

[@primepreowned1]

The 6sn7 amp looks very nice with upgraded Tubes. That’s the one I would buy. It would be nice to change The heaters to DC, I’m thinking that would be a must do. Skunkie you amaze me at times. Love your channel!!! Be Safe Out There

[@sonusancti]

Hi Skunkie. Boy did I enjoy your video. I have a variant of the wooden preamp but mine only has one 6SN7 and yes upgrading to CV-181Z is the way to go. Wait till you upgrade that rectifier to a Cossor 274B. I also upgraded my coupling caps and the potentiometer and the supply caps to Supertechs. Mundorfs should be better for sure Hooked it up to a 24W solid state class A amp, also China, also with upgraded parts, and I'm a happy camper. Here's the mystery. I use my DACs remote as my volume control. So my woody preamp is set to full gain. Yet my speakers, DIY, are dead silent, even at loud setting with my ear right up beside the tweeter. Go figure. More power to your channel Skunkie! Btw, in tube rolling I did try an NIB Telefunken 12AX7 black diamond using a tube converter in lieu of the CV181z and yeah that was a champ as well, still dead silent mind you. Tried 12AT7s, 12AU7s, no problem.

[@zefrog7482]

Just a possible idea for a future video, but is there a way to test if tubes are indeed matched? Only I wouldn't trust just a seller's word for it. Like is there a way to do without expensive equipment, and are there any reasonable priced thing's available for this, can they be tested in another way?🤔 Great content as always.😊

[@SkunkieDesignsElectronics]

Sounds like a fun future project!

[@grhaggerty]

I bought the one in the middle (the worst) and while I been getting a hum when the volume is up all the way. I replaced the tubes with pricey genalax gold lions.The rectifier tubes are not loose like the ones that she is displaying and I have some new ones coming in. I think it sounds pretty good and I also didn't think the stock tubes ones were that bad. I wish that I would have bought one of the other 2 that she is reviewing, but I already spent money on new tubes and a new power chord, (thick as a garden hose) I'm going to keep it and enjoy the upgraded sound in my system. I think that this pre-amp is a hit or miss and maybe being a better build as time goes on.

[@petegaslondon]

So your hum might have been thru heater-cathode leakage, iffy tubes? So maybe the layouts not THAT bad, but yeah I still like that idea about DC conversion... I tried a few of those - theres really good quality SMPS electrolytics that are nice for that

[@ronwebb9249]

What is name or model number of the 3rd preamp with the wooden knob ?

[@SkunkieDesignsElectronics]

No idea, there is nothing on it inside or out.

[@barryhallsack8852]

Still can't wait till spring time for those monoblocks! Nice build keep up the good work!

[@jackdale9249]

have a yamaha M60 amp need a pre amp will one of the cheap ali express tube pre amps w/ remote and tone controls work ? like a Bluetooth Tube Preamplifier Amplifiers 2 Channels HiFi 6H3N Tube Preamp for Speaker Sound Amplifier Audio Home Theater $60.00

[@SkunkieDesignsElectronics]

Will it "work"? Maybe. Will it sound good and be reliable? Highly doubtful.

[@radradratorius2045]

Hey from UK What happened to that board earth on the CJ preamp? You ran couple of black wires for it and planned to earth them, said You gonna see if it makes hum or not, if it needs something else or not, but I fail to find Your conclusion on that. Sorry, if it's just me not being able to find it being mentioned. I'm building one of these on my own (after reverse engineering the schematics for the future use) and would be cool to know what actually happened with it. Regards Arthur

[@radradratorius2045]

sorry, found it - all good, thanks!

[@HawkFest]

I've watched a couple of your clips, and I must say: Lady, you're a God given! I'm not really verse into electronics, but I can understand the underlying basic theories pretty well (when you explain how this or that electronic component is better than another, I catch it). Maybe that one day I'll try to modify an audio component, which I'm currently shopping for a system, and it will be thanks to you. In the meantime, the information you're giving out radically changed my views while looking for those audio components, at least I feel like a better shopper. Thanks! 🙂Subscribed

[@NickP333]

Awesome video. I really enjoyed this bit longer vid with excellently detailed content. Those CV-181’s are excellent tubes. My preamp has four 6SN7’s, and they sound fantastic. I use them in conjunction with two NOS Sylvania tubes, which after plenty of tube rolling, really seems to have hit the sweet spot.

