Amazing Results From A Small Tube! Plus - Build An Amplifier Test Fixture.
Added 2020-02-19 15:15:00 +0000 UTCLet's choose an audio transformer for this project, build a test bed, then see how this little amplifier design performs. Schematic attached below. Enjoy!
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Robert Dreitlein
2025-05-08 13:14:03 +0000 UTCGreat Work Thank You
LoSaYa
2022-10-15 21:27:38 +0000 UTCBring on the monoblocks with variable power supplies!
Jay Cronen
2021-12-02 23:21:11 +0000 UTCThis was a great video! Thanks Mr. Carlson
Tim
2021-10-25 17:03:06 +0000 UTCPaul , I have been around many profession guitar players and they run Variacs on the input line of their tube amps. Just curious what the impact of AC input voltages has on these tubes and why do they feel it necessary to control this value. I mean differences say 95 VAC versus 120 VAC..
Timothy A Holder
2021-01-28 05:26:59 +0000 UTCThese are available cheap if you know how to search and buy tubes on Ebay. $4 per tube delivered when you buy 5! https://www.ebay.com/itm/GE-6360-TUBE-NOS-5-Tubes/383768032542?hash=item595a5b751e:g:YPcAAOSweVdfieqS
Paul Kevin Schwartz
2020-12-16 18:47:18 +0000 UTCThe 6360 tube is definitely a cool looking tube but is not as easy to find for the rest of us. There are "substitutes" out there but I'm not sure if they will have the same neat layout as the original. As far as using a pencil tube I think it would have been great. The 6111 and 6021 tubes are readily available. They aren't for hearing aids though .These were designed for use in ICBMs and have characteristics much like the 12A?7 series. I would love to see a build with either or both. (Especially since I have a couple I planned on using to build a guitar pedal with but haven't designed a good tiny power supply yet.) Maybe a schmitt trigger-diode-capacitor setup might do the trick but haven't decided.
Russ Lewis
2020-08-29 01:26:45 +0000 UTCBit late to the party but I bet you made it adjustable Paul. TFS, G :)
Graeme Brumfitt
2020-07-26 12:17:46 +0000 UTCFirst of all thanks for a very interesting series, Paul. I'm not into a guitar amp, but a hifi amp, so I'll like to see the frequence output at lets say 10 watts 400-420 volts or like that. I think we are several that would like to know about that ;)
Boje Breinbjerg
2020-04-13 11:09:43 +0000 UTCI'd be very interested to see what those selected 250v-screen tubes do at 300, 350, 400 and 450v plate.
Nirky
2020-04-06 22:25:21 +0000 UTCLets make a six pack with these tubes.
Voltage Freak
2020-04-05 03:07:07 +0000 UTCI would run it safe Paul.
Joel Dunn
2020-04-02 07:25:34 +0000 UTCJust got a couple of 6360 tubes off of that auction site for under $15 shipped. Plan to build a hi-fi version of this circuit. I vote for adjustable power supply. :)
Nirky
2020-04-01 09:49:12 +0000 UTCYou can run the vacume tube hard, BUT how much can that speaker take? Isn't it a 15WATT speaker?
David Kuhn
2020-03-30 03:54:07 +0000 UTCI like the idea of 400v :)
Kyle Reed
2020-03-04 22:09:35 +0000 UTCSince this is a musical instrument amplifier, I would tend to run the plate voltage high, regulate the screen voltage to a safe value, and operate the tube in Class AB2, within the confines of the 6360 plate dissipation and the output transformer limitations.
Sam J. Breidt
2020-03-04 17:33:02 +0000 UTCDo resistors always fail open?
Dennis
2020-03-03 21:02:44 +0000 UTCThanks for your kind comment Bruce!
Mr Carlson's Lab
2020-02-28 08:34:58 +0000 UTCI agree. This tube is "undiscovered," and when the HiFi build version for dual mono-blocks is released, the prices of these tubes are going to skyrocket. Get'em now!
Mr Carlson's Lab
2020-02-28 08:24:16 +0000 UTCHi Dennis. The voltages would be about right to operate the amp "somewhat conservatively." The current your transformer provides is an unknown.
Mr Carlson's Lab
2020-02-28 08:21:17 +0000 UTCHi Harry, That tube looks much like a 5984 used for VHF power amplifier service. They are easy to drive, but if you are into that style of tube, you may want to consider the 829 or the 832, they work very nice in audio service. The exposed anodes (plates) require protection as they can be a hazard to people and pets if left exposed.
