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DIY Guitar Tube Amp, Cabinet, and Speaker

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Project by knotscott posted 07-10-2018 11:32 AM 1057 views 2 times favorited 9 comments Add to Favorites Watch

This isn’t exactly fine woodworking, but it is where I’ve been spending a lot of my shop time lately. I actually started the amp about 8 years ago for two of my sons that play guitar, then put it away for several years, and finished it up this spring. The circuit is the Hoffman “stout” version of the classic Marshall 18 watt tube amp…all built from scratch. The amp features two EL84 output tubes in a Class A-B push pull configuration, two 12AX7 preamp tubes, and a 5AR4 rectifier tube. We’ve dubbed ours the “V18”.

The amp cabinet is curly maple, and has a poly finish. It was mainly built just to protect the tubes on the amp, and was made so the amp can be taken out of the box for service if necessary.

The speaker cabinet started out as a pre-manufactured subwoofer box that my oldest son sourced. I cut the back out and mounted the hardware and speakers, then built a simple pedestal. The speakers are wired so they can be used individually or together in parallel. Both are 12” speakers…one is old vintage 12”, and one is a new ET65 from Warehouse Guitars.





-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....





9 comments so far

View DDWW's profile

DDWW

90 posts in 799 days


#1 posted 07-10-2018 01:29 PM

Thats a great project and a classic clone. I like the Maple its elegant with the utilitarian design.
I have an old ampeg that needs a cap job and retube but its too loud to play anywhere but Live at Leeds.

I’m sure after 8 years your sons are ready for it.

View Mainiac Matt 's profile

Mainiac Matt

8498 posts in 2501 days


#2 posted 07-10-2018 02:05 PM

Cool project.

How’s it sound?

-- I yam what I yam and that's all what I yam

View knotscott's profile

knotscott

8138 posts in 3548 days


#3 posted 07-10-2018 02:11 PM

It sounds great IMO, and my son loves it. Hoffman took a great classic circuit and added some more gain. It gives a nice tubey sparkle when it starts to breakup without being insanely loud. 18 tube watts is nice size for local gigs, and jam sessions. I’ll see if I can get some clips of it in action.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View lew's profile

lew

12382 posts in 3928 days


#4 posted 07-10-2018 04:30 PM

What a beauty!

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View Joe Lyddon's profile

Joe Lyddon

10293 posts in 4225 days


#5 posted 07-10-2018 07:24 PM

Very GOOD, knotscott!!

It’s nice to see some OLD-Time tube electronics for a change! LOL

You have some very good space for nice air circulation to keep everything as cool as possible… BUT, it may be a little dangerous with all of that Power open to be easily touched by the human hands… Perhaps some heavy screen should be wrapped to make it safer??

COOL Job!!

Where did you find the circuit? (magazine, etc. Pop. Electronics? Ham mag’s?)

COOL way you handled the various speaker loads 4, 8, 16 ohms, etc.

Those speakers should really sound OFF… although, if the back spaces were enclosed a little better, they might sound better?

Thank you… Yes, a video would be nice…

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"

View knotscott's profile

knotscott

8138 posts in 3548 days


#6 posted 07-11-2018 12:44 AM

Hi Joe! Hopefully there won’t be any curious fingers, but the tubes are hot, so they won’t touch them more than once!

I found the Hoffman circuit while browsing around on some forums. I was looking for something in the 15-20 watt range, and the Hoffman stout was very well liked.

Closing the back of speakers could improve bass response in a hifi speaker, but most guitar speakers have open backs because don’t go into the low frequencies where it would make much difference.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View woodbutcherbynight's profile

woodbutcherbynight

5594 posts in 2581 days


#7 posted 07-11-2018 01:26 AM

Beautiful piece of work!!

-- Live to tell the stories, they sound better that way.

View Kyle Nelson's profile

Kyle Nelson

53 posts in 1487 days


#8 posted 07-13-2018 03:41 PM

Great job! That curly maple looks incredible—did you darken it at all or is that just poly?

This is a dream project of mine, and has been for a while. Maybe I’ll finally do it :)

View knotscott's profile

knotscott

8138 posts in 3548 days


#9 posted 07-14-2018 03:48 PM

I added a little darker stain to the maple, then sanded it back and added oil based poly.

The guitar and tube amp projects I’ve done have been among the most satisfying of all. So many challenges and skill sets involved. None of it rocket science, but more things to think about for sure. Plus, I really enjoy hearing my kids play music in general….hearing them play something I made is very cool. Kinda makes right angled flatwork a little boring in comparison.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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