Never tried my big amp on it as the manufacturer advises against it. Cdp/transport and DAC seems to work well but tubed preamp does not - severely chokes it. |
My front end (Levinson preamp and phono preamp) and sources (Wadia CDT+DAC, Goldmund TT, Technics FM, Nak cassette) are powered by balanced power (Exactpower SP-15A) and sound better than ever before.
However, FWIW, I should disclose a couple of things that were done at the same time as adding the balanced power unit:
The balanced power unit itself gets its power from an Exactpower EP-15A power regenerator unit (which also powers the Levinson amp, Martin Logan stats and sub).
Also, all the power cords were upgraded at the same time, to Purist Dominus/Venustas, Aural Thrills, Audio Metallurgy, and a couple XLOs.
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All of my system is plugged into an Equi-tech 2Q and everything loves it. System is very quiet. No ground loops. All grounds referenced off CT of the 2Q. Front end: K&K phono pre (kit), Cary CD-308 (used as transport), RAKK DAC (K&K Audio kit), Fisher FM-100b (modified). Raleigh Audio line stage (kit, K&K Audio) and currently a restored Eico HF-89 (gutted and rebuilt and modded by me). The line stage is transformer coupled input and output using Lundahl amorphous core tannies. It's a differential parafeed design. The phono pre has a SE parafeed output using same Lundahl iron as does the RAKK DAC which uses a transformer and resistor to provide passive I/V conversion. I think having the galvanic isolation provided by all the transformer coupling can reduce the chance of a bad interaction; no ground currents on the interconnects. One of the mods on the Fisher was to rewire it for a three wire IEC connector. |
John, this is a little off topic, but did you rewire the Fisher because you were using it with a balanced power unit, or just so you could use better power cord(s).
And what is involved with making that mod? (if it's too complicated to explain here, please email me.) I have a Technics tuner and a Nak CR-7a I'd like to mod that way.
Thanks,
Neil
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Neil, had the 3 wire PC conversion done so I could use a better power cord. I had that mod done by the tech who serviced and aligned the Fisher. Can't be too hard; I wired my Eico that way. The two "hots" to the power transformer and the ground to the chassis. Digi-Key sells IEC connectors with built in RFI filters that are kind of cool. My Sun SV-2A3 kit came with one and I used one in the Eico and the RAKK DAC that I built. Anything to kill some of the crap that's coming over the power lines these days. Can't imagine what it will be like if they start sending internet data over the power lines. |
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I have a Furman 20 amp balanced line conditioner run off a 20 amp dedicated line.In it are plugged my pre,turntable,sub, cd player.The noise floor is lower than straight into the wall.I did not like my power amps (Classe DR 8 mono)done this way. They sound better into a Hydra 2 and another dedicated 20 amp line.The sound of the amps in the balalnced conditioner was too rounded off and lacked some life which could be the result of the power conditioner's transformer robbing some life from the amps.Perhaps lower powered integrated amps would benefit more when plugged into this unit.I have no hum, or noise problems,so I feel a balanced power conditioner is useful. |
I am running a BPT fed by a dedicated circuit. I found that the video peformance on my old CRT based TV was phenomenally improved. I don't run my integrated out of the conditioner since I found that it definetely chokes off the sound. |
I use an API Power Wedge Ultra 116 with my front end stuff (it follows an ExactPower EP-15 used for waveform/voltage correction). The PWU provides separate center-tapped isolation transformers for each of its 6 outlets, with switches that allow you to choose between normal, floating, and balanced power options for each attached component. (This unit cannot provide balanced power to power amplifiers, so I haven't been able to test that application.)
Therefore, the PWU provides a reliable test for how each piece of gear reacts to balanced AC on an individual basis, without throwing in confounding variables. To date I've only used one component that showed no improvement from selecting balanced AC (an older Conrad-Johnson tube preamp), and that one showed no degradation either. All other components tried, primarily SS preamps and digital separates (my phonostage is battery-powered, so it doesn't apply here), showed varying degrees of improvement, from very slight to pretty vast as far as these things go, but again never any degradation. (All these pieces also sounded better fed from the PWU than they did skipping it altogether, no matter which switch position was chosen, so the powerline filtration it includes in addition to the iso trannies would seem to be doing no harm here.)
Based on this evidence, I'd say that balanced AC done properly (independent of any other filters or such that might be included in whatever device is balancing your AC) probably rarely has any downside used for line-level components such as sources and most preamps. If there's a problem with a power or integrated amplifier, I'd investigate whether it could be due to inadequate iso tranny capacity. The issue may have more to do with undesired raising of the powerline impedance seen by power amps than balanced AC per se. |
Zaikesman - That's what I thought too and was surprised when it didn't work that way for everything. That's why I started this thread.
Trust me, that 5KVA transformer is not starving anything for power. It is capable of sustained 20 amps in balanced configuration and weighs 120 lbs. The amps I used draw in the neighbourhood of 5 amps at max.
I think it has more to do with how a piece of equipment in grounded internally but I'm not an engineer. Granted, most commercially available products are undersized for amplifiers. |
I'd research the forum archives to see what you can find on this subject (and look for contributions written by Sean). |
The power transformers on my Welborne DRD 300B monoblocks would audibly "buzz" when I plugged the amps into 2.4kVA Topaz Ultra-Isolator trannis wired in balanced config. It was actually so scary that I would have to unplug them after only 5 seconds.
After weeks of frustration, I shipped them back to Welborne. Embarrassingly, the problem was so simple I could have fixed it myself withing two minutes if I had just calmed down and thought it through - the star-grounding just needed to tightened slightly.
Since then, quiet as can be. No problems with the rest of my components, either.
Just remember to turn off the power at the transformer when not in use because the component's own power switch will only turn of off half of the 120V in 60V-0V-60V configuration. |
Darkmo: That last comment I think warrants some elaboration -- my components (except power amps, which don't get the balanced AC) that go on semi-powered standby as well as those that turn all the way off seem to behave the same (meaning the way you'd expect) regardless of whether balanced AC is selected at the Power Wedge's iso-trannies... |
I had a feeling I'd get called on that this morning, Zaikesman, and I'm glad you did.
My comment does not apply to any consumer balanced power products(I assume), only people like myself who bought commercial/industrial isolation transformers and then rewired them for balanced power.
Ok, let me try and explain it as an electrician told me when I was wiring my 2.4kVA Topaz Ultra-Isolator transformers. (anyone more knowledgable please step in to prevent me from passing flawed info)
In normal 120V(0V-0V-120V) wiring, one wire is neutral(0V), another ground(0V), and the third carries the full 120V. Flipping the component's On/Off switch essential connects or breaks the 120V line. So, even turned off, the neutral and ground line are connected.
In balanced power (60V-0V-60v), the same component switch will only disconnect one of the 60V lines, leaving the ground & other 60V connected. So, even turned off, the component will have 60V flowing into it.
For that reason, the electrician advised me to place a switch in the cable feeding(0V-0V-120V) into the balanced transformer to cut the power to everything. |
In a DIY setup, I would suggest using a GFCI on the output. They work by comparing the hot to the "neutral" with a differential transformer (usually two). GFCI's are intended to protect people instead of equipment but, technically, the equipment would not require additional protection.
When the power switch opens either side, it's still off because there is no circuit. The only danger is if you stick your fingers inside an open cover while it's plugged in but that doesn't change either way. Both 60V sides of a balanced system are protected by the same unbalanced breaker upstream of the transformer.
What I'm trying to say is you don't have to turn it off unless you're poking inside. |