Mr Carlson's Lab
2020-02-28 08:15:57 +0000 UTCHi Ralf. This last entire (one month) has been the research and creation time of the latest HP 419A video "just launched now," so lots of time put into both projects, (HP and the amp videos here.) I appreciate your kind comment, and the time you dedicate to the list of video's! Have a good weekend.
Mr Carlson's Lab
2020-02-28 08:10:07 +0000 UTCHi Adam. We will design entire tube amps in the future. This amp is a good intro, with many lessons to give.
Mr Carlson's Lab
2020-02-28 08:02:05 +0000 UTCHi Chuck. But on a scale of 1 to 10.... how right did they get it? If "10" hasn't been discovered yet, how would you know? Maybe tomorrow, the new "10" will be discovered somewhere.... Only until the next new "10" is released. If everybody stopped because they think "10" has been achieved, we would have no innovation.
Mr Carlson's Lab
2020-02-28 08:00:31 +0000 UTCHi Bob. I will talk about this in the next video.
Mr Carlson's Lab
2020-02-28 07:54:43 +0000 UTCHi Sean. Only if the transformer is undersized.
Mr Carlson's Lab
2020-02-28 07:53:21 +0000 UTCThanks for your kind comment Steve!
Mr Carlson's Lab
2020-02-28 07:42:56 +0000 UTCTIP: Do not use the the heater winding CT. Tie it off and reference the heaters to chassis via two 100-220ohm 1W resistors. They can be flame proof type. This way if there is a heater to cathode/ plate short the transformer doesn’t take strain. The resistors act like fuses and you know you have a faulty tube.
Adriaan Diedericks
2020-02-26 06:14:47 +0000 UTCI vote for variable, always nice to have options.
Richard Russo
2020-02-26 06:05:12 +0000 UTCI have a 275-0-275 310am transformer with 6.3v windings and a rectifier socket built in and internally wired. This thing is a beast to say the least! Do you think this could be made to work for the screen and plate? I think I have a little too much power here!
Dennis
2020-02-25 13:17:38 +0000 UTCI would like to see the design going into the direction of the variable power supply. However, I would also like to see the video going into the direction of ClassA single-sided amplification. But, since you already started push-pull, I guess it's a little late for that. It doesn't matter though, an interesting topic anyway.
Kevin Van Hout
2020-02-25 12:11:31 +0000 UTCIf an output transformer is wounded in the simple 'continious' way, the half of the primary located farther from the core has a longer wire length, therefore greater resistance. Of course you can equalize the resistance by adding a fixed resistor to the lower half of the primary, but it’s better to just put up with it.
Gleb
2020-02-24 07:14:43 +0000 UTCDear Amp Experts: I found that the DC resistance across each half of the 1750PA primary winding was slightly different. Then I saw the YouTube video "TTT082 Tube Circuits" and his schematic shows (@4:33) the same values! Is this some kind of standard for audio output? I guess I expected them to be the equal.
Rob Clark
2020-02-23 20:36:57 +0000 UTCI was shocked twice when I was young (once from a toy train transformer's brittle cord, a second from playing with the tube tester at a store) so grew up with a healthy appreciation for electricity. In the last few years, though, by taking things carefully and learning a lot before getting too far in, I've come to a point where I'm quite comfortable working around line voltage and higher. If you take things slow, use common sense, and be extra cautious at the get-go you should be fine. YMMV.
Jim H
2020-02-23 11:45:12 +0000 UTC“Sigh” means what?
Dennis
2020-02-22 05:28:24 +0000 UTCAt the edge of the 18W the transformer is rated at, I would hate to see it die.
Dartrunner
2020-02-22 03:44:17 +0000 UTCThe benefit to tube shields is they greatly reduce the amount of random rf that can enter in the vulnerable preamp tubes. For example my uncles house is very noisy, and something that would be fine at my house sounds like a swarm of bees at his place :) Shields help reduce this noise but most line hum is bad ac wiring grounding to earth I believe. Hope this helps
Jason Doerr
2020-02-22 01:28:48 +0000 UTCIn the video, you mentioned one thing that differs between tube sockets. Another thing that differs is the size of the socket holes. I just got some ceramic 7 pin sockets and the holes are way too snug for the 6J6 I have. It fits, but only just.
