APP Studio Ing's products - APP992 - APP14GE Germanium DOA and other kits

[ppa]

Hi Pier,
I want to build a pair of PM EQ in 500 format.
I like to know what is the in/out impedance of the board in transformless use.

Cheers

the balanced line input's impedance of the board is 20k.

the board has a fet buffer with 10 Mohm of impedance (sbalanced input) for the make-up gain stage,
it makes high to 10Mohm the input impedance of the make-up gain stage.

The make up gain stage has input impedance depending by opamp used.

With fet input opamps (ic opamps or DOAs) this stage can be set for 1Mohm or greater impedance,

with transistor input opamps, this stage can be set for the input impedance of 100k max,

however, even if 100kohm seem good, it is preferable using the buffer stage between the make up gain stage and Pulteq eq net. The reason is to reduce the noise given by input noise current of the bipolar input opamps  used in the  make up gain stage.

if are used fet input opamps into make up stage the buffer can be unused.

the out put impedance of the make up gain stage is of 100 Ohm in trasformerless mode

 

[ppa]

I like to know what is the in/out impedance of the board in transformless use.
Cheers

with +/-16V of power supply is not possible having more than 23 dBu /10kohm out in trasformerless mode, even if 23 dbu are not a bad max level.

with +-24V power in trasformerless mode with my opamps you have 26 dbu on 10kohm.

 

[creal]

Pier, thanks for advices.
i have a pair of neve 1:1 600/600 ohms (neve VT24499).
Did you think they are good for the output?
Best
Cyril

 

[ppa]

yes, it is good

 

[chrispbass]

Hi Pier, when would you like payment for the pultec/psu boards?
best
Chris

 

[Albrebreton]

Hi Pier, Sorry for my delay, I'll take four of the Pultec boards, and 4 PSU boards

Thank you
Alberto

 

[Michael Tibes]

Hi Pier, I'm in for 4 pultec IO boards and 4 psu boards as well.

Michael

 

[ppa]

Hi Pier, when would you like payment for the pultec/psu boards?
best
Chris

I am waiting other orders.

Pier Paolo

 

[Andreas Pfeiffer]

other orders, or more orders for the IO board ???

 

[ppa]

I waiting other customers to permit them to be included in this group buy 

 

[Songguy]

Hi pier,

Can you add to my order:
2 psu's

And 2 germanium DOA's if you have them.

Thanks,
Chris S.

 

[leadbreath]

ahh what the hell, count me in for 1 x Peq board.

so thats 1 x Peq and 1 x Ge DOA

cheers
mick

 

[desol]

I think i've got this all down...maybe a second set of eyes can confirm(tired today. can't.....flip....through pages...and pages...and pages......................and pages, right now.)


So, 1 pier psu will power 1 stereo Ian pultec, right? (ie: 2 i/o boards, for 4 ian pultec eq boards(hi/lo, hi/lo)
and....4 opamps are needed for the two i/o boards. 2 opamps per i/o board..unless you wanna use a transformer for each output...
then requiring just 2 doa's(inputs).


This is correct, right? zzz...

 

[chrispbass]

I think i've got this all down...maybe a second set of eyes can confirm(tired today. can't.....flip....through pages...and pages...and pages......................and pages, right now.)


So, 1 pier psu will power 1 stereo Ian pultec, right? (ie: 2 i/o boards, for 4 ian pultec eq boards(hi/lo, hi/lo)
and....4 opamps are needed for the two i/o boards. 2 opamps per i/o board..unless you wanna use a transformer for each output...
then requiring just 2 doa's(inputs).


This is correct, right? zzz...

I hope so desol, else there's two of us in need of guidance!  ;D

 

[ruairioflaherty]

4 opamps are needed for the two i/o boards. 2 opamps per i/o board..unless you wanna use a transformer for each output...
then requiring just 2 doa's(inputs).


This is correct, right? zzz...

It's late here but the above looks wrong to me.

I think it should read (corrections underlined)

4 opamps are needed for the two i/o boards. 2 opamps per i/o board..unless you wanna use a transformer for each output input...
then requiring just 2 doa's(inputs)(outputs).

Cheers,
Ruairi

 

[ppa]

the input section, that has the function to unbalance the input signal, uses or a DOA or an IC opamp to unbalance this signal (the user can put into it or a DOA or an IC opamp). In the same section there is a servo DC with a fet input IC opamp.

To sbalance the input signal you can use an (external) line trasformer in place of the input section of the IO board.
In this case, you can avoid to build the input section onboard because the line trasformer has the same function of the input section.

So , if you , want to get only DOA's in the signal path the cases are two depending if you use the input section or a
line trasformer to unbalance the input signal:

- if you use the input trasformer (only external) you need only a DOA per board, so for a stereo eq you need two DOA's

- if you use the input section of the board you need two DOA's per board, so for a stereo eq you need 4  DOA's.










edit: for orthographic error correction
 

 

[Songguy]

Green question. What does sbalance mean?

 

[ppa]

Green question. What does sbalance mean?

thanks, I have done an error, I wanted to write "unbalance",

since the verb "unbalance" means "sbilanciare" in italian, I have written "sbalance" instead of "unbalance".

I have corrected it on my previus post.

 

[Songguy]

Grazie!

 

[desol]

4 opamps are needed for the two i/o boards. 2 opamps per i/o board..unless you wanna use a transformer for each output...
then requiring just 2 doa's(inputs).


This is correct, right? zzz...

It's late here but the above looks wrong to me.

I think it should read (corrections underlined)

4 opamps are needed for the two i/o boards. 2 opamps per i/o board..unless you wanna use a transformer for each output input...
then requiring just 2 doa's(inputs)(outputs).

Cheers,
Ruairi

Great. Thanks for catching that..