[wes k]

Nr905 has it. 805 doesn't. Big deal? Also, what is BTL on the onkyo?

 

[michael hurd]

A torodial transformer is a donut shaped coil with copper insulated wire wrapped around it, this is the basis for the power supply in most amps. Some amps use a switch mode power supply that replaces the heavier power transformer with a much lighter setup that has a tiny tranformer that operates at high frequencies.


There are pros and cons to both. Properly designed, both will work well.

 

[oztech]

usually the toroidal transformer will have better dynamics and handle lower impedance

loads,btl is for bridging the unused channels for the rears in case you decide to use 5.1

instead of 7.1 but warning should not use speakers below 8ohms when you use that feature.

 

[Glen B]

A toroid is a transformer that has a donut-shaped iron core versus the rectangular-shaped core of an "EI" type transformer. "EI" refers to the way the core is assembled from thin, alternately stacked E and I shaped strips of iron. Toroids tend to be mechanically quieter, more efficient than EI types and radiate a lower magnetic field. Because of their higher efficiency, toroids tend to be smaller than their EI brothers of similar capacity. BTL stands for Bridged TransformerLess. The term is used by some amplifier manufacturers to describe the feature where two channels can be bridged or combined to form a single mono channel of double or greater power.

 

[MichaelJHuman]



Quote:
Originally Posted by oztech /forum/post/12935668


usually the toroidal transformer will have better dynamics and handle lower impedance

loads,btl is for bridging the unused channels for the rears in case you decide to use 5.1

instead of 7.1 but warning should not use speakers below 8ohms when you use that feature.

No offense, but some of this makes no sense. Toroidal transformers have no more ability or no less ability to handle low impedence loads. That's a function of overall design. If by better dynamics, you simply mean more power, once again, that's a function of design. A 1000 watt pro amp, under normal home use will handle any dynamic peaks. And it's not likely to use a toroidal transformer.


Toroidal transformers are often used in higher end amps due to some of the factors mentioned above such as a lower hum, smaller size and less electromagnetic interference. The main downside is cost. They are more often seen in more expensive amps. I have long speculated that one of the reasons for that is that it's a selling point some people look for. But many good amps don't use them.

 

[dmcdayton]

From Wikipedia:

Toroidal transformers are more efficient than the cheaper laminated E-I types for a similar power level. Other advantages compared to E-I types, include smaller size (about half), lower weight (about half), less mechanical hum (making them superior in audio amplifiers), lower exterior magnetic field (about one tenth), low off-load losses (making them more efficient in standby circuits), single-bolt mounting, and greater choice of shapes. The main disadvantages are higher cost and limited rating.


Google Toroidal Transformer, there's several mfgs with good explanations on their websites. They're used in medical equipment, sensing devices, all kinds of high end electronics...not just audio.

 

[jhe]



Quote:
Originally Posted by MichaelJHuman /forum/post/12936716


No offense, but some of this makes no sense. Toroidal transformers have no more ability or no less ability to handle low impedence loads. That's a function of overall design. If by better dynamics, you simply mean more power, once again, that's a function of design. A 1000 watt pro amp, under normal home use will handle any dynamic peaks. And it's not likely to use a toroidal transformer.


Toroidal transformers are often used in higher end amps due to some of the factors mentioned above such as a lower hum, smaller size and less electromagnetic interference. The main downside is cost. They are more often seen in more expensive amps. I have long speculated that one of the reasons for that is that it's a selling point some people look for. But many good amps don't use them.

And you're missing the point. If you take two transformers with the same ratings sure one will be no better than the other. But if you compare by weight the toroid should be far superior and if you bother to check amps that use them they will virtually always have far better power output ratings than the cheaper non-toroidal models.


You are correct that the whole design matters. What you ignore is the obvious fact that no company would spend the extra money on a toroid and not provide a good design for the rest where incremental costs are minimal.

 

[MichaelJHuman]

I appreciate you clarifying your statement.