Dennis
2020-02-21 20:55:14 +0000 UTCHmmm, maybe a lesson on load lines and plate curves.
Mike Pelletier
2020-02-21 20:48:13 +0000 UTCI just helped a buddy build a Fender Black Face kit. Much of my vacuum tube best practices were quickly remembered - twist filament leads and leave them high in the chassis, signal leads as close to the chassis as possible, etc. We wound up with a very clean and usable amp. Oh - I learned most of these best practices from Mr. Carlson;'s Lab. I vote for variable plate supply - more opportunity to experiment.
Bruce Davis
2020-02-21 17:01:30 +0000 UTCWow. Cool project !!!!!!! Yes to the variable power supply. Yes to being able to run the tubes hot. Having been electrocuted twice (at home & by vending machine), Im a bit wary of undertaking such a project. Although at the same time, I'm reasonably aware of the major threats and have done electronics projects before. Perhaps anonymous is right: “Don’t let fear of what may happen hold you back from following your heart.” Anonymous Any comments ?
MF
2020-02-21 13:26:05 +0000 UTCI am going to throw in +200 votes for the variable power supply. I am in the process of building a 12AX7/EL84 Push Pull HiFi amp and would really love to see how you go about doing up a variable voltage power supply. Also for other vacuum tube amp projects - really keen to do up a low Watt guitar amp using a 6BM8 as a power tube and would like to get some good distortion so will need to play with voltages and would be better to have a variable supply to find the sweet spot! Very keen to see the variable supply.
Anthony Page
2020-02-21 07:01:33 +0000 UTCAnd when you record that guitar at full distortion, make sure you record in analog on vinyl so you'll get the full effect. Sigh.
Dan Swinehart
2020-02-21 06:41:51 +0000 UTCI believe there are 4 major countries manufacturing vacuum tubes. I don't believe they are vanishing yet.
David O. Hamilton
2020-02-21 05:01:54 +0000 UTCI believe Paul said: 'screen grid' not 'control grid'.
David O. Hamilton
2020-02-21 04:59:10 +0000 UTCI totally agree with Guy!!!
Stephen C Simmons
2020-02-20 22:17:08 +0000 UTCI vote setup that sucker right on the ragged edge. Want to hear some damage. Also, enjoying this one, thanks.
jimhoff
2020-02-20 22:00:35 +0000 UTCI vote for the variable supply. I play guitar and am looking forward to the building this amp. I will have to study these circuits to understand and learn all that you are teaching us and it is going to be great fun. The teaching is amazing and the level of your expertise on the subject matter should make each of us look forward to each session. Thanks Paul
Guy K. Griffith
2020-02-20 19:49:20 +0000 UTCHi Paul! I have a few nice double tetrodes QQE 06/40. Do you think it could be run in this circuit or would it need a bigger phase inverter signal??
Harri Lumme
2020-02-20 19:32:29 +0000 UTCI'm looking forward to seeing this project come together, Paul. Thanks for the excellent tutorial. One thing I'd like to learn is noise control in the wiring. Any tips you want to share will be appreciated.
John Inlow
2020-02-20 18:58:27 +0000 UTCI've never built a tube-based project before. Safety considered, looks like fun, especially since I found a nice haul of tubes recently AND you're saying tube sockets are readily available. Great video.
Peter Voss
2020-02-20 18:37:55 +0000 UTCGreat teaching. Thanks for all the info I'd never get any where else. ... I vote for the variable HV supply.
Robert D Speckmann
2020-02-20 17:32:32 +0000 UTCI say run it at lower voltage for a longer life. You don't need that much power if you use an efficient speaker. Would also love to see the variable high voltage supply. Could be a useful thing to have.
Misty Knight
2020-02-20 16:34:52 +0000 UTCUnbelievable how many plate voltage this little tube can handle! One of the things that I usually wouldn't do and naturally stay in spec. But fortunately I have you, showing me this beside other neat little tricks! Thank you very much for taking the time explaining and doing it step by step! Great Project Paul!, I really look forward to the next part!
Reb Elba
2020-02-20 14:20:47 +0000 UTCGreat Paul. My vote is for the variable HT supply!
