SAM 82 mixer

[synthi]

Hi People,

I just got a nice SAM 82 mixer (SATT brand I think) made in Sweden.
Its very nice sounding!! 8 mic pres w/hi-lo eq, 80Db gain, phase and phantom, 2 sends pre/post and pan

I opened it and I`ve found it use lundahl 1515 trafos on inputs, custom trafos for outs and the channels are using SN 72709P except for channel 4 using NE5534AN, could be better replacing all the channels with 5534s? Also does anyone have info on this little beauty??

Thanks!

Synthi.

 

[synthi]

more info:

SAM 82. Small 10 Channel high quality mixer made for Swedish Radio for inhouse use. 1980? Nice solid and compact alu housing. 8 channels with: XLR, 48 Volt phantom power, very low noise preamps, high and low (80/140 HZ) EQ, 2 effect sends pre/post, and panpot. 2 channels extra with only volume (bringing it to 10 channel inputs). Effect send/returns and test-tone, 2 classic VU-meters in the Master section and even further; 2 more input channels that can be routed to the aux return faders (bringing the total input channels up to 12!). Dimensions: 44cm x 34cm x 6 cm. This is a mixer built to very high standards.. Sweet sounding EQ, very low noise on output. Taking off the back-panel reveals that all channels and other modules can be swapped and taken out without any soldering.. New price was 3000UKP.

Photo here:
http://img.photobucket.com/albums/v321/synthi/sam82/sam82.jpg

 

[synthi]

Thanks Butta,

I think the SN72709P is a 709 type.

I checked the mixer with line inputs only so no gain and the amp is barely working, no mic here handy... tThere is not much difference, may be the channel 4 is a bit more bright, but just subjetive. Lets see when I can use the gain with a mic.

I like it a lot, is a very transparent mixer with a very round, clean bass sound but not hyped. I`m using it now as my monitor controller.

Synthi

 

[wolfgang]

Hello Synthi!

How do you like this little mixer so far?
I have purchased one too and was looking on the web for information and a schematic but nothing there....
Do you have a schematic now??

I am courios about the sound of this little thing. But i have to wait for delivery!
How are the preamps? And EQ?

Maybe you have some news!

Regards,
Wolfgang

 

[nilsc]

Hi
I´ve just got this mixer in house from swedish roadcasting and I love it!
Sounds beautiful and in pretty good shape for it´s moe than 30 years.
AND, I also got the manual/schematics with it.
Regards, Nilsc

 

[allintothat]

Hi
I´ve just got this mixer in house from swedish roadcasting and I love it!
Sounds beautiful and in pretty good shape for it´s moe than 30 years.
AND, I also got the manual/schematics with it.
Regards, Nilsc

A question for you Nilsc, do you have the possibility to scan the shematics and the manual? I have a pdf but the schematics is not complete.
Cheers!

 

[pucho812]

Hey I found this on the web this morning....
The service manual for the sam 82

http://secretcircus.se/SAM82_servicemanual_kretschema.pdf

 

[Bill Wilson]

You might think about changing the 709's & the 741's; they are ancient & slow. The circuit will need to be studied to determine which more modern chips would be compatable w the circuits.

Should make a real improvement in the sound.

 

[J0hanne5]

I bought a sam82 a couple of months ago. Pretty nice pres! I paid only 220 euros so it was a real bargain. Mine has op27s which is a very low noise instrumentation amplifier. Those faders and pots are not so good. I think I change faders to Penny and Giles if they fit in.

 

[breakfix]

I have one of these too.  Very nice. 

Really want to create a break out box for the multiconnector on the back but am having trouble sourcing a connector.  Has anybody here done that?

The part number listed in the manual is  00-8257-096-000-129 elco (I believe that's for the male 96 pin connector on the unit so the female end would have a similar code). 

