Help! Save my Sumo "The Power" power amp.

[Chris Dian]

Recently a friend gave me his Sumo power amplifier (model name: “The Power”) as he had given up the hobby. I was told that it has a rated power of 450W per channel and that the maker no longer exists.

When I played the first cd it was the sweetest sound I had ever heard. It was simply out of this world. But upon playing the second cd a tiny red lamp on the left of the on/off switch began to blink and crackling noise was heard from the speakers. As a result, the woofers on both speakers were knocked out (kaput) although the tweeters seemed unaffected. I have not a clue what caused the speakers to blow up. As I was so impressed with what I had heard, although for only a short 50 minutes, I intend to find someone to trouble-shoot and repair the power amp, if possible. If a schematic drawing is still available it would certainly facilitate the repair job. I would also be grateful if I could have some comments and advice that would shed light on the problem I encountered.

Thanks in advance.

Chris.

[Elso Kwak]

Hi Chris,
I would suggest to register with Yahoo and become a member of the SAE forum and post your question there:
http://groups.yahoo.com/group/SAE_Talk/

[destroyer X]

It is class A, the wonderfull sound you told made me think in class A.

And the power consumption is around 450 to 500 watts... consumption, not output in this one.

Is made in USA and put 70 plus 70 RMS power output in 8 ohms.

Put a normal voltimeter in the speaker output, together speaker and goes volume up... if you measure between 22 to 25 Volts AC will be the one!

You do not put mail adress. I do not know if i can put this schematic on forum...maybe not, this way, provide me E Mail then i will gladly send you.

To really produce 450 watts in 8 ohms the amplifier may use supply with a very high voltage...more than plus and minus 100 volts if 8 ohms...you will measure around 60 volts alternated... not common!... can be this one i have schematic...please, measure it.

Regards,

Carlos

[destroyer X]

No one speaker on earth will hold so much power.

In Brazil i never seen unit so strong this way.... but is possible that someone made so enormous thing.

Normally, people when use those monster audio amplifiers use a lot of speaker in series parallell. Here, in Brazil, i could not find any speaker that can "really" hold 100 watts continuous without burn!... this way, if your amplifier can produce 70 watts or 100 watts that's a very good reason to your speaker "Kaput".... and you will "kaput" all you put there...if 450 watts, and using good volume you can burn the AC plug outlet, if long wire from street to your house your lamps will go low brigth, will be flashing yellow color.

Do you have sure this man is your friend, the one gave you this melting monster (hahahaha, joke, kid, smile please).

Carlos

[sreten]

whilst I agree with DX's speculations and know for a fact Sumo
did make some class A amplifiers, the moniker "The Power" is
too OTT to be applied to a class A amplifier.

The bizarre thing here is you claim both channels gave up the ghost.
This is very, very unusual. Could be a protection circuit fault.

Either you are misdescribing the problem or you need a repairer
who really knows his onions, as it doesn't sound simple.

sreten.

[ChocoHolic]

I agree, that it is not normal if both chanels fail at the same time.
Is there something wrong with the power supply?
If both chanels are supplied from the same supply, then a fault in the power supply will affect both chanels.
...by this also most of the internal points of operation will run to somewhere. This may result in DC at the output.

My proposal:
Check the rail voltages first...
If they have issues and you are able to repair them, you should
try to find out why they failed. Usually they would not fail without a reason...

Good Luck
Markus

[djk]

"I would suggest to register with Yahoo and become a member of the SAE forum and post your question there:"

I wouldn't bother.

James Bongiorno will not provide anyone the schematic for this amplifier.

He will offer to re-build it for an enormous price, but he has a third party do the actual work.

The Sumo stuff is not that hard to reverse engineer, and that amp is worth the effort.

[johnkramer]

this amp is a beast. I have had experience with it in the past. A true find!!!

We ran it with a dedicated line right off the mains for starters (a must for this amp, IMO), driving a pair of Dayton Wright ESL's. An amazing sound I really haven’t heard since.

I know enough about that amp that you should be aware that is has some serious voltages in it. I wouldn't touch it unless you’re good with unusual amp topologies.

If certified repair through James Bongiorno is too much money then be very careful who you give it to for repair.

If you ever want to pass it on, wink wink, nudge nudge..

It's very capable of driving difficult loads, if ESL's are your thing, then you have "the" amp to drive them, once again IMO.

[li_gangyi]

he's in Singapore...even if he wanted to pass it on...it would cost a bit...back on track though...maybe you can try to measure the speaker outputs without the speaker connected and see if any voltages are present...if it's the full rail voltage...I suspect a defective output...or maybe one side of the power supply has gone..are there any rail fuses in this amp??

[Chris Dian]

Thanks, friends, for your input. Guess I will just forget about repairing the Sumo -- too daunting a task John Kramer was right, the beast used to drive a pair of Acoustat ESL. The speakers it destroyed, fortunately or unfortunately, were a pair of old 2-way 120W Wharfedale.

Chris Dian.