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

[dingo]

hello! Pierpaolo
here same picture of my summing mixer done with your IO boards ,doa, fet in boards
IO boards are used for master section  and for some input
app2050,app 2055 ,melcor 1731 ,2520bc doa used
for input  your class A fet board
in total are 24 channels organized in 4 mono channels-4 mono chan. with pan pot-8 stereo input
3 stereo buss  , inserts on 16 channels, meter buffer, out transformer option on master buss
sound fantastic,clean,dynamic, very satisfied 

thanks Pierpaolo  for your help !!

 

[ej_whyte]

Hi Pier,

Are your Germanium DOAs still available? If not, any plans to stock them again?

Cheers
Elliott

 

[ppa]

Hi Pier,

Are your Germanium DOAs still available? If not, any plans to stock them again?

Cheers
Elliott

I am replacing a new stock , so i think to finish them soon.

cheers
Pier Paolo

 

[radiance]

Hi Pier,
Hope all's well. Sorry if this has been answered already, but can you explain the FET buffer part of the IO board?
For example, should I use this when the connecting the gain make up opamp to a passive EQ filter like the Pultec? See attached...disregard the tube section...

 

[ppa]

Hi Pier,
Hope all's well. Sorry if this has been answered already, but can you explain the FET buffer part of the IO board?
For example, should I use this when the connecting the gain make up opamp to a passive EQ filter like the Pultec? See attached...disregard the tube section...

Hi,

this FET buffer has the function to give an very high load to the stage connected to the input of the out stage/balancer of the IO board. 
I have insert this fet buffer stage to permit to use the version without inductor of the Pulteq EQ designed by Ruffrecord that needs a 
For the classic inductor based Pulteq EQ the fet buffet is not required because this EQ does not need an vry high input, so the impedance of the out stage/balancer of the IO board goes well in this second case.
BTW I am going to open a support thread for the IO board.

PLEASE ALL , tell me for questions.


Pier Paolo

 

[radiance]

Thanks!

 

[radiance]

Any specific reason for the on-board regulators (U3 & U4) being 12V?
It seems I can use 15V ones as well Right?

And what are the jumpers W1 and W2 for?

 

[ppa]

Any specific reason for the on-board regulators (U3 & U4) being 12V?

the only reason is that if you use +-Vcc of +-16V or +-15V you cannot use 15V regulators, but since the opamps used in the servo circuits can be powered with +-12V as well, these 12V regulators are however right.

It seems I can use 15V ones as well Right?

only if you use +-Vcc equal or greater of 18V you can use the 15V regulators 

And what are the jumpers W1 and W2 for?

many IC opamps can run properly with max supply voltages under or equal +-15V or +-18V,
if you use +-24V of power supply the regulators have the function of to make lower this power supply voltages so the IC opamps used in the servos can run properly as well.
In the case you use power supply voltages for the io board under the max values rated for these IC opamps, you can avoid to populate the IC regulators inside the board.
These jumpers connect the Vcc pins of the IC opamps used as DC servos  directly to the power supply connector of the io board, so you can power these ones with the same +-Vcc used for the board avoiding IC regulators 

 

 

[radiance]

??  ;D

 

[ppa]

Any specific reason for the on-board regulators (U3 & U4) being 12V?

the only reason is that if you use +-Vcc of +-16V or +-15V you cannot use 15V regulators, but since the opamps used in the servo circuits can be powered with +-12V as well, these 12V regulators are however right.

It seems I can use 15V ones as well Right?

only if you use +-Vcc equal or greater of 18V you can use the 15V regulators 

And what are the jumpers W1 and W2 for?

many IC opamps can run properly with max supply voltages under or equal +-15V or +-18V,
if you use +-24V of power supply the regulators have the function of to make lower this power supply voltages so the IC opamps used in the servos can run properly as well.
In the case you use power supply voltages for the io board under the max values rated for these IC opamps, you can avoid to populate the IC regulators inside the board.
These jumpers connect the Vcc pins of the IC opamps used as DC servos  directly to the power supply connector of the io board, so you can power these ones with the same +-Vcc used for the board avoiding IC regulators 

 

 

[radiance]

Thanks! I'll use the 15V ones then.

 

[ppa]

Thanks! I'll use the 15V ones then.

However, I writing a manual for the io board

 

[ppa]

just to say that I have launched a support thread for the IO board  here http://www.groupdiy.com/index.php?topic=46320.0

;D

 

[gemini86]

Hi Pier,

I'm right to assume the gainclone amp card is the PCB, only, right? Just checking...

 

[ppa]

Hi Pier,

I'm right to assume the gainclone amp card is the PCB, only, right? Just checking...

I can sell the components too,  the matter is I have written only the PCB's price.

 

[tmuikku]

Hi Pier Paolo!

how is the MOSFET amp going, did you get boards for it? What requirements for mains transformer and what voltage rails the MOSFET amp requires?

I've got two 160VA toroids that are powering +-35v rails in the amps they are currently in and wonder if I could reuse them for MOSFET mono blocks.

 

[ppa]

I have just the PCB's


the toroidals are fine for two monoblock

 

[ppa]

these boards have the PSU capacitors onboard so they need only a diodes bridge and an  trasformer

 

[zayance]

Your PM's are full, i wanted to have some informations, thanks a lot.

 

[Cormacrestrike]

Hi
I'm just about to embark on my first project building a 4 channel version of ruffrecords PMEQP1 and I'm on the hunt for gain make up and PSU options.

The I/O board looks like a good match for make-up and output for the EQ circuit so I just wanted to check if the PSU2 could potentially provide power for 4 of the boards if matched with an appropriate power transformer?

Many thanks
Cormac