IVP Preamp transistors

D

DDad

Active member
I am ordering parts for an Aion IVP Preamp board (I have mostly PPCB boards). The schematic has modern transistor values but has comments like these 'Substitute. Original uses 2N4401'

2N3904 - 2N4401
2N3906 - 2N4403
2N5088 - 2N5910

Anyone know if these are direct replacements without having to adjust resistors for bias?
Anyone build this with the original transistors?

I have all of the above so would like to use original values if I can.
 
The substitutes are fine, these are general purpose transistors so as long as specs are identical it will function the same. The only reason to source the older components is to pretty much say you have them. Same with the C2M EQ potentiometers, they are out there but very expensive. I recommend sticking to the build doc with the newer parts and EQ scaling correction.
 
anevilspar7an said:
The substitutes are fine, these are general purpose transistors so as long as specs are identical it will function the same. The only reason to source the older components is to pretty much say you have them. Same with the C2M EQ potentiometers, they are out there but very expensive. I recommend sticking to the build doc with the newer parts and EQ scaling correction.
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Just to make sure, no re-biasing is required, correct?
 
Yes, otherwise the build doc would say so. Kevin from AionFX is a solid dude and one of the only diy guys that will explicitly state when you need to change a part to make non 1-1 substitutions work.
 
anevilspar7an said:
Yes, otherwise the build doc would say so. Kevin from AionFX is a solid dude and one of the only diy guys that will explicitly state when you need to change a part to make non 1-1 substitutions work.
Click to expand...
OK, then if you had both sets of transistors, which would you choose?

Are modern transistors more reliable/thermally stable/etc?
 
I would use the modern equivalents, a lot of the nos stock stuff is out of spec so unless you want to test each piece it's not worth it, especially since there is no 'enhancement' in the sound of the pedal using them.
 
Some of the only circuits that benefit from old mojo parts are fuzz and wah pedals. You can get unique sounds from identical pedals by just using a way out of spec part.
 
Of course man. I hope to see that in the build reports soon, we don't see too many of the more involved builds here so good luck and make sure you are using the correct value resistors. I can't tell you how many times I've been stumped by something and it was me using a 1K in place of a 100K.
 
Not ready to build it yet, I have over 100 other boards to build first, this will be the last one I think. I am making a set of heirloom pedals for family, as something they may remember me by (retirement hobby, even though I'm not fully retired yet).

I measure every part that I can. I even have 2 micro protoboards that are set up with ZIF sockets to test single and dual op-amps. I have a peak 75 with a board and ZIF socket to test diodes and transistors. I have been burned before by not measuring/testing. It's hard enough with my old man eyesight to make sure I am putting them in the correct spots. I don't want to spend time on out-of-spec or wrong value components.
 
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