Most Powerful Twin Transformer Receiver?

V

vintagestereo

Addicted Member
Banned
Most of the largest Recievers I own have a single Toroidal Power Transformer with dual windings to create dual power supplies. But, the Concept 16.5 is pretty unique in that it has two seperate power transformers instead. I believe that the Akai 1120 is desinged this way as well, and, the Onkyo TX-8500 Mk II as well. There may be others. So, I'm curious, which is the most powerful "Twin Trannie" Receiver out there?
 
Last edited:
Register to hide this ad
Sansui G-22000 and G-33000 - dual toroids in the power amp, plus a standard tranny in the pre/tuna section...don't know if the Marantz 2500 or 2600 had dual trannies...

TP
 
Pioneer727 said:
By the way this is not the one that was in there. It was a replacement for the toroidal
that went belly up
Click to expand...

That's what keeps me from getting a 2600....all those bad Trannie stories floating around.
 
vintagestereo said:
That's what keeps me from getting a 2600....all those bad Trannie stories floating around.
Click to expand...


No kidding! I have two, each with burnt out transformers. I've been looking for a parts one, but all the "reasonably priced" parts units have bad tranformers too!
 
I didn't mean to imply that the Sanyo JCX 2900K could compete power wise, just that they were twin transformer units.
 
It was a replacement for the toroidal
that went belly up
Click to expand...
That's what keeps me from getting a 2600....all those bad Trannie stories floating around.
Click to expand...
No kidding! I have two, each with burnt out transformers.
Click to expand...

Why they went up in smoke?? Bad design or careless?? or old age??
I don't have a 2600 but I do have two 300DC amplifiers....well, I'm kinda of nervous...
Any tips to take care of trannies???
 
M Jarve
No kidding! I have two, each with burnt out transformers. I've been looking for a parts one, but all the "reasonably priced" parts units have bad tranformers too!
Click to expand...
That 2600 in the pic was one that was on Ebay.
According to the seller he had the transformer custom wound.
If you dont find a good one you might have to do the same.
Its probably pretty expensive to have done.

Marantz3650
Why they went up in smoke?? Bad design or careless?? or old age??
I don't have a 2600 but I do have two 300DC amplifiers....well, I'm kinda of nervous...
Any tips to take care of trannies???
Click to expand...
The 300DC didnt have the same type of problem that the
2600 had. Or at least I havent run into it.
 
Last edited:
Onkyo TX-8500 MK II :
It's a dual mono block design with two transformers, four huge 15,000mu capacitors and 160 watts per channel--a real freakin monster!!
 
vintagestereo said:
That's what keeps me from getting a 2600....all those bad Trannie stories floating around.
Click to expand...

I had a hypothesis at one point that it was mostly the thermal protection thing put into the primaries as mandated in the US. I can't remember what lead me to believe that for sure, but it was "something I read somewhere." It's been a while; if I come up with it I'll summarize. I think I asked in the MarantzTalk forum and expounded a bit more a year or so ago, and I think it went something like the thermal fuse died on the initial power-up when the electrolytics demanded the most.

Anyways, my understanding (right or wrong) was the protection circuit was embedded in the epoxy potting of the transformer and you couldn't get stuff out without destroying the transformer because of the epoxy.

The reason it would be 'nice' if it were true is that the thermal circuit is only in the US models, so I was mostly trying to figure out if mine was as likely being a Euro model. The fact that the US model only has the protection is borne out on the schemos I have as well.

The pic is indeed of a replacement, but the original is a single toroid can as well.

As far as I recall I only got a few responses; they were from reasonably knowledgeble types, and they were somewhat skeptical based on what they'd seen and what they just thought based on their other experience and knowledge; on the other hand, I never got a really solid refutation that it was totally ridiculous either (at least that I saw).

Mike Zuccarro mentioned one 2500 trannie that he got rewound, and I thought he meant he got it in the original can with the epoxy as he talked about getting everything out, but I didn't ever really see the result.

The other odd data point I've observe, again admittedly only anecdotal, is that I've never heard anyone complain about this on a 2385, which also has a toroid. Although it's not the same transformer; I would have guessed that Marantz would have used a similar design and . It is scaled down from the one in the 2500s and 2600s, but I don't know how much in terms of actual oomph as opposed to size. The schemo for the US 2385, though, doesn't appear to show the thermal switch.-kby
 
Last edited:
I know they don't qualify for the most powerful, but the HK 730 and 430 were twin powered, at 40 and 25 wpc, respectively, I believe. They're a good value for a dual power set up.

Jim
 
I know that my Akai AA-1200 has 2 power supplies, at least thats what I think them things with all the wire wound up are? Its 120 watts per channel.
 
