Welcome to Solid State Guitar Amp Forum | DIY Guitar Amplifiers. Please login or sign up.

March 29, 2024, 08:15:04 AM

Login with username, password and session length

Recent Posts

 

Preamp project based on Ampeg VH-140c

Started by DFH120, August 28, 2009, 03:45:14 PM

Previous topic - Next topic

DFH120

Hi everyone,
   I'd like to make a rackmount preamp based on the VH140c.  I have all the schematics (very grainy hard to read) and I'm in the process of making the parts list.   I haven't worked with electronics in about 10 years, so I'm spinning my wheels trying to get started.  I know I can handle the layout/soldering etc...  First I want to ask if anyone has already done this project?  Second, I don't feel comfortable trying to extract the preamp/effects/power supply sections from the schematics.    I'd really appreciate it if someone could draw me a schematic (I don't care if it's crude as long as I can read it) of just what I need, including how it would interface with my rackmount poweramp(Marshall 8008).  I realize this is a helluva favor to ask, but I'd be willing to send compensation via paypal.  I just want that killer death metal distortion, chorus and reverb in my rack setup.  Any help is greatly appreciated.   8| :)

teemuk


DFH120

Wow!  Thanks Teemuk 

Now that I've seen the complete schematics, I'd rather build it without the chorus or reverb.  If I build this without the chorus/reverb circuits, will I need to make any adjustments to the other circuits? I think I can handle this project if someone could give me guidance on the power supply and line-outs?  Is there a way to extract just the distortion and make a stomp box?
I may have to scrap this project if I can't find enough info to put my mind at ease. 

J M Fahey

To begin with:
QuoteWow!  Thanks Teemuk 
again
To go on:
Dear DFH120:
It's a *VERY* complex amp.
Sounds killer and I understand why you want to build one, but cloning it will be a hard job to anybody, I think resurrecting this great amp will need a Team effort, or being ready to spend a very very long time.
Besides I'm not sure that turning it into a stompbox will sound as good as the full beast.
I consider the design of a PCB the hardest part by a long way, and doubling the amount of components quadruples the difficulty.
If absolutely decided to do it, I'd rather copy the original , which at least works, and if necessary just don't populate what you don't need.
I guess that would turn something almost impossible into something just difficult.
By the way, the "clean" channel is very close to the Powerblock preamp.
Not that that surprises me.
Good luck and consider the options.

DFH120

I understand.  8)  Ain't nothing like real thing.  In hindsight, I should've known if it was possible, 'cause someone would have done it.  Thanks!

eze7782

hi man from argentina (bad english), i make this preamp and its a killer amp, tested and verified, the best part is the hi gain channel, the clean one its also very good, i have the pcb on expresspcb, i tried make it as a stompbox and with a 7660 doubling the voltage it work but its better 15v simetrical, i leave you the thing ig you want to build it, here at argentina i workdoing this, amps and stompboxes, so i tried alot of things, and also make my own pcbs, in the schematic  i leave behind the effect loop footswitch  and reverb, just the both channels and buffers saludos.

phatt

Quote from: DFH120 on August 28, 2009, 09:16:43 PM
I understand.  8)  Ain't nothing like real thing.  In hindsight, I should've known if it was possible, 'cause someone would have done it.  Thanks!

Just had a look at the schematic and *IF* you just want the preamp parts (A and B Ch)
Then I believe it would be a doable project.

Even easier if you only want *One Ch* as a stand alone preamp.
Just delete all the relay stuff,, that will bring the part count right down for you.
Just a thought.
Phil.