Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: ilyaa on March 19, 2017, 05:44:42 AM

Title: Sunn Coliseum 300 bass Schematic....
Post by: ilyaa on March 19, 2017, 05:44:42 AM
hey!

i know this probably is not a popular topic, as i just spent a bit too long looking for this schematic in vain.

wtf. i found one schematic for this amp and i was trying to work off of it for a bit until i started to notice some strange discrepancies - the IC used for compression in the schematic has 14 pins - the one im working on has 16! - the input IC on the schematic i was looking at was a dual op-amp - the one i'm working on is a 5534!

this is the schematic i was able to find: http://www.prowessamplifiers.com/schematics/sunn/Coliseum_300_Bass.html

anyone have one for the OTHER version, with the 16 pin compression IC and the single op-amp input IC? can't tell what the other differences are...

the power amp in working and im suspecting its the compression section that's the problem (seeing as the IC is fried beyond recognition) but i cant really work on it with this other schematic that doesn't match up at all....

interestingly enough i think this very amp has been asked about in forums through the years.......we'll see if i become just one of many!

Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: g1 on March 19, 2017, 01:25:50 PM
What might the number on that 16pin compression chip be?
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: ilyaa on March 19, 2017, 01:29:25 PM
wish i could tell you!

it blew up - charred.
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: ilyaa on March 28, 2017, 02:01:44 AM
think ive given up on finding the schematic -

anyone have any luck with asking fender for it?

all i really need, at least to get cracking, is to figure out what this compression IC is - its NOT an ssm2012 or ssm2013 - its some 16 pin thing -

anyone know what the alternate coliseum 300 preamp used for compression IC??
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: Enzo on March 28, 2017, 02:36:37 AM
How old is this thing?  1960s?  Other era?
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: J M Fahey on March 28, 2017, 06:08:04 AM
The old schematic you found belongs to the "real" Sun Coliseum 300 from the 70´s ... and it never had compression, nobody did way back then.

IF it does, then it´s something else, a "reissue" or something a new brand owner made to cash on the name.

IF made by Fender, they bought the Sunn carcass but continued only with the PA equipment, *might*  have made some Bass amps, then they should have a suitable schematic, ask them i any case.

We are in complete darkness here, at least post some pictures, including any "Made by / Made in" labels, some gut pictures and some closeups showing any labels on the boards themselves, both silkscreen and copper side.

That said, "compression"  and "16 pins"  in the same phrase, make me think of LM13600, a very popular gain controlled OTA:
http://www.b-kainka.de/Daten/OPV/LM13600.pdf

For starters check whether datasheet pinout matches what you have on PCB or not.

That said, a cracked IC makes me suspect supply overvoltage or some similar gross problem, check you have proper +/-15V rails or whatever that preamp uses.

FWIW that amp might be a generic Korean OEM amplifier with a Sunn label glued to it.
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: g1 on March 28, 2017, 01:45:16 PM
Have you tried over at the sunn forum?  http://sunnforum.ampage.org/index.php
There was mention over there of 2 different schematics depending on the compressor chip.  No one posted the schematic but someone may know the chip used.
http://sunnforum.ampage.org/index.php/topic,10313.msg35604.html?PHPSESSID=24dhorm58ncmslrf2kgtl3cvi7#msg35604
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: ilyaa on April 03, 2017, 01:13:59 PM
here are some pics!

look familiar?

id say late 70s.....

Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: J M Fahey on April 04, 2017, 12:46:06 PM
That´s why you must post pictures even from burnt stuff.
Model ends in "1N" and I seem to recognize the Signetics "S" .
That plus "16 pins" and "compressor"  makes me think of Signetics NE571N (now NXP)
Check that datasheet pin function matches that in your amp:http://music-electronics-forum.com/attachments/33954d1431700495-ne571-compander.pdf
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: ilyaa on April 04, 2017, 01:48:08 PM
seems right!!!

pins 8,9 are left open in this design - the VCC/ground pins match - and the input/output pins seems right - 6,11 are open, as well -

it would be really great to have the right schematic - kind of a brain-buster to trace the whole circuit around this thing - but i think you might be right on, J M!

Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: Loudthud on April 04, 2017, 05:36:56 PM
The schematic can be found here: http://www.prowessamplifiers.com/schematics/sunn/Coliseum_300_Bass.html

The compression chip is said to be SSM2012 or SSM2013.
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: ilyaa on April 04, 2017, 05:50:35 PM
loudthud - i appreciate the link but if you read above in the post the whole reason im in this fiasco is that ISNT right the schematic - that is NOT the chip in this amp -

that schematic is very similar to this amp but, the preamp at least, does not match up. ive got a 16 pin compression chip, as well as some other significant differences....
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: Loudthud on April 04, 2017, 07:39:03 PM
Trying to attach a different schematic.

[attachment deleted by admin]
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: joecool85 on April 05, 2017, 08:35:14 PM
Quote from: Loudthud on April 04, 2017, 07:39:03 PM
Trying to attach a different schematic.

[attachment deleted by admin]

It seems the forum software didn't like your .gif file.  I think it was mostly due to it being over 7,000 pixels wide.  I have shrunk it down and converted to a .jpg file.  All seems well now!
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: g1 on April 06, 2017, 12:07:15 PM
Interesting, this matches the 16pin compressor that the OP is looking for, but not single op amp input (5534).   ???
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: ilyaa on April 06, 2017, 10:24:46 PM
i know, g1, isnt that weird??

but it matches the compressor and there doenst seem to be a problem with the input so i wont look a gift horse in the mouth!

i ordrd a couple NE571Ns - ill let you guys know what happens!
Title: Re: Sunn Coliseum 300 bass Schematic....
Post by: ilyaa on July 19, 2017, 07:12:35 PM
just an update -

I ended up replacing every IC on the preamp - after a fiddly 'biamp crossover' pot that almost sent me back to square one - it was one of those 'everything works!' and then put in back in the chassis and nothing works again! - but luckily just a bad solder contact -

we are back in business!! I replaced the flimsy ribbon cable with individual stranded wires - time consuming but much more sturdy - and had to replace a couple broken send/return jacks on the back -

looks like there was something serious that happened to the +/- 15 rails because all of the op-amps were fried. but I've ran it for quite a while now and we seem to be back in business. I did replace the zeners and regulator transistors for the low voltage rails  - think those were the initial problem.

anyway, thanks guys! kind of a long saga but all's well that ends well