OEPENED WHITE MARKET!!!Discrete Solid State Gain Stage For Passive EQs

I've ordered 10 boards.Who wants?

Fully working unit.Used in my Poorman's Pultec.You can use with any passive eq.

V2 BOARD






Original circuit

http://i26.photobucket.com/albums/c107/rascalseven/PEQ-2circuit.png

VERSION 2

I saw that Version 1 has problem with Poorman's Pultec about input impedance.So i decided to improve circuit and added well known impedance converter.I used Version 1 with interstage transformer in Poorman's Pultec.There is an option to use it with electronically impedance converter or transformer.

Circuit

https://dl.dropboxusercontent.com/u/91809016/SSGAIN%20V2/Circuit.pdf

By the way my Poorman's Pultec almost done.I'm waiting for enclosure to finish it.When it's done,i will share sound and video samples.So you can hear sound of gain stage.

I would like to hear the end result!

I've already got some PMEQP1A boards from Ian and had some ideas for make up gain, but this is really neat and looks good. I might be interested in a pair.

Humner said:

I would like to hear the end result!

I've already got some PMEQP1A boards from Ian and had some ideas for make up gain, but this is really neat and looks good. I might be interested in a pair.

Click to expand...

Thank you for your interest.For now i'm waiting for enclosure to finish it.You have to wait...But boards are good and working very well.If you want,i can send a pair.Just send PM.

Do you then use the same kind of transformers as the tube pmeqp1a?

Upacesky said:

Do you then use the same kind of transformers as the tube pmeqp1a?

Click to expand...

Yes.10K/10K input and 600/600 output transformer.

Hi Tunca,

Can I use 1meg resistor instead of 1.5meg?

Rob

Humner said:

Hi Tunca,

Can I use 1meg resistor instead of 1.5meg?

Rob

Click to expand...

Yes,you can,i guess.

what is the purpose of "VIA"?

Do I connect those 2 pads together?

Humner said:

what is the purpose of "VIA"?

Do I connect those 2 pads together?

Click to expand...

No.Just i showed them.They're connecting bottom and top layers.Don't touch them.

By the way i'm going out of city.No internet connection.I'll be here after a week.

Thanks. i thought that was the case as it didn't relate to the schematics.

Update!

Pre-order opened.

If i get minimum 10 pre-order,i will make PCBs.

One board for theaterguy.

Updated!

Any major changes in the parts list?  Other than two regulators?

theaterguy said:

Any major changes in the parts list?  Other than two regulators?

Click to expand...

No change.You can see schematic.

The card is here. Just few more questions.

R13  on impedance converter,  how adjust that or more accurately - what is the target?
R14  gain trim, 10k is right?
R10 10k trim, how to deal with that?

I have few trafos  from +-16V to 30V, are those ok?

Cheers

Mika

theaterguy said:

The card is here. Just few more questions.

R13  on impedance converter,  how adjust that or more accurately - what is the target?
R14  gain trim, 10k is right?
R10 10k trim, how to deal with that?

I have few trafos  from +-16V to 30V, are those ok?

Cheers

Mika

Click to expand...

Good to see that you got board.

It's simple Bo Hansen Fet Impedance Converter circuit.Just adjust R13 for +5V  on the FET source.

Yes,R14 is gain trim.Just find sweet spot for your eq.For Poorman's Pultec,need 20dB gain.

R10 adjusting impedance converter's working voltage.Adjust it to 9V.Cause impedance converter working with 9V.

The C12 (TT?) is really  a 0.22uF polarized electrolytic cap? Not the most usual corner-shop item.