Schalltechnik_04 - Pumpernickel  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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dylan159
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Post by dylan159 »

I've had this compressor for a while but put off tracing it more than once because it's a pain to trace a fully assembled, white solder mask PCB. But I made it in the end!
The main reason for me was getting into the design, calculate its parametersand maybe customize it with the help of the great documentation on the THAT website. It's a solid design and I like it even more that I know that. Sometimes I think a schematic is the best advertising for a strange customer like me, and this is one of those cases, I think it's something to be proud about. Also, I don't know if anyone wants to clone this, being it a complex design using a discontinued chip (4320 single supply adaptation? :D), but if you want of just for troubleshooting, here it is.
Since, as I said, using pictures or following traces wasn't very productive in this case, I instead took guesses from experience and datasheet circuits and confirmed them by testing continuity of each component leg with about everything else. Took some time but I'm pretty confident in the result.
pumpernickel.png
pumpernickelLED.png
The compressor part is very similar to the app notes of course: there are some value changes that I have to investigate, while others stay the same. Interesting is the Hard/Soft knee switch: there's example circuits for both but here they are combined. The bypass wiring isn't my favorite but there's a pulldown and I didn't have problems with it.
I even made a custom symbol for the 4301 since the DIP layout didn't help to show how it worked well and it was messy to draw. Enjoy! :)
Personal blog/archive: https://bentfishbowl.wixsite.com/electronics
Find me at https://discord.gg/bMuhX4TkZM Audio Electronics discord server.

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dylan159
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Post by dylan159 »

Corrected the Hard/Soft switching. It never looked right but now that I double checked it's in line with the app notes for hard and soft knee. One pole switches the rectifier's feedback before or after the diode for linearization, while the other connects the thermal compensation diode in soft mode.
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Post by Zokk »

Hi
great work!
An idea would be to design an adapter to use the THAT4305 instead of the 4301.
Like this one for example (no schematic ):
https://www.sonelec-musique.com/electro ... -4305.html

edit: full adapter documentation here
https://github.com/chuckhousley/4305-adapter

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dylan159
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Post by dylan159 »

Zokk wrote: 09 Sep 2021, 12:38 Hi
great work!
An idea would be to design an adapter to use the THAT4305 instead of the 4301.
Like this one for example (no schematic ):
https://www.sonelec-musique.com/electro ... -4305.html

edit: full adapter documentation here
https://github.com/chuckhousley/4305-adapter
yes, indeed that would be the current production replacement. The board seems to have taken care of adding the op amps missing in the newer version. I was thinking the 4320 might work too, and that one has the op amps already.
Personal blog/archive: https://bentfishbowl.wixsite.com/electronics
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Post by Reachahighernoon »

dylan159 wrote: 04 Sep 2021, 18:12 I've had this compressor for a while but put off tracing it more than once because it's a pain to trace a fully assembled, white solder mask PCB. But I made it in the end!
The main reason for me was getting into the design, calculate its parametersand maybe customize it with the help of the great documentation on the THAT website. It's a solid design and I like it even more that I know that. Sometimes I think a schematic is the best advertising for a strange customer like me, and this is one of those cases, I think it's something to be proud about. Also, I don't know if anyone wants to clone this, being it a complex design using a discontinued chip (4320 single supply adaptation? :D), but if you want of just for troubleshooting, here it is.
Since, as I said, using pictures or following traces wasn't very productive in this case, I instead took guesses from experience and datasheet circuits and confirmed them by testing continuity of each component leg with about everything else. Took some time but I'm pretty confident in the result.
pumpernickel.png
pumpernickelLED.png
The compressor part is very similar to the app notes of course: there are some value changes that I have to investigate, while others stay the same. Interesting is the Hard/Soft knee switch: there's example circuits for both but here they are combined. The bypass wiring isn't my favorite but there's a pulldown and I didn't have problems with it.
I even made a custom symbol for the 4301 since the DIP layout didn't help to show how it worked well and it was messy to draw. Enjoy! :)
Lets say I wanna use the led indicator but in a regular 9V build, is it possible to power it by hooking the -9V line to ground and what is supposed to hook to the ground line in the original schematic to 4.5V?

