PRR varu-Mu correction

[Kev]

:shock:
that reminds me !

I have some update info from Kent ... a correct layout I think.
FOR PRR's varimu thingy at the Factory

very sorry people and Kent ... I'll fix early next week when I'm back at work. (All the info is at my work email)
oops

 

[daArry]

I have some update info from Kent ... a correct layout I think.
FOR PRR's varimu thingy at the Factory

hmmz - what was up with the layout already done from ages back? on his own webpage it say's:

*5/28/04 fixed phase of channel one on layout. Added stereo link info."

as the last entry...

Has more happened since then?

 

[Kev]

sorry to hijack the thread
:shock:
and sorry I don't know !!!
need to get back to work to see what Kent has sent me ...

patience grasshopper ... next week I'll fix

 

[daArry]

coo :thumb:

hijacking over, looks like it got moved for yer

 

[Kev]

yes indeed it did get moved

Page is now updated.

*03/1/05 fixed resistor value on PS in the layout. Added newer chassis pic.

 

[kiira]

Where is the diyfactory Kev? I only see a small "data" link with no other information?

Kiira

 

[fazeka]

And where is the update for the PRR vari-mu? I can't find it at DIY Factory? :sad:

 

[daArry]

I dont think the nav/dir structure is sorted on kevs site from the main page - here's a direct link tho: http://www.diyfactory.com/projects/diy12au7comp/diy12au7comp.htm

 

[fazeka]

Kewl! Thanks, mate! :guinness:

 

[tk@halmi]

Thanks to Kev for the update. I have been thinking about building one of these with Edcor transformers. Still need to build or buy a tube power supply for experiments.

 

[Consul]

Every time I see the front panel lettering on those two boxes Kent had done at the trophy shop, I start to giggle uncontrollably...

 

[buschfsu]

kev i never got the jist of the stereo instructions

If you are making a stereo version with pots instead of rotary switches you need to use the resistors shown but only for one side. You then connect the FROM ATTACK of channel 2 to a point after the 1k circled in green (off of that long jumper is a good spot). On the previous version I failed to mention this so if you built it and got some distortion on channel 2 you now know why. If you are using roatary switches like me you can just put jumpers in place of all the resistors circled below. Connect the headers as shown on the schematic.


can you explain which components to leave out of channel 2? leave the second meter disconnected? im trying to make a stereo version with ganged threshold and 1 attach and 1 release.

anyone else that has done this want to chime in???


this is what i have so far



thanks
jason

 

[Sleeper]

This doesnt work. see post below
Jason, that looks pretty correct to me, as far as I've read it. which is alot these days as Im actually going to try (it's wired now, but not quite powered up yet) something different, here's my idea.
connect the sidechains at the point where the sidechain(s) feed attack and release pots and the 2 rectifiers converge (post tlo72)  I have rotary ganged switches for attack and release so I think I can keep the attack and release controls active for each side (left and right)

this way I can have independent sidechains and a stereo summed sidechain.
(a bit like gssl and oxford mode on the ultimate ssl I just built.)

I'm sure there's going to be some difference in compression sensitivity in between the summed and independent modes, but I can live with that.  
I suppose this could even be compensated for by adding a few dropping  resistors to the summed part of the switch network, but I'm unclear what those should be right now. I'll try it without compensation first.

Good luck
Kelly

 

[buschfsu]

sleeper did you ever try the dual mono/stereo mod you described? 

 

[Sleeper]

Hi Buschfu, yeah glad you reminded me about that post, I was wrong. The sidechain and compressed signal got really bent and it didn't sound good at all.

as per kents drawing you need to connect the sidechains at the junction of C1 and the 1k and R4 and R33

Theres already a connection point labelled R

It does work as I mentioned, there is a bit of a jump in compression level as the sidechain is summed.
this means you can't really A-B the signal, and I'm mine I don't have seperate physical control (I'm using 2 pole rotary switches for the ATTACK and RELEASE, 1 pole for each side) but I have seperate controls for input R and L so I can even compress dual mono sources if necessary.  but I like the a GSSL and Oxford style sidechain summing,

Kelly

 

[PRR]

> there is a bit of a jump in compression level as the sidechain is summed.

Shouldn't be.

The strap across the rectifiers does not "SUM", it takes "higher of L or R".

 

[Sleeper]

Hi PRR,
I should have said as the left and right  sidechains are summed.

at the junction of C1 and the 1k and R4 and R33

Summing doesn't happen there?  man I'm confused.
when I switch from independant sidechains to "joined" sidechians I'm seeing more compression happen.(I'd say more, but It could be less... I'm not at my bench now.  there is definitely change.

Just tell me I'm confused and I'll go back to the books again...

 

[buschfsu]

sleeper when you say this doesn't work do you mean my drawing or your "connect the sidechains at the point where the sidechain(s) feed attack and release pots and the 2 rectifiers converge (post tlo72)"???

i thought i had the board part as per kents http://www.diyfactory.com/projects/diy12au7comp/12au7_20stfix.jpg

 

[Sleeper]

OK fixed my post... Yours is fine.

Mine is a little different and keeps the full complement of attack and release gear on each side so I can have an independent sidechain mode.

I'm using 2 pole rotary switches for the ATTACK and RELEASE, 1 pole for each side

Kelly