v72 input pad again

[salomonander]

simple question i could not find an answer to:
i have a rack with 10x v72 preamps. the input pads are a 10k log pots. is this value fine?

 

[Biasrocks]

Probably not.

I would suggest using a switchable fixed 20db pad on the input and a variable fader like your 10k pot on the output.

Are you sure the pot is on the input and not the output?

Regards,
Mark

 

[My3gger]

Probably not.

I would suggest using a switchable fixed 20db pad on the input and a variable fader like your 10k pot on the output.

Are you sure the pot is on the input and not the output?

Regards,
Mark

Are you sure 10k isn't too high for output? I used more like 1k in other preamps, works well.
V71 should be based on the same circuit as V72 and i red it has resistor switchable gain from 19-43dB. It might be done with cathode resistors, similar to Lorenz V241 at 20,25dB, can't find V71 schematic to see what it is about.

 

[Dr_J]

Hi,

maybe have a look at JLM GoBetween plus variable gain Kit.
A search on JLM forum is also worth to do.

ROCK-ON!

 

[salomonander]

hey
i just did some reading. am i right that i need to build a u-pad in order to get a proper input pad? so a 3 pole rotary switch if i want to have some options? cheers

ps: im pretty sure that the pot sits on the input. ill have to double check though and im on vacation now...

 

[Biasrocks]

Yes a U pad, 20db being the best impedance match.

Mark

 

[salomonander]

hey
regarding the pots.... could i use them as output faders? or is the impedance wrong (v72 have 32ohm the pot is 10k)?

 

[salomonander]

ps: i want to go straight to my converters after the pres. my converters have a 10k input impedance. i was told to try strap a 390ohm resistor between hot and cold on the v72 output in order to match impedance. but i have no clue how connect this all to a pot on the output. would be great if i could use my 10k pots somehow. they are very nice alps and setereo.