Vacuum Tube Amplifier

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Project by DBrown52 posted 09-05-2013 06:25 PM 2201 views 12 times favorited 14 comments Add to Favorites Watch

This past winter, I discovered a community of people online who build their own audio equipment based on old vacuum tube and transformer technology. I’m an engineer by trade (BioEng/ChemEng) and couldn’t help myself so I learned all about audio circuits, ordered a bunch of components, and got to work with the soldering iron to build this SE amplifier. It needed a chassis, so I built this box from red oak and cherry with an aluminum top. It is constructed with mitered ends, supported by corner keys and splines – alternating the contrasting wood for aesthetics – and the polished aluminum top rests in a rabbeted groove. There is quite a bit of hidden support because the transformers (blue things) are mostly steel and very heavy. It was a really fun project and I love how it turned out. And it sounds great. This photo was taken before the wood was finished with a simple clear coat; at some point I’ll add the final photo of it operating in the entertainment center that I previously posted.

14 comments so far

View HillbillyShooter's profile


5550 posts in 1385 days

#1 posted 09-05-2013 07:19 PM

Neat project—I’ve heard that the old vacuum tube and transformer technology has a much “warmer” sound than the modern digital, any observations you’d care to share in a woodworking sense of course.

-- John C. -- "Firearms are second only to the Constitution in importance; they are the peoples' liberty's teeth." George Washington

View DBrown52's profile


58 posts in 823 days

#2 posted 09-05-2013 09:13 PM

Thanks Hillbilly. You can find plenty of science, and unfortunately plenty of pseduo-science, on the internet about digital vs analog sound amplification. I’m probably not the best person to ask. For me, it was more about a fun winter project than anything and a chance to try out corner keys. Although I will say that hi-fi audio like this really can make a difference in listening, even for a novice ear like mine.

View theoldfart's profile (online now)


6591 posts in 1544 days

#3 posted 09-05-2013 09:47 PM

DB, specs ? Wattage, SN. Is it a mono block. Really nice work. I really want a set of mono blocks for my system.

-- "With every tool obtained, there is another that is needed" DonW ( Kevin )

View Gassit's profile


37 posts in 1330 days

#4 posted 09-05-2013 10:29 PM


Is there any chance you could provide a link to the details for constructing the SE amplifier you built?


View crank49's profile


3903 posts in 2063 days

#5 posted 09-05-2013 10:42 PM

I grew up with tubes and such. Second job out of high school was working as a TV repair technician.
Here’s a link to Macintosh Amps to see some new tube stuff.

The only source for vacuum tubes today is Russia. No one in the USA in making them.
And get ready to spend some jack.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

View DBrown52's profile


58 posts in 823 days

#6 posted 09-05-2013 10:43 PM

I’ll tell you what I know. It’s a stereo, not mono, amplifier. You have options for tubes and a choice of ultra linear or triode mode as well as a switch for cathode feedback so wattage can vary anywhere from 5 to 14 watts. Not much juice, but it will shake the walls with my 90 dB Polks. I can tell you the noise is low enough that there is no hum with these high-ish efficiency speakers. It runs between 450v and 500v of B+. You can read more about the circuit design if you google “Tubelab Simple SE”. Tubelab provides the PCB and the circuit design and you do the rest. There us a huge support community however. Currently I’m using Edcor transformers and JJ EL34 tubes, but would like to try 6L6 sometime soon

View DBrown52's profile


58 posts in 823 days

#7 posted 09-05-2013 10:45 PM

Crank, you can get these pentode tubes pretty reasonably priced online. There are markets in Eastern Europe, Russia, and China. It is true that old American made tubes are expensive.

View Gassit's profile


37 posts in 1330 days

#8 posted 09-05-2013 11:12 PM

Never heard a tube amplifier, except for an old AM radio when I was a kid.

Really happy with a Denon AVR-1911 solid state receiver at the moment but I’ll try and get a listen to some tubes next month.

Hope I don’t get hooked cause cash is running out fast.

View Mark Gipson's profile

Mark Gipson

184 posts in 2473 days

#9 posted 09-05-2013 11:35 PM

Careful Gassit, I started with just a listen and have tube mono blocks driven by a tube pre amp now!

Nice job on the build, both wood and electronic.

View Albe's profile


201 posts in 1103 days

#10 posted 09-06-2013 01:45 AM

Nice amp and chassis.

-- Pain is temporary, quitting last forever.

View SirFatty's profile


510 posts in 1304 days

#11 posted 09-06-2013 01:51 AM

nice work!

The “warmer” sound is from the smaller dynamic range and lower slew rate.

-- Visit my blog at

View Gassit's profile


37 posts in 1330 days

#12 posted 09-06-2013 02:00 AM


Sounds like a girl I used to know…


You’re right. I’ll drop a hint for Christmas.

View robscastle's profile


2576 posts in 1297 days

#13 posted 09-06-2013 07:07 AM

OMG Bottles haven’t seen any for years.
Always produced the best sound.

I had a EHT rectifier tube ages ago and it was like a girl also, every time you went near it or touched it you got bitten (tee hee)

Oh BTW nice wood work too!

-- Regards Robert

View Ken90712's profile


16047 posts in 2281 days

#14 posted 09-06-2013 08:45 AM

Awesome love this old technology.. What a fun and cool project!

-- Ken, "Everyday above ground is a good day!"

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