Sumo The Power Schematic

Zero Cool

Paid Member
2004-09-20 6:10 am
I worked on one of these once. Huge pain in the rear. Massively heavy, built monaco <sp> style. the entire chassis is built around the HUGE power transformer. Each channel is a pair of amps in bridged mode with lots of complicated servo circuits etc.

When it worked, it worked great, tons of power, but when it blew, i took out a pair of brand new JBL 15" woofers POOF! what a waste..

Best of luck, i never was able to find a schematic way back when.


Alex helge

2002-10-10 12:40 am
Sumo The Power

Hello Zero Cool
thank for your answer

I will buy the Sumo for 1500€, but I have never heard a Sumo amp.
The transformer of the Sumo Power to growl lout.

The Speaker membrane to bang at the Sumo switch off and switch on.

It´s the tone of the Sumo Power better than the Krell ksa 100.



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My limited exposure to Suo amps tells me that the servo control op-amps will need upgrading, but doing so blindly can lead to real issues. Please seek expert advice on that aspect of modification. Also, tons of bad and weak wiring, cheap diodes and capacitors all over the boards. The circuits -tend- to be over complex and rely heavily on feedback for damping. And two of these circuits, bridged, per channel? Eeeeekkk! :xeye:

If i recall correctly, they are re-visions or off-shoots of the GAS amplifiers, all of them being designed by James Bongiorno. Not that he's a bad designer, but I only repair the sound of his amps, not actually listen to them beyond that. I might use one for bass use, for a the same way I might use a Bryston or the like. But I'll never try and listen to one. They just don't sound like music. Very much. :rolleyes:

Just my opinion, like backsides, we all gots one! :D

I rebuilt one of these about a year and a half ago. It sounds
like yours has the same problem as mine did...full DC on one channel. Measure it with a DVM on the outputs. It will be about 100vDC. The designer of this amplifier is James Bongiorno. You can contact him via the Yahoo group "SAE_Talk. If you search that forum you'll find many posts about the Power. (Many of them mine). James will not give out the schematics ( if anybody HAS one, I'd be willing to pay $100 for it). The other posts here are correct: It is a monocoque construction. The op-amps can be upgraded and topics on SAE-Talk cover this. Each channel is a pair of amps in bridged mode with lots of complicated servo circuits. The "transformer growl" you hear is from the full DC on one channel. Mine did it too.

Essentially what you can do to start is this: If you have one good channel, use it as a reference and compare the voltages to the bad channel. Start at the power supply and move outward. The design is fairly straight forward until you get to the servo boards. These are the boards that sit on top of the heatsinks on each channel.

I found this amplifier to be excellent sounding, even better than "The Nine" (another Sumo design) and MUCH BETTER than an Adcom 555 II. It is now in my main system. Good Luck

Alex helge

2002-10-10 12:40 am
Sumo The Power

Thank Comuteruser for your answer.
It´s the price of 1500€ for the Sumo Power OK ? I will try to buy the schematic of the Power,too.
The circuit of the Sumo is not easy.
I have not to see the inside of the amp, but I think, I can not buy the components of the Sumo Power.



2010-12-07 4:57 pm
sumo the power... the schematic has gone!

Hi every one! just an update: Some years ago I sold the amplifier to somebody in to the States I sent the schematics too! and for my misfortune the copy I got prior to ship the amplifier, got lost after moving home. Sorry.
However , seems like everyone faces the same problem. DC voltage at the output terminal, sometimes it is intermittent, and when it apears of course it comes accompanied by a good barbecue of Speakers!
Well in my case a pair of early collective Altec Lansing 605 speakers were burnt out!:mad: my big mistake, never should connect them to this amplifier , a 15 watts amplifier would be enough back then!
So, I found the problem were related with the CLAMPS of the AC on transformer. The were dirty and from my humble point of view, a real cause of a potential failure, -no complex FMEAS were used back then-. In my advise remove the clamps and solder the wires to the board , that's how I solved the problem. In the other hand , I took the opportunty to upgrade the amplifer replacing the OP amps for a better ones, options are: NE5532, TLE2082 (not suitable for all sections due BiFet technology), LM4562 (the one I used to improve it) Nowadays the are a lot of OP amps very suitable for upgrade like ADs, LMEs, TLEs, OPAs, LTs and so on. Change the signal and decoupling electrolitics for OSCON and Nichicon audio grade, believe me the final result kicks all super mega buck amplifers into the market!! Good luck!! cheers!!
Well in my case a pair of early collective Altec Lansing 605 speakers were burnt out!:mad: my big mistake, never should connect them to this amplifier , a 15 watts amplifier would be enough back then!
What were you thinking? :eek:
No need for DC, just the turn on thump from this beast of an amp will murder these delicate Senior Citizens.
Personally I would connect them only to Tube amps or maybe a 20W Class A SS one.
And given speaker value (not cost, different thing) I would add a dedicated DC protector if used with direct coupled amplifiers.


2008-06-12 3:43 am
I just received my second "THE POWER" last week which came in three seperate boxes as the seller didn't want hurt his back trying to ship it in one piece. He had wanted to part it out but I was able to get all of it before he had a chance to sell any of it. This was "Computeruser's" amp at one time.

Everybody familiar with this amp knows about the intermittent problem with DC on the speaker terminals. Mtubes seems to think he figured it out by removing the "CLAMPS" and soldering the wires directly to the board. The "CLAMPS" I am assuming are the quick disconnects on the low current power supply board, correct? The high current connections are by barrier strip. The other problem described by Computeruser are the intermittent/bad TO-66 collector connections, basically Pem Nuts, on the one of the drive boards.

In checking out this new one I found a piece of wire insulation in the connector that supplies +12VDC to the right drive board. This +12VDC supplies power to the DC Servo opamps so maybe that's the problem with the one. We'll see.

My first one works OK but occasionally pops the 10A fuses on the output boards, in fact they were blown when I received it. It's tried to blow up the woofers in my Dynaudio speakers but they are pretty tough drivers.