2. tech-talk
  3. 133511-1464

Isotek EVO3 Sigmas

I recently splurged on this power conditioner, and after a fairly lengthy back-ordered wait, it finally arrived recently.  There's good news and there's bad news.

The electricity coming into the house clearly isn't great.  There's a pair of built-in ovens in the kitchen, and the upper one has the control panel.  Evidently, this includes some kind of transformer, as you can hear a low-level hum/buzz through the kitchen cabinetry night and day.

Likewise, the amp's transformers have a similar fairly mild hum, AND this also appears in the speakers.

The reviewer of this Isotek model in The Absolute Sound said that it tamed a mild hum in his transformers.  I've also seen the youtube video with the noise-sniffer, where its insertion completely eliminates the nasties on the line.

The bad news: the hum (amp + speakers) is identical to before.  On bad days, when the music falls silent, you can hear it from the listening seat.  (BTW, I've already tried Audio by Van Alstine Humbuster and also Ebtech HumX, both to no avail.)

The good news: there was a distinct improvement in the presentation of the music.  It was louder--I was immediately reaching for the remote control, fuller, with more body, more texture, more presence, more resonance, with sparkling highs, and particularly a great sense of ease on the fortissimo passages.

So there's the quandary.  Is the good news worth 4K?  Or does it go back, and I keep experimenting with Equitech, Torus, PS Audio, Audioquest, Shunyata, etc. in the perhaps futile search for a unit that actually quietens the hum?

128x128twoleftears
twoleftears's avatar
twoleftears OP
5,318 posts
 
I've been watching the THD display through the day.  I presume this displays the THD of the AC going into the unit, rather than that coming out of it.  It started off at 1.25%, peaked at about 1.37%, and is now, Saturday mid afternoon, down around 1.10-1.15%.  The read-out changes up and down by one click almost every second.  I don't know enough about electricity and mains supply to know if these values are high, typical or low.
jim204
881 posts
 
I don't know if you have thought of this before but is your elctric supply to your system from your ring main or a dedicated supply from your box to your system alone . I have made myself a new spur with Neotech 3001 mains cable, it's fantastic stuff but expensive. It is very well shielded against RFI and mains nasties and it has made an amazing difference to my system ,no fridge clicks or transformer hum anywhere. It was the best couple of grand I have spent in a long time.
twoleftears's avatar
twoleftears OP
5,318 posts
 

Although this mini-review doesn't seem to have spurred any real interest, report further adventures in power conditioning.

I dragged home a Furman IT Reference 15i--50 lbs of isolation transformer.  Inserted in the system, it, like the Isotek, does not remove one jot of the hum from transformers or speakers.  Disappointing.

In a shootout between it and the Isotek on overall musical presentation, the Isotek won, but not by much.  Isotek sounded a little more natural, particularly on solo piano, where it sounded more like being in the same room with someone playing live.

I then reinserted the Ayre AX-7 into the system.  Absolute silence all around, with or without any conditioning.  I had to jam my ear against the speaker drivers to hear anything at all--after checking that everything was turned on.

Conclusion.  The Rogue CMII is a really great-sounding amp, especially for its price.  Overall, I still think it sounds a little more fully fleshed than the Ayre, which is itself no slouch.  But it is not silent.  I don't know if it's just the example I have that is a bit noisy, particularly in the very quiet listening room that I have, or whether the model is inherently that way, especially with reasonably efficient speakers.

(BTW, before all this I tried every hum-reducing trick in the book, including all the recommendations from the PS Audio webpage, a phone call with Rogue, an Audio by Van Alstine Humdinger and an Ebech HumX.)

More to discover