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May 20, 2024, 06:04:59 AM

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Lab Series L4 Bass Preamp

Started by Tassieviking, September 05, 2022, 12:19:54 PM

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G'day guys and gals
I have been wanting to make a Lab Series Pedal for a while, recently I was talking to a young dude who plays Bass in "June And The Desert Flames".
While I was talking to him I realized he does not have a lot of gear and I can easily build some Pre-Amp pedals and some effect pedals for him fairly easy.
I have some PCB's for Sunn Beta pedals, Chunk System Brown Dog/ Agent 00Funk, etc at home.
I also thought it might be a good time to get into a Lab Systems PCB, the L4 Bass is simpler then the L5-L11 pedals so its a good starting point for me.

I have tried to change the CA3094 and CA3080 IC's to one LM13700 IC, but I am not that good on theory, I gave up working as an electrician 15 years ago because of all the narcotic pain killers I have to take every day.

Could some of the really great people who post here check my changes please and see if it is feasible to replace the 2 IC's with one LM13700 please.

I have read through lots of posts on this type of modification on the net and did the best I can, my brain is too forgetful to try working it out or trying to simulate it.
If someone knows how much the +- 15V rails use would also be great, I would love to power it from a LT1054 or similar on 9V supply.


There are no stupid questions.
There are only stupid mistakes.


I should also include the original schematics I started with I guess.
Also the OTA's datasheets.

I would love to make up a PCB for a full preamp and use a class-D power amp with it.
And also a Pre-amp pedal.

Has anyone else ever noticed that the TPA3116D2 Bridged 100W amplifier module with XH-M542 written on the bottom fits easily into a 125B pedal enclosure with plenty of room for 2 jack sockets and a power socket at the top end. (2-4 ohm in bridged mode)

Run it on a 4.5V wall wart for approx 5W output to 24V for 70Watt output at 1% THD
Advertised as 100W output or 120W on most E-bay stores, but distortion is 10% THD.
Google TPA3116D2 or XH-M542 amp and you will see the one I am talking about.

Rock up to practice with 2 pedals and a speaker cab and blow them away ?
 Most of us can grab an old laptop power supply from somewhere to power it,

Anyhow, here are the rest of the schematics :-
There are no stupid questions.
There are only stupid mistakes.