I built a nasty little dual chip-dual stage op amp based on the Ruby amp that turned out very good.

Here's a schematic if anyone is interested in building their own.

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Thanks again. I really appreciate all your help with this. I'm very excited about this amplifier project. A LM386 amp with guts!

No Problem. 

I love my Ruby amp's sound and really wanted something louder with a little more balls. This fit the bill.

I tend to play my acoustic CBG through the regular Ruby most of the time because it just sounds so good through it's 6" speaker The dual chip amp is hooked up to a old Jensen 15" speaker that I pulled from an old Motorola phonograph that was powered by a tube amp. Going to build a Fender Bassman/Tweed circuit out of that when Get around to it.

Any updates Erik?

nice and simple circuit.. what gain is set on the J-FET input do you know? do you play with a wound pickup or a piezeo? with the 1M5 input resistor i am guessing a piezeo?

No Gain setting on the J-FET, each 386 chip has a 2k Gain pot.

This is a great little amp for Magnetic pickups or piezo's.

The 1M5 resistor in question is just that - a 1/4watt resistor. The J-FET circuit is the same circuit found in the Ruby amp which was my initial inspiration in making this dual chip circuit.

However, lately I made a change to the schematic and thought that I had posted that change here. The new version deletes 1 of the volume pots because both stayed all the way up in all scenarios. I also added a B100k tone pot . 

thanks. i will have to look up the circuit for the Ruby amp.

are the two gain pots ganged? that is two pots but one shaft? because if they are different pots i can see asymetric gain possible. because you are using one as an inverting amp and the other as a non inverting amp and stringing the speaker between them you can get a a full 9v swing on both positive and negative parts of the wave.a single amp is internally biased to 1/2 the supply voltage giving a 4.5V swing positive or negative. with this setup you can make the negative part of the wave less gain/quieter ot the positive. or even vice versa.... must have an interesting sound...

2 separate gain pots. When I use it the volume stays all the way up and the 1st gain at about 75%, then I can dial up the 2nd gain for what ever level of nastiness I want.

I prefer using big speakers over the small ones. My current speaker is a 8ohm-15watt WGS 10" Veteran(American Voiced) speaker, but would like to try out a British Voiced speaker some time.


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