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SUPPORT FORUMS FOR CURRENT DECWARE GEAR >> SE84UFO >> SuperZen transformer hum?
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Message started by MoNelly on 12/30/12 at 03:45:01

Title: SuperZen transformer hum?
Post by MoNelly on 12/30/12 at 03:45:01

Hey all,

I recently acquired a lightly used SuperZen. It sounds amazing in my near field setup, but I eventually noticed a slight hum. I chatted with Steve, and later ruled out bad tubes or a ground loop. The hum seems to be coming from the amp itself. I plugged it into an isolation transformer, but no change.

I'm wondering if I'm just being overly sensitive since the amp is so close to my chair. Do any other owners of the amp hear a slight hum/buzzing from the amp itself?

Thanks!

Title: Re: SuperZen transformer hum?
Post by Rivieraranch on 12/30/12 at 13:42:49

Do you mean mechanical hum/noise? I have none of that with mine. I don't hear any tube hum, either. Keep looking into it.

Title: Re: SuperZen transformer hum?
Post by rockn on 12/30/12 at 15:57:07

I also have a hum coming from the transformer as well as a low buzzing coming out of the speakers. Not sure if this is the norm. I didn't have this with my last tube amp. I do like the amp, would just like to loose the hum n buzz.

Title: Re: SuperZen transformer hum?
Post by MoNelly on 12/30/12 at 20:51:43

Thanks for the response, guys. Seems like it's hit or miss on the hum/buzz with this amp. I may just need to send it back to Steve for a look.

Title: Re: SuperZen transformer hum?
Post by busterfree on 12/31/12 at 00:09:18

My SuperZen is very quiet. I have no hum.

Title: Re: SuperZen transformer hum?
Post by rockn on 01/01/13 at 17:04:20

Ok gang, i got rid of the hum in the transformer! I had a Rel sub connected to my amp using the Neutrik Speakon hook up and that was causing hum in both the S zen and the sub. Now i have the sub connected to my idecco dac instead and things r much better. Not sure if that is defeating the purpose of Neutrik connection but i don't see any alternative. Happy New Year!  

Title: Re: SuperZen transformer hum?
Post by smoitessier on 02/16/15 at 07:30:43

I received my new super zen, and I have quite a lot of hum (for my taste), I don't know what to expect from a tube amp, but when I turn it on the amp buzzes in the low frequencies (similar to a refrigerator). After about 30 sec later after the tubes warm up, the 97 db (super 8" Audio Nirvana) FR speakers pick it up, and my living room is flooded with the sound, which I notice in between tracks or low  musical passages.

Using my old 89 db speakers the hum is much lower, but I can still hear the amp itself from about 10 feet if the room is quiet.

I have tried identifying the source, removing all interconnects, and the input tube, but no luck, hope it's the rectifier tube. After 40 hours of break-in I don't notice any difference.

btw i'm in France with the 240V version, I'm curious if others have had the same experience both in the states and Europe

Title: Re: SuperZen transformer hum?
Post by mark58 on 02/16/15 at 13:25:13

smo...  Hum can be a bitch.  I am convinced that a little hum will always be present especially when using my ZP3.  I don't have any with CD playback at normal listening levels on either system with speakers. When I read your post I recalled someone mentioning the below article by Steve.  I haven't read it yet but I'm sure it's helpful.  Mark.

http://www.decware.com/paper41.htm

Title: Re: SuperZen transformer hum?
Post by DBC on 02/16/15 at 14:53:36


Quote:
smoitessier wrote:

I received my new super zen, and I have quite a lot of hum (for my taste), I don't know what to expect from a tube amp, but when I turn it on the amp buzzes in the low frequencies (similar to a refrigerator). After about 30 sec later after the tubes warm up, the 97 db (super 8" Audio Nirvana) FR speakers pick it up, and my living room is flooded with the sound, which I notice in between tracks or low  musical passages.

Using my old 89 db speakers the hum is much lower, but I can still hear the amp itself from about 10 feet if the room is quiet.

I have tried identifying the source, removing all interconnects, and the input tube, but no luck, hope it's the rectifier tube. After 40 hours of break-in I don't notice any difference.

btw i'm in France with the 240V version, I'm curious if others have had the same experience both in the states and Europe


Assuming your wall power outlet has a proper Earth Ground and you do not have a subwoofer connected via speaker level connection then I would tend to agree it might be the Rectifier. Over the years I have had a couple rectifiers produce noise in both channels.

As far as how much Hum you should expect from the Super Zen. I have Klipsch RF-7 mains (102db) and Mid Bass Module (350 watt amp reinforcing 50 to 150hz frequency range). My system is Brutally Revealing to any High or Low frequency distortion.

With my Oppo BDP-105D player ON and connected to my Super Zen at 50% volume setting:

There is NO low frequency Hum from my Mid Bass Module with my ear 6 inches from it's 12" driver.

