the pimp / mod the Poor Man 660 thread

[lolo-m]

Hey guys... sorry if I missed it but what is the Fastest Attack Time with the "Stock" circuit?

Actually, what are the ranges of the Attack & Release with the stock circuit?

I can check more precisely later if you want, but faster attack time is around 1 or 2 ms stock... But the attack look like the second wave curve there, Fairchild's position 1,2,3 and 4 look like the first...

Release time is program dependant from 48ms up to 2,3s but again program dependant. Don't think I don't like the Analag's design. It does work perfectly as is . I will leave Analag's time constant circuit in mine... But I want more !!!
I'm just playing with a marvellous toy ! I would be proud to say Rowan made an error there or there but he didn't make any error... Analag's gave us a really finished compressor that poeple would buy 2500€ in the shops as is...
There are some limitations that I want to overpass... And most of all, I learned more in 2 months than before in 2 or 3 years !!!

 

[Moby]

Great Lolo, I think that Volker will have one more PCB design to do  Volker, are you around?  ;D

 

[emrr]

Lolo, your second attack response appears to show tube imbalance, since the shape is not symmetrical.  That looks like the example given in the Collins 26U manual.

 

[analag]

I can't help to wonder where the "Designer" of this project is & his input on the "Side-chain" subject or even an explanation of WHY he chose to build it this way.  ???

If nothing else... it could help those of us who wish to have more options with the sidechain understand a little better what direction to go.... or not to go.

Rowland... you out there bro? :-X

I do follow this thread. I try not to influence the direction the DIYers want to take.

 

[lolo-m]

Yes, there's maybe some unbalanced tubes. But what I want to point is:
The same channel was used for the two waves. The only difference is that I changed the network. The attack isn't linear because the first peak charges the 220nF (100nF in my example) and then the 10uF (1uF in my example) gets charged through the 10K resistor... This is why the volume changes after the peak reduction down to stabilisation. You've got the same attack shape in the position 5 and 6 in a real Fairchild (more symetrical with well balanced tubes). Analag's time constant network is a usable position 5 and 6.

Analag, am I right ?

 

[[silent:arts]]

Volker, are you around?  ;D

I'm lurking :-X

so many options ;D

and I'm still happy with my unmodified prototype ;D ;D

 

[lolo-m]

As I said sooner, I will keep a non modified mode in mine... Plus a modified one for different purposes.

Stock mode does work really well... Better than what I was thinking when I received the boards  ;D !!!

 

[analag]

Many things can be done with the TC network...the observations I made with this was modified and coupled with a 50Watt CV amp to achieve some extensive settings. The PM660/670 was designed to work well at reasonable cost as the name implies, but if you guys want to take it up a notch, then I got just the thing fer ya. Will require some point to point wiring though.

 

[lolo-m]

yes ! yes ! yes ! I want to know  ;D

 

[Moby]

The PM660/670 was designed to work well at reasonable cost as the name implies, but if you guys want to take it up a notch, then I got just the thing fer ya. Will require some point to point wiring though

 

[SaMpLeGoD]

The PM660/670 was designed to work well at reasonable cost as the name implies, but if you guys want to take it up a notch, then I got just the thing fer ya. Will require some point to point wiring though

I just can't wait for your mods analag! althrought Lolo's mods are nice too!!! great job people!!! It's a very nice comp... I'll put some my gear's photos in a near future!

Cheers,

Eddie  ;D

 

[smallbutfine]

Oh WOW!
I'm already very impressed now after I listened to the samples and read this thread today.
Great work, Lolo!
I don't even dare to imagine what Rowan might come up with now ...
...but I am pretty sure it can be a brilliant way to pump up the circuit even more ...
tube or silicon
who knows? (haha sure we know....)
Exciting!!!

Thanks for the excellent read so far!  8)
I had to extend some kudos while lurking here and waiting for my tubes.

