I Just Bought a ShoBud/Evans Compactra... Now Working w/Pics

Geoff Cline · Post by **Geoff Cline** » 4 Aug 2011 11:22 am

Seemed like a good idea at the time....
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 702wt_1348

Ken Fox · Post by **Ken Fox** » 4 Aug 2011 12:08 pm

Very nice! I have schematics for it that Jim Evans gave me. Cool amp! The 6L6 GC is actually part of a regulated power supply. Very advanced think for a tube amp design by our own Jim Evans!

Ken Fox · Post by **Ken Fox** » 4 Aug 2011 12:18 pm

The reverb tank on those is driven directly from a tube, not a reverb drive transformer. Not sure what Jim would recommend there. There is not a part # on the schematic for it. Most definitely not a Fender tank for it, is it has a low input impedance, which is why they used a drive transfomer.

Ken Fox · Post by **Ken Fox** » 4 Aug 2011 12:19 pm

http://bb.steelguitarforum.com/viewtopi ... 9154beaa60

Geoff Cline · Post by **Geoff Cline** » 4 Aug 2011 12:55 pm

Cool stuff Ken. I got a copy of a Compactra schematic from Woody Woodell here on the Forum. It shows a Hammond reverb tank...but I am NOT an electrician. The schematic is also for a stereo amp with more tubes than this one has. Hmmm?

I do have a good tech locally though and I can fashion a head cabinet so I'm hoping to make this thing sing again.

Mike Schwartzman · Post by **Mike Schwartzman** » 4 Aug 2011 2:24 pm

Good find, congratulaions! I'm not familiar with that amp at all, but should you (or your tech)need any odd ball tubes, just give me a shout. I have 2 old boxes full of tubes that I inherited from a rocket scientist (literally a rocket scientist), and I'd be glad to look thru them if you need something other than the usual guitar amp tubes.

Geoff Cline · Post by **Geoff Cline** » 4 Aug 2011 2:47 pm

Thanks Mike. We'll be "neighbors" soon...my wife and I are moving back to the Baltimore area...assuming we get our house sold here.

Derrell Stephens · Post by **Derrell Stephens** » 4 Aug 2011 7:09 pm

Geoff:

I rebuilt one of those last year ... absolutely an awesome find!

Derrell

Geoff Cline · Post by **Geoff Cline** » 6 Aug 2011 9:27 am

Thanks Derrell:

I am looking forward to getting this one back in service. Having done a bit more "research" it appears to be one of Jim Evans' originals and should be a tone machine.

Lee Baucum · Post by **Lee Baucum** » 6 Aug 2011 1:29 pm

Geoff Cline wrote:...my wife and I are moving back to the Baltimore area...

What? You're leaving Texas???

So, it gets up over 100 degrees every day, for like six or eight weeks straight, and you bail out on us.

Ken Fox · Post by **Ken Fox** » 8 Aug 2011 12:54 pm

I have been having some great discussion with Jim Evans about the Compactra amp. He is going over theory of operation, etc with me via email. A very interseting piece.

Albert Talley has the first tube amp built by Jim Evans and will be delvering it to me in Nashville at the Super Jam. I will be doing a lot of investigating of the amp very soon. He told me today that Jim had in fact built around 300 of the tube amps for Show Bud.

Albert was playing with the Playboys at that time (around 1964). It was thru Albert that Shot Jackson heard the amp and contacted Jim. His first order was for 100 amps!

Geoff Cline · Post by **Geoff Cline** » 8 Aug 2011 3:35 pm

Ken Fox wrote:I have been having some great discussion with Jim Evans about the Compactra amp. He is going over theory of operation, etc with me via email. A very interseting piece.

Albert Talley has the first tube amp built by Jim Evans and will be delvering it to me in Nashville at the Super Jam. I will be doing a lot of investigating of the amp very soon. He told me today that Jim had in fact built around 300 of the tube amps for Show Bud.

Albert was playing with the Playboys at that time (around 1964). It was thru Albert that Shot Jackson heard the amp and contacted Jim. His first order was for 100 amps!

VERY cool Ken. FWIW, my amp has serial # 2045 etched into it. I should have it in hand at the end of the week. Looking forward to getting it up and running as soon as possible.

Derrell Stephens · Post by **Derrell Stephens** » 8 Aug 2011 8:18 pm

Ken: the 7027A's are key along with awesome reverb circuit ... 6CS7
D

Ken Fox · Post by **Ken Fox** » 9 Aug 2011 3:51 am

Thanks, Derrell. I just rebuilt an old Attec with the 7027 tubes and was very impressed. I am studying the schematics now and with Jim's excellent guidance I am getting a grip on the wonderful aspects of this amp.

I checked my schematic and the same was on the net for the Compactra amp. The right side was missing critical info, cropped off. Jim just sent me the full schematic and I will be glad to share that. Just PM me with an email and I will share it with anyone needing a copy.

Ken Fox · Post by **Ken Fox** » 11 Aug 2011 4:22 pm

Derrell, it just looks like the coolest tube amp circuit for steel I have ever studied. I am in the process of laying it out on a tag board style circuit with 4 x 7027 power tubes, instead on the 2 x 7025 orignal arrangement. This will be a fun project for sure. I hope to have it ready and tested for the Dallas Show!

