[KeithA]

James

I was having a conversation with a buddy of mine today and I was simply talking about my decision to order a Torus. So, part of my rationale was the following info contained in one of the reviews on the Torus site...

So we started doing some tests. We hooked up one of our 4B (300 watt per channel) amplifiers -- plugged it into a standard wall plug --- connected it to an 8-ohm speaker and drove the speaker at 200 watts. We found that the amplifier, over very short periods, would attempt to draw up to 48 Ampere peak. The wall plug has way too much resistance (typically 1 to 1.5 Ohms of impedance) so the amplifier was starved for current under these short-term transient conditions. With the 20 Ampere Torus inserted (designed to have very low impedance and very high current) we were able to draw up to 400 Ampere peak under these very same conditions.

So, in response to this my buddy basically said this..

I have to admit that you've lost me here!  It seems to me that the power supply of any amplifier is designed to operate within the limits of the AC circuit it has been designed to be plugged into (either 15A or 20A).  The transformer is designed to operate within strict AC current/voltage guidelines, and it should not exceed them.  Otherwise, if a 4B-SST or any other amp decided it needed at any instant to draw 50A from the wall, you'd be tripping the circuit breaker.  Amplifier power supplies/circuits are each designed to convert and step up/store the incoming AC current as DC, and the execution of this process is what separates the great amps from the rest.  The amplifier circuit operates on the DC energy produced by the transformer and stored in its capacitors.  So if an amplifier is required to produce 50A of DC current at any instant, its ability to do so is governed by the abilities of its transformer's instantaneous production + storage capacitance.  If it cannot meet the demand, it will clip - not overdraw the incoming AC.

I am curious about this as well. I think I understand his point, and it's somewhat along the lines that I've always thought as well. I think what he is saying is that the power/current that drives the amp is a product of the transformer/power supply in the amp (storage) and is restricted to the 15 amp or 20 amp feed in and how the amps power supply converts and stores it. So, he's questioning the point that an amp will draw 400 amperes of instaneous current from a unit like the Torus. I think his point is that the amp will clip from the inability of it's own internal transformer/power supply to supply the necessary current and the amp will not look outside of it's internal transformer/power supply for anything that remotely looks like 400 amperes.

Am I correct from reading your blurb above that an amp like the 4B will draw the peak 400 amps from the Torus?

Just curious....

Keith

[James Tanner]

Hi Keith,

As I understand it the ability of the amplifier to draw 'instantaneous current' is a function of the very low output impedance of the Torus ( .02 ohms) relative to the typical wall plug (1 -2ohms).

james

[KeithA]

Thanks James

I understand the concept of the reduced impedence allowing the opportunity to draw higher current. However, I guess what I'm looking for an answer to is that an amplifer (like the 4B) that has it's own rock solid transformer and power supply, will look for super high current outside of it's own internal power supply on transients?

My buddies point, and something I always thought as well, is that on transient music, an amp will draw from it's own caps, etc, to meet the need. Most great amps have ample storage based on capacitance. However, if I am reading things correctly, Torus claims that an amplifier will draw up to 400 amperes peak on transients if the source is there (which it is according to Torus and the concept of low impedence vs the receptable at the wall). So is it the case that even with an amp like the 4B that on transient music, the 4B will normally 'drain' it's own stored capactiance and then look past it's internal power supply for high current power to support the signal or at least replenish it's own internal power supply/caps?

I guess I always thought (and was my buddies point as well) that an amplifier with a properly designed power supply would store ample power to meet transient needs and would not look past it's own internal power supply for instantaneous current requirements but merely use the wall power supply to replenish the amps own stored capacitance. My buddies point was that an amp will clip off of it's inability to feed the current to the transients from it's internal power supply and will not look out side for anything more than the wall source (15 to 20 amps).

