SSL Mix Compressor + Summing Amp idea

I'm considering building a GSSL Mix Compressor with an analog summer built into it. The idea would be to have four stereo pairs (probably on a DB25 connector) mixed together using the summing amp from an SSL 4K, followed by the Gyraf GSSL Mix Comp.

Does anyone have the schematic for this circuit so I can see how involved a project it would be? I looked at the lo-res schematics of the 82E26 on Gyraf's site, but it's tough to read the values and for me to suss out exactly what's going on.

http://www.gyraf.dk/gy_pd/ssl/ssl_82e26.gif

I see pin 5 labeled "- mix buss", and theres a pin below that with no label. Is that "+ mix buss" or voltage? I assume that the output of T2 is the end of the mix amp and the beginning of the mix compressor?

Assuming that I would start from a GSSL board, some of the components of the mix amp may already be there. I was thinking about a small additional board to contain the mix amp.

That's enough questions for one post. Thanks for your help.

Bump

SSL designer Andy Millar is talking about designing a summing amp for us. I think we should just build the SSL Comp as-is and wait for that project to take shape.

Thanks, I found the topics about here
http://www.groupdiy.com/index.php?topic=7725&postdays=0&postorder=asc&highlight=ssl&start=60

Anyway, will be nice if somebody can clear some blurred parts from 4k schemo. Or simply to upload better scan of ssl_82e26 :green:

OK, I tried to redraw and simulate... Seems that works like this, but will be great to hear comments about mistakes :wink:
[/img]

Is this the correct schematics? There seems to be one capacitor missing. Anybody checked it?

http://www.analog.com/UploadedFiles/Data_Sheets/44787917SSM2402_12_a.pdf#search='SSM2402'

check out the summing buss on page 10

yes. there is also one here: http://ezphysics.nchu.edu.tw/prophys/ael/File/Datasheet/SSM2017.pdf and here: http://www.analog.com/UploadedFiles/Data_Sheets/452248524SSM2019_0.pdf

I still have some ssm2017 lying arround, so I may just go for ssm2017 version. What do you think, will it be ok?

Would there be any advantage in building SSL summing bus? Will SSL sound better? SSL is basically NE5534, and SSM2210 can be used to reduce noise (I also have some arround). But if SSM2017 bus would sound fine just as well, then I'd rather make that one, it is much simpler. Any suggestions?

thnx

hey gnd!
Do you realise that 2019//2017 is an opamp and 2210 is a pair of matched transistors in a DIP?

No offence intended.

Do you realise that 2019//2017 is an opamp and 2210 is a pair of matched transistors in a DIP?

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:grin:

I was talking about summing buss amp. One idea is simple one-IC module with SSM2017 or ssm2019 or similar. Other is SSL summing buss, as on gyraf page, and redrawn by Moby. Original SSL mix bus uses two dual NPN pairs LM394 (if I see schem properly). Moby replaced those two dual LM394 matched pairs with single SSM2210 mathed NPN pair. And he also ommited one 10u capacitor, and some other values in his redraw are a bit uncertain.

I was hoping that somebody could come up with final, working schematics of SSL Mix Bus. I would like to build it, for sure. I have SSM2210, ne5534 :razz: , and bc184b in my drawer. I'm just not sure about schematics.

Can somebody please help?

thnx

I was hoping that somebody could come up with final, working schematics of SSL Mix Bus.

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They are already at the gyraf/ssl-diy page - or do I miss something?

Jakob E.

They are already at the gyraf/ssl-diy page

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Really? Jakob, can you kindly post the link? I've searched your web page left and right, and all I can find is ssl_82e26.gif, which is a bit hard to read in several places. Is there a redrawn version, possibly pdf?

Also, I cannot figure out where to connect that empty pin going to LM394 over R1 and over that C, which I cannot see the value. Moby connected that pin to ground, via 13k resistor. Is that proper?

How about two LM394 NPN pair, can they be replaced by single ssm2210 NPN pair? How about replacing two LM394 with two SSM2210? Are they more or less the same? SSM2210 is somehow cheaper, and I have four in my drawer.

And what is that cross-pin connection, at output of mixbuss, on input to compressor part? Are those just pins on the board? Why is it cross connected with dashed lines?

Also, I know that this s SSL, but is this quality bus? I mean, there are cheap ne5534 inside. Any recommendation for better ICs? I saw it mentioned in another thread, that for 16 or 24 channels ne5534 are just fine. I have 16 channels in mind, so probably it will be fine, is it?

thnx

http://www.gyraf.dk/gy_pd/ssl/ssl_82e26.gif

http://www.gyraf.dk/gy_pd/ssl/ssl_82e27.gif

Jakob E.

thank you both. Really.

Mediatechnology's scan is somehow higher res, and clears ou some hard-to-read part of gyraf scan. There are some component values missing on both. I will try to redraw the bus mixer schematics, and try to find out missing values.

What about LM394 <-> SSM2210 replacement. What do you think?

Wayne, thank you again. All values are perfectly readable, just some are missing. I rechecked schematics, and the only thing missing are the following:
- two times two diodes D6, D9 and D10, D11. Probably they can be just 1N4148, is it?
- C21 is missing value too.
- cap on T8 between pins 5 and 8 is missing value.

