why don't we make a SSL channel compressor clone?

barclaycon · Feb 9, 2010

Thanks Pietro.
I was actually contacted by Colin Saunders after somebody had seen my rack at a studio, and he asked me not to make any of these for other people - but that was 22 years ago!

Sono Inglese. Da Londra.
I have done a lot of work in Italy though - mostly Rome and Naples. Never been to Florence.

Which diode are you referring to ?

barclaycon · Feb 9, 2010

Those particular SSL EQ modules were made by the tech dept at the Townhouse.
(Andy and Geoff if I remember correctly).
What happened is that the Townhouse took over Ramport in Battersea and wanted a rack full of SSL stuff to go in that studio. They also racked up some Gain Brains and Kepexes into Scamp modules.
I believe all those modules were inherited by Mick Glossop.

phishman13 · Feb 9, 2010

wow those things look great! very nice work!

pietro_moog · Feb 9, 2010

i mean 1s44, the comp diodes from schematics

helterbelter · Feb 9, 2010

Barclaycon, that looks neat !

pietro_moog said:
i have a lot of questions:
1 -i used that 1240 and 1640 for input and output, but i'm not sure of what i've done.. however, do i have to connect them to +/-15v rails?
2 -the icon of that 2181 has no V in and V out, how can i connect them? (i can connect the pin on the pcb design,is that the way to proceed?)
3 -same question as PeterC about 0v on the release pot of comp.
4 -why ad536j is +15v / -18v?
5-what is "P11 out" near 250k log expander release pot? and why a leg of this pot is not connected to anything? it seems to go on ground, but it misses the oblique line..
6 -why negative rails of T3 and T4 should be connected between R18 and C20 on the power supply (near 79L15), and not to the -15V rail?

Well, I'll try to help a bit, as far as my knowledge reaches !

1. The 1240/1640 note a powersupply of 6 to 36 volts, meaning +18 and -18 volts maximum. So, you can use the voltagerails that will suit your design best. http://www.thatcorp.com/datashts/1240data.pdf It also notes that the pinout is the same as the DRV134 and the AD SSM 2141, this is great, I still have got a load of those !

2. The 2181, simply compare the pinout already known to the datasheet : http://www.thatcorp.com/datashts/2181data.pdf . ( +VE is 7, -VE is 5.)

3. Looks like a variable resistor to me, with that taper to 0v. But if PeterC has his "???" with it, I'm probably wrong on this...

4 this is a mistake in the schematic. It should be +15 and -15, referring to the datasheet : http://www.alldatasheet.com/datasheet-pdf/pdf/48036/AD/AD536A.html

5 P11, it looks that this "thingy" is located near the pot on the motherboard. Do you have the schematic of the motherboard ? This might clear things up. ....
But eeeeehhhh, Looking at the dual pot : ?!?!?!?!, Is this a dual taper pot of 250K Log and 25k Lin ?!?!? This means that we have to do a custom order, I think). I'm not so sure if the pot's third leg has to be connected to ground though. If this is indeed a dualtaperpot, it looks to me that they've done this connection to get a special tapercurve. If so, the leg you're referring to must not be connected at all.

6. This is pretty common for all kinds of audio boards. I think this is for decoupling or filtering.

Hope this helps, I'd be happy to do a testbuild !

strangeandbouncy · Feb 9, 2010

Hi Martin

Those are lovely lovely things . . . and with the extra un-used part of the pots you could do TR . . . ;D

Nice!

ANdyP

helterbelter · Feb 9, 2010

1S44...

http://www.datasheetarchive.com/1S44-datasheet.html

"General Purpose Diode". VF : 1.15v, IF 10mA.

Can't we use an 1N4148 as replacement ?
VF :1V, IF 10mA, diode capacitance is 4 instead of 6 pF.

pietro_moog · Feb 9, 2010

helterbelter said:
Barclaycon, that looks neat !

pietro_moog said:

i have a lot of questions:
1 -i used that 1240 and 1640 for input and output, but i'm not sure of what i've done.. however, do i have to connect them to +/-15v rails?
2 -the icon of that 2181 has no V in and V out, how can i connect them? (i can connect the pin on the pcb design,is that the way to proceed?)
3 -same question as PeterC about 0v on the release pot of comp.
4 -why ad536j is +15v / -18v?
5-what is "P11 out" near 250k log expander release pot? and why a leg of this pot is not connected to anything? it seems to go on ground, but it misses the oblique line..
6 -why negative rails of T3 and T4 should be connected between R18 and C20 on the power supply (near 79L15), and not to the -15V rail?

Click to expand...

Well, I'll try to help a bit, as far as my knowledge reaches !

1. The 1240/1640 note a powersupply of 6 to 36 volts, meaning +18 and -18 volts maximum. So, you can use the voltagerails that will suit your design best. http://www.thatcorp.com/datashts/1240data.pdf It also notes that the pinout is the same as the DRV134 and the AD SSM 2141, this is great, I still have got a load of those !