Maybe the simple answer is that all great amps do not store all the power to meet transients internally and they all look for extra high current to support the signal? I don't know, I'm an accountant

Sorry if this seems to be getting very technical, but I am curious about the concept. Any chance someone on the tekkie side of Torus or Bryston could answer this?

Keith

[James Tanner]

I will ask at Torus and see what they say.

james

[KeithA]

I think I have been able to rationalize my query and I think what my buddy implies is somewhat incorrect.

I suspect that any decent amplifier has as much capacitance in it's own internal power supply as practically possible to handle short-term transients. I guess if an amplifier were to try to have enough capacitance to store energy for long-term transient performance, the size of the toroid and # of capacitors would not be practical. Long and short of it, an amplifier will almost always need the ability to draw from the wall peak current in excess of RMS current to either replenish it's own internal capacitance or to support the signal. I guess if you built an amplifer, like the 28B SST, for example, in which one puts 120,000 pf of internal capacitance and then "clamps down' on the amplifiers ability to attempt to draw peak current from the wall, the amp will run out of gas more often than not.

So, I guess my buddies thought process is that a 'good' amplifer with a properly designed power supply effectively does what the Torus RM-20 does in that it separates the power supply before and after the toroid? However, I suspect this is not practically possible unless one was able to build, say, an RM-20 into a 28B SST!

So, I suspect that what my buddy describes as 'clipping' is when an amplifier runs out of juice in it's internal power supply capacitance is the attempt at an amplifier to draw ample peak current from the wall, but as Torus and yourself point out, most amplifiers may try to draw up to 50 amps peak and will not be able to do it because of the nominal resistance of a wall outlet. So, in essence, the amplifier runs out of short term gas becuase it can't draw what it needs from the wall. So, the clipping is actually the starving of the amplifier by trying to draw peak current from the wall becuase the transients (which are likely more than 'short-term') have exhusted the internal capactinace of the amp and now it's looking to the source for more.

I guess the simple way of looking at it is that the internal capacitance on an amplifer is like a 'memory cache' on a computer. The memory cache stores little bundles if information that the computer will use over short periods to help speed up processing. It doesn't store 'all' of the info it will need. Most stuff is still kept on the hard drive or elsewhere. When the cache is emptied, the computer will go back to the source to replenish the cache and/or get additional information, if needed. So, a faster hard drive will get you better performance. So, if a stereo system were compared to a computer, the Torus would be the really fast hard drive.

It seems to sound right to me

Keith

[James Tanner]

I think I have been able to rationalize my query and I think what my buddy implies is somewhat incorrect.

I suspect that any decent amplifier has as much capacitance in it's own internal power supply as practically possible to handle short-term transients. I guess if an amplifier were to try to have enough capacitance to store energy for long-term transient performance, the size of the toroid and # of capacitors would not be practical. Long and short of it, an amplifier will almost always need the ability to draw from the wall peak current in excess of RMS current to either replenish it's own internal capacitance or to support the signal. I guess if you built an amplifer, like the 28B SST, for example, in which one puts 120,000 pf of internal capacitance and then "clamps down' on the amplifiers ability to attempt to draw peak current from the wall, the amp will run out of gas more often than not.

So, I guess my buddies thought process is that a 'good' amplifer with a properly designed power supply effectively does what the Torus RM-20 does in that it separates the power supply before and after the toroid? However, I suspect this is not practically possible unless one was able to build, say, an RM-20 into a 28B SST!

So, I suspect that what my buddy describes as 'clipping' is when an amplifier runs out of juice in it's internal power supply capacitance is the attempt at an amplifier to draw ample peak current from the wall, but as Torus and yourself point out, most amplifiers may try to draw up to 50 amps peak and will not be able to do it because of the nominal resistance of a wall outlet. So, in essence, the amplifier runs out of short term gas because it can't draw what it needs from the wall. So, the clipping is actually the starving of the amplifier by trying to draw peak current from the wall becuase the transients (which are likely more than 'short-term') have exhusted the internal capactinace of the amp and now it's looking to the source for more.

