Robben Ford Discussion

glasman · Posted: Wed Jul 14, 2004 9:01 am Post subject: H.A.D. Inspired Amp Project

For those of you that like to build your own equipment (I am one of those) I have just completed the first phase of my Dumble inspired amp. Still have to complete the cabinet and footswitch. I have always like building my own equipment, especially like it when you apply power and no smoke is let out and even more so when it passes a signal from gozinta to gozouta. Measured "clean" output of 49 watts. Have not tested the overdrive section, that will be tonights project.

Anyone else on this board DIYers? Just curious?

If interested take a look at my website for more details. I will post final schematics on all sections as soon as I finish the "tweaking" phase.

Here is a picture of the rear of the amp.

URL to amp project
http://www.glaswerks.com/cloneproject/clone_project.htm

Thanks and comments are always welcome!

Glasman
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bluesman · Senior Member Joined: 28 Oct 2003 Posts: 219 Location: UK

Nice one Glasman,

I also love to tweak my amps, but never built one yet.
I guess you've got good transformers and as far I can see 6L6 power tubes.
Love to see the schematics on your site and Mp3s also.

Good luck

kirk95 · Posted: Wed Jul 14, 2004 1:01 pm Post subject:

Please post some clips when you are done! Looks very cool!
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glasman · Posted: Fri Jul 16, 2004 6:07 am Post subject: Thanks for the comments

Thanks for the comments on the amp. I still have not hooked it to any speakers and hope to have time this weekend to complete the amp. I just got the footswtich finished for the amp. I will probably start on the cabinet tonight. Haven't decided on a color yet, will have to stop by my favorite vinyl shop today and see what I can find. Maybe white, cream or ???? Any suggestions??

As far as the transformers, I used Marshall 50w replacement type that I bought at Antique Electronics Supply in Tempe Arizona. I am lucky enough to work about a mile from AES and they always seem to have what I need. You are right on the tubes, right now the amp has Winded "C" 6L6's. I also have a pair of Telsa's and Ruby's to try as well. But I think it is the set of GE NOS 6L6's that will make it into the amp. Tried them in a friends Hot Rod Deville and they were just awesome.

I picked up a pair of Electrovoice OEM EVM 12L's to try with the amp. If they are too clean, will put them up on Ebay and try some Celestions.

I will put some sound clips up on the site as soon as I get it tweaked to my taste.

See ya later...

Gary (aka) Glasman
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Playing Bass, one thump at a time.
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scottl · Posted: Fri Jul 16, 2004 9:44 am Post subject:

Nice amp Gary!

You are using almost the exact specs that I revised my Fuchs with. A few differences in the midboost and the PI but other than that almost the same. Same preamp plate/cathode values and caps.

Here is a clip I just recorded of my 100 with EVM12L. I bet yours sounds even better!!!

http://www.scottlernermusic.com/new/EVMdance1.mp3

Let me know how she sounds....

Scott
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glasman · Posted: Sat Jul 17, 2004 5:16 am Post subject: It barks and speaks

Hi Scott, nice sound clip!

I finally hooked it up to a cabinet (closed back with two Vintage 30's) last night and I was very pleased with the results. The overall sound is excellent. My youngest son wants me to build him one now (he has already taken off with the other amp that I built). The only problem that I need to fix is what appears to be a ground loop that happens only when the volume control is turned all the way off. I am hoping that this will be an easy fix. Even the reverb works great. Overall I am grinning from Ear to Ear. This thing stays really clean until you hit the overdrve and then it really sings. Very touch sensitive. I may have to go back to playing guitar.

As far as schematics, I used a few different pieces. Something called the Hybrid_A, Humble overdrive specimen, reverb circuit lifted from the Mesa Mark IV. I designed my own split bias supply system, relay supplies and footswitch matrix (required using a 5.1v zener to set the correct level to the relays). As far as the relays, there are no pops or cracks in the amp when you switch, so the diodes and caps across the coils seem to be doing what they are supposed to do...

I will try to post sound clips over the weekend. But now it is time to build the cabinet (as soon as the rest of family crawls out of bed).