There is a very faint High Frequency Hiss from my RF-7 horns with my ear 6 inches from the horn. With my ear 24 inches from the horn I can not hear any hiss.

So in my case the Super Zen is for all practical purposes Dead Quiet. I would think yours should be also with nothing connected to the amp other than your passive speakers. This leads me back to suspect the Rectifier or wall outlet Earth Ground ???

Title: Re: SuperZen transformer hum?
Post by smoitessier on 02/16/15 at 23:06:07

Thanks Mark, I have read that white paper, but unfortunately couldn't follow through the rest of the diagnostic lacking a rectifier tube, and yeah the hum comes from both channels.

Does anyone know if you can check a rectifier at home with just a multimeter?

Title: Re: SuperZen transformer hum?
Post by smoitessier on 02/17/15 at 00:14:04

DBC I had checked my Earth a few months ago by curiosity, with a dedicated tester I had access to, and it showed all well, I will however put the amp in another room to see if it's the circuit breaker, or room acoustics, I have stone/brick walls on 3 sides of the living room and a drywall, and roughly the same in a smaller bedroom.

I have no subwoofers, just DIY marin ply minimonitors (10.5" W x 19" H x 11.25" D) I made with Audio Nirvana Super 8" cast frame FR drivers. (they are very quiet and nice with my old 7W Cambridge SoundWorks DTT 3500 Digital 5.1 Speaker System)

To play music I have a new Teac PD-HO1 CD player or macbook pro via ethernet airplay via a Freebox's minijack.

Also don't know if it will help, going out on a limb, I ordered some cheap alluminum speaker dampers to put underneath the amp, thinking it could alleviate some noise from it's vibrations on my book shelf... ?

Title: Re: SuperZen transformer hum?
Post by smoitessier on 02/17/15 at 12:26:13

Put the amp and speakers in the other room, tried all the wall outlets and still no joy.

Also used a tone generator online (onlinetonegeneratorDOTcom) and my best guess is it's a 100 Hertz hum.

other than that all I can say is, using a volt meter between i.e. the red and black terminals of one side, I get consistently .001-.002 volts once warm, and once after 5 hours loud, .005-.01v, loud for me being 9 o'clock and around 70-75 db @ 10 feet. I don't recall extra hum then but reckon my ears were lightly fried

Title: Re: SuperZen transformer hum?
Post by smoitessier on 02/18/15 at 16:34:15

Mr. Deckert thinks it's the rectifier tube damaged in the 90 G shipping service, and is sending me a replacement, what a 1st class customer service... can't wait

Title: Re: SuperZen transformer hum?
Post by Tube-aholic on 12/17/15 at 12:09:01

I received my new SE84UFO on Monday.  When I first turned it on there was a hum as you described. I didn't notice until last night that it has diminished to all but nothing. I can hear it coming from the transformer if my ear is next to it. But from my listening position, approx. 8 ft, it is no longer audible.

Title: Re: SuperZen transformer hum?
Post by neubian on 01/06/16 at 03:12:22

I recently purchased 2 x UFO2 (select) amps and they both hum. One hums louder than the other. They both also produced hum from the speakers (with nothing else connected to the amps). The gauge on the amp with the louder hum shows that the one is close to the 40 mark. The other is just past the 20 mark. The other amp shows both gauges just past the 20 mark.

Not sure what can be done. The hum from the speakers is bothersome since I can still slightly hear it from my listening position (about 8 feet away).

Title: Re: SuperZen transformer hum?
Post by Tube-aholic on 01/07/16 at 02:40:26

I have about 50-60 hours on my amp now and the hum is all but gone. Perhaps it's part of the break-in process. I do know that it gets better sounding the more I listen to it.

Title: Re: SuperZen transformer hum?
Post by 4krow on 01/15/16 at 23:12:45

It's been a long time since I have chimed in this forum. Then, today I started reading a few posts, and this one caught my eye. I will state my opinion in a broad sort of way. There are times when anomalies can drive us to drink, and other times they just don't matter. No doubt, I have had things like come to my attention over the years of listening to my system. And, there is nothing wrong with chasing down a little demon and squashing it. The time that I regret was many years ago when I owned a fine pair of mono amps with a system that had everything that I could hope for...except one thing, hum. To be more specific, a small amount of hum. You had to be close to hear it. The listening chair about 10 feet away, and you would have to strain to hear it. But no, I wouldn't allow that sort of thing in such a fine system, and I didn't. Sold the amps for a dead quiet piece. Ahh, no hum...and dam, no magic either. Next time that I pick my poison, I should be more careful. Having said all of this, I can easily say that if a problem is worth the effort to get rid of(I mean larger than a small problem), then of course, do it. It is difficult to know something lurks behind the music at some level and ignore it, unless of course, you can't hear it even in quiet passages of the performance.

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