Charles Riley
2020-02-20 13:19:13 +0000 UTCYou don't need this much power to drive a headphone. most headphones need only a few mW, typical max power input is as far as I know around 100mW (0,1W). So you can use an ECC82 = 12AU7 in both output and preamp. Like in this one that I build, and I can confirm it sounds good. I didn't bother to make the HV regulation but it's still great. http://jogis-roehrenbude.de/Verstaerker/Kopfhoerer-V.htm
Mikael Hansen
2020-02-20 10:04:43 +0000 UTCGreat work Paul! As interesting as the original pre-amp is with its features, I'm wondering if a tube pre-amp would suit the power stage better. Or are you set on maintaining your original idea of the hybrid design?
Adam
2020-02-20 08:23:02 +0000 UTCBut I'm a Bassist and I need a good amp to play with the drummer 😆... I'd need a hi-fi output transformer though to get those lows.
Adam
2020-02-20 08:13:35 +0000 UTCCould this be used as a headphone amplifier with the right audio transformer to work with 300 ohm headphones?
robotwizard
2020-02-20 06:52:34 +0000 UTCThanks, Paul! I guess it doesn't matter to me since I am a drummer and don't play guitar.
Robert Calk Jr.
2020-02-20 04:29:43 +0000 UTCI don’t play guitar but last time I wanted to learn I decided I needed to first build an arch top. Well that didn’t happen, (though don’t count me out yet!) but I think I could manage to build the amp as a first step.
Dennis
2020-02-20 04:22:01 +0000 UTCI’m going to build this this weekend. I have the parts aside from the opt, but I have a power transformer with the same impedance ratio which I hope will at least make a sound of some kind
Dennis
2020-02-20 04:18:30 +0000 UTCQuestion, I see you are running a 400 cycle tone, I would be curios as to the freq. response curve, non distorted. Should match the Hammond xformer closely. After that, let her rip.
Tom Harris
2020-02-20 03:36:05 +0000 UTCI think I'll stick to Fender. They got it right YEARS ago.
Chuck Kirchner
2020-02-20 03:04:29 +0000 UTCRun the tube safely? NO WAY!! Drive them so as to have fun :)
Carlos Pechiar
2020-02-20 02:03:07 +0000 UTCRunning this amplifier at super-safe conservative Voltages it makes plenty of power, the transformer is fine down there and the power supply would be straightforward. Thanks for explaining what is happening at various power levels! Variable power supply would be lots of fun!
Inventor Pardue
2020-02-20 01:18:44 +0000 UTCI love this! I like the idea of having a switchable plate voltage between 300 and 425. Sorta safe.
Jordan Levantini
2020-02-20 00:55:43 +0000 UTCHi Paul, new Patreon member. Awesome learning here. Thank you! I vote for the Adjustable PS version. Distortion at lower output like Graham L suggests. Also like Gleb L's comment.
Kurt
2020-02-19 23:40:30 +0000 UTCPaul, here's my vote for an adjustable PSU (with a built-in voltmeter to prevent putting too much on the tube as the amp is used). Also, how do you _know_ when you are pushing a tube too hard -- is it simply looking for "glowing" elements? Is there a recommended (tube?/amp?) book to 'teach" how you can "safely" push tubes and also basic tube amp design?
Bob Vines
2020-02-19 22:10:50 +0000 UTCVacuum tubes are pretty withstandable guys comparing to modern solid state stuff. You can scratch their limits and still be happy, unless you're going to force your tube device run 24/7 for years.
Gleb
2020-02-19 21:16:07 +0000 UTCPaul, would there be any benefit at all to using tube sockets with metal shields? I know that downside is can't see the glow. :) But, just wondering if there if any benefit would be had with shields?
Michael, KE4EST
2020-02-19 20:37:22 +0000 UTCHi Paul, I am a guitar player and have worked in that industry for many years. I'd recommend designing it distort at lower volumes. 5 Watts of clean power is plenty into a typical 8 ohm load for home/recording use. I would also like to see a bias control on the front of the amp allowing the user to adjust it within safe limits to hear the affect of it.
Graham Leggat
2020-02-19 20:21:58 +0000 UTCThe variable PS will make for a better learning experience and experimentation as well as being able to taylor the amp to one's liking
William Miklavic
2020-02-19 20:16:00 +0000 UTC5844 and 6j6 tubes are so easy to find
God 420
2020-02-19 19:49:34 +0000 UTCA pretty nice design for a guitar amp, thanks Paul! I have only two things to add: 1) If the maximum output wattage isn't critical, a triode amp (even with the same tubes but in triode mode) would be more musical, yet less powerful; 2) The tubes have easy-to-find Russian equivalents: 6J6=6N15P, 6360=GU-17
Gleb
2020-02-19 19:35:01 +0000 UTCWould running the plate voltage above recommended voltage (300V) to say 400-450 Volts draw excessive plate current through the transformer and burn it up in a continuous duty cycle?
