HA-4741 and pots

[Dimitree]

Hi

I've got a project that need a HA-4741 or 4156 chip.. How could I replace it without changes in the sound?
And in this project there are some NEGLOG pot.. Are these pots REV LOG?

thank you very much and sorry for my bad english
Dimitri

[analogguru]

HA-4741 was originally produced by Harris (later by Rayethon oand Fairchild) and is a quad op-amp pinout is the same like LM324 or TL074, but it is a low-noise version (9 nV).

RC 4156 has also the same pinout like the Lm324, but has the same chip-structure as the 4136 which is the same like a 4558.

neg log is the same as reverse log.

analogguru

[Dimitree]

So I could use a TL074? what would change?

[analogguru]

TL074 has a little bit more noise (17nV) and is faster than the HA-4741.

It depens on the circuit - without knowing the schematic, any answer would be the same as to talk about which weather will be in one year.

analogguru

[Dimitree]

it's a parametric eq.. Tomorrow I'll post the schematic.. 
thank you very much analogguru

[Dimitree]

here the schematic



there is only one IC..

could you help me now?

thank you very much

[oldschoolanalog]

Knowing what the component values are; especially those around the input op amp; would help greatly.
Also, are you using this for guitar, or something else?

[Dimitree]

yes..for guitar.. 

here some values:

C8 = 220pf
R9 = 2,2k
C11 = 100pf
C1 = 4,7uf
R18 = 10k
C14 = 22nf
R23 = 1,8k
R24 = 680 ohm
R27 = 10k
R22 = 1,5k



do we need some others?
thank you

[oldschoolanalog]

If it's for guitar, a TL074 should be just fine. Why not just put a socket there and "test drive" whatever quad op amps (same pinouts) you have?

[Paul Perry (Frostwave)]

If you can't get a reverse log, use a linear.
It will be a bit crowded at one end, but not as bad as if you used a normal log pot.
And of course read this: www.geofex.com/Article_Folders/potsecrets/potscret.htm 

[Dimitree]

could this IC be the right choose?
is it a 4156?

http://cgi.ebay.it/ws/eBayISAPI.dll?ViewItem&item=7559069504&fromMakeTrack=true&ssPageName=VIP:watchlink:top:it

[Dimitree]

please..does anybody could help me before the end of the auction? thank you.. Dimitri