2. The 2181, simply compare the pinout already known to the datasheet : http://www.thatcorp.com/datashts/2181data.pdf . ( +VE is 7, -VE is 5.)

3. Looks like a variable resistor to me, with that taper to 0v. But if PeterC has his "???" with it, I'm probably wrong on this...

4 this is a mistake in the schematic. It should be +15 and -15, referring to the datasheet : http://www.alldatasheet.com/datasheet-pdf/pdf/48036/AD/AD536A.html

5 P11, it looks that this "thingy" is located near the pot on the motherboard. Do you have the schematic of the motherboard ? This might clear things up. ....
But eeeeehhhh, Looking at the dual pot : ?!?!?!?!, Is this a dual taper pot of 250K Log and 25k Lin ?!?!? This means that we have to do a custom order, I think). I'm not so sure if the pot's third leg has to be connected to ground though. If this is indeed a dualtaperpot, it looks to me that they've done this connection to get a special tapercurve. If so, the leg you're referring to must not be connected at all.

6. This is pretty common for all kinds of audio boards. I think this is for decoupling or filtering.

Hope this helps, I'd be happy to do a testbuild !

thanks.

1) cool
2) oks. so we'll connect them on the pcb design
3) oks. the strange thing is that everything goes on ground with the usual sign (vertical line into the oblique line), but the rel pot on the comp goes to 0v. i don't know..
4) cool
5) ok. i'm not worrying about this now, i have other corrections to do. i'll look on the input/output schematics
6) ok. the strange thing to me is that the positive rail do not.
only the negative rail for t3 &t4 is separated and different from the rest..

barclaycon · Feb 9, 2010

I think I actually used 1S44 diodes if I remember correctly.

pietro_moog · Feb 9, 2010

guys, do you think it's a good idea to use 7815 & 7915 instead of 78l15 and 79l15?

i had problems with my gssl, and that thing has less ics.

peterc · Feb 10, 2010

Very nice builds!

helterbelter · Feb 10, 2010

pietro_moog said:
3 -same question as PeterC about 0v on the release pot of comp.

helterbelter said:
3. Looks like a variable resistor to me, with that taper to 0v. But if PeterC has his "???" with it, I'm probably wrong on this...

pietro_moog said:
3) oks. the strange thing is that everything goes on ground with the usual sign (vertical line into the oblique line), but the rel pot on the comp goes to 0v. i don't know..

Well, I'm not completely sure on this, as said. But are you designing the board for on-board pots ? In case the pots are going to be off-board, then you can check later whether the pot needs to be connected to 0v or grnd (as a matter of fact, aren't these one and the same ?!?) - ah, checked the schematic again, grnd is used for both audio as PSU parts, so 0v should be exactly the same as grnd.

pietro_moog said:
5-what is "P11 out" near 250k log expander release pot? and why a leg of this pot is not connected to anything? it seems to go on ground, but it misses the oblique line..

helterbelter said:
5 P11, it looks that this "thingy" is located near the pot on the motherboard. Do you have the schematic of the motherboard ? This might clear things up. ....
But eeeeehhhh, Looking at the dual pot : ?!?!?!?!, Is this a dual taper pot of 250K Log and 25k Lin ?!?!? This means that we have to do a custom order, I think). I'm not so sure if the pot's third leg has to be connected to ground though. If this is indeed a dualtaperpot, it looks to me that they've done this connection to get a special tapercurve. If so, the leg you're referring to must not be connected at all.

pietro_moog said:
5) ok. i'm not worrying about this now, i have other corrections to do. i'll look on the input/output schematics

Cool, I'll do some online searching for 250klog and 25klin Clarostats. These are pretty easy to de-mount, and rebuild. This way we can build our own !

pietro_moog said:
6 -why negative rails of T3 and T4 should be connected between R18 and C20 on the power supply (near 79L15), and not to the -15V rail?

helterbelter said:
6. This is pretty common for all kinds of audio boards. I think this is for decoupling or filtering.

pietro_moog said:
6) ok. the strange thing to me is that the positive rail do not.
only the negative rail for t3 &t4 is separated and different from the rest..

Ah, yes, you're right, I have overlooked this. In case of doubt, simply add that part to the positive rail as well.

pietro_moog said:
guys, do you think it's a good idea to use 7815 & 7915 instead of 78l15 and 79l15?

i had problems with my gssl, and that thing has less ics.

IMHO go for the 7815/7915 combo. I used 7812/7912 in my GSSL as well. Easier to obtain. Pinout of one of the 2 is different though, keep that in mind.

helterbelter said:
1S44...

http://www.datasheetarchive.com/1S44-datasheet.html

"General Purpose Diode". VF : 1.15v, IF 10mA.