[@sonusancti]

Hi Skunkie. Nice shootout. I got something very similar to your winner, same wood chassis. Difference is only 1 6SN7 and 1 tube rectifier and has a choke. I also rolled a cv181-z to good effect. But what I ended up with is a Cossor 274B rectifier and 12AX7 instead of the CV181. Alternating between a Telefunken and an old Sovtek 12AX WXT+. I'm quite happy with either. More power to your channel!

[@SkunkieDesignsElectronics]

Thanks for the info

[@WesFanMan]

Regarding the tube rectifiers on the clone, I though you said the amp didn't had an on/off indicator? Sorry.

[@jessecummings5589]

I bought the diy version you losing choice, i did ground it though. Im about halfway finished so its unfortunate uve come across your video so late. Any advice on improving the build? Ive actually made my own copper runs because ive felt that the cables that came with it were lacking a bit. Also im wondering why my amp comes 1 of the bigger tubes and 3 of the smaller 12ax7s

[@mosfet500]

There is a way to twist wires on a pcb. Run one wire on top and the other wire on the bottom both in a weave pattern crisscrossing. Running a three terminal regulator at a lower input voltage won't cycle. What happens is that the regulator will drop the input voltage 1.2 volts (called insertion loss) for LM317 regulators, so if you have 7 volts the output will be 5.8 volts to the filaments.

[@SkunkieDesignsElectronics]

Looking back, I think that is the issue with that one pre-amp, there isn't enough voltage on the regulators. Might be better to just use a dropping resistor there to get the heater voltage in line.

[@mosfet500]

@@SkunkieDesignsElectronics I'm not big on using resistors, in fact in my new designs I'm designing for filament current not voltage. I tested a bunch of 6922's which I really like and at 6.3 volts the current varied wildly. I've got a couple of designs running several years current regulating the filaments with good success and long tube life. If you want to regulate voltage you might be able to use an LDO like the LT1763 if the current is under 500ma., the voltage drop is only about 300mv. at full load: www.analog.com/media/en/technical-documentation/data-sheets/1763fh.pdf

[@mohinderkaur6671]

regarding chasis ground, Ground loops can be formed and cause real problems with hum. This can happen in any audio equipment. Specifically ground loops induce mains hum in audio circuits by their ground circuit currents. 10 to 30 ohm 25 watt resistor in series will reduce mains voltage enough to make it 6.0 volts

[@SkunkieDesignsElectronics]

WARNING! DO NOT FOLLOW THIS ADVICE HERE OR ELSEWHERE! It is NEVER safe to put resistors between the chassis and the safety ground. You can have a short to ground and not blow the fuse or the breaker. All my gear is solidly grounded and none of it hums. If you have hum because you have safety grounded gear, you are doing something else wrong.

[@mohinderkaur6671]

@@SkunkieDesignsElectronics Resistor in mains lead to reduce mains voltage, not ground lead

[@SkunkieDesignsElectronics]

@@mohinderkaur6671 you said "regarding chassis ground", and a bucking transformer is a much better solution that sticking a hot running resistor in series or better yet, don't buy that over priced piece of crap pre-amp with the wrong voltage transformer.

[@mohinderkaur6671]

@@SkunkieDesignsElectronics Exactly. so. Transformer is better. Regarding Chasis ground - refers to Ground LOOPs issue. 2 different topics. Sorry for the confusion. Ground loops is a problem .

[@SkunkieDesignsElectronics]

@@mohinderkaur6671 But you don't resolve them by removing the safety ground. Ever.

[@DavidParker-jr5bd]

I'm confused about why you're looking at gain when the goal is a line level signal from your preamp to your amplifier?

[@SkunkieDesignsElectronics]

Because how much gain you need depends on the signal you are starting with. The vast majority of people wanting a pre-amp today are already starting with a line level signal and don't even need a pre-amp. They just think they do or are looking for some "tube sound" from one.

[@DavidParker-jr5bd]

Thank you for the clarification. You're a breath of fresh air and knowledge.@@SkunkieDesignsElectronics

[@CoquiAudio]

oh man no GND connection? 😮 3:00 they skipped that wow!

[@SkunkieDesignsElectronics]

Yeah and people would think it's safe because it comes with a 3 wire cord, not knowing the safety ground is open...