Kind regards

 

[analag]

My mod would be to redesign the boards. Replace the 6BZ6 with 6BJ6's, replace the 5687's with EL84's and have Edcor bring up the secondary of the transformer to 600 ohms
http://www.edcorusa.com/products/transformers/gxpp/GXPP10-8-8k.html. Call it GXPP10-600-8k. Move up the B+ to 280V to the SC amp and down to 240V for the GR tubes. Add a driver tube to the SC amp, a 12AT7 would do. That's sounds more like a rebuild I think.

 

[jackies]

Wow, thats cool! So do we have to organise another edcor group buy for this transformer?
;D

 

[lolo-m]

My mod would be to redesign the boards. Replace the 6BZ6 with 6BJ6's, replace the 5687's with EL84's and have Edcor bring up the secondary of the transformer to 600 ohms
http://www.edcorusa.com/products/transformers/gxpp/GXPP10-8-8k.html. Call it GXPP10-600-8k. Move up the B+ to 280V to the SC amp and down to 240V for the GR tubes. Add a driver tube to the SC amp, a 12AT7 would do. That's sounds more like a rebuild I think.

That's sound more like a rebuild indeed !!!
But having a varimu comp in the studio bring you to own another ! 
Looking at the Fairchild schematics, I was planing to make a sc -amp with EL84... And to go for 6BA6 as remote cutoff tubes... These should work too, aren't they ?
Out topic question: I bought a C-core kit to make an output transformer... Must I wind the primary on one bobin, and the secondary on the other, or is it better to wind both on both bobins ? Analag, I know you've got the answer... I'm quite sure it's better to wind on both and if it is, primaries closer to iron or secondaries ?

 

[Moby]

Out topic question: I bought a C-core kit to make an output transformer... Must I wind the primary on one bobin, and the secondary on the other, or is it better to wind both on both bobins ? Analag, I know you've got the answer... I'm quite sure it's better to wind on both and if it is, primaries closer to iron or secondaries ?

I think that it will be better to start completely new thread about it. Here is a lot knowledgeable TX guys who can really help, but they are not involved in the PM660. (CJ, Max...) So start the thread and ask exact question about TX you are trying to wind and viola  ;D . And yes, post the link here so we caln lurk 

 

[lolo-m]

post the link here so we caln lurk 

Here it is :
http://www.groupdiy.com/index.php?topic=32204.0

 

[smallbutfine]

Ha, looks like some of us will build another varimu additionally...
I guess p2p....
Now following 2 threads.
More than a mod, it's more like a new design, Rowan. Great!

 

[SaMpLeGoD]

Well, nice to start an almost new project, but I just finished my PM670, didn't tested in the studio yet, and did'nt do any mod for the TC network so far... Is better leave this this way and dig into the new one? That will be so much different than this? what i understand so far is the new mods will get this unit's behaviour near to the original Fairchild, am i right?
Well I really don't care about if it is a Fairchild or not... just want a versatile unit can I get that with my stock unit? any experiences?

Looking forward to see the mods

Cheers!  ;D

Eddie

 

[lolo-m]

Well, nice to start an almost new project, but I just finished my PM670, didn't tested in the studio yet, and did'nt do any mod for the TC network so far... Is better leave this this way and dig into the new one? That will be so much different than this?

Test your PM670 stock if you finished it. Listen... listen again... Then you'll know if it is what you were looking for... There's a lot of chances that it'll be what you were searching... The PM670 is a really great comp, musical and sweet...
To leave this one and to dig in a new one is a solution... but at a cost 

what i understand so far is the new mods will get this unit's behaviour near to the original Fairchild, am i right?
Well I really don't care about if it is a Fairchild or not... just want a versatile unit

I don't care too to have a Fairchild or not... I won't have one... I'm certainly too poor !!!
The Fairchild is the holy grall of the tube comps because is was the faster and certainly the cleanest one... To reach its performances is having the most opened possibilities... You can slow down a Ferrari, but you won't go 350km/s with a cheap car ;D. I don't own a Ferrari but I would like an ultra fast comp ;D

can I get that with my stock unit? any experiences?

Listen to your comp !  ;D ;D ;D