New VariMu Comp

peter05

I thought I would share what I have been up to over the winter months....

Vari Mu compressor I have been building for a few months, it is a monster point to point. It is a bastisd between Altec436C and a Chiswick VK1 which later went on to become the Thermionic Phoenix. The Compressor has defined output, instead of moving in 5db steps it now moves in 1db steps. The closer to 0db it gets it starts moving in .5db steps. It has a more defined Threshold/Attack and release. Can be a very quick to very slow attack/release. Also included is an internal sidechain which will be controlled from another 1U rack and Thump function which mimmicks a DC attack. Final version will have Lundahl trafos on the input and some Sowter trafos on the output. I am hoping to have this in the racks CHR-Mastering sometime over the summer.

My main love is varimu and opto comps. The reason for this build really is that 99% of varimu comps are slow compressors and the 1% I have come across I are not transparent enough for mastering. This one can be very fast when setting radio masters.

Build cost is somewhere between 2.5k and 3k not including the labour.
The I/0 trafos alone set me back just over 1k.

I dont put this down as an easy build as I am dealing with AC voltage and current and safety comes first. I usually leave sitting for 2/3days after a power up as the PSU caps can hold a voltage of 350ac and its nowhere clever to go near the circuit till they discharge their voltage and current. So, you can imagine its a very time consuming build.

fitz

peter05 wrote: »

I thought I would share what I have been up to over the winter months....

Vari Mu compressor I have been building for a few months, it is a monster point to point. It is a bastisd between Altec436C and a Chiswick VK1 which later went on to become the Thermionic Phoenix. The Compressor has defined output, instead of moving in 5db steps it now moves in 1db steps. The closer to 0db it gets it starts moving in .5db steps. It has a more defined Threshold/Attack and release. Can be a very quick to very slow attack/release. Also included is an internal sidechain which will be controlled from another 1U rack and Thump function which mimmicks a DC attack. Final version will have Lundahl trafos on the input and some Sowter trafos on the output. I am hoping to have this in the racks CHR-Mastering sometime over the summer.

My main love is varimu and opto comps. The reason for this build really is that 99% of varimu comps are slow compressors and the 1% I have come across I are not transparent enough for mastering. This one can be very fast when setting radio masters.

Build cost is somewhere between 2.5k and 3k not including the labour.
The I/0 trafos alone set me back just over 1k.

I dont put this down as an easy build as I am dealing with AC voltage and current and safety comes first. I usually leave sitting for 2/3days after a power up as the PSU caps can hold a voltage of 350ac and its nowhere clever to go near the circuit till they discharge their voltage and current. So, you can imagine its a very time consuming build.

Beautiful, Peter...

TroutMask

Hi Peter,
what a wonderful project! Thanks for sharing this. PSU caps can be easily and safely discharged with a low-wattage mains lightbulb–say a 15–25 Watt 240 Volts AC bulb. The type that go in a cooker work quite well–get a bulb socket and wire a couple of tails to it. I built a fancy set once that consisted of a bulb wired to a pair of multimeter probes–touch the probes to the cap terminals and the bulb will light up and then fade gently as the caps discharges–when the filament lights, the increased resistance prevents any damage to the cap, and any dangerous sparking of the type that you might get it you tried to short the cap directly (not recommended–bad for the cap and bad for humans!).

peter05

Ah I still dont like to be messing around those caps. All it takes is a bad shake in the hand and you have shorted the pins.

TroutMask

Shrouded alligator clips are your friend Just got the CD back from Disk Wizards BTW - sounds great!

peter05

Didnt even think of those. Now I can leave a multimeter attached the whole time. Thnaks Rich. Glad that CD came back. When is your release date?

TroutMask

March 7th (last night) in Holland! I'll get you a copy, please PM your address Cheers, TM

mart1977

Wow! Was this a kit from somewhere or where did the schematic come from?
Looks a little like a Fairchild aesthetically

peter05

I am afraid there are no kits available for this. Just two schematics.....