[@gee3883]

Wow, what a great channel. Greetings from London.

[@SkunkieDesignsElectronics]

Thanks and welcome

[@SkunkieDesignsElectronics]

Thanks and welcome

[@MrSemperfidelis225]

Love your videos. So the reason you get lower total thd from the pre with the higher thd is this: Tubes in SE mode (such as the Spud) produce mostly even order thd. This is a slight assymetric reproduction of the input signal. Tubes turn easier on than off. So as you input a signal, the output goes slightly more in negative direction than positive. Say the input is exact +-1Vp input. The output may be +9.9Vp and -10.0Vp if the gain is 10x (20dB). So if you drive the 20dB gain stage with a preamp/driver with some of it’s own even order thd, this can cancel out some of the lone amp’s thd. This b/c it is now driven from a signal slightly assymetrical in a manner to cancel out the lone amp’s assymmetry.

[@petegaslondon]

Playing with this stuff to seek a 'null' could be fun - maybe by tweaking operating points and levels ?

[@MrSemperfidelis225]

@@petegaslondon Absolutely. Same tube driving the output is probably best at this. I have both used a 6AS7 driving a 6AS7 and a 6G6 driving a 6V6. 6AS7 have wonderful amounts of 2nd harmonics but very little else. When matched the effect of same driving same is very good cancellation. Perhaps too good because part of the magic w 6AS7 is the 2 harmonics. There was a japanese designer guru who was famous for the ‘same driving same’ topology. I cannot remember his name.

[@traveledman]

The one that got last place, anything you would do to make it respectable or is it a lost cause? Would like to see what could be done as I am one of those that was seduced by good reviews on that like the A10/12/50 Amps.

[@SkunkieDesignsElectronics]

Possibly, but it just has so much going against it, I feel it's kinda a lost cause.

[@randomsuper]

Amazing video! So glad I watched this as I'm in the market for a tube preamp and was close to buying the Marantz clone. Where can I purchase the wooden case one from?

[@dmark2639]

Nice series, Skunkie! Has anyone figured out which Conrad Johnson model this clone board is based on??

[@stive828]

So who manufactured the winner preamp?

[@SkunkieDesignsElectronics]

I have no idea. It's some random made in China unit.

[@ohyesitsme]

Hi from the UK, new here to your channel. I've just watched your video and have located the source of the 6SN7 preamp. I was thinking of ordering one but am concerned that you mention a hum problem. Was this discernable from your listening position. Unfortunately I don't have the skills to do what you suggested of changing the AC to DC. Would this pre be OK as it comes out of the box or would you recommend to look elsewhere. Thanks for all the time and effort you put into your videos.

[@SkunkieDesignsElectronics]

If you are sensitive to hum with no music playing, look elsewhere.

[@Moejoe69]

What is your opinion on the DIY Kits from Japan called Elekit TU-8500 preamp with Phono equalizer, and the TU-8900 300B, Tube Amplifiers? I built both of these but do not have any other amps to compare them with.

[@SkunkieDesignsElectronics]

I've read good things about them but have no personal experience.

[@jukingeo]

What is the make and model of the 6SN7 pre-amp. Also I would like do know where to get it and the cost. Thnks

[@SkunkieDesignsElectronics]

I have no idea who makes it, you can look on some of the chi-fi sites? I believe the last time I saw it, they were selling for $130+ shipping.

[@jerryhribal3695]

Have you completed the upgrades on the 6SN7 preamp yet? If so where can I find it? Tube selection as well. Thanks, enjoy your efforts.

[@SkunkieDesignsElectronics]

I think the "upgrade" is doing to be a gut and rebuild as a point to point pre-amp in the future.

[@ramenhausten]

Can’t wait for that clone to be built sounds epic, go double sixes !!!!

[@Nihil1st1347]

I bought an OTL headphones amp for a 100$, but it broke. The builder repaired it, upgraded some parts like potentiometer and transformer, but it broke again. With a friend I figured out, the heating for the 6SN7 does not work properly. The builder had that done by a computer psu. How You recommend me to fix that thing.

[@SkunkieDesignsElectronics]

I would use a small 6.3V transformer and just run AC heaters.

[@garykarczewski6678]

Thanks for the video. Curious on your thoughts of Decware Preamps. Not the amps just the Pre's?