I read somewhere that the 00 stands for Special Unit, 8257 is the part #, 096 is the max number of pins (the SAM only has actual 32 pins - the rest are empty - the 000 is? and the 129 is some kind of tolerance, quality code) 

By the way check out this beautifully modded Sam 82A for sale on German eBay:

ebay.de    item# 231829827867

 

[J0hanne5]

The first channel does not work and I pretty sure that a swhitch is the problem. There is signal coming through only at  the "line" position. All of the OP amps work.

So, does some one know where to get these switches? Manual says "ITT BRP 2x6 rotary switch"  but Google does not give me any info... Despite the fact that Sam is a semimodular it is still real PITA to repair.

 

[Conviction]

The first channel does not work and I pretty sure that a swhitch is the problem. There is signal coming through only at  the "line" position. All of the OP amps work.

So, does some one know where to get these switches? Manual says "ITT BRP 2x6 rotary switch"  but Google does not give me any info... Despite the fact that Sam is a semimodular it is still real PITA to repair.

Hi Johannes!

Perhaps I'll be able to help as I'm gonna dig into one next week. This unit is showing the exact same symptom on channel 1. I believe the problem's the gain setting rotary switch.

Have you modded yours for direct outs? It's not as easy as one could think, as you'll likely need some additional gain staging (JFET:s?) for the unbalanced outputs to prevent loading. Once upon a time SATT provided all this in a nice little breakout box.

I guess it depends on how you're going to use the SAM82, as this won't be a problem as long as you don't use the summing stage, i.e. use the mixer as originally intended. Still, I'm not sure about the output levels. I suspect one would get something in the range of -10dBV.

 

[Conviction]

The first channel does not work and I pretty sure that a swhitch is the problem. There is signal coming through only at  the "line" position. All of the OP amps work.

Did you check the switch shaft? There's two types, a longer and a shorter. The short shaft wont reach the second (part of the) switch on the input board. In "my" machine someone had accidentally placed a short shaft on channel one where a long shaft is needed. Perhaps they took them out (from the top, remove the top lid) while cleaning the unit.

 

[warro]

Hi. I am so glad this thread is revived. I just bought a SAM 82 as well. Good condition and mostly original. Even original case (will post a photo later) I will try to help you out as much as I can and hopefully you guys can help me as well.

I have gone through every thread I can find about the SAM and all of it's components and possible upgrades. But still wan't more input. I also have a home made breakout box so I can guide you through that.

And for the switch. I'm pretty shure it's a ceramic rotary switch with 2 poles and 6 positions made by ITT (I doubt you will find an original but there is others). The rest of the specs may be measurements and materials I guess?

I still have the 709C IC's on the inputs. Have read alot and it seems like the 2 best replacements are NE5534AN and LME49710(ha). According to the threads I've read it seems like 5534 is better than 709 but still sounds vintage, warm with some rolloff in the highs. The LME seems to have more detail and flatter response. To some it sounds sterile and boring. I really want to maintain the vintage sound but also want resolution and detail. To put the sound in words: Warm, punchy, airy and defined/detailed. Maybe thats too much to ask for? I did order 10x Philips NE5534AN. Specially seems many vintage, famous consoles (Neve and MCI etc) had them. I think I know what changes to make for puttningen the the 5534 or the LME in. But I'm concerned about the increased current draw of the 8x 5534.

I also thinking about upgrading the 4741's in the EQ and mix amps for LME49740 or TL074. One IC in my SAM was actually replaced with TL074. I found out when I did open it.

So, please help me. I really want to do the "necessary" upgrades while it's still disassembled and I have the 5534s showing up any day. Still concerned about increased current though.

Cheers!

 

[PRR]

'709 is tricky to design around. But if it works, it is a great opamp. In a few ways, better than many modern chips. I'd leave it be.

'741s in tone circuits would seem to be inviting something better. TL07x is the obvious thing to try. Check pinouts: a "4741" may be a Quad but maybe not the same pinout as TL074.

 

[Conviction]

And for the switch. I'm pretty shure it's a ceramic rotary switch with 2 poles and 6 positions made by ITT (I doubt you will find an original but there is others). The rest of the specs may be measurements and materials I guess?

