Setchell Carlson Score

[Horn Head]

What? Setchell Carlson? Yep, out of a thrift shop about to be chopped or tossed in the dumpster.

Some limited research tells me these units were modular - i.e. pick a tuner modle (AM or FM) and insert it with a few screws and plug unit into chassis....) Pretty flexible. It's a model RP90 (sometimes referred to as RP91 with the other modular devices connected).

The unit I got seems to have the FM module removed, but the whole power amp and am receiver is there (and TT).

Amp uses 2 x 6CL8 tubes pushing 4 x 6CM6 output tubes in PP stereo.

Neat thing is the PT is there and the OPTs are encased in circular cans....very exciting.

The thing is mosty a parts doner now and wondering if anyone knows about thoe OPTs. Never saw circular OPTs expect for some of those old Sansuis and other high class stuff.

Would Like to know more about this chassis, especially the OPTs, and still looking for a schemetic...

 

[Thespeakerdude8]

6CM6 = 6AQ5 = 6v6 types, only in a 9 pin bottle. Cool! Round cans mean potted transformers! Could be special. SC pioneered the "modular" unitized construction with their TV's in the 50's and 60's.

 

[spaceman]

Oh yeah, those OTs look cool as heck. :thmbsp: I haven't read much at all about Setchell Carlson yet, but someone pointed out to me, that it's NOT related to Stromberg-Carlson, they're completely unrelated. Good save, I'd hate to think of it in the trash.

 

[Tom Bavis]

I just happen to have a scan of the schematic for this beast... tbavis(at)rochester(dot)rr(dot)com

 

[Blast]

Looks like a great rainy day project. Great score!

 

[gadget73]

Nice little project. I can see why you'd want to make that a donor, its kind of ugly stand-alone and the cab is kind of beat looking. I'd probably try and bring it up as-is just to get an idea how it might perform. Looks like an interesting one to say the least.

 

[Horn Head]

Thanks for the responses guys... Yeah, this one is a little wierd.

Funny, when I first saw the amp I assumed the the power transformer was hijacked from it (leading to the big hole in the chassis) and that largish transformer left was the OPT. Drove back home from the thrift shop and did 15 minutes of research (not a lot on ol' Setchell phono/radio units on the net). But did read that they were modular.

Back down to the thrift shop more informed and realized the FM unit was robbed....but the good amp stuff was all there - to include all transformers. And those 6CM6s look interesting with those round OPTs.

Will try to decipher this thing and decide how to proceed...

 

[Thespeakerdude8]

if I don't like the way a console amp looks, I have a nasty habit of removing the x-frmrs, drilling out ALL rivets and re-using the tube sockets, standoffs, jacks, switches, and pots that I can in a new chassis. Usually takes me about an hour to totally gut an amp like that- I tore a beat up silvertone reel-to-reel apart to the last resistor the other night this way
Gonna be a nice guitar amp.

 

[Horn Head]

Thinking about putting those potted OPTs into my Maggie 8802 to gain some low end (lower end).

Anyone know if these will be a sufficient match for PP 6v6?

Originally the OPT ser serving 65 CM6 in PP.

Thoughts?....will I get better low end from the Maggie 8802?

 

[Tom Bavis]

Sure - they'll match the 6V6 - the 6CM6 is the same as 6V6 in a smaller bottle. Whether they'll be better than the Maggies... if they outweigh 'em it's a good bet...

 

[Horn Head]

Tom, Thanks for clarification....may test them out to see what happens on the 8802.

Was going to spend the evening disassembling organ tone boards for the parts and pieces but swapping these OPTs seems like a more fun thing to do now...

 

[jaymanaa]

FWIW a lot of Setchell Carlson tubes were actually made by Amperex.:yes:

 

[Horn Head]

Actually installed (temp job) one of those potted Setchell Carlson OPTs into the Magnavox 8802 this evening....see picks. Then did left/right tests.

No revelations. The SC OPTs may have had a bit less booming down in the bass - 100-150hz. But they did seem to saturate before the original Maggie OPT.

So, doesn't seem the trouble to swap. They'll make good xfrmrs for another project.

Guess I need to get a pair of those big Edcors for the 8802. I think the OPTs are the last 'big' improvement I can make on the amps.

Too bad,they looked really cool. But, I have some of those old 'cans' that were used to cover the RF coils in antique radios,and they slip perfectly over the normal sized Magnavox OPTs. Am going to paint them black I think then install them on the 8802 and 9308 to clean-up the looks of those open frame OPTs.

 

[gadget73]

Sounds like a nice improvement. Visually, there is certainly not a lot to love about the stock Magnavox iron, but at least they sound pretty decent.

 

[Horn Head]

Sounds like a nice improvement. Visually, there is certainly not a lot to love about the stock Magnavox iron, but at least they sound pretty decent.

gadget, yep still with the 8802 stock xformers...and they perform well enough after some PS upgrades suggested by PIO1980.

Regarding the beauty of the 88XX series, I finally cleaned mine up by removing that silver cap can from center stage.....ripped the bugger out and put caps below. Cleaned-up the line on the top and less obstruction to view the good components. Covered the cap hole with a small aluminum plate.......looking less and less 'industrial'. Not sure why folks restuff these things for looks. Guess to each his own.

Next is the cans over the stock OPTs. (Unless I switch to the Edcors...then those can probably wont fit - and it would be nice to see the blue on the chassis anyway.) A couple months away from that project.

 

[Phototone]

You may actually find that those OPT are not potted, rather just have a round can on top.

 

[Horn Head]

When the potted xformer was first mentioned I had no idea what that was. But those round OPTs from the Setchel are filled completely tight with something of the consistency of polyurethane - up to about a 1/4 inch below the lip (when held upside down. then a piece of craft paper covers that with a hole where the leads come out.

I believe they're potted from what I've read.

Only problem is, in the test I posted earlier (subbing them into my Maggie 8802), they don't sound any better, actually started distorting a bit earlier than the stock Maggies. Too bad.

Please let me know if 'potted' means something else than what I described.