LIne level converter - need some help please.

[Beaker]

I have built some of the pre-amp circuits on here for my son. They all sound great in front of a guitar amp, and with a DI box can be run into his mixing desk for recording.

However, he wants to go the other way - guitar into pre-amp, then into his Marshall 9000 power amp and out to speaker cabs.

Not suprisingly it sounds bad, the stomp box pre-amps just don't put out enough juice to effectively feed the power amp. Hence he needs something between the pedal and the power amp to bring the signal up to the correct level.

I've scoured the web looking for something to do the job, and come across this on the geofex site.

http://www.geofex.com/circuits/Adjusticator.gif

I think it's going to do what I need it to do, but if anyone knows different, or can suggest an alternative solution, please let me know.

If it's a go-er, I'll post the link up on the requests page. Thanks guys!

[Neil mcNasty]

This might be an alternative:http://www.cgs.synth.net/modules/cgs60_sba.html
But I think you are on the right track with the Adjusticator though...

I drew up a layout for The Adjusticator, as it is a circuit that will fit nicely into my studio setup.
Give a shout if you spot any mistakes.

[Beaker]

Wow, talk about quick!

Thanks a load Neil.

[Neil mcNasty]

You are welcome Beaker!

When I saw your post, I immediately thought: "just what I've been looking for!", so I went straight to the task and drew up a layout.
Will try to find the time to build it tomorrow, so hopefully I'll be able to verify it as well...

Got lots of spare time these days since I just finished this years festival tour (doing lights for Norway's most legendary punk-rock band "Raga Rockers").
Finally some time to draw layouts, build pedals and some Cigar Box Guitars again!

[Neil mcNasty]

A thought just popped into my head:
When using just one converter, you will get an inverted signal and might come across phasing issues if you want to blend it with the original signal, or when adding a side-chain to the signal in a studio environment.
So in order to avoid this, it might be a good idea to build and Inverting Line Buffer that can be placed in front of the circuit...

This circuit will do that: http://colomar.com/Shavano/opamp-s1.gif
And here is a layout for it:

[Beaker]

Thanks Neil.

[induction]

If you don't need sub-unity gain, then a simple, super-clean, non-inverting amplifier like a Micro-amp will get the job done without any of the phase reversal or impedance issues you'll get from an inverting stage.

The only real benefit I see from the Adjusticator is that it allows for attenuation as well as amplification, but a simple volume knob on the input or output of the Micro-amp would solve that problem.