[Lkdog]

As I have noted- the new Kismet amps sound great.

One odd thing is that there is a weird hum that occurs every once in awhile.
No rhyme or reason. Not related to when any lights or anything else in particular is on. This occurs when nothing is playing.

It is not coming out of speakers. It is the amps making the hum.

System is dead quiet most all of the time. All new electrical.
Alan Maher EMI/EFI line filter boxes.

Here is link to video I took of the hum. It goes away on its own. Sometimes I do not hear it for a couple days.
https://drive.google.com/file/d/1rJIvYy8xoZmhh_0AdhvshX_0bg3-1-Ol/view?usp=sharing

Any ideas?

[SJ David]

Annoying, no doubt. Since it is intermittent with long intervals that seems to rule out something in the vicinity of the audio equipment.

Maybe you have done this already but first thought is to walk around the house/garage/backyard lights/and so on, and look for ANYTHING that may have a plug and could be powering-on coincidentally to when you hear the hum.

[jmolsberg]

it could be your surge protector. i had a tripp lite which cause an intermittent noise in my system. replacing it solved my issue

[genjamon]

I'm wondering whether there's any DC riding on the AC into your house.  I would especially wonder this if you were powering your amps straight from the wall or from a power strip with no filtration on it.  Have you called Klaus?

[lokie]

Intermittent hum is no fun.

Have had several. One took me three different techs to find.
 My last one was a short at the input. If the interconnect was pulled slightly in one direction it created a short.

[genjamon]

Yeah, but this is transformer hum in the chassis itself.

[JackD]

Check the transformer bolts.

[DaveC113]

Check for DC offset when the hum occurs. If that's the issue finding the source may not be easy but you can eliminate it locally.

[Lkdog]

Thanks for the replies.

I will try and respond to the posts in order. Excuse me if I sound ignorant about any of this.

1) SJ David- Will check next time again it happens, but there is nothing that is plugged in that is turned on that seems to trigger it (internal or external lights, TV, sprinkler system, furnace/AC, street light, sump pump, etc)
2) jmolsberg I use Tripplite ISOBAR surge protectors and the lights are all green. There was no noise of any kind in system before the Kismets showed up. As noted all new wiring. New cable modem and router and Coax runs. All good.
3) genjamon Amps running from Tripplite Isobars as noted. Not sure what DC riding on the AC into house means?? This is where I feel ignorant.... Have not talked to Klaus. Maybe he will see this thread.
4) lokie  Will check all of the connections, but if it is that wouldn't it be constant hum?? Nothing gets moved around. As you know these things weight about 800 lbs each. LOL.
5) JackD  That seems easy enough. It may only be one amp that is humming. Hard to tell. Its kind of a general non localized  hum when it happens.
6) DaveC113  Not sure how to do that??  I do have a mulitmeter.

This is a weird problem in that it seems to be totally random. I seemed to have happened more in the first couple weeks of break in so I thought it was calming down and it is less than before.
Still happens though once in awhile.
It has not reoccurred today and I worked down here in same room all day.   

[JackD]

Even though they are boxed up pretty well there is no telling what kind of "help" the folks at UPS gave them.

[Doublej]

I would plug the amp directly into the wall and see if the problem goes away.

I would also read this thread, https://www.audiocircle.com/index.php?topic=172731.0

[Rusty Jefferson]

It's transformer hum, and pretty common.  Discussed frequently, most recently here:
https://www.audiocircle.com/index.php?topic=172731.0

The OP of that thread should be receiving a regenerator soon and reporting back about the results.

[klaus@odyssey]

OK:

1.  this is the Gen 2 of the 850 VA big momma trannies.  They are dual shielded and by themselves extremely quiet.

2.  the hum is without doubt  strain or garbage related from the AC

3.  the trannies are fine,  as the hum is intermittant,  yes.

4.  Question arises as to changing outlets,  avoiding filters etc.  makes a difference....problem with AC is always a bit of the needle in the haystack scenario.

5.  Try turning off the amp for 5 seconds and turn it on again......

6.  Turn off the amp for 10 minutes or so...when turning it on and the relays let go after 7 seconds,  is there an audible hum or "rush"  or is it quiet ???

7.   strangely,  5 + 6  can alleviate the problem itself,  as sometimes the "garbage" in the AC accumulates and "stores" itself.

8.  Offset bias was set by myself...non-issue

[genjamon]

The Tripp-Lite units use MOVs for surge protection, which as I understand it can degrade over time and become noisy. First step IMO should be to use them straight into the wall for a while, or at least through a power strip with zero filtering. If that solves the hum problem, then you know it’s the Tripp-Lites. If you still need the surge protection, then I would look into a design that doesn’t use MOVs. Dave at Zenwave offers one such solution. The other Dave at PI Audio offers a different solution. Both are high quality. I’m sure there are others too.

