[BUILd] PM660 / PM670 SCAmp Booster build and tips help thread

[lolo-m]

Just need to clarify...are you saying to remove R16? or to jumper it? In the Scamp wiring guide R16 is still shown.

Look at the PM660-670 schemo and after a few seconds you should understand  :...

Isn't R16 a little lonely ?

 

[Freddy G]

Umm, thanks. I guess you're saying it should be removed then. Looking at the scamp schematic R*01 takes the job of R16 from the PM circuit right?

 

[lolo-m]

Umm, thanks. I guess you're saying it should be removed then. Looking at the scamp schematic R*01 takes the job of R16 from the PM circuit right?

If you cut the diodes (and you should have), R16 is connected now to : nothing... You just losse a resistor if you leave it there. Connected to nothing a resitor doesn't hurt, and except if you've got real horrible money problems, you'd better leave it there  ;D ...

 

[Freddy G]

I've got it working. WOW! Now this sounds like the kind of compression I was hoping for. Thanks lolo-m! Your Side chain amp booster did the trick!
I will not be using Analag mode.
I have to say I don't know what I would ever use Fairchild TC postion 5 and 6 though!

Any suggestions for different R/C networks for position 5 & 6 that are more usable than the Fairchild.

 

[lolo-m]

Thanks  8)  8)  8)
On the 2nd page, 3rd post gives you all the tips to calculate a "a la Fairchild" TC network to get the attack and release you want... This is better to make your own as anyone likes different settings...

 

[Freddy G]

OK! Got my TC networks in place and it sounds good.
I'm having a problem on one side of the Scamp board though. Hopefully someone can help me through this.
It's definately the one side of the scamp board because I switched everything from one side to the other and the problem remains on the same side of the Scamp.
The VU meter is getting pinned all the way to the left. Voltages on the problem side are higher than the working side. If I unplug the connectors from ModeB-R and ModeA-R the meter goes back to zero.
Any help appreciated...what should I check?

 

[Freddy G]

Oh man! I've been trying to figure this out with no luck. Looks like I will end up taking the scamp board out and just going back to the Analag mode :-[

 

[Moby]

Oh man! I've been trying to figure this out with no luck. Looks like I will end up taking the scamp board out and just going back to the Analag mode :-[

Why? If you have one channel working you just have to compare voltages from point to point and find the faulty one. Then you will probably find some wrong value or misplaced component on "bad" side

 

[Freddy G]

Ha! I think I found it....bad TIP42C.

 

[creal]

Hi all
I finished my PM670 and it work nice.
Now it's time to play with TC network...
I have all my SCAB stuffed except the 12pf caps on (c101,201).

I don't have any 12pf at home, can i replace this caps by 10, 22, 33pf?
what's the best value? I will use a OPA604s

So other questions,
If i understand well, the R* connector is used for the release time res and the C* for the attack time caps?
I'll like to use 2 switches on my unit, one for the attack and the other for the release.
It is correct?

Cyril

 

[lolo-m]

I have all my SCAB stuffed except the 12pf caps on (c101,201).

I don't have any 12pf at home, can i replace this caps by 10, 22, 33pf?
what's the best value? I will use a OPA604s

For c101/201 use anything between 10pF and 47pF and you'll be fine !
If you use OPA604 don't stuff c102, c202 as they are not compatible with the 604...

So other questions,
If i understand well, the R* connector is used for the release time res and the C* for the attack time caps?
I'll like to use 2 switches on my unit, one for the attack and the other for the release.
It is correct?

You're right. BTW notice that they are paralleled. You can only use one if you prefer and feed the attack switch (caps) and release switch (resistors).

 

[skal1]

Hi lolo-m

hopping you've got 1 scamp board lying around

cheers

skal1

 

[creal]

Hi Lolo,
it's works perfect now, i like what the scamp add. it is very differrent of the analag mode.
I tested the fairchild network and it's great.
Now i play with different values for caps and res on a separate switches before order the front panel.
Thanks for this great addon.

Cyril

 

[Studio Mollan]

Hi.
Any chance there's more pcbs around for sale? I took over a project and would like this mod.
I can't find schematics?
/
Emil

 

[duantro]

I'd take another one also. I've got enough spare parts to build another M670 down the road and honestly couldn't imagine using it without the scamp, or something similar.

 

[lolo-m]

Sorry for being away during such a long time, but days are only 24 hours long and I need about 48 hours each days to acheive what I started...

Anyway, I won't do another run of SCAB PCB's as there's nearly no demand. You can find the schematics and everything to etch the boards yourself in this thread :
http://groupdiy.com/index.php?topic=45556.msg570789#msg570789

Have fun, give me time  ;D

Laurent

 

[marcus4audio]

Hi guys. I finally finished my PM670 build and I'm happy with it but I have a problem with timing network in SCAMP mode. I would like to have separate attack/release controls. Can somebody share successful "working" values? I read all the pages related to this build and at the end my brain hurts 

 

[duantro]

Hi guys. I finally finished my PM670 build and I'm happy with it but I have a problem with timing network in SCAMP mode. I would like to have separate attack/release controls. Can somebody share successful "working" values? I read all the pages related to this build and at the end my brain hurts 

I know your brain pain from all of this up and down train ride. My m670/ pm670 uses the same time constant network for with and without scamp booster. Look back for Lolo's pimping the pimp comment (reply #22 in this thread), Bluebirds comments on the pm670 thread, or on Kingston's m670 thread for starting values to experiment with. http://groupdiy.com/index.php?topic=51478.0.

 

[marcus4audio]

Thanks Duantro. So If I choose to go with values of caps like Lolo's (reply #22) can you suggest value for "universal" release pot? I understand that release will depend from capacitors values so for every possition it will need to be trimmed again. Right?

 

[duantro]

Thanks Duantro. So If I choose to go with values of caps like Lolo's (reply #22) can you suggest value for "universal" release pot? I understand that release will depend from capacitors values so for every possition it will need to be trimmed again. Right?

Sorry for the delayed response, I guess I don't get notifications from this thread. I used a dual 6 pole switch for the time constant, but you could easily make a switch for attack and one for release. Check out Bluebird's original values and experiment.