matthias

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« on: July 30, 2004, 03:09:15 PM »
Hi ,

I want to build a few ssl comps in the next weeks...

I've read in some other threads about that problem with bal and unbal.


so can anybody tell me in which cases I have to change the 15k resistors (that are leading into the vca in) to the 27k ones??

Is there a possibility to implement an "input gain" pot ??

If I would use a stereo pot at the place of the two 15k resitors, I'll get problems with l/r tracking, because of the tolerance of the pot

any suggestions ??

thank you
mat...


gyraf

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #1 on: July 30, 2004, 03:22:07 PM »
Input gain control is not easily obtained. And you shouldn't really need one in this circuit.

For the unity gain mod, use the 27K resistors - this behaves best in any case.

Jakob E.
..note to self: don't let Harman run your company..

matthias

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #2 on: July 30, 2004, 03:31:15 PM »
do I get unity gain at both cases (bal. and unbal.) when I put in the 27k resistors??

gyraf

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #3 on: July 30, 2004, 03:35:06 PM »
Yes, for all normal cases 27K should do. I used those when I last did a test-clone, and it worked well.

The original 15K's had to do with some transformer balancing and debalancing stuff.. it's all very long time ago now...

Jakob E.
..note to self: don't let Harman run your company..

matthias

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #4 on: July 30, 2004, 03:52:13 PM »
ok, thank you...

a lot of other equipment have a level switch for +4 and -10 dbu on the rear..

this made me curious, I thought it concerns to the 6db 15/27k thing..

ytrehalf

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #5 on: April 13, 2006, 03:42:47 AM »
Does the 27K resistor value for the VCA input also apply for 202C?

Greg

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #6 on: April 13, 2006, 07:53:42 AM »
Yup.
Greg Stein
New Orleans, LA

mathflan

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #7 on: October 03, 2006, 10:33:12 AM »
I'd like to put a toggle switch to pass from 15k resistors to 27k resistors.
do you think that it's a good idea since I have to use long cable so as to connect the switch to the board? Perhaps it will give some noise?

Greg

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #8 on: October 03, 2006, 11:40:53 AM »
It'll take you 10 minutes to wire it up, so just try it out and let us know  :thumb: !
Greg Stein
New Orleans, LA

dukasound

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #9 on: October 03, 2006, 11:48:30 AM »
I did it with one switch on rear panel, if I used in insert unbalanced or in line - balanced with other stuff.


mathflan

SSL : bal. / unbal. / 6db ? / 15k <-> 27k
« Reply #10 on: October 03, 2006, 12:21:00 PM »
Quote
It'll take you 10 minutes to wire it up, so just try it out and let us know


you're right greg! let's go...


 

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