Last edited:
I guess a key question one might ask is what is the various advantages and disadvantages of single power supply Vs dual supply with single transformer Vs dual supply with dual transformers, in the overall system performance.

I assume that the limiting spec one is trying to minimize is power supply ripple voltage at maximum system power draw and possibly input surge current at turn on. There is always going to be some power supply component limiting this spec, either main filter capacitance or transformer core saturation. I'm not sure what method matters, if the unit meets it's FTC wattage output specification.

I personally feel the best design for the buck is the dual supply with single transformer. This allows the diodes and filter caps from only having to deal with half the current Vs a single supply. A proper sized single transformer should perform just as reliably as a proper sized dual transformer. Any quality or reliablity difference between a single and dual transformer design would be how well the engineers spec'ed the amount of iron and wire size for the actual transformers. That is to say one could undersize a dual transformer design such that a properly sized single transformer would have better performance.

So I feel it's all in the details of the individual design and specification of the transformer, rectificer diodes and filter caps. No single design is better or worst just by design, but rather by the specifications and material used in the implementation of the power supply. Funny thing is that the most over stressed part of a high power amp or receiver might very well be the main power on-off switch. That's why many of the better units have a input current limiting circuit that allows the power supply to charge up slowly thus elimenating the high start up current surges that stress the DC power supply components. Of course the current limiting comonents themselves have a reliablity vulnerablity if not conservitivly rated, there you go once again :scratch2:

Lefty
 
Lefty said:
I guess a key question one might ask is what is the various advantages and disadvantages of single power supply Vs dual supply with single transformer Vs dual supply with dual transformers, in the overall system performance.

I assume that the limiting spec one is trying to minimize is power supply ripple voltage at maximum system power draw and possibly input surge current at turn on. There is always going to be some power supply component limiting this spec, either main filter capacitance or transformer core saturation. I'm not sure what method matters, if the unit meets it's FTC wattage output specification.

I personally feel the best design for the buck is the dual supply with single transformer. This allows the diodes and filter caps from only having to deal with half the current Vs a single supply. A proper sized single transformer should perform just as reliably as a proper sized dual transformer. Any quality or reliablity difference between a single and dual transformer design would be how well the engineers spec'ed the amount of iron and wire size for the actual transformers. That is to say one could undersize a dual transformer design such that a properly sized single transformer would have better performance.

So I feel it's all in the details of the individual design and specification of the transformer, rectificer diodes and filter caps. No single design is better or worst just by design, but rather by the specifications and material used in the implementation of the power supply. Funny thing is that the most over stressed part of a high power amp or receiver might very well be the main power on-off switch. That's why many of the better units have a input current limiting circuit that allows the power supply to charge up slowly thus elimenating the high start up current surges that stress the DC power supply components. Of course the current limiting comonents themselves have a reliablity vulnerablity if not conservitivly rated, there you go once again :scratch2:

Lefty
Click to expand...

Good analysis. I agree that it's all in the details. I have two receivers with dial power supplies but both have single primary transformers - and I agree with the engineering decisions to go that route.

On vintage equipment I always use an external power switch - never the the unit's own switch. As EchoWars so aptly puts it: these are unobtanium parts that can never be replaced! :cry:

Paul

PS: Sorry, I forgot to mention the two receivers: Sansui G-8000 and Kenwood KR-9600.
 
Pioneer727 said:
I have seen a nudie of the 2600 it has a single trannie.

Here

Ron
Click to expand...

Here's the official Marantz picture of the 2600 internals. Apologies that the magazine this ad came from has seen better days; someday maybe I'll get around to photoshopping it.-kby
 
The concepts for the full dual ps design was that you actually could make smaller powered amps that could develop the full range as larger amps. The theory went something like this. I a single transformer supply, when 1 channel hits a high dynamic peak immediately followed by the same on the other channel, the PS may not have recoverd sufficiently to be able to supply the second instancce fully. By having 2 individual supplies this problem is solved. A single transformer feeding a single supply was the worst design for these folks, bettered but not by much with a single transformer feeding 2 supplies, still better was the dual wound secondary feeding 2 supplies but best was the complete dual mono design. Also, and I've never compared, is the theory that channel separation would be improved. Dual mono amps and preamps have complete separation so the systems, separation is limited to the source material. This of course is the justification for some purist who prefer mono preamps and power amps as well as older reel to reels with either the mono playback preamps such as the old Ampex, Roberts/Rheem and Crown.

Another consideration and probably as real is that sourcing 2 pair of smaller transformers with dual windings could be cheaper than a single transformer of sufficient quality to handle the job and developing a dual PS sufficently fast in recovery and cap capacity to prevent the problem of inadequate recovery. The marketing department of course, in the case of H-K found it to be an exceptionally big plus.
 
You must log in or register to reply here.
Back
Top Bottom