I am in the midst of completely upgrading my home theater system. I have decided on the Panasonic 50" TH-50PHD7UY plasma display. My next decision is an A/V receiver. I've narrowed the choices down to Denon and Marantz, most likely the 4806 or the 9600 (neither of which have been released, but there are rave reviews already), respectively. I've been told that the way to go is a receiver with a toroidal transformer as the power supply. Can anyone educate me on what these are, and the benefits to an A/V receiver?
You'll typically see one of two types of power transformers in an AV receiver; a box type square unit or a toroidal transformer. All transformers will radiate noise. There is a device called a Faraday Shield which can be placed around a box transformer to reduce the radiation. Put "Farady Sield" in a search engine to find more information about transformer radiation. A toroidal transformer looks like a doughnut from the top. Because of this design, the radiation tends to collapse inward rather than outward as it does in a box unit. This makes a toroidal unit less likely to radiate its noise into sensitive circuits in an audio product. This is of more importance in a receiver because small signal levels are present with the need for high current delivery. In a power amp the toroid will usually mean a better amp due to the quietness of the circuits. A toroid is also more expensive, so the manufacturer that is willing to use the more expensive component might have other more expensive and hopefully better components in the rest of the unit. In a pre amp, the level of radiation is kept at low levels due to the amount of current required and a toroid is seldom found in less expensive products.
Thanks Jan. So, would you then recommend to go with those receivers that incorporate a Toroidal transformer (budget allowing, of course)? The other technology that is driving my receiver choice is the presence of HDMI switches. Any thoughts on those and whether or not they're worth investing in now?
I thought about answering, but as I suspected Mr. Vigne's response was superior to anything I could have offered.
While the Toroidal transformer is definitely an excellent feature, it is only one of many components that make up the receiver. Same with HDMI, if you have other components that can output HDMI it may be one of the features that make a particular product attractive. Ultimately, you must weigh the sound qualtiy with your components in your listening environment combined with the feature set you are looking for across prospective products to find the one that is best for you.
Both the products you are looking at are excellent, btw.
To expand further on what Jan said a torrid transformer is superior to the usual "box" type transformer because it's hysterisis losses are much lower. I'll try to explain this simply as possible but hysterisis losses are eddy currents or current in opposition to the primary current which create heat basically from the constantly expanding and contracting magnetic field of the transformer. A torrid is superior in this aspect because it is basically a continuous length of wire. HDMI and video switching is a good feature in a reciever or a pre/pro but keep in mind that video switching is best done through your tv as this keeps the source as direct as possible without adding further noise,or insertion loss to the video transfer. E.Ramsey
The most important part of any amplifier is its power supply. If the power supply is well specified, the amp has a good chance of doing a decent job. As described above, toroidal transformers tend to be used in many of the better solid state designs (although tube amps almost invariably use C-Core - box - transformers) so it's a fair bet that if a toroid is in use, then the designer has given significant thought to the power supply section of the receiver.
That said, the amplifier is a combination of compromises to give an ultimate sound. There are enough stereo amplifiers at similar money with toroids in them giving different sound, so a toroidal transformer is not necessarily the be-all and end-all of the question. It may be nice to have, but if you prefer another amp with a c-core transformer, don't worry about it. In the end implementation is just as important as componentry.
The upshot of this is that you have to listen to the options if you really want to know what you're buying. Visit a dealer and see what the things sound like. Then you'll know which you prefer, irrespective of whether they use toroidal transformers, tantalum or foil capacitors, voodoo, mysticism or just plain ol' good design...
As to the HDMI switching issue, do you intend to have multiple sources providing an HDMI feed? At the moment, this would be multiple DVD players or a DVD player and a digital TV or set top box. As Eric says, the best result is usually achieved by going direct from the source to the display. However, there are some receivers which enhance picture quality and some (few) can even upscale a standard signal to quasi-HD quality, which is nice if you anticipate having an HD display. I'm not sure about your Panasonic, but it's not the same thing to be HD-Ready and to actually be HD capable. Most sets in the UK are just standard (584x480 or so) displays. A true HD picture needs something like a 1024x768 display and these all carry a premium here of £500 ($900) or so over the equivalent standard model. Get the higher res model if you can - much better definition even from a standard DVD player usually.
So far I would say the answers run torward a basic piece of advice. Don't get bogged down in the gobble-d-goop of buying a system. AV receivers are the hottest portion of the market right now. They are dominated by the Asian manufacturers who have, for the last forty years, been able to turn out new circuits and features with interesting names that will be gone when next year's models arrive. Though not a hard and fast rule, I have found the more time the salesperson spends talking about the outside of the amp, the worse the sound. If little time is spent on the features and more on the construction of the amplifier or receiver, the better the sound. You probably won't use half the "features" found on most AV receivers. Buy the one with the best internal construction and you will probably be getting the best sound. Connectivity is convenient, but doesn't always account to the best signal path. It does become a nice feature to discuss, however.
Thanks to everyone who has provided a response; all have been very educational. Frank, the Panasonic display I am looking at has a resolution of 1366 x 768 (I assume that's good enough for HD-capabilities?), with an HDMI output. The only components I intend to hook up via HDMI are the TV and a DVD player (of which I have not quite decided on either). The Denon AVR-4806 has a nice feature, as you mentioned, video up/down conversion.
From what it sounds like, budget-allowing,in general it's best to go for the A/V receiver with the Toroidal transformer.
I haven't decided on a DVD player, I was leaning toward the 2910, but will look at the 3910. As for speakers, I was originally thinking of the B&W VM1s across the board, but, after reading many posting regarding budgeting for speakers vs. receivers, I've decided to up the budget on speakers and go for the B&W FPM5. Anyone have any thoughts on those speakers?