building an etherwave

So I made a similar post a few days ago but i dont think i posted in the right place. i have a guitar amplifier i no longer use because the input is broken. the schematic for the amp can be found HERE. What i would like to do is use this amp as the base for a theremin however i am a novice at circuit construction. i have some skill with electronics but im not confident enough to just jump into this project by myself. making a component list shouldnt be too hard for me but the first problem i see myself running into is that the amp is designed to run with a 120V~60Hz 38W power supply and the theremin design calls for only 12V. I'm not sure how to make this work, my first thought is just a big resistor but it cant be that easy. also, could i potentially cut out some of the theremin circuitry and integrate it with the amplifier somehow? how would i do that? if i could i feel like i would need to change all the values on the plans

this is the schematic i found for a theremin i like

The question is "What is wrong with the amp ?" and "What do you intend to do with it?"

I see +12V and -12V in your amp. You can power the EW with that as it only draws 30ma.

(The amp wouldn't even notice it). If your DSP is bad your controls are not going to work.

You can feed the Theremin in on the long connector where it says LOUT+ LOUT-.

It might be a bit much of a project for you. Maybe you could buy a complete PCB from Moog?

There was a repair place selling them for $96 but they do not anymore. I'm not sure if Moog 

will sell you one direct... 

It took me a month to obtain all the parts. Here's a picture of mine (I haven't powered it up yet);

"The question is "What is wrong with the amp ?" and "What do you intend to do with it?"

the only problem with the amp is the input jack. i could replace it easy and have a working amp but i already have a newer and better one i use regularly. the only reasons im doing this is because it will be a challenge and i really want a theremin but im pretty broke. now, would integrating the theremin circuitry with the amp make anything redundant? perhaps i wont need to build the VCA or something?

Well you wouldn't have to build the power supply. You would want the Theremin to control volume so it's

VCA would have to stay. You can put the theremin signal in at the input and use the DSP for effects though.

The AC transformer and Speaker in the cab might modulate the tuning coils and mess up your signal if the

board is not positioned in a good spot...

 I'm not sure about saving money too. I'd guess you would spend $50 in parts to build it yourself.

"Well you wouldn't have to build the power supply. You would want the Theremin to control volume so it's VCA would have to stay. You can put the theremin signal in at the input and use the DSP for effects though. The AC transformer and Speaker in the cab might modulate the tuning coils and mess up your signal if the board is not positioned in a good spot...    I'm not sure about saving money too. I'd guess you would spend $50 in parts to build it yourself."

 $50 isnt so bad, i was planning around $80 anyway. as for the tuning coil modulation i was thinking of what i could use for sheilding, i read about aluminum being used so my first thought is that aluminum tape used in ducting, think that would do the trick if i use it to isolate the coils? 

Well it's not really possible to shield a magnetic field, you can only direct it a bit.

The coils come with a shield on them, but magnetic fields can flow into the ferrite

and excite an output in the coil. In say a TV set they shield the speaker and in some audio

equipment they shield the transformer. By squeezing the field closer to the object creating it

it doesn't get far enough to disrupt other things. Of course it responds to the 6x law so

distance will make a big difference. Here's an old Theremin with an unshielded AC transformer

that's less than 2" from a coil. I say build it and try it just keep in mind there may be problems...

These types of transformer would be a good choice (I think). Your amp might have a shielded one in it.

you can find the latest board design here. if you have eagle layout editor you can view the schematic.