[James Tanner]

Would the 240volt version of the 14BSST require the 240 volt input - 240 output international series Torus?  If that is the case then the Torus unit could not be used to power any 120 volt front end equipment?

Correct.

james

[smerlas]

Thanks James,

That will certainly help with my equipment plans.

[werd]

I think Werd brings out a very good point. I have a 20A version of the 14B, but it is only fitted with a 15A plug for obvious reasons. I have debated the benefit that I would derive from having an electrician install a 20A line + adding a 20A Torus. I don't have any doubt that the Torus would make a big difference based on what all the owners have blogged. But how much current can one need for listening to music? Let's take Werd's 3A average draw from the plug. At 120V that translates to 360 Watts (V x I). Assuming a 90dB/W sensitivity on the speaker the 360 Watts translates to 90 + 10*(log 360/1) = 115 dB!!! A 15A plug at full draw means the amp is running at 5400 W: you are looking at 127 dB. Ouch. So if you listen at 115dB, you have enough headroom for an additional 12dB using the 15A plug. I have not taken into account heat loss etc.. this is a rough calculation. So the question remains, do I really need to upgrade from 15A to 20A wall socket and circuit?
To look at it from the other end, at most I have run my system at 100 dB (average, not accounting for transients). My speakers of 90dB/W, will then need 10 more dB. 10 = 10*(log Wf/1) where Wf stands for final Watt power. Solving for Wf, Wf = 10!! And 100 dB is pretty loud to begin with. You don't need that much current on 120V line to achieve 10W (0.08 A). Ok, let's assume 10% efficiency with heat loss etc.., you will need 0.8A to run 10W which with a 90dB/W speaker would give you 100 dB average loudness. There is still plenty head room.
My friend, who uses a 50W F5 Pass amp, used a similar argument to show me that 50W was enough power for in-home listening. I still think having ample power on board improves the sound and dynamic range. No questions there. That's why I have the 14B as opposed to the 4B for my 200W max B&W 804S speakers. But how much is too much? I am relatively new, and I may have made a mistake in my calculations. But before the electician comes, I have to justify why I need a 20A line.
Thank you for reading this somewhat long and numeric post.

Hey SF

If i had a choice and was willing to go through all the effort of a 20a dual phase i would do it. I think 20 amp circuit is quieter and the rm-20 would probably perform better on a 240 v circuit. Its something that is just not in the cards for me so i dont  bother entertaining it. 

I agree with the 50 watt analogy being enough, but only in a class A configuration and more so with tubes. Definetely out with class A/B. Didnt realize how much lustre and performance loss i was getting with all my previous A/b gear until i got my first 4bsst. The size of the transformers needed to replicate the performance of class A operation in class a/b configuration have to be quite large at a comfortable listening levels(not to loud).  Thats why i would love to hear a 28b and all its bloom at late nite listening.

[SF]

Thanks Werd. Out of curiosity, why would the dual phase be better?

[werd]

Thanks Werd. Out of curiosity, why would the dual phase be better?

Hi SF

The 240 volt is a forced dedicated line, that and it being balance makes it a much quieter power source for your gear to run off of. Also the current demands are eased, as its easier to maintain the current from a 240 volt line. The current comes it around 10 amps to keep a 20 amp output of a rm-20. That is basically taken right off the Torus site in FAQ page. It is the way to go, but the only drawback to this is, imo, is the resale on these dual phase units  have got to be taken into account.  I dont know what kinda used market there would be for a unit that requires so much attention to installation.

[James Tanner]

Hi James;
 
Here's that explanation of high instantaneous current vs. average current from last month.  This makes the reasoning behind a Torus a lot more clear.
 
cwr

--------------------------------------------------------------------------------
From: Christopher W Russell
Sent: March 17, 2009 10:52 AM
To: James Tanner
Subject: Torus questions


Hi Bill;
 
Sorry for the confusion, I should have been more clear:  The short-term current peaks that I referred to in my previous answer were actually short-term RMS current levels.  That was confusing because the current waveform to the power supply of a large amplifier is quite non-linear.  The DC power-supply actually only recharges the filter capacitors over a small portion of the waveform, at the peaks of the AC Voltage sinewave. With an undistorted sinewave, the peak-to-average ratio is 1.414:1, so an RMS current of 15A calculates to peaks of 15A RMS X 1.414 = 21.21A pk.  However, when charging the filter caps in a DC power-supply, the peak-to-average ratio of the distorted current waveform can be as high as 3:1 or 4:1.  Thus, a 15-Amp RMS current from the wall-socket to a power amplifier can easily translate to 50 or more Amperes of peak current being asked for over parts of the waveform.
 
When that happens, the wiring in the house and in the power lines restricts those peaks, due to resistance in the lines, and drops them by as much as 20%.   The Torus Power Conditioner solves that problem by supplying the peak current from its huge magnetic energy-storage capacity.  The house wiring 'sees' only the 1.414:1 peak-to-average ratio of a relatively undistorted current sinewave, while the Torus Power-Conditioner supplies the full 50-Amp peaks without restriction.  That allows the dynamic energy in the music to come through much more powerfully, eliminating any mushiness or loss of focus in the reproduction.
 
Thus, when talking about a 7B SST2 amplifier drawing 36 Amperes RMS, that can easily translate to instantaneous peaks of 125 Amps or more over parts of the waveform.  The larger the amplifier, the greater the need for these high charging currents.  The ideal solution would be to use a Torus Power transformer inside the amplifier, but we shall address that concept in a later article.

[klao]

Hi James,

So at least the 16A Int'l or 20A North American models of the Torus, not anything smaller, would be sufficient for a pair of the 7BSST/2's?

You told me a class-D amp draws similar amount of current like class A/B amp when playing loud music.  Should I get a Torus 16A model, instead of the the 8A you recommended earlier, for a pair of my 1,000wpc @ 4 Ohms class D amps?  (According to their spec sheet, each of those class D monoblocks can give maximum output of 40A.)  I'd also be using a sub with 1,250 Watts RMS class D amp and an AV receiver that consume no more than 1,100 Watts.

Thank you,
Klao

[James Tanner]

Hi Klao,

Yes if the budget allows go for the 16 amp 240 volt.

james.