[@SkunkieDesignsElectronics]

I have no personal experience with them, likely they are very good.

[@garykarczewski6678]

My thoughts as well. @@SkunkieDesignsElectronics

[@driftwoodturning6846]

Hi everyone. New boy here. Where can I find a plan or kit for that twin valve winner 6sn7 I thin. I would live to make the outside look amazing also. It would be my first valve preamp project. Thanks for the video well done.

[@SkunkieDesignsElectronics]

I plan to do a clone of it in the near future.

[@hearingthings1200]

Hi Steph - I still am curious if you remember what weirdness was occuring in the zerozone CJ7 clone pre when you had 12ax7 tubes in there that seemed to be better when you put in 12au7 tubes...my tech looked at mine and wrote this to me when he sent it back... "A couple more things: This preamp uses 12AX7 (ECC83, ECC803) tubes. To put it bluntly, that's a terrible tube for a linestage. It has too much gain, and can't drive long cable runs. Your preamp has 20dB of gain. This might be way too much, and results in using the low end of the volume control, and is noisier than it should be. And while it puts out more than enough voltage to drive your amp to full power, when it runs out of gas, it distorts rather abruptly. So, I did some experimenting with different tubes from the same family. I replaced the output tubes (the two closest to the heatsinks on the left side) with ECC81 (12AT7). Big difference. Maximum output nearly doubles, with much better distortion characteristics. You will never reach maximum output. It drops the gain to a more usable 15dB, lowers the output impedance by a factor of 10, and reduces hiss substantially. I then replaced the input tubes (two on the right) with ECC82 (12AU7). Not as big a difference, but quieter still. The ECC81 also work well here." What do you make of this?

[@SkunkieDesignsElectronics]

I honestly got side tracked and never finished dealing with that pre-amp. What he said makes a lot of sense!

[@hearingthings1200]

@@SkunkieDesignsElectronics thank you! Both you and him were the only ones who mentioned this strangeness. I also remember something of the regulators being underpowered and am trying to figure out if this is tied in with that. I am otherwise addicted to your channel and all the monologes. Great stuff!!

[@SkunkieDesignsElectronics]

Yeah, I recall someone msg me about the regulators too.

[@legione1capone]

What preamps are in the test? Sorry if I missed something

[@jerryhribal3695]

I have upgraded the two tubes as in your video and would like a recommendation for the rectifier tube as well. Obviously not going cheap...so what would be a very good upgrade? And would a adapter be needed? Fore some reason I'm hooked on this pre amp 'lol' and will be experimenting with some of my vintage Marantz amps. Thanks again

[@SkunkieDesignsElectronics]

I don't think you would ever hear anything changing the rectifier, as this preamp draws so little power.

[@AudioCat-h9g]

Hi I have done to same as I bought the cv181z tubes as well. But they have a really loud buzz when I put them on. Is this normal and the buzz will be gone later or I have got some bad tubes?

[@locmanw1583]

I noticed you use Alps volume pot! Any Advantage of using fancy stepped attenuator with discreet resistors? Is it audible?

[@SkunkieDesignsElectronics]

My main problem is stepping, it's always one click is too low, the next is too much. It would drive me crazy!

[@locmanw1583]

@@SkunkieDesignsElectronics True but isn't it more transparent then a volume pot?

[@SkunkieDesignsElectronics]

@@locmanw1583 I've never tested it, so really can't have an opinion. I think this is getting into some very nuanced territory.

[@robcaputo9708]

Can you build one of those pre amps for me? I wouldn’t know where to start.

[@SkunkieDesignsElectronics]

Stay tuned for round 3 of my Pre-amp shootout! And sorry, at this time I don't do custom builds for the public.

[@Bisen222]

Anyone knows the name or where to find the wood amp?

[@dr.dianaungureanu6750]

What is the name of the one in the right?

[@RobertCunningham-u9p]

New to your channel. I have a question to ask. I see you wearing a doraville t-shirt on some of your videos. Is that Doraville GA. By chance?

[@SkunkieDesignsElectronics]

Yes it is :) Little country in the city!

[@RobertCunningham-u9p]

@@SkunkieDesignsElectronics I lived in Chamblee Ga. For thirty years owned my Business Audio Exchange LLC. I have designed and built audio tube amps, preamps and speakers under the name Cunningham Audio. I retired and moved to Myrtle Beach SC. I'm sure you know a lot of people in the business there such as Audio Lab of Georgia I use to buy parts for those guys. Really enjoy your KZbin channel.

