700 Series Preamp Project

AC4, AC10, AC10 Twin, AC10 Reverb Twin, AC15, AC15 Twin, AC30 Twin, AC30 Super Twin, Top-Boost, Non-Top-Boost, AC50, AC100, 710, 760, 7120

Re: 700 Series Preamp Project

Postby davefx63 on Mon Apr 10, 2017 5:09 am

Hey everyone,

As RG says, life pulls you away from your projects once in awhile, but looking to get driving further on this!
I'm getting back to where I left off which is drilling the holes, filing the slots for the switches and receptacles, etc. And I have to confess a bit of trepidation on this as I
do not want to ruin a $35 Hammond chassis, which is not steel but thin aluminum. So I'm trying to find suitable clamps and wood pieces that will support each area I drill so it doesn't buckle on me!
Also RG suggested the titanium nitride step bits that Harbor Freight sells. Just picked them up yesterday A set of 3 different sizes that fit the bill for what I need for this project and also for drilling
cast boxes for pedals, which I've done a lot of in the past. $14 and RG says they are great, so that's all I needed to know! :) I'll be taking it into work with me tomorrow and hopefully get it done this week!
Then I can paint it and mount the components and wire.. Fun fun! :)

Looks far simpler than the tag strip builds I do for these. Great job. Looking forward to getting my hands on when you release them.


I had fun stuffing the board and soldering the board that is fun to me. One thing that made it simpler for me with the organizational aspect of parts gathering, I made a project list at Mouser for this.
Since I'll likely be only building one of these (unless someone absolutely wanted one and paid me a lot of money :P) it was easier to just order it and have the parts kit ready to go.
I have a ton of resistors, caps, transistors, etc. that are not organized and for which I'm in the process of using Baseball card holders and binders to organize them with, seems a sound Idea.
So the Mouser project was great as far as my not having to search my masses of parts for everything.

EDIT: wow cool you did the whole preamp! Probably not a diy etching project. 8)


Definitely not! lol... If you are savvy with any of the PCB CAD apps, it really is so worth it to send the Gerbers to a fab house and have pro boards done.
I like OSHPARK in Oregon for small quanities (minimum of 3) and ITEAD, China for larger. If I don't want more than one, usually someone sells a board for pedal clones that are fabbed with awesome plated through holes and much easier to work with.. Speaking for myself of course ;)
I just never was that great with PnP Blue.. :P And of course, RG's boards are beyond reproach.. He's a board Piccaso :)
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Re: 700 Series Preamp Project

Postby skumberg on Tue Apr 18, 2017 9:19 pm

I still do some pnp blue and very simple pcb designs but now I usually buy boards if they exist. I value the time saved more these days. So I'd be glad to purchase a board from R.G. If that can be done. If there is some small prototype error I'm sure it can be fixed. I remember there was an error in the os117 schematic compared to pics of a real amp. I think R9 should be something else, not 3.3k?
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Re: 700 Series Preamp Project

Postby R.G. on Wed Apr 19, 2017 12:43 pm

Check your messages.

skumberg wrote: If there is some small prototype error I'm sure it can be fixed. I remember there was an error in the os117 schematic compared to pics of a real amp. I think R9 should be something else, not 3.3k?

Both the 700 series and Supreme/Conqueror/Defiant schematics were difficult to read, and contained differences from what people reported from actual amplifiers, so I'm not surprised that there would be a part value discrepancy. So far I think I got the actual part-to-part connections correct. The part values may need to be adjusted. And, just as you say, small errors even in trace routing and connections could be fixed by the trusty X-Acto knife and small wires. So far, the traces look OK.

I've sent out three of these so far. I'd really like to get feedback on whether they really do sound like the original amps before dumping them on an unsuspecting world. :lol:

Dave is my current best hope to get some auditory feedback. :D
Best regards,

R.G.
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Re: 700 Series Preamp Project

Postby skumberg on Sat Jun 17, 2017 12:57 pm

Hello everybody, how are things going? Has anyone completed one of these boards? R.G. did you receive my response? Summer is short here in Sweden so I'm not building much right now. If there are more research to be done before you'd like to sell more of these prototype boards I can wait for sure. But if there are no plans on making more of them I'm still interested in buying one for a rainy day. 8)
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Re: 700 Series Preamp Project

Postby R.G. on Tue Jun 27, 2017 6:17 pm

Found the "700" boards. Yours is in the mail.
Best regards,

R.G.
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Re: 700 Series Preamp Project

Postby skumberg on Tue Jun 27, 2017 10:11 pm

Thanks R.G, don't forget to pm payment details. 8)
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Re: 700 Series Preamp Project

Postby OASISBLUENOSE on Wed Jun 28, 2017 1:43 pm

Hi RG

Followed the thread with great interest. I'd love to get one of the 700 boards if possible.

Cheers

Steve
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Re: 700 Series Preamp Project

Postby R.G. on Wed Jun 28, 2017 8:33 pm

Well, bear in mind that although the board has been verified to work - signal comes through, and is amplified, and can be used to drive a power amp, etc. - it still hasn't been verified to produce the genteel tone of Paperback Writer yet. Still waiting on someone with time to hook this up to a tube power amp and let 'er sing. I believe in circuits, and the circuit remains the same, but still - hearing is believing!

If you're sure you want to get into it, PM me.

Forgot - I have actually located the PCBs from the back closet, so their location is known now! :lol:
Best regards,

R.G.
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Re: 700 Series Preamp Project

Postby gusfinley on Thu Jun 29, 2017 3:24 pm

I would love to see one of these connected to the effects return of the AC30CC2 or AC30C2 series amps. I ran a tubescreamer (TS9DX) directly into the effects return of my AC30CC2H when I had it and it gave a completely different sound then running it into the front end.
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Re: 700 Series Preamp Project

Postby gusfinley on Fri Jun 30, 2017 6:47 am

While we are on the subject of the 700 series amps, has anyone seen any such thing as service manuals for these?

I am more interested in the vox tube amps, but a fellow at work used to be an amp tech. He allowed me to scan his Sunn service manuals and I recall him mentioning that he had vox solid state information also. I have no idea what it is, but if there was interest, I could ask him again. I work at a different location that him now and have only since him once in the past few years.
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Re: 700 Series Preamp Project

Postby OASISBLUENOSE on Fri Jun 30, 2017 9:49 am

Never seen a service manual for the 7 or 4 series. Plenty of schematics out there now. That's about as good as it gets.
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