The AIWA TP-1011 is the reel-to-reel tape preamp Richie Blackmore from Deep Purple used to drive his Marshall. I'm not a huge Deep Purple fan, but I do like the sound of some of these old reel-to-reel preamps. This layout is for the stock circuit running at 18v. If I ever get around to breadboarding the mods I tried in LTspice, I'll post another layout.
Here's the discussion on FSB, including a verified layout with a trimmer to control the first gain stage.
AIWA TP-1011 REEL TO REEL PREAMP - VERO LAYOUT
- The stock version sounds awful at 9v
- Replacing the 56k with a pot is necessary to control gain
SCHEMATIC AND POTENTIAL MODS
Reduce down from 18v to 9v. 18v had mountains of output level on tap - I can see how stories of Blackmore cooking amps could be true.
- Reduce coupling cap size to roll off some low frequencies
- Very flat response with the stock circuit
- Aiming for clean boost all the way to fuzz
- Try NPN germanium for Q3
- Trimmer to control gain of the first stage (as per FSB thread)
NOTE: images below are from the modded circuit running at 9 volts. The original will distort quite quickly, which seems to be normal. Basically to the point of fuzz.
Yessss!🤘 I'm going to try this, looking at the modded schematic you change quite a few values so I probably use sockets for all of them.
ReplyDeleteThe cap values should be safe to change without any impact. The resistor values i adjusted for 9v - not confident about that. It looks ok on LTspice…. But you never know for sure until it’s tested.
ReplyDeleteI had another look on spice. I’d say on the modded version, reduce the emitter resistor on Q1 back to 1.5k (Q4, R23 on the mod schematic).
ReplyDeleteCould increase the output cap a little, but not sure it will make any difference when it comes to guitar signals.
Got it! Thanks.
ReplyDeleteI built the stock layout. My build goes into distortion almost immediately if the Mic Level is not set to minimum. I may try out the listed mods to see if there is more clean headroom if I wanted to try to run it as a clean boost.
ReplyDeleteHello - are you running at 18 volts? It is a mic input, so it will distort quickly, but maybe not that quick.
DeleteI was running it at 18v; 9v sounded terrible with the stock layout. I will try the 56k resistor replaced with a trim pot and see how that goes.
DeleteReplacing the 56k resistor with a 50k trim pot most certainly made this more useable!
DeleteThanks for the update - I’ll make a note in the post later. I haven’t tried this one myself.
DeleteI found this digging about on FSB. Basically change the 56k resistor for a trimmer to tame the gain of the first stage.
ReplyDeletehttps://www.freestompboxes.org/download/file.php?id=14030&mode=view
Hi, thanks for the tagboard! One question, I noticed 10k 1uf after the MIC level is inverted, is there a problem?
ReplyDeleteThanks for pointing that out - corrected.
Delete