M670 compressor

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I must stop by here again and say that this thing sounds so sweet now. Many thanks again for doing this Kingston. I plan on building another when I find  some nice looking meters!
 
As a nice 'making it through wintertime' I want to start redoing my (hardly used) PM670.
I was wondering about the 5687 tubes, I used it with 1 tube in the sidechain because it was hard to get it right. But now I wanted to start using all 4 of them again but found out that one of the tubes is gone..  :eek:
So.. what are good 5687 tubes to go for right now that don't pull 20.000 of amperage and get to 23.000 degrees.  :p
Any other news on the M670 that might be of interest?
 
Just a quick headsup to Kingston for this.

This afternoon I had some spare hours and did the basic 'mods' on one channel. So no PSU, no trannies, no T pad on input but the stepped switch before the input tranny (doesn't like the load), so basically just the extra resistors, caps and things. It worked on first start (hooray  ;D).
The meter tracks a lot better and compared to the other stock (both with scamp btw) the stock channel has quite a lot of distortion while the m670 channel still sounds pretty good at 10db of compression.

Still a long way to go to get it the way I want it, but thank you Kingston!
 
stitch-o said:
https://groupdiy.com/index.php?topic=28274.msg814377#msg814377

Jumping in here now...



So the Time constant will need to be rewired as well...add to the list.
Prolly do a 'fast slow' release toggle instead of a rotary.

The 3 x 10UF can be electrolytic?


 
OK, both channels are working in testmode.
I had one issue with one of the channels at first (the one that was already working) and it turned out that T1 , on the input had died..
One of the outter legs has a broken wire/doesn't make contact any more. Those edcors are cheap, and I know the reason why.  8)
I'm about to order cinemag CMLI-10/600 trannies so I don't worry to much now. I have sound on the input, but 6 db lower since I have only connected one side to centertap now.  :p
I had mine running with the SCAMP board, and I  left it that way since I like what it does.

There is one thing that I should be taking care of now, the input T pad. I want to make it into one set of controls, so one knob for gain L R and one knob for threshold LR and 1 switch for attack and 1 for release for both channels. I don't need seperate  control for LR.
So.. for a stepped T pad, I need a 4 deck switch (I have one) but just wondering what would be a good one when it comes to values. I found this https://groupdiy.com/index.php?topic=58750.0, but not sure if it's right or not. Anyone? Or maybe another option instead of T-pad? I want/need it stepped.

Overall, props again to Kingston, finally it's working the way it should be and it can be used the way it was meant to be  :D
 
Still trying to figure out what the best solution would be for the 600r stepped input attenuator.
What would be the result if I use a regulator stepped attenuator of 600r (or maybe 1k with a sweet spot at approx 600r) instead of a t-pad? Do you think the cinemag tranny likes a lower load than 600r?
For me T-pads are new.
 
Almost done with my Mu666 compressor.  8)
Cinemag on the input made a large difference compared to the edcor's, they simply suck, soundwise but also mechannically.
I went for the 600r stepped (23 steps) T pad on the input which works like a charm.
Things to be done: replace tbe edcor on the output with a cinemag.
For the rest, it really sound great now and already used it for doing some masters and it's clean though still 'tuby', whatever that is.
mu666_1.jpg

mu666_2.jpg
 
I'm a bit behind the times, but I was thinking about doing a poor mans 670.... after reading this thread I'm going to do  a from scratch build of this instead. 8)

Thank you Kingston for all the time and energy you put in this, and for sharing it here!
 
dagoose said:
Almost done with my Mu666 compressor.  8)
Cinemag on the input made a large difference compared to the edcor's, they simply suck, soundwise but also mechannically.
I went for the 600r stepped (23 steps) T pad on the input which works like a charm.
Things to be done: replace tbe edcor on the output with a cinemag.
For the rest, it really sound great now and already used it for doing some masters and it's clean though still 'tuby', whatever that is.

Looks great ! May i ask where you got the stepped attenuators ? Are they pre-made or you built them ? I'm slowly building one of this things on a giant breadboard to experiment with it but getting the stepped T-attenuators seems quite difficult (at least pre-made)

Thanks !
 
Silvas said:
Looks great ! May i ask where you got the stepped attenuators ? Are they pre-made or you built them ? I'm slowly building one of this things on a giant breadboard to experiment with it but getting the stepped T-attenuators seems quite difficult (at least pre-made)

Thanks !
Thanks! And works brilliantly now. So much difference compared to the original design..
I uild the att's myself, I used this one: https://groupdiy.com/index.php?topic=58750.0
 
dagoose said:
Thanks! And works brilliantly now. So much difference compared to the original design..
I uild the att's myself, I used this one: https://groupdiy.com/index.php?topic=58750.0

Appreciate it. Thanks ! Very useful information.
 

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