Sumo Nine Plus output transistor replacement - Sanken 2SC1831 - diyAudio
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Old 14th August 2014, 09:25 PM   #1
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Default Sumo Nine Plus output transistor replacement - Sanken 2SC1831

A friend wants to bring over an early (1987?) Sumo Nine Plus amplifier with blown outputs. According to him, the original chips are the obsolete Sanken 2SC1831. I've had no luck sourcing a suitable replacement or finding the early version of the schematic. The later model of the Nine Plus uses NEC 2SD555 chips, which are also obsolete.

What would be a suitable replacement for the original Sanken 2SC1831? Attached is the schematic for the later version of the amplifier.

Thanks in advance.

-Stan
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File Type: pdf hfe_sumo_the_nine_plus_schematic.pdf (19.4 KB, 71 views)

Last edited by Tone Meister; 14th August 2014 at 09:45 PM.
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Old 14th August 2014, 10:29 PM   #2
llwhtt is offline llwhtt  United States
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My last couple of visits to James Bongiorno's place was all about the SUMO NINE, there are NO replacements, period. That's right from the horse's mouth. Sanken pretty much made them for him and his SUMO GOLD. The later NINE+ has drivers so normal output transistors could be used, MJ21194s would be great here.

If you look for replacements you'll end up with Darlingtons, no good. The 2SC1831s are called super betas and that's what allowed the LF353 front end to drive the outputs by itself.

So if it is a NINE+ go ahead and use MJ21194s. The bias on the PLUS is set by removing one of the fuses, connecting a DMM set to amps, and adjusting the pots, keeping them even, for 1 amp. I'm not a big fan for the "keeping them even" but that's how it's done. On the regular NINE you need a distortion analyzer with a balanced input to set the bias.

If his NINE+ used the 2SC1831s that was after James left SUMO and not correct according to him. Beancounters.

I have schematics for all three versions.

Craig

Last edited by llwhtt; 14th August 2014 at 10:38 PM.
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Old 14th August 2014, 10:49 PM   #3
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Thanks for your reply Craig. Truth is, I don't have the amp in front of me yet, but I do know it is an earlier version with the Sanken 2SC1831s in it. I had narrowed down my search to the MJ21194s as well, but I wanted to be sure before we took the plunge for 20 of those puppies.

BTW, how will the MJ21194s stack up against the original Sankens soundwise? My buddy is concerned that any replacements won't sound as good.

I'm not a solid state guy, actually I'm not even a tech. I'm just a hobbyist with a grasp of the basics and a decent electronics workbench. I'd appreciate any help with the Sumo amp, including a copy of the schematic.

Thanks again
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Old 14th August 2014, 11:06 PM   #4
llwhtt is offline llwhtt  United States
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Once you get the amp in front of you look for the TIP31C (TO220 case) driver transistors, two per channel. If those are there it's a PLUS. A far as sounding the same it's either the "new" sound, if there is a new sound, or silence. The dual opamp should be an LF412.

Go to the ON Semi site, sign up as whatever and you'll be able to buy them for about half price.

Craig
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Old 14th August 2014, 11:20 PM   #5
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Went to the On Semi site and wasn't able to find where to sign up.
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Old 14th August 2014, 11:26 PM   #6
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The amp is a Nine Plus, according to my buddy who's owned it since 1987.
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Old 14th August 2014, 11:31 PM   #7
llwhtt is offline llwhtt  United States
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Near the top center of the home page there is "MyON", click that and register. Might have make up a business name, "Joe Schmo Audio Repair" or whatever floats your boat.

Craig
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Old 14th August 2014, 11:50 PM   #8
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That was a good lead Craig, thanks.
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Old 15th August 2014, 12:33 AM   #9
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Craig,
The 2SC1831 is a Darlington, so can you explain how the MG21194 is a suitable substitute in this amp?
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Old 15th August 2014, 12:57 AM   #10
lms is offline lms  Micronesia
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super beta, not darlington
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