Gary
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Funkalicous · Member Joined: 03 Feb 2004 Posts: 9 Location: Denver, co

I have a couple of questions for you: What process did you use to Label your faceplate?? It looks very nice! I have an ODS clone project in the works myself, my only holdback is screenprinting the chassis. I build some HAD inspired amps m'self, although the tone is pro'lly more a'kin to a Steel String Singer. How did you supply power to your relay's? I've tried to rectify my fillament current but that seems to make a hum, did you use a separate transformer?
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glasman · Posted: Sat Jul 17, 2004 7:35 am Post subject:

The faceplate is actually pretty simple. The complete layout was done in corel draw version 8. Once I was happy with the layout, I printed both panels on one sheet of Epson panoramic photo paper. This paper is 8.3" by 23.4. I printed using an Epson 740 printer. Once the panels were printed I sprayed them with a Satin finish photo laquer. You can get this laquer at any pro photo shop, runs about $7 a can. After the laquer dries (about 15 minutes). I cut the panels out to final size and allow about .5 inch for wrapping around the edges of the chassis. When I al ready to mount the panels, I simply spray the backside of the paper and the chassis (masked off of course) with 3M 77 spray adhesive, count to 60 and then carefully attach the paper panel to the chassis, smoothing from center to edge. With the spray adhesive you have ONE change, otherwise start all over again from scratch. You can (but I didn't) spray the panel with a clear matte acryllic spray to add a little protection. I used this on my VT-50 that I built about 4 years ago, and it still looks great.

The relays are powered from a separate transformer (25.2 volt CT) and supply, I did not use the filaments as I could not find 6v relays locally. I used a cheap 12v relay from Radio Shack and they work prefectly. The relay supplies output was about 18v (expected) so I compensated this in the actual footswitch. Here is how I did it....

The PS is applied to the relay (reverse bias diode and a cap across the coil), the other side of the relay went to my Neutrik connector for the footswitch. Inside the footswitch the wires went from the switch to an LED (forward biased) and then to a 5.1 volt zener (reverse bias). Between the LED and the Zener (one LED and Zener per switch) the total voltage drop was about 6.8 voltages which left about 11.4 volts for the relay.

Hope this made sense.....

Gary
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Playing Bass, one thump at a time.
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glasman · Posted: Thu Jul 22, 2004 6:26 am Post subject:

Just a quick update on the clone project. Spent the last few days putting the cabinet together for the amp and that portion of the project is completed.

I learned one valuable lesson while building the cabinet. If you live in the desert (I reside in Arizona) do these projects in the winter time. I was approximately 120 degress in my garage when I was building the cabinet.

I have posted pictures of the amp in cabinet on my Glaswerks website. Here is the thumbnail of the amp.

My youngest son will be using the amp tonight at the weekly youth Jam session. Off topic, a good friend of mine runs a youth Jam session once a week at a local sports bar. It is a great experience to see the teenagers (ages run from 14 to 18 ) up there playing Clapton, Tom Petty, SRV and a lot of other great classic rock and blues.

I will attempt to get some recordings done over the next few days. The cabinet took a priority. Now it is on to the 2x12 cabinet.

Regards,

Glasman
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Playing Bass, one thump at a time.
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scottl · Posted: Sat Jul 24, 2004 9:42 am Post subject:

Nice!!!!!

You da man. Gonna sell more of these?

Scott
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midc74 · Posted: Sat Jul 24, 2004 10:19 am Post subject:

Very nice...

I just looked over all your pics and read all the information you posted on your site. You do good work! Smile

I have yet to build my first amp. My workbench is such a mess right now, I couldn't get to anything. heh

I was thinking of starting with a little 5F1 champ (single-ended 6V6). For my first project. I want to keep it simple, then move up from there. Maybe someday I will be able to build something as nice as what you've done.

Thanks for sharing Glasman.

Patrick

glasman · Posted: Wed Jul 28, 2004 7:56 am Post subject:

Hi scottl,

I have already had several requests from people to build these things. These include my son (wants a 100w version), the guitar player that I work with and a couple of local shop owners. Hmmmm, starting to sound like work to me.

But I probably will not sell these commercially, I really have limited spare time to build these in any quantity. So I will probably build a couple of these style and move onto the next amp project.

I kinda have a hankering to build an "Express" and "Liverpool" type amp. You just cant have enough toys.....

To midc74,

Thanks for the comments on the site, I like to post this stuff on the website, maybe it will help others that are trying to build their own amps.

Good luck with the 5F1 amp, should be nice when you get around to building it.

I will be taking on one commission job to build a Tweed deluxe amp for a local player friend of mine, he is wanting "an ol' tweed' to do some recording.

For those that have been following this thread... The 2x12 cabinet is almost complete. I will post pictures of the cabinet over the weekend. I cant wait to hear the EVM's with this amp.

Oh forgot to also mention that I will probably be adding the "sky" eq board to the amp. Just have to see what the difference is in the sound.

So stop by and say hi...

Glasman
(aka Gary, Opa and Hey You)
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Playing Bass, one thump at a time.
www.glaswerks.com
www.tsjband.com
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