Help! Save my Sumo "The Power" power amp.
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.
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.
Dead Sumo
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/
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/
I have found one Sumo model nine
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
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
If it really put 450 watts output...
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
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
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.
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.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
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
"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.
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.
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.
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.
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??
Put it up on ebay. I had 2 of those, also not working right, several years ago and sold them on ebay for $300 each. As I remember, the buyer was in Japan and he didn't mind paying the expensive shipping and professional packing from the U.S. He might see your auction and want another. You might get more because you are nearby, shipping wise, to him.
when you do pass it on, please try and get it to someone who will appreciate it for what it is. Sure it'll make a nice sub amp, but that would be like using a corvette to tow a trailer. It would be a shame to get it to someone who doesn't know its full potential.
From what I recall, James intended the amp for high power ESL's. THe rumor mill at the time suggested he designed it specifically for the Dayton Wrights (the only high power, high spl ESL that I can think of) In fact, The Power has the same panel size as the Dayton Wright PS unit. They really did look impressive together.
The manual was pretty specific that it needed its own leg off the AC power mains. Preferably as close to the entrance as possible (first circuit breaker)
I also remember a brag in the manual. "100% stable into any load angle whether inductive or capacitive, regardless of waveshape".
Another thing to consider, it is a fairly modular amp, it could be broken down and shipped in pieces, but that is just an assumption. I really don't remember too much what it looks like on the inside or how easily it could be broken down. Care to open it up and take some pictures?
I really wish I could make an offer to you (by the way, I've been to Singapore, lovely place). But I really can't shell out the funds and I am not in any position to use it well. It is my personal favorite amp of all time and there is a bit of envy
It idled class A and ran as such up to a point, but I can't remember how far.
I remember it being a 450watt/channel amp, never advertised as a class A design. ALthough it did run class A from idle up to a point. Full complemtary differential design from input to output. THe idea was to deliver lots of power to difficult loads.
I think it was "The Gold" that was true class A. It was the same size as the Power and something like 70watts/channel.
From what I recall, James intended the amp for high power ESL's. THe rumor mill at the time suggested he designed it specifically for the Dayton Wrights (the only high power, high spl ESL that I can think of) In fact, The Power has the same panel size as the Dayton Wright PS unit. They really did look impressive together.
The manual was pretty specific that it needed its own leg off the AC power mains. Preferably as close to the entrance as possible (first circuit breaker)
I also remember a brag in the manual. "100% stable into any load angle whether inductive or capacitive, regardless of waveshape".
Another thing to consider, it is a fairly modular amp, it could be broken down and shipped in pieces, but that is just an assumption. I really don't remember too much what it looks like on the inside or how easily it could be broken down. Care to open it up and take some pictures?
I really wish I could make an offer to you (by the way, I've been to Singapore, lovely place). But I really can't shell out the funds and I am not in any position to use it well. It is my personal favorite amp of all time and there is a bit of envy
It idled class A and ran as such up to a point, but I can't remember how far.
destroyer X said:
I remember it being a 450watt/channel amp, never advertised as a class A design. ALthough it did run class A from idle up to a point. Full complemtary differential design from input to output. THe idea was to deliver lots of power to difficult loads.
I think it was "The Gold" that was true class A. It was the same size as the Power and something like 70watts/channel.
More on SUMO "The Power"
About a year and a half ago, I, too, was given one of these because it had the same symptoms as the original post - It would pop in one channel and usually blow the woofer.
James Bongiorno does frequent the Yahoo SAE forum and he was very helpfull in my getting it re-built but he did suggest I send it to
one of his technicians to have it repaired. He will not give out the schematic for this unit. I chose to go at it on my own mostly because of the cost of shipping it to be repaired - it must weigh 90 lbs and also not knowing if the amp was worth even repairing sonically. Most high power amps of that era did not sound all that great. Well...It WAS worth repairing..and the unit has now been running in my system for almost a year with no problems at all. The amp it replaced in my system was a Sumo NINE which up to that time I thought was the best sounding amplifier I had ever heard. The Power sounds even better.
What I can do - if people are interested - is post a summary of all the work I did inside the unit. (I kept a log) It IS modular in construction and what I did was swap these modules from the working channel to the faulty channel in order to track down where the problem was. James provided information to upgrade the op-amps and caps and how to set the DC balance (very critical). The problem turned out to be a cold solder joint. The only way even found this was once I had narrowed down where the problem was, I unsoldered each component on the suspect board and measured it.
This amplifier was built in 1980 around the same time as the "Gold" but before the "Nine" and retailed for $3000USD. James estimates that if this unit were to be produced today (taking into consideration same build and parts quality) it would retail for between 15K and 20K USD.
About a year and a half ago, I, too, was given one of these because it had the same symptoms as the original post - It would pop in one channel and usually blow the woofer.
James Bongiorno does frequent the Yahoo SAE forum and he was very helpfull in my getting it re-built but he did suggest I send it to
one of his technicians to have it repaired. He will not give out the schematic for this unit. I chose to go at it on my own mostly because of the cost of shipping it to be repaired - it must weigh 90 lbs and also not knowing if the amp was worth even repairing sonically. Most high power amps of that era did not sound all that great. Well...It WAS worth repairing..and the unit has now been running in my system for almost a year with no problems at all. The amp it replaced in my system was a Sumo NINE which up to that time I thought was the best sounding amplifier I had ever heard. The Power sounds even better.
What I can do - if people are interested - is post a summary of all the work I did inside the unit. (I kept a log) It IS modular in construction and what I did was swap these modules from the working channel to the faulty channel in order to track down where the problem was. James provided information to upgrade the op-amps and caps and how to set the DC balance (very critical). The problem turned out to be a cold solder joint. The only way even found this was once I had narrowed down where the problem was, I unsoldered each component on the suspect board and measured it.
This amplifier was built in 1980 around the same time as the "Gold" but before the "Nine" and retailed for $3000USD. James estimates that if this unit were to be produced today (taking into consideration same build and parts quality) it would retail for between 15K and 20K USD.
I put one of these MONSTERS into a large Home theater system running a modified pair of JBL L300 studio monitors i built for a client in Dallas TX. One day POP, smoked the H*ll out of one of the freshly reconed JBL 15" woofers. 90VDC on the speaker outputs!
Yes these babies are 400+ watts per side @ 8 ohms and there built Monoco style. IE, the entire thing is built around the mosterous I-E core power transfomer. each channel is a bridge in balanced operation if i remember correctly with some very complicated servo circuity. I remeber trying to trouble shoot that beast and just trying to move it around the bench to get at various parts required huge amounts of effort. and in the end. we ended up scrapping it. Just way to difficult to repair without a schematic.
all of the output devices were fine, there was some sort of problem in the servo system that was driving one side of the outputs to the rail. I spent about 2 months trying to get that dang thing running and never made any progress.
Zero
Yes these babies are 400+ watts per side @ 8 ohms and there built Monoco style. IE, the entire thing is built around the mosterous I-E core power transfomer. each channel is a bridge in balanced operation if i remember correctly with some very complicated servo circuity. I remeber trying to trouble shoot that beast and just trying to move it around the bench to get at various parts required huge amounts of effort. and in the end. we ended up scrapping it. Just way to difficult to repair without a schematic.
all of the output devices were fine, there was some sort of problem in the servo system that was driving one side of the outputs to the rail. I spent about 2 months trying to get that dang thing running and never made any progress.
Zero
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