[@scaryperson27]

Do you think there is a good advantage of going with a stepped attenuator with resistors versus something like an Alps pot?

[@SkunkieDesignsElectronics]

I honestly haven't tested that, but I would be shocked if it was audible. But I've been shocked before!

[@scaryperson27]

@@SkunkieDesignsElectronics Haven't we all. It hurts every time :( I may give it a shot. If anything, it will be bling factor. I just built a BA2018 solid state amplifier designed by Wayne Colburn from Pass labs. That is the amp that I want to try it on. Thank you for your input! You are the best!

[@SkunkieDesignsElectronics]

@@scaryperson27 I wouldn't say it hurts, more like "Oh wow, well I learned something new today!"

[@petegaslondon]

@@SkunkieDesignsElectronics My understanding is, you dont get any wavering 'panning' like with a consumer grade pot, like 'more stable stereo image' as theyre only matched to like 3dB? I'd dig playing with / making some, if them lil SWITCHES werent so darn expensive ;)

[@kgtaillon27]

Could it be that there is a mis-match of impedance between the preamp and amp.

[@SkunkieDesignsElectronics]

If any of these distort because they can't drive a 470K load, they are pretty useless for anything.

[@mfr58]

The 6SN7 pre has it's input very close to the power transformer, which may be causing the the hum pick up. Interesting shoot out. Thanks.

[@SkunkieDesignsElectronics]

Good point too!

[@maryjaneevadiamond6359]

Steph, are you sure that blue capacitor going to ground is not a MOV. It looks close to one, and it is going to chassis ground, and they didn't use the power ground. Not that this idea offers correct protection, but I could see someone doing that. And the sticky ties can come unglued after time (;;;;;;; On the 3rd amp, that is correct on the 6 volt ic regulators, the standard rule on those is a minimum of 2 volts over, and I believe they can typically handle inputs up to 37. I think your trying to explain they might be lethargic from being so close to the minimum required input. I agree. It's an odd situation because I understand those transformers are made with multi taps typically to provide you with exact needed voltages in AC, and when mixing solid state, here is a good example where it's going to be a problem. So MAYBE, and I don't know, but is it fine to run the heaters at 5 volts, if yes, then pull those out and replace them with 5 volt regulators. The cross reference is easy too, they are probably 7806 that's in there, and you can put in 7805s, That would be the positive series starting with 78.. where as the negative series starts with 79

[@SkunkieDesignsElectronics]

Nope, even 6V is too low IMHO. I think the best solution is to use use dropping resistors to lower the voltage from 7 to 6.3-6.5V. As far as the "blue cap", you may be right as I didn't look very closely, but honestly that just makes it more dangerous lol. These are designed for use in parallel to AC mains and in case of a component failure would reduce any resistance between the high voltage and the exposed chassis to zero!

[@EskWIRED]

@@SkunkieDesignsElectronics Is that the "Death Cap" that is sometimes included in vintage guitar amps? kzbin.info/www/bejne/h2HNfmNrqN2saJo

[@goaway2174]

@@SkunkieDesignsElectronics Thanks for the shootout! Yes - that is the best solution. I just did this on a preamp with the same issue and used two 0.15 ohm 5 W resistors and dropped from 7.2 to 6.3V. Easy calculation as heater current was nominally 3.1A for the tubes combined. Should greatly improve tube life. Operating heaters down to 5 V is a bad idea unless it is a rectifier tube as it will cause cathode poisoning and the tube will have greatly diminished emissions. Just a note, you may already be aware but exercise caution converting heaters to DC as it is a greater load on the power transformer.

[@lastscatteringsurface9950]

Have you considered the 6P15P-EV tubes for the Spud ala the Decware Zen Triode? They are interchangeable with EL34 but have a wider frequency bandwidth. Love the videos, as a diy audiophile your channel is exactly what I'm looking for. Thanks.

[@lastscatteringsurface9950]

Sorry meant EL84.

