Stevenson Interface Electronics 108k Q's Now have schematic

anticpunk · Post by **anticpunk** » Thu Jul 05, 2007 9:47 pm

Hey,

I just bought a pair of SIE 108 channel strips. Stevenson gets mixed reviews, but the price was right. Now, They have the Beyerdynamic input xfmrs but what can I do for an output transformer? Can I just use a generic transformer to couple it or is there a better-than-the-rest alternative?

Anyone have experience with these strips or stevenson in general? Suggestions?

Thanks Much,

Jay

brianroth · Post by **brianroth** » Fri Jul 06, 2007 12:57 am

I am vaguely familiar with Stevenson/Interface mixers, but find little or no info in my file cabinet.

They were somewhat popular back in the 1970/80's, at least around my neck of the woods, as they were based in Houston. I actually toured their factory in 1979 when I breifly relocated to Houston to work for a sound/lighting company.

Do you have schematics?

I suspect the output stages of Stevenson modules aren't beefy enough to drive a 600 Ohm load. But, you can add an output transformer to just about anything, even if the upstream circuitry can't drive 600 Ohms. You just can't the module into, say, an LA-2.

Look at Edcor for inexpensive, but quite decent, output iron:

http://www.edcorusa.com/products/transf ... 0-600.html

http://www.edcorusa.com/products/transf ... 0-600.html

Bri

anticpunk · Post by **anticpunk** » Fri Jul 06, 2007 3:02 pm

thanks for the reply!

No, i haven't got a schematic for the strips. It looks in the pics like there could be an output transformer on the board, but I'm not overly familiar with channel strip circuitry. Now, if these strips can't drive the load that you mentioned (600 ohm), where does that leave me? I want to use them either infront of my interface (directly) or through another means of input like a mic input just to add flavor. What would I have to do to make it happen if they don't have output transformers and if they are low output? a summing amp perhaps? (to get to line level?) if they are really a PITA, maybe I should just get some PM1ks like everybody else does.........

I am sorry if these seems like dumb questions, but my audio electronics has always been limited to basic amp repairs and building/modding stompboxes.

Any help is appreciated greatly.

Thanks,

Jay

brianroth · Post by **brianroth** » Sat Jul 07, 2007 12:43 am

Wish we had schematics....

That said, I assume you want to use these as mic pre's or for the EQ. The trick is figuring out what pins on the module allow in/out, and what the specs are for each.

Just because an output cannot drive 600 Ohms doesn't mean it is unusable. Most "modern" gear has 10K or higher input impedances, with some exceptions, like the LA-2 I mentioned, and other vintage pro gear.

Drill down through Google to see if you can find more info.

Bri

anticpunk · Post by **anticpunk** » Sat Jul 14, 2007 9:20 pm

So I got the strips in hand now.

The IC is labeled Rc4709/1437db and Ray T7603 both on the same chip.

Found orig. specs, now need source/cross for replacement.

Part Number = RC4709C
Manufacturer Name = Raytheon Electronics
Description = Single General Purpose Op Amp
Input Bias Current Max. (A) = 400n
V(io) Max. (V) = 10m
Com Mode Inp Range (VICR) = 20
Input Resistance Typ. (Ohms) = 150k
P(D) Max.(W) Power Dissipation = 225m
Nom. Supp (V) = 15
Status = Discontinued
Package = DIP
Pins = 14
Military = N

I was hoping to rechip them.

Also, I need an edge connector with 2 rows of 25pins each, mouser is a strike out, ideas?

I thought this would be easy, but its looking impossible........ crap!

-Jay

anticpunk · Post by **anticpunk** » Sun Jul 15, 2007 8:16 pm

I found a pinout on the chip today. I have all but a few edge pins figured out now. The output isn't clear, and it has all kinds of routing buttons which I don't really understand the connection of. the are 8 balanced pairs as far as I can tell, but they run to one of three seperate rails....... i don't know what to make of it........ Also, every input and (what I assume are the) outputs have 10K resistors inline in both the hot and cold sides.......

