Another vari-mu: Chiswik Reach Compressor

[TonyMN]

Hi,

Thank You. Yes, I silk screened it using a Yudu machine. Which I do not recommend to anyone. There are better ways to silkscreen. The lettering came out ok, but not as good as I wanted.


Prescott, I used a 100 ohm trim pot for VR103 (schematic). The BOM calls out for a 10k. (DC balance)

- Tony

 

[dmp]

Mine sounds great with the HPF on, but motorboats with it off. Tried the balance trimmers to no avail. Do I need better matched tubes?
Anyone else been through this?

 

[TonyMN]

Hi DMP,

I guess I would check to see if it's wired according to the 1SC.pdf. It sounds as if a cap might be shorted somehow in the off position.

- Tony

 

[skal1]

hay lads i confused about how to calibrate they thing the process makes no sense to me , please help..

cheers

skal

 

[dmp]

Hi DMP,
I guess I would check to see if it's wired according to the 1SC.pdf. It sounds as if a cap might be shorted somehow in the off position.
- Tony

Pretty sure it is. And it motorboats in the lower positions, not just off. There is a very low frequency oscillation through the sidechain I think.

 

[TonyMN]

Hmm, I'm just guessing here.

Is this on both channels (stereo) or is it different for one or the other channel(mono)?

Have you tried different tubes?

Are all your Sidechain caps rated for 250v+? A faulty cap?

Also you could wire the SC Backwards (Swap A for B and vice versa) so that the switches are after the caps and they are not getting blasted with the b+ voltage every time you switch. I'm not sure what the contacts are rated for.

- Tony

 

[dmp]

Is this on both channels (stereo) or is it different for one or the other channel(mono)?

Yes both channels

Have you tried different tubes?

No, but I think that I should.

 

[Tubefreak]

Just to let you know: just did a mastering job on some electro type of music and the Vari Mu was too slow to maintain the punch in the kick even with all compression off. And mine is fitted with premium NOS tubes and Sowter transformers. Api2500 and a vintage Philips compressor did the trick with this song.

With rock, the varimu is a godsend.

 

[analogica]

Hi fellas,

this is what mine does, there is a huge cut on highs from 5 K, and abit happening also on lows, some armonics appear on mids so the sound gets weird. Not sure about the transients, but the loss of air is noticible and not nice.

I went for maarten mods, sowters and same tubes...(not matched, at least by me). Is there any solution to this?

This pics are on bypass, and On with 0 compression. thanks fellows!

http://tinypic.com/view.php?pic=2ewnpci&s=5#.UtzXhhDFLIU  bypassed

http://tinypic.com/view.php?pic=kco088&s=5#.UtzZDRDFLIU  ON

http://tinypic.com/view.php?pic=35ing35&s=5#.UtzZZhDFLIU White noiz, comp ON

 

[analogica]

I mean ;D ;D ;D ;D ;D.....tubes not tested by me, I dunno if they are matched, both channels seem to behave the same...

 

[mikeyB]

Here's the one I completed about 6-months ago. I love it. It makes almost everything sound awesome.

http://www.moddefecation.com/images/crcomp/Chiswick%20Reach%20Coffin%20Vari%20Mu001.JPG

Here's More:
https://www.facebook.com/media/set/?set=a.566584430101894.1073741831.478520652241606&type=1&l=71a5846419

Hi TonuMN
Hows the bump-thump-crush implemented and whats the lo/mid/hi FD?
i'm guessing the -7dB is an input attenuator?

 

[TonyMN]

Hi MikeyB,

The -7db is the input attenuator. The Bump is the regular setting, the Crush is the thump setting on the others and the thump is somewhere in between those two (I forget the exact resistance).

The lo/mid/hi FD switch is just a switch that selects a different resistor for r102 and r103. So Low-FD would be off/no connection, Hi-FD would be 100k, and Med FD 470k. This was just an experiment and I've only used in the Low-FD (off) setting so far.

- Tony 

 

[skal1]

can a kind soul , give me the the voltages at the node of 470 ohm resistor of 12at7 and the cathode of the 6bz7 please .

cheers


skal

 

[ilfungo]

Hi
I'm starting to build this comp and need some info:
Can i use for input transformer Marinair t1148?

"
T.1448 Line Bridging Transformer. Designed specifically to isolate equipment with previously unbalanced input arrangements, this transformer may be inserted without serious loss of level.
Rated impdances: 10,000/2,5000 : 9,600/2,400
Nominal Ratio 1+1: 1+1
Primary Pins 2-4, 3-5
Secondary Pins 7-9, 8-10
Screen pin 6
Rated max input: +20 dBm (above 40 Hz)
Distortion: <0.1% (above 40 Hz)
600 Ohm source, 9K6 load <0.01%
Square waves (10 KHz, 9K6 load) No overshoot, no ringing
(Avoid stray capacity across secondary)"

There is a cheap alternative for output transformer that work?

For main transformer(toroidal)?
http://www.don-audio.com/g-pultec-power-trafo-sec-220v-9v-5V???

THANKS!!!

 

[ilfungo]

???

 

[skal1]

can a kind soul ,measure  the the voltages at the cathode of 12at7 and the cathode of the 6bz7/ ecc8* please , no compression.

cheers


skal

 

[Dr Gris]

Done.

//M

 

[Dr Gris]

Done!


Best
//Magnus

 

[ilfungo]

No prob...
Thanks!!!

 

[ilfungo]

Hi
I'm at the end of the of VK1 construction
but I have a problem with the output pad ....
the attached diagram is correct?
I do not know why but from the position 0 dB to -5 I have about 20 dB of difference
I double checked a thousand times the resistors but it's all right ...
Thanks