[@petegaslondon]

@@lastscatteringsurface9950 Hold on, arent 6P14 more like EL86 Or something? The Russian 6P14's Ive had have been VERY tough, working in my AC30-like designs (with crazy high HT) But I'm pretty sure 6P15's are more delicate, and def expect a lower screen voltage... Skunkie ?? PS Wider bandwidth? How so? I dont think tube capacitances make much odds til youre well into megahertz

[@jkjome4095]

Skunkie- I am hoping that you can help shed some light on a question that I have. I have one source (Bluesound Node 2i) which I plug directly into my tube amplifier (VTA ST-70). The Node 2i has plenty of gain to make my system loud with my Klipsch Fortes and LaScalas and it sounds great. My question is, would there be any benefit to adding a preamp into the system? Thank you!

[@SkunkieDesignsElectronics]

No, I see no reason to add one.

[@brucetaylor7095]

@@SkunkieDesignsElectronics Good advice. Mostly it's the hifi gear sellers that say you need one lol

[@Gullsz]

Whats the 6SN7 called?

[@SkunkieDesignsElectronics]

CV181 is what is in that amp.

[@whiting444]

Like the whole series of your videos, where can one buy candidate no. 2

[@SkunkieDesignsElectronics]

The one with my logo? I build it from a board I got off ebay. Here is their "production" model using the same board. www.aliexpress.com/item/32923155401.html

[@whiting444]

Hi, thanks for getting back to me, however I meant the pre amp with the wooden base surround and metal top. Cheers

[@stevesmullen7735]

@@SkunkieDesignsElectronics Love your videos! They are out of stock. Any ideas of another supplier? Thanks.

[@nuttyl283]

Wow A lot of good equipment.

[@allenwalters8812]

Hey I was thinking. If they are running the left and right channels from the rca's are they using the shield wire for the ground? Wouldn't that turn the shield in an antenna?

[@SkunkieDesignsElectronics]

It's not ideal at all, but many people wire them this way.

[@allenwalters8812]

@@SkunkieDesignsElectronics I'd say. Seems crazy putting the shield in the signal path. Kinda defeats the purpose.

[@flyingmattyboy]

Wondering what you thought of the Spud, and how those Transformers worked out in the end. You were a little concerned about Frequency response of them before. Nice work though Skunkie and I wonder how the nu tube pre-amp kit would workout too.

[@SkunkieDesignsElectronics]

Plan to do a final review on the spud amp in the next day or so.

[@jungtarcph]

What is the name of the tube winner? That sounds like tubes...

[@SkunkieDesignsElectronics]

No name china pre-amp.

[@1mctous]

I'm part of the minority who likes clarity over warmth. I'd go pure Skunkie in the signal path.

[@SkunkieDesignsElectronics]

I tend to agree, but I honestly think people who are looking at tube pre-amps are expecting "tube sound", and only one in this shootout is going tom deliver that. And driving this spud, to me the 6SN7 still won.

[@1mctous]

@@SkunkieDesignsElectronics We both know that tube sound covers a wide range from nearly solid state to thick and buttery. I also want to find out how much quieter you can make the AC-heated 6SN7's.

[@praxicoide]

This is very interesting. ¿Could the 6SN7 preamp be used for a turntable, or is it better suited as a headphone amp?

[@SkunkieDesignsElectronics]

It can't be used for a turntable because there is no RIAA equalization and I'm not sure it could handle driving a headphone unless they were the high impedance type.

[@praxicoide]

@@SkunkieDesignsElectronics Thank you very much for responding! Follow up question. Is there a way to get a separate RIAA equalizer, in order to plug that into this preamp? Does such a thing exist?

[@SkunkieDesignsElectronics]

@@praxicoide You are MUCH better off building a "phono stage", I did a video series on an easy to build kit off ebay that sounds amazing! kzbin.info/aero/PLtEhh3UpOsiDnO2PW6gI38UtZLk-4PFQc

[@praxicoide]

@@SkunkieDesignsElectronicsGotcha! I did see the videos. I just really liked the look of this. No problem then.

[@joemartin6439]

What type of a tube preamp needed to drive my Son of AmpVilla

[@SkunkieDesignsElectronics]

Not sure what the input sensitivity is.

[@johnjackson7162]

We're you using the spudamp in pentode mode?

[@SkunkieDesignsElectronics]

Yeah. I tried triode and lost 1/2 the power.

[@grogmonster2408]

Not sure if you ever mentioned it, but what exactly is the brand of the 2nd preamp ? Great video, well done !

