Spencerleehorton

1176 Gyraf compressor with 2520 DOA mod
« on: July 11, 2016, 05:16:53 AM »
Hi guys,

I am wanting to change my Gyraf 1176 compressor to use the 2520 doa as input opamp.
Is there any major changes I need to make to the circuit?

Regards

Spence.
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!


Harpo

Re: 1176 Gyraf compressor with 2520 DOA mod
« Reply #1 on: July 11, 2016, 06:09:38 AM »
Input section is built around two inverting unity-gain buffers (IC2a and IC2b=dual opamp NE5532) with their non-inverting inputs held at half supply voltage thru R3 and R4. I don't see any advantage in using a DOA in this spot and for adding colour, using a transformer instead of a balanced line receiver circuit might be the better plan. YMMV.
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Spencerleehorton

Re: 1176 Gyraf compressor with 2520 DOA mod
« Reply #2 on: July 11, 2016, 06:26:25 AM »
Ah ok, so the input to transformer and using a 600ohm T attenuator?

What about output stage?

I suppose I want to do this like the Igor F76, it's just my Gyraf 1176 sounds like crap compared to the mnats blue face 1176.
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!

Spencerleehorton

Re: 1176 Gyraf compressor with 2520 DOA mod
« Reply #3 on: July 12, 2016, 02:15:49 AM »
On investigating why the Gyraf version didn't sound very good, I have replaced all leads to patch bay and now sounds much better!
As long as I keep output down it sounds pretty good, albeit a bit lifeless and lackin character compared with blue stripe.

Going to look into API style compressor, as have  four spare 2520 doa.

Spence.
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!

Murdock

Re: 1176 Gyraf compressor with 2520 DOA mod
« Reply #4 on: July 12, 2016, 05:54:14 AM »
I Don't know if you already knew it, but there is a mod for the GSSL which incorporates four  2520 DOAs and two 2503 transformers. It is called cavendish mod. Maybe you can use them for that.