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My Homebrew Vacuum Tube iPod Stereo Amplifier and Speakers


Audiophiles and hamfest regulars concur...  vacuum tubes simply produce the best audio for your stereo setup.  Why?  I can't give you the technical explanation, I'm neither an audio engineer nor a self-labelled stereophile.  I can't say that I'm opinionated one way or another as to whether vacuum tubes sound "better" than solid state.

Why I Love Vacuum Tubes

Vacuum Tube iPod Stereo

What I will profess, however, is that tube-based electronics exude a Fallout-eque, 1940's chic and mystique that new-fangled, button-ridden solid state products simply cannot emulate no matter how hard they try.

I got turned on to tube amplifiers when I was in the home audio business, selling home theater products for a living.  I found that most of the speakers I dealt with didn't really appeal to me, and frankly, were just too expensive.  After months of searching, I finally found the love of my audio life at a rickety, disorganized audio hobby shop - the Moth Audio Cicadas.  (See a review of the speakers here.)

Fortunately for me, my father is an electronic engineer and an avid hobbyist, and couldn't wait to create a tube amplifier to drive these single-driver, full range beauties.  In a weekend, it was done - a 13 watt per channel homebrew masterpiece (using original tubes from the 50's and 60's) that has worked flawlessly for daily use for almost 8 years.  I was hooked... the gentle orange glow of the tubes, the smooth analog dial... the complete lack of remote... mmm...

Best... Gift... Ever!

I digress.  For Christmas this year, my father pulled out all the stops.  We had discussed creating a tube-based stereo amplifier for my iPod.  There's a lot of commercial alternatives, but nothing's better than your own brand.  Shamefully, I kind of forgot about this discussion and he never brought it up, and I took on other projects (like my newfound love for model planes.)

iPod Vacuum Tube Amplifier

On Christmas morning, I found out why he never mentioned it.  The skilled engineer created for me a beautiful vacuum tube based iPod stereo, complete with speakers.  The wood grain cabinet complements the copper plate perfectly, and the black lacquer speakers are gorgeous.  It sounds as clear, crisp, and detailed as small tube-driven speakers can sound, and blows my Altec Lansing portable iPod stereo out of the water.  It now has a permanent spot in my living room!

Technical Details of the iPod Tube Stereo

Here's some technical details straight from the master:

Amplifier:  In order to keep the design small, I am using a hybrid design for the amplifier. A push-pull driver using a OP275 dual opamp is used to drive a pair of 5902 output tubes for each channel. A small amount of negative feedback is employed to control distortion and level the frequency response. The amplifier produces about 1.25 watts per channel. The overall gain of the amplifier is set to be used with the output from a portable MP3 player. The volume control on the MP3 player is used to set the output level.

iPod Vacuum Tube Stereo

Speakers:  The system also needed a pair of small speakers to go along with the amplifier. A two inch full range driver was available from HiVi. I put the numbers into BassBox Pro and worked out a design. I ended up with a ported box of about .035cubic feet in size. The speakers have a low frequency point of about 120HZ. They sound much better than most desktop computer setups.  A subwoofer would be a great addition, but that's a project for another day! 

On to the next project...

Vacuum Tube iPod Stereo

I'm sincerely hoping that I'll be able to use my homebrew iPod stereo for a lifetime.  I hope that my father and I will be able to share projects like this for years to come.  When I have children of my own (I know, clock's ticking, but I'm not in a hurry) I know I can't pass along his amazing technical knowledge of old and new electronics - but I just might be able to pass on this stereo.  Thanks Dad!

Read More In: Receivers and Audio Components Speakers and Subwoofers Accessories and Software

Fueled by obscene amounts of coffee and a love for all things 8-bit and shiny, Pete wants to share his experiences with you. He'll try not to twitch and fidget too much, so as to not distract you from sharing his Apple vs. PC thoughts and comparisons, wistful yearning for a return to classic gaming, and focused spout-offs inspired by a life circling around computers, video games, and gadgets.


