Another vari-mu: Chiswik Reach Compressor

[ujszaszyistvan]

Hello dear experts including Master PRR
Can I have some questions?
It is about the 12AT7 output stage of the Tubefreak/Chiswick VK1
Please forgive my english...its not my mother language

At the moment I havent got a Sowter 8650 push pull transformer.

I have a Neutrik line transformer that can handle line driving up to +24 dBm, it is 10K:10K.
I know the Neutrik transformer not a 10K:600  but my soundcard has 1M input impedance.

Can I use my Neutrik NTL1 10K:10K line transformer for an output stage a la resistance coupled with 100K plate resistors sitting in the 12AT7 anodes and 470 ohm cathode resistors coupling with a 10mF capacitors?
By the ampbook calculator I would get 34.66 dB and 9.83K output impedance.

 

[Dr Gris]

And done...

best
//M

 

[ilfungo]

Thanks Dr Gris!!!

From some pictures I've seen that The Phoenix use as output trim  stereo 4K7 pot between secondary of transformer and output XLR...
There is also a resistor in series with a + between pot and XLR output ( seems 430R).
Can someone explain?
Impedance?
Thanks!!!

 

[JayDubrek]

So I'm having a slight issue on this... R14 6.8k resistor keeps burning out on my right channel. Using a 2 Watt resistor here...all voltages on both channels check out fine. Any ideas....probably missed something dumb...this connects to the center tap of the output transformer. The trannie measures out fine and can't trace any shorts anywhere.... Dodgy 12AT7 maybe? Hmmmm
Jay

 

[skal1]

seems you are pulling a lot of current through R14 6.8k, have you check out  vr103, R7 ?  these maybe shorted out, have a look...


skal

 

[JayDubrek]

Yep, it was a short. Couldn't see the wood for the trees, or in this case the valve base for the wires! A tiny sliver of wire had bridged pins on the valve base. This is a PTP build, not the PCB that has been discussed on here. Voltages all good now.  Just need some time to test with audio.
Cheers
Jay

 

[mrkrawn]

hi people
i buy this toroid from donaudio
http://www.don-audio.com/power-trafo-sec-220v-9v-5V

i 've wire it in serie like the picture on website.
orange and grey together.
I put L on yellow N on purple like the picture.
When i put my multimeter between purple and yellow without 230v it detect a short.
I think if i put the 230v my fuse will blow
I find that strange
Maybe i did something wrong or these transformers are faulty i don't know
if someone have the same transfomer please can you explain me

 

[mrkrawn]

Problem solved by put a bigger fuse like 500ma
Now work perfect

 

[mrkrawn]

Hi everybody

i start to build this great diy compressor
i will remove the R102 and R103 resistors.

I just want to know if i need to put a jumper or just remove these résistors

Thanks

 

[JayDubrek]

Looking good Peter! Any internal pics?
Jay

 

[mrkrawn]

Hi
anyone know what's the goal with  the dc balance trimmer?
Nice  big box peter where did you get it?
thanks

 

[mrkrawn]

Hi
anyone know what's the goal with  the dc balance trimmer?
Nice  big box peter where did you get it?
thanks

Adjust your DC offset.

ok Peter thanks
and what the good value for DC offset.

The case is from modushop. I tend to use these as if you dont want the front panel they will give you a discount and the rear panel is easily drilled.

Frank in NRG CNC cut and engraved the FPD file for me.

 

[mrkrawn]

Anyone know where connect the sidechain input jack.
should i connect it to the 6AL5 pins 2&7?
Thanks

 

[echoplex]

super old thread.. I know.
but has this ever been a DIY clone project?
can I still buy PCBs and case anywhere?

cheers

 

[ilfungo]

Hi echoplex
I've bought the PCBs time ago from
Tat Purusha.
I don't know if are still for sale, can you try contact him...
ciao

 

[dustbro]

can I still buy PCBs and case anywhere?

I have an enclosure / PCB / and toroid transformer. PM me

 

[directdriver]

I can post some circuits, let me know.

Hi KickBack. Please post some circuits please as I would love to see some of your solutions!

 

[mjrippe]

Hi KickBack. Please post some circuits please as I would love to see some of your solutions!

You are responding to a ten year old post, so don't be surprised if you get no reply.

 

[protools]

Here we are.....

 

[thomasdf]

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