TG1 - advice from any one who has built it...

Majestic12 · Feb 4, 2017

You have to look at the schematic. The 3 way bypass switch consists of two pairs of relais. One does hard bypass from input to output. The second arrangement of relais switch between transformer or IC input and output stage.

Strawtles · Feb 5, 2017

Hello, what's the best input transformer for this compressor?

salomonander · Feb 5, 2017

Strawtles said:
Hello, what's the best input transformer for this compressor?

as far as i know its a 10K:10K when used with a 600:600 output iron. see the attached document.
the original emi input trafos in the threads beginning are looking like sowters. im using gardners in and out.
oh - and cheers majestic!

Rob Flinn · Feb 5, 2017

salomonander said:
as far as i know its a 10K:10K when used with a 600:600 output iron. see the attached document.
the original emi input trafos in the threads beginning are looking like sowters. im using gardners in and out.
oh - and cheers majestic!

I'm using Gardners too. Nice to keep the unit British

duantro · Feb 5, 2017

I'm using Marinair's t1448's on the inputs

Gearsix · Feb 5, 2017

I have used Lundahl LL1540

salomonander · Feb 5, 2017

Rob Flinn said:
I'm using Gardners too. Nice to keep the unit British

i love gardners. problem is, they do not show up anymore. im using some weired version on the input. its black and much smaller than the regular ones. its still listed under the proper octal types in the data sheet. nr MU7570. its black and small (not much bigger than the actual octal socket) i have MU7524 on the output. not finished yet. anyone have experience with the small black gardners?
im not sure if they are a MU7530 in a smaller package or a cheapout version - they weight half.....

Strawtles · Feb 5, 2017

Thank you.
Someone has compared the difference between a transformer and an opamp to balance the input of this circuit?

Rob Flinn · Feb 6, 2017

salomonander said:
i love gardners. problem is, they do not show up anymore. im using some weired version on the input. its black and much smaller than the regular ones. its still listed under the proper octal types in the data sheet. nr MU7570. its black and small (not much bigger than the actual octal socket) i have MU7524 on the output. not finished yet. anyone have experience with the small black gardners?
im not sure if they are a MU7530 in a smaller package or a cheapout version - they weight half.....

I like Gardners a lot too.

I'm using the big silver ones on input & the small black ones on output. I never had a problem with the smaller ones. They work great. I have a stash of both types for future projects .

Rob Flinn · Feb 6, 2017

Strawtles said:
Thank you.
Someone has compared the difference between a transformer and an opamp to balance the input of this circuit?

I built one with an op amp input and a carnhill output. Sounded very nice.

Strawtles · Feb 6, 2017

Thank you Rob
What opamp/circuit have you used ?
I'd like to try this solution
I'm interested mostly in balancing the input ... the circuit adds his colour, so I don't think it is really necessary an input transformer to increase it

Rob Flinn · Feb 6, 2017

Strawtles said:
Thank you Rob
What opamp/circuit have you used ?
I'd like to try this solution
I'm interested mostly in balancing the input ... the circuit adds his colour, so I don't think it is really necessary an input transformer to increase it

I think I used an OPA604 as suggested by Igor. You're right in that a lot of the vibe comes from the circuit. If one does the chandler type circuit I think the transformers would make a much bigger difference since from what people say the input transformer is saturating quite a lot.

Strawtles · Feb 6, 2017

Rob, do you have this circuit?

Rob Flinn · Feb 6, 2017

Which circuit ?

salomonander · Feb 6, 2017

Strawtles - this might help:

Strawtles · Feb 6, 2017

Thank you Salomonander but I'd need the OPA604 input schematic

Rob Flinn · Feb 7, 2017

Try that. I seem to remember using jumpers instead of the relays in places. It took some head scratching to get it all working because you want half of one varient & half of another working at the same time.

Strawtles · Feb 7, 2017

Thank you Rob, I'll try to take away what I don't need

salomonander · Feb 13, 2017

does anyone know the value for "CZ" on the bypass board? right next to the big molex header.... i cant find the info. im using 1:1 transformers. cheers

ps: also wondering if this willrun with 2520 opamps or only 990 types.....

Majestic12 · Feb 13, 2017

salomonander said:
does anyone know the value for "CZ" on the bypass board? right next to the big molex header.... i cant find the info. im using 1:1 transformers. cheers

ps: also wondering if this willrun with 2520 opamps or only 990 types.....

The zobel capacitor and resistor depends on the kind of transformer you're using. If the datasheet does not specify a suitable zobel network you can only measure the frequency response and adjust the value to compensate any high frequency bump.

The opamps will run on the same voltage as your power supply. If you are using +-24V it will burn out any opamp that runs on lower voltages (2520 and similar).

TG1 - advice from any one who has built it...

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