Still no schematic but I may just draw it up myself and see if anyone can make sense of the connects.........

Also found a guy who had done a few rack jobs on some Stevensons in the past, hopefully some info or a quote will be along shortly..........

-Jay

princetown · Post by **princetown** » Mon Jul 16, 2007 5:26 am

jay ,iam very interested in your progress,i am in the same boat as you,any schematics/help/leads greatly appreciated, solder on, Tony

anticpunk · Post by **anticpunk** » Mon Jul 16, 2007 4:46 pm

Tony,

I'll definitely keep you posted. I will be drawing a schematic over the next few nights(as time allows). if you want the info I have so far, PM me your email and i'll send it over. No sense in wasting board space with my notes and chicken scratch.

BTW, Did you get them from ebay off a guy called "UnkleDik" from NYC?

He has some racked up so I hope he'll reply to my request for the info on his tech. Maybe the tech can get me an actual schematic.

-Jay

anticpunk · Post by **anticpunk** » Mon Jul 16, 2007 9:24 pm

Maybe I got something here Brian........

Alright so I drew a schematic as accurately as possible at 12am. Parts count is off by 2....... Should be a REALLY REALLY good starting point.

Also scanned in the pinout and notes and the EQ section as a seperate unit since it wouldn't fit on the sheet with the main circuit........

Any body want to check it out and see if you can:

Explain the phantom connection and how it doesn't smoke the IC,
Explain how to connect the outputs since it is giving me only a single out from the fader

I'd like to rig one up with a Hi-z input for use as a DI box, I'm guessing i can just tap after the input xfmr (?) and put in a level pot and a jack.

Normal operation VDC is 15-18....... source for best supply?

Do I need a transformer to couple to the line in on my DAW? or will that bring me back to Lo-z?

Tired and Confused,

Jay

PS - If you want to peruse the info I have generated, I'll make a ZIP or PDF or something so I can share them. They are high DPI scans and big files.......

nclayton · Post by **nclayton** » Tue Jul 17, 2007 2:31 pm

Put your schematic up somewhere and post the URL here. It would be interesting to look at.

I have a feeling there might be some errors in it, though. I don't think there should be any confusion about how the phantom power avoids frying an ic. phantom should go in, through a couple of resistors and then to the input transformer. It shouldn't go anywhere near any IC, just to the transformer. Another good thing to post up would be a large hi res close up photo of both sides of the boards.

Ned

brianroth · Post by **brianroth** » Thu Jul 19, 2007 10:23 am

anticpunk...email me the schematics and I'll temporarily post them on some section of my website so we can all look at them.

Bri

(Note: I am away on a project Friday through Monday, so there may be a delay....)

anticpunk · Post by **anticpunk** » Thu Jul 19, 2007 8:11 pm

Hey guys,

I went ahead and uploaded them to a directory on my site.

The schematic is messy and I make no excuses for that, but it should be helpful in this whole deal.

so.........

http://www.fartoofrail-music.com/stevenson/

I will take some pics when I find my camera cable.

Thanks,

Jay

anticpunk · Post by **anticpunk** » Wed Jul 25, 2007 7:37 pm

Brian,

Have you had a chance to review the schematics? I am going to build a box for them this weekend and *try* and get one functioning. I'll post results.

Thanks,

Jay

brianroth · Post by **brianroth** » Fri Jul 27, 2007 2:30 pm

Sorry,,,I've been out of town and busy with two projects. I'll try to wander through the schematic this weekend.

Bri

nclayton · Post by **nclayton** » Fri Jul 27, 2007 8:24 pm

hey, jay, have you tried looking at your schematics as posted? For some reason when I try to look at the "main schematic" it doesn't appear completely. i think maybe that file might be bad?

Ned

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Stevenson Interface Electronics 108k Q's Now have schematic

Stevenson Interface Electronics 108k Q's Now have schematic

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