Tags : diyhome audioipodspeakersstereovacuum tube

Discussion:    Add a Comment | Comments 1-15 of 15 | Latest Comment

January 27, 2009 3:16 PM

wow! this is faaaaannnntastic! sooooo jealous.

I'm sure I'm not the only one that would LOVE to build something similar for myself... Can you harass your dad (nicely!) into putting together a wiring diagram (assuming he doesn't already have one)?

January 27, 2009 3:22 PM

Maybe this will help? ;)

http://www.rvrlabs.net/docs/5902_Amp_Schematic.PDF

I truly wish I understood it. He's very skilled at what he does.

Thanks for your enthusiasm as well. I'm really enjoying it.

Peter Redmer
Administrator
Blog | Twitter

January 27, 2009 3:38 PM

So cool! I knew every good engineer would already have a diagram :)

Time to dust off the old circuit books and get a parts list together!

January 28, 2009 6:50 AM updated: January 28, 2009 6:50 AM

Very nice.Isn't it amazing what old people have in there head Would be nice to visit some of them locked up in homes with no one to come and visit them.
Your lucky to have your Dad and your Dad to have you cause you really like what he does for you. It sucks getting old but it's better then the alterative.

Later
Mike

February 9, 2009 5:36 PM updated: February 9, 2009 5:45 PM

wow!!! Brings back memorys, the good old days a very good website to explain the vacuum tube, how they work, how they are made. and why it is still used in a lot of applicationd in todays solid state world.
http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm
or go to the library and try to find an old RCA tube tech manuL, In the Back of the tech manual are many great do-it -yourself tube projects, inculuding the amp, described and shown here THE VACUUM TUBE IS NOT DEAD AS A LOT THINKS IT IS!

"Those who do not know their opponent's arguments, do not completely understand their own".**For complete TV repair kits including parts goto www.TvRepairKits.com

September 29, 2009 10:46 PM updated: September 29, 2009 10:54 PM

The amplifier you built is just great. I am a fan of DIY amplifier. I just built a headphone amp for my self. I like the warm orange light from the tube. It makes me feel warm. Of course, the sound is warmer than the light.

http://astore.amazon.com/iphone-amp-20

September 30, 2009 9:01 PM

Thanks for the kind words. Care to post pics of your amp? :)

Peter Redmer
Administrator
Blog | Twitter

October 1, 2009 10:55 AM

I would like to post my amp's photo here. How to do it? Please advise.

October 1, 2009 10:57 AM

Now I can only put it as my photo. I would like to put a bigger one.

October 1, 2009 12:40 PM

Have you tried the advanced editor for making posts? It makes it much easier to insert photos in threads. Click "Go advanced" underneath the Quick Reply text.

Peter Redmer
Administrator
Blog | Twitter

October 2, 2009 1:07 AM

Sorry, cannot see the "Go advanced" button. May be something is wrong. Anyway, you can see my amp as my photo. I built it by 6N1P x 3. It is thin and flat. The sound is thick and warm.

November 19, 2009 8:52 PM

I'm honored to see that someone has recreated this project here:

http://www.antiqueradios.com/forums/viewtopic.php?t=121453&postdays=0&postord...

How awesome! I hope he enjoys his as much as I have enjoyed mine.

Peter Redmer
Administrator
Blog | Twitter

April 10, 2010 11:12 PM

Dear Peter, As an old (68 yrs) stereo buff and having owned a specialty stereo shop back in the hay days of the 80's, most of us agreed that the TUBE amp. had a smoother, warmer sound to them and the TRANSISTOR amp. of the day had a harsher sound due to the "switching effect" of the transistors,   I remember those that paid high dollar for Saul Marantz's equipment and yes,  Macintosh too.  Your article brings back many fond momeries of the early days of stereo and building our own speaker baffels and using such brand name speakers as Electro-Voice and Altec-Lansing drivers. Keep up the good work!

April 11, 2010 12:23 PM

Thanks, at. I'm very fortunate to have been exposed to tube technology through my dad, and to own something so unique. I use it every day!

Peter Redmer
Administrator
Blog | Twitter

May 30, 2011 2:02 AM

NICE PIC AND SERVICES SO COMFERTABLE TO ME
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