I guess the simple way of looking at it is that the internal capacitance on an amplifer is like a 'memory cache' on a computer. The memory cache stores little bundles if information that the computer will use over short periods to help speed up processing. It doesn't store 'all' of the info it will need. Most stuff is still kept on the hard drive or elsewhere. When the cache is emptied, the computer will go back to the source to replenish the cache and/or get additional information, if needed. So, a faster hard drive will get you better performance. So, if a stereo system were compared to a computer, the Torus would be the really fast hard drive.

It seems to sound right to me

Keith

Hi Keith,

I have not heard back from the PHD guy at Torus yet but the way you describe the 'reservoir' of power is correct as I understand it.  Maybe you should be writing the Torus literature?

james

[James Tanner]

I will ask at Torus and see what they say.

james

Reply from Torus:

Hi James,

I agree with Keith in saying "It seems to me that the power supply of any amplifier is designed to operate within the limits of the AC circuit it has been designed to be plugged into (either 15A or 20A).  The transformer is designed to operate within strict AC current/voltage guidelines, and it should not exceed them."

The Torus transformer does follow the same guide line, however, the circuit breakers or fuses have short time ratings much much higher than their tripping rate. Therefore, if there is a need for surge current the circuit breakers would not trip.
 
The Torus transformer is designed to possess the ability to store large amounts of energy and be able to release the energy, unrestricted, if it is requested by the load over as short period of time - half a cycle (60 Hz). This instantaneous energy request cannot be provided through a standard wall plug.

Regards,
Henry Pajooman
Plitron Manufacturing Inc.
Research Engineer


Comment from Chris Russell at Bryston:

Hi James;
 
From reading this, it seems to me that part of Keith's confusion lies in his somehow thinking that the wall sometimes needs to supply '400 Amps' to the amplifier's power supply.  The number used was 48 Amps, which is not unreasonable, given circuit-breaker's short-term surge capability.
 
cwr

[KeithA]

Thanks James

There was never any confusion, though, about the 400 amps. I was always targeting a '50 amp' peak in my discussion with my buddy. The 400 amps merely comes into play in the Torus literature where they say they were able to draw this peak "...under the same conditions as was used to draw the 48 amps peak with the amplifier at 200 wpc into 8 ohms". I'm not sure what they meant by this comment or if it was, indeed, even a power amplifier that they used to get this type of peak draw from the Torus.

I think this clears it up for me, though. It is actually what I thought, but it was actually my friends theory that an amp would not draw peak current (or attempt to draw) from a source in excess of the 120 volt line rating (15 or 20 amps).

So, the long and short seems to be that an amplifier, even with a rock solid internal power supply, may from time to time look to draw instantaneous peak current well in excess of a stated limit (ie, 15 or 20 amps). In other words, it is not a "design flaw" of an amp that it cannot continually feed peak current demands internally and may need from time to time attempt to draw these amounts from the plug.

So, under circumstances without a Torus, the nominal impedence of a standard outlet will not let the amp draws what it may be looking for (say up to 50 amps).

However, the Torus unit has large storage potential by virtue of it's design (one massive transformer donut!) and since the interface between the Torus and the amp has much lower nomial impedence, the instantaneous peaks of say 50 amps are easily attainable if required.

Clear as mud Now I just need my RM-20 to show up so I can give it a whirl.

Thanks again James. Sorry if this got really technical, but inquring minds wanna know

Keith

[James Tanner]

Thanks Keith,

I think your Torus was shipped on Friday.

james

[KeithA]

Thanks

Everyone should have a 100-lb donut power their audio system

Keith

[James Tanner]

Thanks

Everyone should have a 100-lb donut power their audio system

Keith

Imagine the size of the coffee!

james

[KeithA]

You know James, a few more of these types of technical discussions and the Engineering group at Bryston might show you the "Secret Handshake" 

[James Tanner]

Hi Keith,

I am working on a new Torus literarture package and I have this paragraph going in.  I think it will better explain your question.