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dylan159
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Post by dylan159 »

Reachahighernoon wrote: 16 Apr 2022, 09:12
dylan159 wrote: 04 Sep 2021, 18:12 I've had this compressor for a while but put off tracing it more than once because it's a pain to trace a fully assembled, white solder mask PCB. But I made it in the end!
The main reason for me was getting into the design, calculate its parametersand maybe customize it with the help of the great documentation on the THAT website. It's a solid design and I like it even more that I know that. Sometimes I think a schematic is the best advertising for a strange customer like me, and this is one of those cases, I think it's something to be proud about. Also, I don't know if anyone wants to clone this, being it a complex design using a discontinued chip (4320 single supply adaptation? :D), but if you want of just for troubleshooting, here it is.
Since, as I said, using pictures or following traces wasn't very productive in this case, I instead took guesses from experience and datasheet circuits and confirmed them by testing continuity of each component leg with about everything else. Took some time but I'm pretty confident in the result.
pumpernickel.png
pumpernickelLED.png
The compressor part is very similar to the app notes of course: there are some value changes that I have to investigate, while others stay the same. Interesting is the Hard/Soft knee switch: there's example circuits for both but here they are combined. The bypass wiring isn't my favorite but there's a pulldown and I didn't have problems with it.
I even made a custom symbol for the 4301 since the DIP layout didn't help to show how it worked well and it was messy to draw. Enjoy! :)
Lets say I wanna use the led indicator but in a regular 9V build, is it possible to power it by hooking the -9V line to ground and what is supposed to hook to the ground line in the original schematic to 4.5V?
The resistor ladder can stay between 9v and ground, same as everything else concerning that part, as long as the values are scaled correctly for the desired levels and LED current, it's a matter of a few calculations. That said, that seems a secondary issue in converting it to single supply.
Personal blog/archive: https://bentfishbowl.wixsite.com/electronics
Find me at https://discord.gg/bMuhX4TkZM Audio Electronics discord server.

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Post by Reachahighernoon »

dylan159 wrote: 16 Apr 2022, 09:29

The resistor ladder can stay between 9v and ground, same as everything else concerning that part, as long as the values are scaled correctly for the desired levels and LED current, it's a matter of a few calculations. That said, that seems a secondary issue in converting it to single supply.
I plan on making a built based on the THAT4315 chip and I wanna add a LED indicator much like this one and the schematic itself for the 4315 compressor is almost identical to that of the Pumpernickel, with the exception of the power supply needed

Supposedly I can hook this LED indicator to the ratio pot of the 4315 compressor and it will work, the question is of course what are these calculations you mentioned?

Thank you anyway for your help

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dylan159
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Post by dylan159 »

Reachahighernoon wrote: 16 Apr 2022, 09:54
Supposedly I can hook this LED indicator to the ratio pot of the 4315 compressor and it will work, the question is of course what are these calculations you mentioned?

Thank you anyway for your help
The 4315 and the other in production analog engines are surely worth using over the 4301. There are small differences between each but if you've checked the documents you're good.
I mean the calculations to convert the voltage on the ratio pot to dB. In this one it's amplified 3 times and then compared against the voltage levels of the resistor ladder. Those are all worth recalculating.
Personal blog/archive: https://bentfishbowl.wixsite.com/electronics
Find me at https://discord.gg/bMuhX4TkZM Audio Electronics discord server.

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Post by Reachahighernoon »

dylan159 wrote: 16 Apr 2022, 11:05
Reachahighernoon wrote: 16 Apr 2022, 09:54
Supposedly I can hook this LED indicator to the ratio pot of the 4315 compressor and it will work, the question is of course what are these calculations you mentioned?

Thank you anyway for your help
The 4315 and the other in production analog engines are surely worth using over the 4301. There are small differences between each but if you've checked the documents you're good.
I mean the calculations to convert the voltage on the ratio pot to dB. In this one it's amplified 3 times and then compared against the voltage levels of the resistor ladder. Those are all worth recalculating.
Here is the schematic for the 4315 compressor, it is very similar in structure to the Pumpernickel

My issue is just that I dont know how to do said calculations, hell I still have no idea how to adapt the LED indicator to the 9V supply like you said

http://www.thatcorp.com/pedals/4315%20G ... 0r0A.1.pdf

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