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In Reply to: Re: How to Spec a Dedicated AC Line? posted by tomservo on April 2, 2007 at 07:16:19:
Feroresonant transformers did not sound as good as over-sized E-I core transformers in my own testing.( See: http://www.geocities.com/jonrisch/catch2.htm )
In fact, of all of the ferroresonant transformers I tested, including a couple of Sola brand units, NONE of them sounded very good on an audio system.
What works on a computer (with it's switching power supply) or on one of the older style mainframes (which had incredibly beefy power supplies in one sense, but without enough AC line protection from surges, spikes and EMI), doesn't necessarily work well for an audio system.
I found this to be true for surge suppressors as well, (see: http://www.geocities.com/jonrisch/surge.htm) the cheap ceramic caps, the low capacity inductor cores, etc., all conspire to reduce performance under extreme conditions.
What about a ferroresoant transformer could cause such a sonic problem?
It could be any one of a number of things:
The resonant beahvior could be extending the duration of line transients or 'events', this could then create a background of noise to blur the playback performance.
The resonating cap could be of poor quality in terms of audio power usage, again, instead of shortening line events and transients, increasing their length, smearing them out in time.The saturated portion of the circuit could be adversely affecting peak current delivery.
The extra windings would increase the output impedance, and even though the average AC voltage was "regulated", the peak current would be stiffled.
In any case, many folks have found out the hard way that ferroresonant transformers are not all that great for audio systems, at least, if you want them to sound good.
As a last comment, unless there are compelling reasons to use armored AC wiring, such as extreme rat infestation or a real chance of physical abrasion of the wiring, sonically, it is not a help, but a hinderance.
The AC wiring should be kept away from steel, iron, and metals of any sort, as much as this is possible, for maximum sonic performance in a home playback environment.
Follow Ups:
I use Sola transformers between the wall and my amps, and between the wall and my pre-amp. When I first placed a Sola transformer between my pre-amp and the wall, I noticed that the noise floor dropped significantly. I could not hear the high frequencies stifled any. But I put new capacitors in before I began to use them permanently. I put an industrial noise filter (Tokin) between the Sola transformer and the pre-amp which cleaned up the signal, put space between the instruments, improved the imaging.If these devices hadn't improved the music, I wouldn't have used them, but YMMV.
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Hi JonI had a big Sola in my home system for a while but I can’t say it made a difference and it did make acoustic noise on its own. It was quickly located to another room.
Here, if a person were wiring a dedicated circuit and plumbing (code here requires steel conduit or BX if less than 3 feet) then the isolator can be located at the breaker box end.At Intersonics, we were in an industrial park and line voltage usually didn’t look pretty on a scope and varied all over the place during the day. They got a bunch of Sola’s which were used on the test benches and computers and such.
At least by measure, the voltage coming out looked nice on a scope and meter and it ended the issues that existed with the sensitive stuff although being all over the room, there was a steady audible buz if the stereo wasn’t on to mask it, the speaker division made sure it was always on.A more well thought out answer to the original post would have been to ask a few more questions like “what is the problem you have which makes you consider a dedicated line”. “Is everything on one circuit now?”
Most of the time, when people get desperate and look at the power end, they are chasing hum or noise that while driven by AC, is a result of ground loop currents in the signal cable.
It is unfortunate that hifi isn’t balanced as in Pro but good transformers or circuitry cost more than the unbalanced RCA cable.
In this case, a good AC or signal isolation transformer would provide the rubber glove for a leaky pen fix.
While having a given item may give conflicting result due to additional unaccounted effects (like for example not also having a parallel choke to block common mode noise), I am not clear how having clean quiet constant voltage AC alone, could cause a decrease in accuracy in the performance of the what is connected.
Best,Tom
My main problemt that I'm trying to solve is that my music has a certain harness or glassiness at the top end. I like adult contemp and rock, and I like it pretty loud. No buzz or hum.Other factors working against me (that, unlike my musical tastes, I could change) are that I listen to CD's exclusively, and my Thiel speakers can be very revealing. Also, use solid state amp (Ayre) to drive the Thiels.
I am RCA to the preamp, then balanced from the BAT tube preamp to the Ayre SS amp.
-Tim
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