Benefit #1:

Very low source impedance and high current for the power amplifier.

Torus power isolation units present low impedance to any electronic device that is connected to them. A Single 20 amp Torus PIU has an output impedance of 0.2 ohms and can deliver 400 amp peaks (instantaneous current). The 100 amp unit only has .04 Ohms of output impedance. There is no electric (ohmic) connection between the outside power grid and the equipment plugged into the Torus and power is transferred magnetically. Magnetic transfer of power eliminates the effect of the source and the line impedance and also eliminates the transfer of DC components to the equipment.  A typical 200 watt audio power amplifier demands 10 amps RMS current from a 120 volt line (1200VA) but may demand up to 50 amp instantaneous peaks. The standard residential wall receptacle can't supply the 50 amp peaks because they typically have higher nominal impedance. A Torus 20 amp PIU plugged into the same wall plug can supply these peak current requirements quite easily.

james

[KeithA]

Ah, the beauty of flux and induction!

Yeah, I guess that's the the nature of how a transformer works, hey?

It sounds pretty impressive. Still a little too tekkie for me The only reason I have half a clue about the concept is I have a relative who helps design software for modelling magnets and transformers! Up until now I still thought the receptacle was hard wired to the equipment somehow through the mound of wire that makes up the transformer.

Now I'm more impressed But you are right, this explanation at least puts out there the concept that there's a special reason as to why the input the equipment sees is very low impedence.

Now, with all this 'flux' talk, I hope when the unit hits '88 amps peak' we don't go "Back to the Future" (Bad Joke)

Keith

[KeithA]

Funny...

Here's an email I just got from my dealer to let me know my RM-20 showed up...

Hey Keith.
 
The unit has arrived and it weighs a freaking ton!.
 
Seymour

 

[James Tanner]

Funny...

Here's an email I just got from my dealer to let me know my RM-20 showed up...

Hey Keith.
 
The unit has arrived and it weighs a freaking ton!.
 
Seymour

 

Hi Keith,

Great news - please let me know your impressions.

One of the things we found in doing the research on Torus was that a lot of the tansformer based filters and power conditioners in the marketplace were using transformers that were too small.  In the Torus the transformers are TWICE the size they are rated for - so they weigh a lot!

james

[KeithA]

Will do....

You may have been speaking to Seymour (the sales rep at my dealer) about overnighting a 20-to-15 amp cord?

That would be great. However, I'm pretty sure I'm covered in the short-term as I have an after-market power cord on my 6B, so I believe the stock power cord that came with my 6B is the same type of 20-to-15 amp cord that the Torus would take and I can use that to hook everything up in the interim.

Keith

[James Tanner]

Will do....

You may have been speaking to Seymour (the sales rep at my dealer) about overnighting a 20-to-15 amp cord?

That would be great. However, I'm pretty sure I'm covered in the short-term as I have an after-market power cord on my 6B, so I believe the stock power cord that came with my 6B is the same type of 20-to-15 amp cord that the Torus would take and I can use that to hook everything up in the interim.

Keith

Hi Keith,

Yes I spoke to Torus and they are over-nighting you a cord.
Yes you can use the 6B cord.

james

[DeanSheen]

Threadjack/

I emailed Torus a week ago with an inquiry on these units and I'm still awaiting a reply.

The site really could use a bit more information.

/end threadjack

To KeithA, the unit you bought is going to feed how many components?

Keep us posted on your impressions.

Regards

~DS

[KeithA]

At this point it will feed power to the following

6B SST - 3 front channels
Rotel 200 wpc amp - rear channels
Cd player
BDA-1 DAC (when it's built and shipped)
SP 1.7 preamp/processor
DVD player
TV
Logitech Squeezebox

So that's 8 components. As well, I'm looking at a pair of 7B SSTs for the front 2 channels later this year, so that will make 9 components all in when all is said and done.

Keith