Can't we use an 1N4148 as replacement ?
VF :1V, IF 10mA, diode capacitance is 4 instead of 6 pF.

barclaycon said:
I think I actually used 1S44 diodes if I remember correctly.

Any ideas for a replacement ?!?

It's a pity that I don't have an original board to compare the schematic with. But I do have the SL510 channelcompressor schematics, maybe this will clear some things up.

[edit] : 5 : The range and release pots aren't one and the same, sorry for the mistake. In the 510 schematics, the release pot's third leg is connected to the wiper, what I already expected.

peterc · Feb 10, 2010

But I do have the SL510 channelcompressor schematics, maybe this will clear some things up.

It would be nice to see these to compare them.

Peter

helterbelter · Feb 10, 2010

Hi Peter,

Yes, you're right, so I've mailed it to the group's emailaccount.

[Peter, off-topic : I still have to get the appropriate pots for my 2 S800 boards, but then they're ready to be fitted in my superspecialcustomsslconsole, ha !]

timshel! · Feb 11, 2010

barclaycon said:
I think the fly in the ointment is the RMS chip. I just had a quick look on the web for the AD536 and noticed that prices for NOS units are about 50 Euro's a piece.

+1

pietro_moog said:
you can find ad536a at digikey, at a fair price.

...

if we change rms chip the comp won't react the same way, so it will not be a SSL channel comp..
i'd like this to be an affordable good copy, not a cheap crappy copy..

As I mentioned on the first page of this thread, the 9k channel comp does use the THAT rms chips, and I'd neither call that cheap nor crappy!

Farnell has the THAT parts for £3, whereas the ad536 is about £9 or £18 depending on the package. I know which I'd pick!

Also, on the power supply front, why not go with LM317/337 regs instead of the 7815/7915? I've not done any comparisons, but a lot of people have said that they regulate better and give better noise performance.

barclaycon · Feb 11, 2010

Timshel.
Do you have the schematic for the 9k channel comp ?
I'd love to see that.

I didn't realise that the 9k board dynamics section was a complete re-design.
I don't have any info on that console.
I mixed an album on a 9000 series SSL very recently and didn't notice anything different about the dynamics section. It still sounded great.

When the SSM2110 in the 9k channels went obsolete, it was replaced with a 2252 on a small board that slotted into the 2110 socket.

If you got any info on this as well I would be most interested.
Thanks in ant.

signalflow · Feb 11, 2010

barclaycon said:
Timshel.
Do you have the schematic for the 9k channel comp ?
I'd love to see that.

It should be in the Groupdiy account 2nd page. I recently downloaded it from there again.

-Casey

barclaycon · Feb 11, 2010

Thanks very much for that Casey.

I've downloaded the 9k and SSL510 schematics. Both are using the SSM chips for RMS level detection.

Anyone have the dynamics section using THAT RMS chips ?
(Or the conversion board to put a THAT2252 into a SSM2110 socket).

Much obliged.

pietro_moog · Feb 12, 2010

i've seen 9k schematics, it seems easier.
no dual release pot with different values. cool.
a 2 sides pcb is still needed. i tried to arrange mentally the 4000 schemos only to one side, but we need a big board and lots of wiring on it.
how can we use the that 2252 and 2181 on this? if we have infos and schemos on that, this project would be easier and cheaper

phishman13 · Feb 12, 2010

timshel! said:
As I mentioned on the first page of this thread, the 9k channel comp does use the THAT rms chips, and I'd neither call that cheap nor crappy!

Farnell has the THAT parts for £3, whereas the ad536 is about £9 or £18 depending on the package. I know which I'd pick!

Also, on the power supply front, why not go with LM317/337 regs instead of the 7815/7915? I've not done any comparisons, but a lot of people have said that they regulate better and give better noise performance.

The 7815/7915 regs are only there on each individual board to step down the incoming already regulated +/-18v coming from the offboard psu. So there isn't really a need, or much room, to add the extra circuitry needed for the 317/337 regs, and we don't need it to be adjustable either, so having those 2 regs, save us space.

The schem in the gdiy gmail shows an ssm2118, is there a schematic around that shows the THAT chip? It would make it slightly easier to convert the SSM to the THAT since THAT has a design note about it, but from what I've gathered so far, a good part of the operation and compression properties of the 4000 dynamics come from the ad536. And we've found it for pretty much no more than $12 each for the package we need (much cheaper if we get a group buy organized). Yes, thats double the price of the thats chip, but if your only gonna build less than 8 channels (more situations than not, probably much less than 8 channels), that's not that much more to pay to ensure that we capture the essence of this module, then to pay less, somehow not get the adaptational circuitry just so for the THAT rms detector, and then have to rework it. Its a security blanket for me. ;D I'm willing to pay a few extra bucks for that.

why don't we make a SSL channel compressor clone?

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