Hi,
It's not an Altec 436 clone but a variation around the theme. To be acurate this is a reverse engineering of an early unit Chiswick Reach's compressor ( designed by Vick Keary ) with some mod on it ( attack and release, and dual mod). Did you spot the missing parts on this schem?
I reverse engineered a later unit and there was some slight variation with that schem.
If you want the last version of the one you posted take a look at Bernbrue's 436 on Groupdiy.
https://groupdiy.com/threads/build-nu-varimu-436-build-help-thread.69593/
Basically it is an RS124 with different tubes... sounds good if you are not about 20db gain reduction and 'slamming' things.
Here is the rs124 partial schem for comparison:
https://groupdiy.com/threads/emi-rs124.41314/page-4#post-579423
There is a bunch of mod that could be implemented like sidechain hp, very long release time,...
It's not an Altec 436 clone but a variation around the theme. To be acurate this is a reverse engineering of an early unit Chiswick Reach's compressor ( designed by Vick Keary ) with some mod on it ( attack and release, and dual mod). Did you spot the missing parts on this schem?
I reverse engineered a later unit and there was some slight variation with that schem.
If you want the last version of the one you posted take a look at Bernbrue's 436 on Groupdiy.
https://groupdiy.com/threads/build-nu-varimu-436-build-help-thread.69593/
Basically it is an RS124 with different tubes... sounds good if you are not about 20db gain reduction and 'slamming' things.
Here is the rs124 partial schem for comparison:
https://groupdiy.com/threads/emi-rs124.41314/page-4#post-579423
There is a bunch of mod that could be implemented like sidechain hp, very long release time,...
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Yes, I know it's not a clone of Altec and have a bit other question. Schematic from LTSpice will work well with 6CC42 and 12AT7 tubes?
I can't speak of unknown tubes (6cc42). The unit i've reverse engineered had 6bq7a selected tube at varimu stage.
Ask PRR about other substitute for tube. Or check what Bernbrue use ( he is the guy who drawn the initial schematic which was then 'stolen' by another member ( with incomplete pcb..) and sold on ebay at 'friendly price'... given the unit was still in production ( and the pcb was incomplete) at that time it ended... bad as there was zero support about it.
The Nu436 is the final pcb, made public 10 years after the facts...
There is a doc with possible interesting mod but there is some wrong info in it too.
If you are interested i can dig in my archive.
Ask PRR about other substitute for tube. Or check what Bernbrue use ( he is the guy who drawn the initial schematic which was then 'stolen' by another member ( with incomplete pcb..) and sold on ebay at 'friendly price'... given the unit was still in production ( and the pcb was incomplete) at that time it ended... bad as there was zero support about it.
The Nu436 is the final pcb, made public 10 years after the facts...
There is a doc with possible interesting mod but there is some wrong info in it too.
If you are interested i can dig in my archive.
Please apologise for delay.
All experiments relative to attack/release/thump are worth investigating. For the rest, well,... it's interesting to experiment but changing a stage design from feedback to nfb will change bandwith, freq response,... even more when it drive an output transformer... and given the out attenuator is a bridged T requiring impedance matching... i strongly recommend to follow 'Nu436' schematic if you want something close to an original ( don't skip the 100k feedback R 102/103 and if you use the 8650 then 160r and 200r on secondary side must be present (r143/144).
That said if you want something which add harmonics to your signal it might be fun.
But as i had an original to compare the one i built follow the original schem.
I must have the hp filter capacitors values somewhere but it isn't difficult to define anyway ( halving and playing with value of c5/c6).
All experiments relative to attack/release/thump are worth investigating. For the rest, well,... it's interesting to experiment but changing a stage design from feedback to nfb will change bandwith, freq response,... even more when it drive an output transformer... and given the out attenuator is a bridged T requiring impedance matching... i strongly recommend to follow 'Nu436' schematic if you want something close to an original ( don't skip the 100k feedback R 102/103 and if you use the 8650 then 160r and 200r on secondary side must be present (r143/144).
That said if you want something which add harmonics to your signal it might be fun.
But as i had an original to compare the one i built follow the original schem.
I must have the hp filter capacitors values somewhere but it isn't difficult to define anyway ( halving and playing with value of c5/c6).
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