I plan to do a Fender Twin size chassis and Vibrosonic size cabinet with a 15" Neo speaker. We have been testing the 350 watt SICA Neo standard light and it will be the one for this amp. The results have been great! Also in the works may be a digital reverb and a true effects loop designed for a tube amp. However, that original spring circuit sure looks interesting!!

David Collins · Post by **David Collins** » 11 Aug 2011 5:02 pm

Ken,

By all means, keep us up to date. Sounds really interesting for sure.

Geoff Cline · Post by **Geoff Cline** » 12 Aug 2011 2:17 pm

Ken--That idea sounds awesome. Good luck and definitely keep us informed of the progress.

I dropped off my Evans/Compactra @ Austin Amplifier today. They recently worked on a Compactra for Jason Roberts of Asleep At The Wheel...so I'm feeling pretty lucky that my local go-to amp tech has actually worked on one and got it running fine! Can't wait.

BTW, the transformers on my amp are HUGE.

Mike Schwartzman · Post by **Mike Schwartzman** » 12 Aug 2011 6:46 pm

Looking forward to seeing how this comes out Geoff. Also how Ken's new project comes out as well.

I played bass before I played steel and I have an Ampeg 1977 V4B that runs the same power tube set up...4 x 7027A's. I've plugged my steel into that amp and played it through a closed back 15" bass cab. (Steel to Volume pedal to Amp only, no effects at all). With a little adjustment on the stock controls it sounds great.

That model (V4B) comes in a shock mounted head cabinet so it's mighty heavy to haul around...huge trannies as well. But I'll bet your Compactra with the right speaker, cabinet and reverb will be a winner. I'll stay tuned for updates on the Compactra, and Ken's design too.

BTW: JJ 7027A tubes are doing a nice job in my V4B and they won't break the bank either.

Geoff Cline · Post by **Geoff Cline** » 13 Aug 2011 7:12 am

Here's a cell phone picture of the guts of my amp...before any restoration begins. Talk about your point to point!

Ken Fox · Post by **Ken Fox** » 14 Aug 2011 11:21 am

I had Jim look over the JJ 7027 tubes and he was impressed as well. I have already used them in an old Altec amp I rebuilt and they performered very well. Per Jim Evans, he chose them as they are more linear than the 6L6GC tubes and provide a better low end. Very interesting! Albert talley has the very first amp Jim built. It was called the Telstar! It is very similar to the Compactra 100. Albert is bring it to me at the Nashville Super Jam in September. I will have it in the shop for observation purposes and deliver it to the Dallas Show, along with an amp for Albert and Jim both to test out.

I have the circuit almost laid out now. I will be touching bases with Mercury Magnetics on the transformers next week as well.

Derrell Stephens · Post by **Derrell Stephens** » 15 Aug 2011 5:38 pm

keep up the vigil ken. jim turns 80 in sept.
D

Ken Fox · Post by **Ken Fox** » 15 Aug 2011 5:46 pm

Will do for sure. Working on the transformers now. Looks like Mercury Magnetics has us covered. Lots to do, but making progress!

Joel McCoy · Post by **Joel McCoy** » 21 Aug 2011 6:27 pm

This is great news. I was always hoping that someone would make an honest copy of the Compactra with a couple of modern touches (but not to many, it's just about perfect as it is..) and offer them for sale so I wouldn't have to bring my original amp out of the house. I was wondering if there's any way to date these amps? Is there a date code in the serial number? Does the Tru-Sonic 15" mean a certain year?

Ken Fox · Post by **Ken Fox** » 22 Aug 2011 5:00 am

Not sure how you would date the amp. Very nice looking example of Jim's amps there for sure.

Still working on a board layout and other issues. Transformers for a 4 x 7027 version of the amp are over $400.00 (not including freight). Looks like a very expensive amp to build and may not be feasable with today's economy. People are gravitating toward cheap Chinese amps with light weight speaker cabinets. There is not much of a market for handwired amps, I fear. An amp such as this would have to be around $2500.00- $3000.00. Considering the origianl was around a $600.00 amp in the 1960's I can see where we would easily land in such a price range or higher. I am not so sure we have any market left for such an amp.

Still, I want to develop at least one and see where it all comes in. Having built many tube amps I can easily see where this one cannot be produced as easily or economically as the steel amp we already produce, based on the old Fender high powered tweed Twin. There are no readliy avaiable chassis, fiber boards or cabinets for this amp. Everything will have to be custom made.

So, I will plug along and see where it all leads.

Geoff Cline · Post by **Geoff Cline** » 22 Aug 2011 6:58 am

Joel McCoy wrote:This is great news. I was always hoping that someone would make an honest copy of the Compactra with a couple of modern touches (but not to many, it's just about perfect as it is..) and offer them for sale so I wouldn't have to bring my original amp out of the house. I was wondering if there's any way to date these amps? Is there a date code in the serial number? Does the Tru-Sonic 15" mean a certain year?

Hi Joel:
Cool amp. Can you please tell me how the knobs are labeled, going from left to right? I am going to have to create a faceplate for the one I'm restoring now.

Also, good way to date it might be to look at the date codes on the pots...that will at least get you in the ball park.

Thanks!

Geoff

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