[Kevin C Brown]

Right now, I have a stereo power, and a 5 ch amp for 7.1. Both amps have just 1 transformer. (Acurus A200 + A200x5.)

But there are also amps out there (Bryston, I'm thinking of), that have individual transformers for each channel.

I guess for a stereo amp, I'm convinced that this is probably the way to go. (I'm 80% music, 20% HT.)

But for a multi channel "home theater" amp, I'm not convinced. Because the power demands in a movie sound track can be so transient and so spatially selective at times, I continue to think that an amp with individual transformers might artifically limit power to an individual channel.

Obviously, if the individual transformer channel has enough power available, would never be an issue. But the 9B (ST, SST) that I would consider (or Lexicon NT-512), is "only" rated to 125W/ch.

Just curious if any of y'all had thought about this much...


(Yes, Ricky, passively looking again... !)

[Kevin. W]

Its not just the transformer thats needed to power the speakers. You also have to look at capacitor storage as well as output devices per channel to deliver the power. If an amp with an individual transformer per channel is similar in spec to that ao an amp with one transfomer, you shouldn't have any problems.

Kevin

[DaleBesh]

Look for similar specifications, and one that sounds good. One or multiple transformers is a designer's choice. Some have more than one but less than the number of channels.
This may also be a choice related to design layout and packaging and represent no audible advantage, regardless of the 'hype'.

[Kevin C Brown]

Yeah, the sub-text of my question: maybe both designs are valid, and maybe under extremely rare circumstances one may be better than the other or even vice versa. Kind of like a Ford vs a Chevy... Kevin, yeah, I forgot about the capacitance (charge storage) being a factor too...

[Arthur S]

Kevin

In my opinion, separate transformers in an amp do not provide any audible advantage. Separated transformers may minimize inter-channel crosstalk, but with good single transformer amps the crosstalk is below audibility anyway.

Especially since you go 80% music, an amp with one large transformer has an advantage. For example, Bryston 9-B can only put out what 2 of the 5 transformers can deliver. With a single, much larger transformer, the entire capacity of the transformer is available for 2 channels.

As Kevin W says, there are several other design issues that determine ultimate available power.

If I was making a decision on a new amp, I lean towards a single transformer. My old Technics receiver circa 1976 had a 22 pound transformer, and could deliver 165 watts per channel into 8 ohms, and 205 watts per channel into 4 ohms (with both channels driven).

Having said all that, there are subtle differences in sound between amps that have nothing to do with transformers. Unfortunately, you would have to have all the contenders at home and swap them out till you decided which one sounded best to you.

Also, no single amp has the best sound quality in all areas. One may sound more natural, another a bit better bass, another a lot of "slam". So in the end you have to make a compromise but if you can hear them in your system, you will know what compromise suits you best.

Artie

[MikeTz]

Kevin:

They are both valid amplifier designs. Many of the single transformer amps are designed that way for cost reasons (one high quality power supply/transformer is cheaper than five). That's why an Anthem PVA-5 (or B&K, Rotel, etc.) is less than $1500 and a Bryston 9BSST is $4300 (that and the 20 year Bryston warranty). I have a Bryston 9B SST and it's great, I've also heard the Anthem, B&K and Rotel amps and they're also very good for the price.

Most good single transformer amps have lots of capacitive storage power for the transient demands of home theater. They also rely on the fact that the side/rear channels are primarily for ambiance/effects and do not require high average power.

I recommend you listen to the Bryston and several of the cheaper multi-channel amps to determine if the cost difference is worth it. One other thing to consider is amps using independent power supplies for each channel usually require more input power (the Bryston 9B with 5 channels requires a 20 amp dedicated outlet) and run hotter. This may be an issue in your theater set-up.

MT

[Kevin C Brown]

More good input, thanks...

[Michael R Price]

A single transformer can be better since it costs less than two half-as-powerful transformers. So, for the same price, you get more power. And that advantage is probably more significant than the reduced channel interference.

[Kevin. W]

Quote:

A single transformer can be better since it costs less than two half-as-powerful transformers.

In my case I picked up at Rotel RMB-1095 for 18% below cost, an this puppy comes with 2-1.2KVA transformers. Sounds awesome to boot. For Kevin's prespective I think he's best to take home the amps to demo. Only his setup cam tell him which one is better for him.

Kevin

[Michael R Price]

Right, the transformer size and other specifications aren't all there is to describe the performance of an amp.

And Kevin, 2.4kVA for a 200 watt amp? Sheesh I've never heard of such power capability, although it does seem to contradict there being only 3 pairs of output devices in that amp. My crazy DIY amps have 750VA per channel.

[Kevin. W]

Quote:

And Kevin, 2.4kVA for a 200 watt amp? Sheesh I've never heard of such power capability, although it does seem to contradict there being only 3 pairs of output devices in that amp

Its actually 5x200watt and 30-150watt/15amp output devices(6 per channel). Straight from Rotels website.

Kevin