[@grogmonster2408]

The one with the black tubes ?

[@SkunkieDesignsElectronics]

It doesn't seem to have a brand name on it? And those black tubes are Shuguang Treasure CV181, a variant plug in replacement for a 6SN7.

[@mantolis33]

You can find it as: "6N8P 6SN7 tube preamplifier 6Z5P bile rectifier"

[@robertbishop9229]

I come across your channel recently.. Wow lot of cool stuff I'm just getting into tube preamps and as you say I'm trying to give my solid state amp that I built the Leach amp a nice tube sound I like the distortion of tubes But can't achieve the higher wattage. Not to mention the expenses. So as a experiment I bought a toy FX audio tube-03 tube preamp (China) I did some modifications to it has two opamps for the tone control and volume. Changed to Lm4562's and swapped out the cheep China tubes for 2x Voshkod 6ZH1P-EV. Sounds a lot better. But I don't know if it qualifies as a true tube preamp buffer. It is hard to find a true buffer not needing the gain. What is the kit for the clear winner and what is the price I'm trying to do this all in a budget. I think it's super great what you do on your channel sharing this information I have to go back and watch all your videos try to learn about tubes. I'm all about solid state I can't do all the math but I can follow schematics make my own PC boards wire things up etc etc. Just need good advice on a good starting point to add that sound to my SS Amp ! Thanks for sharing. I'm sure all is greatly appreciated amongst all of us !!

[@primepreowned1]

The cost of the 6sn7 preamp shipped to your door is a little under $200. On AliExpress.

[@joemartin6439]

I sure like the to dc heaters , great idea my it drive my Solid state Son on AmpVilla Gus . It sound a sweet powerful amp darling

[@alexzildjian]

Thanks A Lot for your video 🙏🙏☺️👋

[@sethjohnson1590]

I forgot to mention. I've heard a lot of things about 12ax7 and I've come to a conclusion. They are excellent for guitar amps! Watched guys play different brand and study/ record the different sonic characteristics. And some just had no personality. None! Some really sing. Wondering if this ties into line on the graph during the test.

[@petegaslondon]

That IS kinda weird - I mean its a pretty low level phenomena, might not be that significant, but it sure is interesting (I'm a bit cynical about tube rolling unless somethings def measurable)

[@greggb681]

Hey Skunkie, I have a question, and I will probably make myself sound uneducated because I am new to tube amps, but I bought an EAR834 circuit board but was wondering if could use the cv181-z tubes with the ear834 clone. I know some tubes won't work with some amps, but from what I have heard, the cv181-z tubes are amazing sounding! Keep up the amazing work Skunkie and look forward to learning more about this new hobby of mine!

[@SkunkieDesignsElectronics]

Possibly but also be aware these have high gain so low noise tubes are best. The new production EH7025 work well as do NOS 7025 tubes.

[@nakfan]

Great video - Great channel 🙏 Just found it today… BR, Per (Denmark)

[@SkunkieDesignsElectronics]

Welcome aboard!

[@nickk6109]

M7 WIMA caps look wrong too..

[@SkunkieDesignsElectronics]

You know those are fakes.

[@petegaslondon]

Gadzooks! You know your capacitors, Skunkie ! (Fake CAPS now? Sheesh!)

[@ramenhausten]

Everyday I’m loving the channel even more !!! Hey question any chance you would make a “doge 10 killer “ amp ?

[@SkunkieDesignsElectronics]

I'm planning a KT88/KT120 PP amp soon.

[@parryflynn3704]

WERE YOU ON JEOPARDY???

[@SkunkieDesignsElectronics]

No lol

[@martinmartins5293]

The looser is.... The one with the least distortion! The winner has a lot of distortion and a lot of humm..

[@SkunkieDesignsElectronics]

If you are looking for tube sound, yup.

[@Fishbowlfx8]

Yes 100% agree. Get that sand out of my pre/amp.

[@jked7463]

I have a friend with some very expensive and very powerful tube amps that have extremely low distortion. It has powerful tight lows, gobs of low distortion power. You know what? They still sound like tubes. What makes a tube amp sounds like tubes is not distortion level.

[@petegaslondon]

Zero distortion implies perfect linearity, and for you to claim a certain 'sound' there must be SOMETHING going on - mild 'reverb' from the amps microphonics? Or that kind of unlinearities that dont show in tone tests, like dynamically shifting tube operating point at high levels?

