Transistor replacements for CS-2 compressor

[shattered]

Hello! I'm building a CS-2 compressor and would like to know if these transistor replacements would work:

• 2SK30A-Y with 2N5457 Fairchild
• 2SC732TM-GR (hFE 200-400) with Siemens 2N5172
• 2SC1815-BL (hFE 350-700) with Siemens 2N5172

I have some Siemens 2N5172 in those ranges and it would be great if they are correct for this application. If not, information about viable replacements would be greatly appreciated.

[antonis]

Hi & Welcome..

As far as I can see, JFETs serve either for buffers or switches and BJTs for buffers, phase splitters and differential & CE amps, all in rather undemanding configurations..

So, your substitutes shouldn't have any issue..
(just try for Q8/Q9 - not necessarily tight - matching..)

[shattered]

Great, thank you so much!

[shattered]

Hello! Today I've assembled the compressor and I have a problem. I didn't notice the 2N5457 pinout was different than 2SK30A-TM-Y so I installed it wrong...  I replaced it with the SMD version of a 2SK30A-TM-GR (instead of 2SK30A-TM-Y, with IDSS of 2.60-6.50 instead of 1.20-3.00). Apart from that I used the transistors specified in my first post (and pretty tightly matched Q8/Q9).

I am using this BA662 clone.

The pedal seems to work coloring the sound in a beautiful way, but volume drops intermitently while playing.

This is the schematic. I followed the original design removing the switching circuit to make it simpler and true bypass:

https://i.imgur.com/7u3Bhkm.png

Any idea on what may be failing here? I plan to make another BA662 clone to discard there's some bad connection there (SOT-363 footprint is pretty small).

[antonis]

Wire LEVEL pot lug 1 to GND instead of VB(C9)..
(same for R21 & R29)

Or make C9 value 100μF, at least..

[shattered]

Thanks for your input. I tried both mods, there's still intermitent volume drop.