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How do you perceive SE34I.3 "hum" NEARFI (Read 2967 times)
Lon
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #15 - 03/11/13 at 01:51:36
 
Well. . .one would think not then, though the way tubes are it could still be a tube.

I hope you can resolve it!
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busterfree
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #16 - 03/11/13 at 02:04:12
 
Posted by: Fireblade      Posted on: Today at 17:14:33
FWIW, my Mini does not make any noises that I can hear, even with my ears significantly closer to the speakers than the std reference of 3 ft.  My speakers are DM945's, at 94 dB @ 4 Ohms.

Therefore, in my case, the Mini's noise is indeed 'too low to hear.'

I agree Fireblade. This is what makes me think I have a problem, but it is not a big enough problem to ship my amp back. I am still on the fence about upgrading it. That would be a good time to check it out.

I using the Rachael right now with Trapeziums and enjoying it.  ;D
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Fireblade
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #17 - 03/11/13 at 13:24:18
 
IMHO, If you're planning on eventually replacing those speakers with higher sensitive ones, getting rid of that moderate hum is essential.
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Rizlaw
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #18 - 03/11/13 at 15:26:28
 
Fireblade & Busterfree,

Busterfree, I completely agree with Firebird on getting rid of hum first in your MT before considering higher sensitivity speakers down the road; particularly if you're considering speakers like Omega's cross-over-less fast full range single driver types which don't filter out anything coming into them. You need a pure, quiet and clean signal. The nearfield hum problem I'm having with my Rachael is evidence of that.

It's been so long since I owned Klipshorns (back during the Quadraphonic craze), that I forgot just how revealing truly high efficiency speakers can be; irritating, too, with the wrong electronics.

I think you already know this. Wink

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« Last Edit: 03/11/13 at 18:51:12 by Rizlaw »  

System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
System 2: Yamaha PX-2 (Shure Ultra) / Oppo DV983H > Classe CAP2100 > Thiel 7.2
System 3: Fisher:R200/X202B > Magnapan MMG
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78 archivist
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #19 - 03/11/13 at 18:01:01
 
Hi Fireblade,

I've been using Rachel bridged to mono on a full range 15" Audio Nirvana speaker. I definitely get audible hum at three feet, and it would be intolerable if I were using it nearfield. Luckily I'm usually anywhere from six feet and beyond where it doesn't bother me. Similar to your Fisher, my 60 year old H.H. Scott 299a was dead quiet up to one foot of my old Klipsch Heresy's.

78 Arch
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Rizlaw
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #20 - 03/11/13 at 23:36:57
 
I heard from Steve this afternoon. He says that the "less than 1.5mv" noise/hum rating for SE34I.3 and Zen amps is equal to about -72db for those who may be interested.
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System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
System 2: Yamaha PX-2 (Shure Ultra) / Oppo DV983H > Classe CAP2100 > Thiel 7.2
System 3: Fisher:R200/X202B > Magnapan MMG
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Palomino
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #21 - 03/15/13 at 20:07:48
 
I have a new Rachael and I get slight hum on 89db 8 ohm drivers, but need to be right next to the driver to hear it.  I don't think I would hear it nearfield.

Last night I hooked up 89db 4 ohm speakers and noticed no hum what-so-ever.  Not sure why hum on 8 ohm and no hum on 4 ohm.
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Rizlaw
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #22 - 03/15/13 at 23:27:44
 
Palomino, when you say:

Quote:
Not sure why hum on 8 ohm and no hum on 4 ohm.


Here's my take on a possible answer.  The "Rachael" has a noise/hum rating of "<1.5mv" or about -72db according to Steve. The amp is designed to be most efficient with 8 ohm speakers from what I've read. From what Steve has told me, the "slight" hum you hear with your ear right next to the speaker driver is normal. It's what you should hear, at worst, so to speak, with speakers in the 94 or less db range. At best, you would hear nothing or perhaps a slight soft hiss. In all cases, from 3 or more feet away, you should hear virtually nothing in terms of noise/hum unless you have 103db, or greater, sensitivity speakers (again, according to what I've been told by Steve). This all assumes, that the hum is not being caused by other factors like: poor grounding, bad tubes, a problem within the amp like a bad solder joint or defective part. There could be a few other factors I'm not knowledgeable enough about to list.

From my own experience, two way speakers with crossovers are going to produce the inherent hum of the amp differently than high efficiency, single full range crossover-less speakers.

In the later speaker design (high efficiency, single full range crossover-less), given an accurate driver, there is nothing to reduce or modify the noise/hum coming from the amp before it gets to the speaker. In the former speaker design (2 way crossover) the crossover can soak up a good deal of the amp's noise (hum) making it very low to inaudible.

For example, on my 4 ohm MMG's, the Rachael produces virtually no hum (nearfield). However, the MMGs are known to be highly inefficient (about 83db) speakers which require a great deal of power. On the other hand, my vintage Allison Six's ( 86db, 2 way crossover @ 4 ohms) produce a hum similar to the hum I hear from my new Omega Super 3E (94db @ 8 ohms). On my Thiel 7.2 speakers which have a complex crossover network and are 86db 4ohm speakers, you can only hear a faint buzz from the Rachael with you ear right up to the woofer cone. So four different speakers with four different audible hum results.


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System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
System 2: Yamaha PX-2 (Shure Ultra) / Oppo DV983H > Classe CAP2100 > Thiel 7.2
System 3: Fisher:R200/X202B > Magnapan MMG
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hifitubes
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #23 - 03/26/13 at 12:27:15
 
I'm running USB > Zodiac Gold > Rachel.

DEAD QUIET. Barely audible whisper that you can just tell the system is on, and not off.

97db/w Hoyt Bedford.

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Rizlaw
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Re: How do you perceive SE34I.3 "hum" NEARFI
Reply #24 - 03/26/13 at 16:30:10
 
hifitubes,

I appreciate the info. Steve and I are at a loss to explain why my "Rachael" produced audible (annoying) hum through my speakers, but not through his. As a matter of fact, on the second go round, Steve measured the noise in my modified "Rachael" to be lower than a Torii III.

I've gotta say that in 50+ years of High End audio, I've never met an audio manufacturer and person more concerned and dedicated to resolving legitimate customer problems than Steve.

I'm now waiting on a new Taboo III. I'm praying to the "Tube Gods" this will end my hum issues and allows me to concentrate on my next Decware purchase: perhaps the phone stage.
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System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
System 2: Yamaha PX-2 (Shure Ultra) / Oppo DV983H > Classe CAP2100 > Thiel 7.2
System 3: Fisher:R200/X202B > Magnapan MMG
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