[@jked7463]

@@petegaslondon agreed. But whatever it is, it sounds very organic. Some things human measurements cannot reveal. Humane devise measurements that make sense to them. That by its very nature means that not every characteristic is being measured, only the ones that make sense to us.

[@petegaslondon]

Sounds like a mild cop out, @@jked7463 - if one can HEAR it then I'd.. 1- Confirm you or I CAN hear the difference in a double blind test 2- If one CAN hear it, the waveforms gonna be different, so you can devise SOME way of looking at the phenomena - whether its random and noise like, or, what we're seeing here something noise LIKE yet harmonically related? Which IS pretty mysterious! If you've ever watched Glenn at Spectre Sounds, he did a shootout (guitar amps) to prove 'fancy tubes dont make a difference' - I've got a slightly different test in mind, to prove that output tubes certainly DO - yet I've gotta test that hypothesis in one of my new builds - THATS taking a while... But " Some things human measurements cannot reveal"? I try and send out welcoming messages, but so far no aliens have picked up the phone! Yes our distortion measurements are way crude (you need at LEAST 2 tones, preferably something with hi and lo freq transients, to really clobber and amp with a music-like signal on a realistic load) but I dont buy into this 'imperceptible mysteries' stuff, thats how the HiFi biz sells snake oil - do you remember the Tice Clock? ;)

[@jked7463]

@@petegaslondon You can call it whatever you want. I used to worry about all that you talked about. Now I just listen to what I like. While my friends system is high buck, mine is rather humble. But I like it. I have a dc amp that I like for it's clarity, pace and depth. Some would say the bass is thin but I say it is nimble and impactful. Sparring is not my thing anymore. You enjoy what you like and I will enjoy what I like.

[@petegaslondon]

@@jked7463 Direct Coupling? I've got some TUBE direct coupled things that I'm hoping might interest a few people...

[@DuanTorruellas]

Hahahaha she chewed that Marantz a new Ahole hahahaha

[@phillipmorris9847]

Great job, thank you

[@petegaslondon]

Oh you do Pre's too huh ? :) The differences will be WAY to subtle to hear on a YT vid, but I bet they're nice to look at - watching now ! Ohh, OTHER peoples Pre's? 1 - Gulp! THAT;S why they gave em mains taps, back in the day , right? Heater volts is s'posed to be +-10% iirc? Sheesh! ... Yeah cheapo hi capacitance cable seems so WRONG for a tube pre and 'stereo'' cable brings MUCHO crosstalk!) If I found one in the trash it'd be fun to rework (and fix the ground), but otherwise... 2 - Cant see the PCB layout, but yeah, not so bad .. AC heaters, good point - be fun to rewire or convert..? I try and do the twisted wire thing even if I'm using DC - it just feels.. 'right' 3 - Ah this IS one of yours - ohh, that's NICE ! (cant you just switch the regs for LDO's? They can be noisier, but long as your decoupling is good? (I'm sure it is!)) Hi from London x PS I've got some orig Mullard AU7's but pers not so fond of em in Gain Stages - dist tests seem a way worse than 6SN7's (and I try and avoid octals) - I figure those Russian things the perform like ECC88's should be a tad nicer, have you ever tried 'em ?

[@davidjones5013]

Yes when I seen those marant 7 copies I know they were junk.I have the original marant 7 much better built

[@joemartin6439]

It would be so nice to be your neighborhood friend darling

[@kalleklp7291]

The first amp is a rip-off! I mean the build quality of this piece of sh.. is nothing a 1-year apprentice could do without getting yelled at Full Metal Jacket like.

[@paulconteyoutubesucks2931]

You ok ? Haven't seen you in a long time hope you're ok

[@SkunkieDesignsElectronics]

I just posted a video yesterday!

[@paulconteyoutubesucks2931]

@Skunkie Designs Electronics I have to look at it thanks for the update

[@Psychobeppe]

In a tube system set up, is the tu e sound predominant in a preamplifer or a power amplifier?

[@SkunkieDesignsElectronics]

It's heard most in the "front end" so the driver tubes or the pre-amp would likely impact the sound more. The problem with preamps today is very few "power amps" have low input sensitivity and actually need the gain provided by a preamp, so most of this gain ends up being shunted to ground.