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

[ForthMonkey]

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

 

[ForthMonkey]

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.

 

[Humner]

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.

 

[ForthMonkey]

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.

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.

 

[Upacesky]

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

 

[ForthMonkey]

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

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

 

[Humner]

Hi Tunca,

Can I use 1meg resistor instead of 1.5meg?

Rob

 

[ForthMonkey]

Hi Tunca,

Can I use 1meg resistor instead of 1.5meg?

Rob

Yes,you can,i guess.

 

[Humner]

what is the purpose of "VIA"?

Do I connect those 2 pads together?

 

[ForthMonkey]

what is the purpose of "VIA"?

Do I connect those 2 pads together?

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.

 

[Humner]

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

 

[ForthMonkey]

Update!

 

[ForthMonkey]

Pre-order opened.

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

 

[ForthMonkey]

One board for theaterguy.

 

[ForthMonkey]

Updated!

 

[theaterguy]

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

 

[ForthMonkey]

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

No change.You can see schematic.

 

[theaterguy]

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

 

[ForthMonkey]

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

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.

 

[theaterguy]

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