[Lkdog]

OK:

1.  this is the Gen 2 of the 850 VA big momma trannies.  They are dual shielded and by themselves extremely quiet.

2.  the hum is without doubt  strain or garbage related from the AC

3.  the trannies are fine,  as the hum is intermittant,  yes.

4.  Question arises as to changing outlets,  avoiding filters etc.  makes a difference....problem with AC is always a bit of the needle in the haystack scenario.

5.  Try turning off the amp for 5 seconds and turn it on again......

6.  Turn off the amp for 10 minutes or so...when turning it on and the relays let go after 7 seconds,  is there an audible hum or "rush"  or is it quiet ???

7.   strangely,  5 + 6  can alleviate the problem itself,  as sometimes the "garbage" in the AC accumulates and "stores" itself.

8.  Offset bias was set by myself...non-issue

Klaus-

Thanks for your input.

In answer to your test scenarios in #5 and #6 above-  there is an audible hum or "rush" as you state after I turn them off and on again for 5 seconds.It goes away.
When I turned them off for 15 minutes and turned them back on they were dead quiet.

I noticed the rush hum thing you mentioned when I first plugged them in when I first got them last month. I leave my amps on all of the time so your thoughts that "garbage" in the AC accumulates and "stores" itself makes sense and might explain the random occurrence.If all I have to do is bleed the build up every few days, that is easy.

It is happening less as they have broken in (over a month now). First week or two it was happening quite a bit more. 



One product mentioned in the thread referenced by Rusty Jefferson and Doublej is this Isobar Isolation transformer.
Would this help at all? It sounds like it might be of some value no matter what.
https://www.amazon.com/Tripp-Lite-Isolation-Transformer-Outlet/dp/B00006HPHN/ref=pd_lpo_147_t_1/141-3856641-9364810?_encoding=UTF8&pd_rd_i=B00006HPHN&pd_rd_r=68495003-f2c8-4fc8-b9d9-d4abb9c91676&pd_rd_w=jvAeS&pd_rd_wg=e59hq&pf_rd_p=7b36d496-f366-4631-94d3-61b87b52511b&pf_rd_r=5MW1319H4KX5KEVSHRYZ&psc=1&refRID=5MW1319H4KX5KEVSHRYZ#customerReviews






I do have these Alan Maher EMi/RFI things in one of the outlets that I use for the system.
https://www.alanmaherdesigns.net/product-page/harmony-one

[Early B.]

Tripplite is OK for computers, etc., but in the audiophile world, it sounds like crap. Genjamon provided much better alternatives.

[abd1]

I had a slight hum from my odyssey kismet, as well as some other gear I use, so it's more my power causing it than the amp. I got a PS Audio P5 regenerator and it is dead quiet now, as is my whole system. I can't recommend one enough.

FYI - I'm thinking of moving to the P12. So my P5 might be available at some point soon.

[Tyson]

PS Audio P5 is amazing and would be my recommendation for solving any/all AC hum related issues.  Works great on tube gear (which is even more finicky than SS gear), so you're all set if you ever decide to get a tube preamp or tube DAC. 

[Rusty Jefferson]

...One product mentioned in the thread referenced by Rusty Jefferson and Doublej is this Isobar Isolation transformer.
Would this help at all? It sounds like it might be of some value....

Just for the record, I recommended the OP of the other thread look at the PS Audio regenerator to solve his problem, not the isolation transformer. He posted that he purchased one and we've been waiting to hear if it cured his problem. His transformer buzzing is apparently constant, not intermittent.

....Consider reaching out to members of this forum or others you use for someone who has a PS Audio regenerator and lives near you and would be willing to let you try it. Power conditioning won't prevent this issue, but the regenerator will. Worst case, pick one up on the 30 day evaluation. Probably money better spent than running a new panel with separate grounds from the main panel and dedicated lines to your equipment, only to find out there's still mechanical hum in your equipment....

[Lkdog]

Just for the record, I recommended the OP of the other thread look at the PS Audio regenerator to solve his problem, not the isolation transformer. He posted that he purchased one and we've been waiting to hear if it cured his problem. His transformer buzzing is apparently constant, not intermittent.

....Consider reaching out to members of this forum or others you use for someone who has a PS Audio regenerator and lives near you and would be willing to let you try it. Power conditioning won't prevent this issue, but the regenerator will. Worst case, pick one up on the 30 day evaluation. Probably money better spent than running a new panel with separate grounds from the main panel and dedicated lines to your equipment, only to find out there's still mechanical hum in your equipment....

Got it. Thanks. 

Sounds like my options are to bleed out or discharge the built up AC grunge by rebooting when needed; or to get a PS Audio unit which will clear this up and also do other positive things in the system.
How big a power regenerator if I go that route should I be looking for since the Kismets have 850 VA transformers?

Thanks.