Unfortunately it's not  It's a weird little plastic rotary divided in two parts (for each channel): one on the main board and one on the input boards. Then there's a long shaft connecting them two.

I gotta ask: did you bother with a buffer/driver in your breakout box? Just making one is a piece of cake, yes, but then there's the problem with loading down the channels (as I wrote in my last post).

I've seen the original made by SATT. A nice box with driver stages and 8 Lundahl output transformers. But I doubt they ever supplied the schematic.

 

[warro]

Hi.

Thanks for the replys.

@PRR The SAM 82 is using HA-4741 wich is a Harrison quad 741 which, according to another thread is suppose to be superior to the regular 741. But will it be good enough? Does anyone have further info about this? I have checked that the TL074 is pin compatible. But it seems to have more noise than HA-4741. But can the noise be more or less depending on load and frequency?

Here is also a official instruction how to replace 709 with 5534 on an Auditronics Console.
http://groupdiy.com/index.php?topic=36535.0

@Conviction A 2x6 rotary switch is just that. 2x 1x6 rotary switch. Which is 6in 6out x2. The one on the input board is gain switch (also turning off +48V at 0) and by reading the schematics I think the other one is just using 2 of the 6 switches (5 is shorted) switching between mic and line. In this case I think is actually 2x 1x6 switches sharing the same shaft.

As for the breakout box. Mine is made by the former owner and is just signal out from the input board before mix amp and faders at +6dB (see shematic).

I would love to have the original box! But there is only picture of one unit on the whole wide web.
http://forum.studio.se/topic/79111-satt-sam-82-mixer/

And analyzing the picture compared to the SAM 82 I would say they must have just reused the output board and transformer. And that would be logical, right. So (transformer if mic) Input -> straight to output + transformer, out. See attached pic of my output board and compare to the breakout unit, also called Pre Fader Unit. Same amount of components, same layout and samt type of components. The resolution of the picture of the original box is too poor to read resistor and caps values though.

I will use my SAM for tracking and mixing 8 channels independently. So I will mod it using the 6 output transformers in the SAM for 6 outs and either try 2 find 2 original transformers or 2 substitutes. For monitor out I will use my audio interface/tape recorder I guess. Or maybe find substitute trannys for monitor on the SAM.

@synthi If you are still online this days I would love to here your opinions on 709C vs 5534AN preamps.

 

[Conviction]

@Conviction A 2x6 rotary switch is just that. 2x 1x6 rotary switch. Which is 6in 6out x2. The one on the input board is gain switch (also turning off +48V at 0) and by reading the schematics I think the other one is just using 2 of the 6 switches (5 is shorted) switching between mic and line. In this case I think is actually 2x 1x6 switches sharing the same shaft.

I'm aware (but apparently I failed to make myself clear). These are rather peculiar looking... I'm not talking about function.
I take it you've opened your unit up? Then you'll know.

If J0hanne5's (ping) unit has a bad switch, or part of it, I think he'll have a hard time sourcing another.

 

[MeteorMan]

could the rotary switch be the part on page 19 of this:

http://datasheet.octopart.com/RBP12304B04CFS-ITT-datasheet-138375.pdf

double pole 6 position model says "no stop" though. dunno what it means.

anyone know a suitable replacement fader part/model by the way? all the channels in mine need new faders.

thinking of refurbishing the one i have but if it gets too tricky or expensive, i probably just rack the 8 input channels at some point. that way could forget about the faders and use some other rotary switches.

 

[J0hanne5]

If J0hanne5's (ping) unit has a bad switch, or part of it, I think he'll have a hard time sourcing another.

Actually I got a couple of these switches! (Thanks to Meteorman) However I have not had time/energy  to replace it since I have several projects going on. I think these switch tend to fail quite easy. I studied my Sam more and now  I am sure that the switch is the only problem.

At the moment I have two Sams. The first has this dead channel and another has some problems with a power supply. My plan is combine these two in order to have one that works.