CBS Audimax ll mod

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dtrnick
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CBS Audimax ll mod

Post by dtrnick »

I'm doing the JLM mod on both of my CBS audimax units. All is going well, but I have one question; Your schematic calls for eliminating R34. That being done, does R35 now connect directly to C15C, or is that entire connection eliminated?
Thanks,
Nick Stevens, Downtown Recording

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Joe Malone
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Re: CBS Audimax ll mod

Post by Joe Malone »

The mod below makes a CBS Audimax II into a fully controllable Mu comp with remote threshold. The threshold and attack and release are in a external box that plugs into the old memory plug on the back panel. Release can be done as shown or with a fixed 3.3Meg resistor and switched capacitors from 1uF to smaller values instead which is what we did in Matt's Mastering ones.

Original Audimax II circuit.
http://www.jlmaudio.com/Audimax%20II.pdf

Modified Audimax II circuit.
http://www.jlmaudio.com/Audimax%20II%20JLM%20Mod.pdf

Control box to go with above modified circuit.
http://www.jlmaudio.com/Audimax%20II%20JLM%20Mod%20control%20box.pdf
Joe :-)
JLM Audio
Capturing Audio without Injury

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Joe Malone
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Re: CBS Audimax ll mod

Post by Joe Malone »

dtrnick wrote:I'm doing the JLM mod on both of my CBS audimax units. All is going well, but I have one question; Your schematic calls for eliminating R34. That being done, does R35 now connect directly to C15C, or is that entire connection eliminated?
Thanks,
Nick Stevens, Downtown Recording
Just R34 is cut out and the green mod wire added. The rest of that connection is not used so no other changes are needed.
Joe :-)
JLM Audio
Capturing Audio without Injury

dtrnick
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Re: CBS Audimax ll mod

Post by dtrnick »

THANK YOU

Link555
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Re: CBS Audimax ll mod

Post by Link555 »

Hello thank you for posting your mod, it is very helpful. I have a CBS audimax II limiter on my desk that has been modded differently , and needs some repair. I am thinking of converting it over to you mod. I am struggling to understand how your using the 6AL5. I would be very grateful if you could explain how that part works as shown in your modified schematic? Thank you you in advance.

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Joe Malone
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Re: CBS Audimax ll mod

Post by Joe Malone »

Link555 wrote:
Wed Jan 27, 2021 12:19 am
Hello thank you for posting your mod, it is very helpful. I have a CBS audimax II limiter on my desk that has been modded differently , and needs some repair. I am thinking of converting it over to you mod. I am struggling to understand how your using the 6AL5. I would be very grateful if you could explain how that part works as shown in your modified schematic? Thank you you in advance.
The old sealed control module is removed and the voltage sum from the 6AL5 is wired out to pin 4 of the socket on the rear with the threshold reference voltage wired to pin 10 and after the new attack and release and threshold the control voltage returns on pin 2 of the socket to control input pot reference voltage (once it is cut away from the 0v ground reference) so its control the Mu gain of the 6386 tube via the linked over R40,R41 & C16&C17 so dc can pass. If adding the controls to the existing front panel then the rear socket is not really needed at all.
Joe :-)
JLM Audio
Capturing Audio without Injury

Link555
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Re: CBS Audimax ll mod

Post by Link555 »

Perfect thanks for the help and the MOD!

Link555
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Joined: Tue Jan 26, 2021 4:54 am

Re: CBS Audimax ll mod

Post by Link555 »

Thanks again Joe, you Mods worked well. The journey is here:
https://recording.org/community/threads ... bay.65248/

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Joe Malone
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Re: CBS Audimax ll mod

Post by Joe Malone »

Link555 wrote:
Sat Feb 27, 2021 1:57 am
Thanks again Joe, you Mods worked well. The journey is here:
https://recording.org/community/threads ... bay.65248/
Wow finally got to checkout the link. Nice build. Really like the new front panel look :-)
Joe :-)
JLM Audio
Capturing Audio without Injury

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