Forums - Slight bit of hum normal?

MarkBlair

Senior Member

Posts: 59

Re: Slight bit of hum normal?
Reply #15 - 03/21/11 at 02:21:12

Mark and Gary -

I wish Steve could chime in here regarding Mark WIlliams' second cap replacement -- and I hate to make any modifications that might void my warranty. But Mark, I'm going to send you a PM ASAP. And Gary, if Mark doesn't post pictures, if you do just one more response, I believe you'll have enough posts to send him a PM!

Mark Blair

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GaryAR

Verified Member

Posts: 6

Re: Slight bit of hum normal?
Reply #16 - 03/21/11 at 03:10:31

Well, I figured out the biggest cause of the hum... once I disconnected the plate amp that powers my bass enclosures it decreased dramatically. It's now getting a line-level signal out of the preamp and there is almost no hum. Certainly not that can be heard from my listening position anyway.

I'm hoping that if I am a little more careful about the routing (and quality) of the wires I can go back to speaker-level inputs. Anyway no need for me to modify the amp so I'm happy.

gary

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Mark Williams

Verified Member

Posts: 16

Re: Slight bit of hum normal?
Reply #17 - 03/21/11 at 21:44:37

Hi you guys,

Well, that's my problem -- not enough posts yet to P.M. anyone yet.

I don't know how to post photos here and there's really nothing to post. Just unsolder the existing cap (one lug at at time) and replace it with a higher value one.

But, I would be happy send a photo to anyone. Just write me directly: ms_williams@hotmail.com.

Like I said in the last post, I don't know if this if wise or advisable but it works. I never got a straight answer on it....just was told some hum was normal.

Mark

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MarkBlair

Senior Member

Posts: 59

Re: Slight bit of hum normal?
Reply #18 - 03/28/11 at 19:08:34

I've sent Steve a couple of e-mails on this -- but still haven't heard anything back. Perhaps he's just very busy right now.

But I actually hope Steve replies to this post instead so everyone can see the response.

Again, I'm **very** pleased with the amp (although I think I might have a rectifier problem right now because of a few recent intermittent failure-to-start problems) -- but I'd really like to know Steve';s thoughts on this possible solution for addressing the hum (very minor though it is in my situation) in the SE84C+...

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Brett

Senior Member

Posts: 69

Re: Slight bit of hum normal?
Reply #19 - 04/01/11 at 20:19:56

I would be reluctant to modify the power supply cap values without talking to Steve about it first. It has been said by many amp builders that the power supply design is the single most important thing about an amp. The type of power supply and the values of the components that comprise it effect its speed and phase among a whole host of issues that I have yet to understand. By changing the value of the second cap to 80uf you may be trading one problem for another such as a phase shift that causes the music image to be skewed.

Then again it might be just fine, but this is a reasonable concern.

I've had the fortune to build two zen kits and two zen clones for my buddies. In my experience the power transformers were the culprit if there was any hum. When these amps are running properly there is ZERO audible hum from the listening position. You should have your ear to the dust cap to hear hum. That's the case with my 95db Parkers, as well as my friends zen open baffles.

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« Last Edit: 04/01/11 at 20:41:37 by Brett »

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MarkBlair

Senior Member

Posts: 59

Re: Slight bit of hum normal?
Reply #20 - 04/01/11 at 21:43:25

Good point, Brett.

Well, I've done my "due diligence" by e-mailing Steve (three times) AND by kicking-off this thread (this is a support forum after all).

But I've still heard nothing back. So I guess this isn't a high priority for him at this time. But I really am extremely surprised that he hasn't chimed-in to this somewhat long-runnung thread.

Oh well -- even though it's harder than I had hoped to get some after-purchase support, I still really like the amp a lot.

In all fairness, I know Steve tends to have quite a bit going on at any given time. And if I was him, talking about hum-related problems would probably be one of my least pleasant "chores"...

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Brett

Senior Member

Posts: 69

Re: Slight bit of hum normal?
Reply #21 - 04/02/11 at 00:00:57

He does get busy at times as he puts it "wears a lot of hats". He single handedly handles the manufacture of amps, cables, speakers, speaker repairs. And when he's not doing that he's tinkering, designing, updating his website, writing white papers... I've been a long time Decware customer and I've noticed that his involvement with the forum is hit and miss. Lots of topics go unanswered that would greatly benefit from his perspective. Even emails get missed sometimes cause they can get lost in the sea of spam he gets due to being a rather big target as a manufacturer.

The best way to get a hold of him is to call. Even if he's unavailable someone else will answer and every one there is friendly and ready to help. I'm sure he's concerned about your hum issues and will get to the bottom of it.

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Brett Senior Member Posts: 69	Re: Slight bit of hum normal? Reply #22 - 04/02/11 at 00:03:51 Oh one more thing... http://www.decware.com/paper41.htm His paper for troubleshooting hum issues. If you do catch him on the phone I would imagine the first thing he'll try is to direct you to this paper, so you'll want to have done all of these things first to speed up service.
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MarkBlair Senior Member Posts: 59	Re: Slight bit of hum normal? Reply #23 - 04/02/11 at 03:14:32 Thanks again, Brett. And how coincidental that I just stumbled onto that hum paper a bit before you sent your response! Anway, I may end up calling Decware to see if I can get some sort of response -- but I'm still hoping Steve will either respond to my e-mail(s) or chime-in here on the support forum.
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