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Vacuum Tube Amplifier

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Project by DBrown52 posted 09-05-2013 06:25 PM 1779 views 11 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

HillbillyShooter

4905 posts in 1046 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

DBrown52

30 posts in 484 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

theoldfart

4778 posts in 1204 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.

-- "Aged flatus, I heard that some one has already blown out your mortise." THE Surgeon ……………………………………. Kevin

View Gassit's profile

Gassit

33 posts in 991 days


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

Hi,

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

Thanks!

View crank49's profile

crank49

3524 posts in 1724 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.
http://www.mcintoshlabs.com/us/Pages/Home.aspx#

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 :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View DBrown52's profile

DBrown52

30 posts in 484 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

DBrown52

30 posts in 484 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

Gassit

33 posts in 991 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

178 posts in 2134 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

Albe

185 posts in 764 days


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

Nice amp and chassis.

-- Pain is temporary, quitting last forever.

View SirFatty's profile

SirFatty

472 posts in 965 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 dave.spalla.com

View Gassit's profile

Gassit

33 posts in 991 days


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

Albe,

Sounds like a girl I used to know…

Mark,

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

View robscastle's profile

robscastle

1881 posts in 958 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

Ken90712

15337 posts in 1942 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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