There are also some different values on both schematics:
- C1 C2 are 470u on your verssion, and 100u on gyraf version. Probably bigger is better here, is it?
- C21 is missing, but I think it says 1n on gyraf version. But it is hard to read. Is 1n proper value here?
- R50 says 15k+1k on yours, and just 15k on gyraf's. What is this 15k+1k? 16k? Do I make 15k or 16k?
- there is a added cap on your verson on T8, 100p over 15k resistor. Gyraf's version has just 15 resistor. Why is that cap?
- Cap on T8 between pins 5 and 8 is missing value, and gyraf's version puts is as 22p, if I can read properly. Is 22p ok?
- output resistor value is different. Yours gives 47R and 10R to ground, while gyraf's gives 10R on both. Which is it?

Also I'm wondering about the 0volt mix bus pin. It is not ground, but seems to be connected to 0Volt in console. How do I connect it in my mixer? To ground directly? Or via resistor to ground? What value of resistor?

Regarding SSM2210, I just checked data sheet again, and found out, that it says that SSM2210 is direct replacement for LM394BN/CN. I have four peaces of ssm2210 at hand, so I'll just use those. Thank you for THAT300 proposition. If I make another bus, I can try and get those.

I got ssm2210 locally for about 9$ a piece. They have LM394 at stock too, but it gets arround 15$ each. Also SSM2210 is DIL package, which I prefer somehow. Less chance for me to make mistake with pcb.

thnx

Thank you for your fast and precise answer to my extensive question. It is really helpful.

I'm a bit unsure about this pin8 - 0V ref. There is something I don't understand. In my mixer channel output ground will be the same as 0volt. (There is no separate 0Volt and ground, both are the same, all 0volts are grounded) So, when I will connect 0volt from my channels to 0Volt on mix buss, I will be actually connecting mixer ground to 0Volt mix buss. And thus R1 and C21 will become connected to ground from both sides, and SSM2210 will also become connected directly to ground. This seems wrong to me. Is it?

Shouldn't there be some potential difference on both sides of R1/C21?

What is the use of R1 and C21 if they are from both sides connected to same ground?

What am I missing? How do I connect pin 8 (mix bus 0V)? Shall I just leave it disconnected, so that 0V (pin 8) of mix bus is not tied to ground directly, but via R1 and C21?

One another thing with SSL input pins: Here is similar schematics, from ssm2210 data sheet. http://84.255.203.119/ssm2210_Page_06.jpg
It is just that here signal comes to SSN2210, and upper resistors are connected to ground. Layout is similar to SSL, just inputs are reversed. Following this layout, in SSL mix bus, pin 5 should be connected to ground, and pin 8 should receive signal from channels. Why is SSL circuit taking signal from other side than similar circuit from Analog Devices?

thnx

EDIT: One thing I believe should be mentioned here is that the source(s) feeding the input to the 82E26 circuit should have 15K series resistors to perform the voltage to current conversion. The 82E26 and op amp summing amplifiers have what's called a "virtual ground" input. On the SSL channel strips there are 15K resistors in series with the buss assign switches.

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Would you possibly have schematics of channel strips, with their connection to buss? I'm looking at your scan of channel amp card, but connection to buss with switches is not on that sheet. There are some more things inbetween inputs and buss obviously....

Regarding my mixer, I was anyway thinking of replacing combined mic/line channel strips in my mixer with line only, since I don't need mic inputs. Looking at SSL line channels, it is very tempting that I make SSL line mixer with SSL mix buss, and SSL/Pultec eq. Now I have inputs, EQ and buss schematics. I would just need that section, where channel strip connects to mix buss pin 5 and 8.

What is the block diagram of SSL mixer? Inputs (mic/line) -> EQ -> compressor -> bus assign switches -> buss -> mix compressor -> output ?

Here's the pan pot output assign for a hex buss 6K console.

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Thanx for this. There also seem to be resistors connecting to ground. Do I read schematics properly?

There really isn't a channel schematic but schemos of each of the daughter cards and then a broad drawing showing how the glue together on the channel strip.

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I'd most interested in this block diagram, how modules fit together. Is this the A1-sized drawing? I hope you will be able to make it. No need to edit images, I'll be most happy with 4 separate parts too.

I already have some stuff posted. See: www.tenmilecreek.net/images/ssl/ssl_drawings_index.htm

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Yes, I already checked those some hours ago, printed them all out and now I am eagerly contemplating how to put them together.

Hope this helps. I really need to update the SSL index page because there's more there.

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It is most helpful. I'm sure everybody will be most happy, if you will add even more of SSL data. It is hard to get.

I'll have my version of the buss schematics up soon too if you can wait a few more days. I'll have a layout for a channelstrip soon after.

It'll have the substitute parts I have chosen also and possibly a BOM.

Any chance you know where to get a 9k schemo?

I'll try and get that A1 up as a four page pdf. The other thing that would help would be the daughter card connector lists.

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Yes, thank you Wayne. Both would be most apprecieated. Thank you.