Sean P. O'Connell
2020-02-19 19:26:53 +0000 UTCHere is one possible EU source for terminal strips: https://www.reichelt.de/Loetleisten/2/index.html?ACTION=2&LA=2&GROUP=C9B&GROUPID=7792&START=0&OFFSET=16&SHOW=1&nbc=1
Mikael Hansen
2020-02-19 19:11:23 +0000 UTCJust go over to the community tab and upload it there. :)
Michael, KE4EST
2020-02-19 19:08:08 +0000 UTCIf you / we are going to build a PSU that can handle 0.00 - 400v and 0.00 - 40 Amp independently of each other, then I am 100% for it :)
Björn Ahlström
2020-02-19 18:57:27 +0000 UTCGive it all she has ;) hehe
Björn Ahlström
2020-02-19 18:53:04 +0000 UTCI’m for an adjustable plate voltage all the way to 450v (11)! It is a guitar amp after all. Great video! Looking forward to the next one.
Jeeptechfred
2020-02-19 18:38:53 +0000 UTCUser adjustable plate with a safe-ish high limit (375v ??) sounds good. Tubes are yearly maintenance for me anyway.
racerbob
2020-02-19 18:38:23 +0000 UTCPerfect timing with building this amp! I've been telling my bandmates that I'm going to build a nice tube amp. I think I'll go along with this one. I'd like to see it with the adjustable plate voltage :) And the feedback control will be nice too! Looking forward to peering inside the tubes. Thanks for making me a better tech, albeit just a hobby.
Donald R. Hricko
2020-02-19 17:58:33 +0000 UTCOH, and i really enjoy your videos and have learned so much from you, THANKS.
Ron Lander
2020-02-19 17:09:42 +0000 UTCYou are always critical of Chinese designed products that run components at their extremes. You always brag about designing your products at center values for the components. So how are you going to design this amp?
Ron Lander
2020-02-19 17:08:34 +0000 UTCJust schematic alone is a years worth of patreon. I have many power supplies to choose from a Heathkit IP-17 to a BK PVS60085MR, to power this and future projects.
Steve Foudray
2020-02-19 16:49:37 +0000 UTCTubes are a vanishing resource. I would run it at high safe. Push the ratings but not to daft levels.
Mark Baker
2020-02-19 16:36:56 +0000 UTCI have a 6146 tube that was running as an RF power amp in at 29 MHz ham transmitter that overheated and sucked a hole in the glass. Let me know how to send a picture if you want to show it.
Tom Schupbach
2020-02-19 16:34:46 +0000 UTCCould you quickly explain why the screen grid has to stay at 200v?
Oliver Prosperi
2020-02-19 16:26:42 +0000 UTCMake the variable PSU, for science, and then crank it up to 11
Oliver Prosperi
2020-02-19 16:26:03 +0000 UTCLooking forward to the next one,,, I'm building amp right now based on EL34 and seem to be having some power output issue problem (low power).and seem to think it's the output Transformers, your tips may point me in the right direction.
Silvia
2020-02-19 16:22:26 +0000 UTCrun it at 375 volts plate
God 420
2020-02-19 16:22:19 +0000 UTCPlease make the design as variable as possible. More fun for us knob twiddlers and more cause and effect to learn from. Where do you regularly buy your components from?
Mike Leslie
2020-02-19 16:11:09 +0000 UTCJust the project I’ve been looking for, Hooah
Gary Wobig
2020-02-19 16:07:28 +0000 UTCWow that tube is a beast! I’d be very interested in seeing you correlate the bias points to the tube data charts. Variable feedback is a great add. Can’t wait to see what the freq response looks like and maybe where those nice harmonics come in. Thanks!
Jason Doerr
2020-02-19 16:07:04 +0000 UTCAny chance of a part number somewhere for those terminal tie strip (Ideally in Europe?) Many thanks
Twobob
2020-02-19 15:59:01 +0000 UTCYou aren’t gonna be a rock star if you play it safe, my vote is to run it wide open.
Scott
2020-02-19 15:50:08 +0000 UTC
