Post by Danny Boy on 03/25/23 at 01:41:53
I cannot see a break, but it looks like it took a shot. Does anyone think this might be a problem, or at least what is causing my hum?
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https://www.decware.com/cgi-bin/yabb22/YaBB.pl AUDIO FORUMS >> General Discussion and Support >> Recent hum - Here is what I found... https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1679704913 Message started by Danny Boy on 03/25/23 at 01:41:53 |
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Title: Recent hum - Here is what I found... Post by Danny Boy on 03/25/23 at 01:41:53 I cannot see a break, but it looks like it took a shot. Does anyone think this might be a problem, or at least what is causing my hum? temporary image share |
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Title: Re: Recent hum - Here is what I found... Post by Lon on 03/25/23 at 01:52:09 I would replace it and yes the hum might go away. |
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Title: Re: Recent hum - Here is what I found... Post by CAJames on 03/25/23 at 02:05:46 What he said ^^^ With fuses there is no downside to replacing one you think might be a problem. Even if you can't see anything obvious. |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/25/23 at 02:18:13 Thanks to you both. I remember the rectifier flashing/popping recently, and I noticed the low hertz hum became louder. If I place my ear up to my woofer, it's there pretty good. I figured I was going to need to replace it, but I just wanted to get a consensus. |
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Title: Re: Recent hum - Here is what I found... Post by CAJames on 03/25/23 at 02:22:35 Did you replace the rectifier? If not I would strongly recommend you do that too, otherwise you're likely to blow one or more fuses again and sooner rather than later. |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/25/23 at 02:34:18 CAJames said: Did you replace the rectifier? I will be after seeing this. I just put it back in and started it up. It's definitely a hum I hear in my listening chair. Time to contact Sara for a couple of sets... |
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Title: Re: Recent hum - Here is what I found... Post by CAJames on 03/25/23 at 03:16:36 Just FWIW, if you haven't considered NOS here is a link to a discussion about buying NOS rectifiers, which many of us think are superior to average current production. Also Steve's thoughts on the subject: https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1605822949 |
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Title: Re: Recent hum - Here is what I found... Post by will on 03/25/23 at 05:06:10 I wonder what rectifiers are people getting with their amps these days. Was this a premature rectifier blow, or was this an older pair??? I seem to remember in the past some of the Shuguang variants of 274Bs were a bit sketchy for reliability. |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/25/23 at 06:44:41 I believe it happened when I popped-in my 1960 RCA 5R4. I certainly was impressed with the wiring under the hood. I was able to confirm I got the Miflex cap upgrade back in April 21. |
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Title: Re: Recent hum - Here is what I found... Post by will on 03/25/23 at 07:08:44 Bad luck I guess. I have used that tube and other 5R4s for extended periods in my Toriis. |
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Title: Re: Recent hum - Here is what I found... Post by Dominick on 03/25/23 at 07:50:16 Like the others have said…. definitely replace the fuse and see if by swapping out the rectifier that the hum goes away. Just the other day I noticed that my SE84C+ 25th amp has developed a hum. I was originally running a Raytheon 5Z3 rectifier, so tomorrow I’m going to pop in the original stock PSvane 5U4G rectifier and stock fuse that came with the amp as part of my warranty transfer. I’m hoping that my SR orange fuse that’s currently in the amp isn’t compromised….but thankfully I have a backup Orange for moments like these. To the OP…. Keep us posted on what the cause was. I’ll do the same. Dom |
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Title: Re: Recent hum - Here is what I found... Post by CAJames on 03/25/23 at 15:13:48 Dom, the fuse the OP is talking about is on the board under the rectifier. Did you put an orange fuse there? If you're talking about the fuse on the main power receptacle then you wouldn't get anything at all if that fuse blew. I hope the Raytheon rectifier isn't a problem. 
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Title: Re: Recent hum - Here is what I found... Post by Dominick on 03/25/23 at 23:07:03 James…. I put the orange fuse at the main receptacle. I knew if that fuse blew I wouldn’t get any sound…just wanted to cover all bases with swapping things out in trying to narrow it down. So far nothing. The Raytheon rectifier is fine. Heck I even swapped out amps and speakers and the hum is still there. Next I’m going to try and individually pull components from the signal chain and then swap out my ZSTAGE and ZROCK2 tubes. I’ve already checked to make sure I have no ground loops from the power and audio cables coming in contact with each other. Since I’m getting hum with the Torii and Zen amp connected, don’t think it’s the amp. I’m guessing maybe a tube from the ZSTAGE or the ZROCK2. After that I’ll start swapping out audio cables and then power cables. I only hear the hum when I put my ear close to the speaker grill…. So maybe it’s just low level hum that my system is producing but lots more to tinker with. Thanks for the info. Dom |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/27/23 at 20:28:22 So I've been looking for replacement fuses and I noticed something confusing. The manual states the UFO2 amp should have a 3 amp fuse near the plug, a 5 amp for the heater, and 2 - 250 mA fuses for the high voltage. The photo I submitted earlier says "T500," which is a 500 mA fuse. It also looks to be a slow-blow fuse, and the manual says both are fine. Is the manual correct and a 500 mA fuse was put in by Steve as an error, or should this fuse really be a 500 mA fuse? |
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Title: Re: Recent hum - Here is what I found... Post by Lon on 03/27/23 at 20:37:28 In my experience with my amps that have the fuse board under the chassis there are 5A fuses in that spot for the rectifier. |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/27/23 at 20:53:54 "There are 5A fuses in that spot." So that would mean I had a fuse installed there that was .5 amps vs. 5 amps. Am I seeing that correctly? By the way, I have not changed any of these fuses before. These are factory. |
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Title: Re: Recent hum - Here is what I found... Post by Lon on 03/27/23 at 21:38:25 I don't have your eyes, can't say what you are seeing. But I do remember reading about 500 ma fuses and perhaps in some components that is correct. It's rather confusing and there is not a lot of straight-from-the-horse's mouth information easy to find. Fuses can easily be confused and installed incorrectly. I've done that several times myself. |
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Title: Re: Recent hum - Here is what I found... Post by will on 03/27/23 at 21:58:12 Sorry for the confusion, confounding when addicted to audio! How about calling Decware and find out exactly what they recommend. The manual not matching what is in your amp is unfortunate. |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/27/23 at 22:02:17 Steve just emailed me and said they were putting 500 mA fuses in the UFO2, and now they recommend the 200 mA. He mentioned the manual is incorrect. And yes, calling Decware is a good idea. I will when I get the chance. Thanks for all of your responses, gentlemen. |
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Title: Re: Recent hum - Here is what I found... Post by will on 03/27/23 at 22:19:11 So are you good to go then? |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/28/23 at 02:11:59 I am good to go. Sorry if my answer earlier sounded abrupt, but I was leaving for work. :) I ordered what I need, and when I take it apart tomorrow, I will take note of everything in each position. I have some 500 mA fuses on the way. I will replace what I have just to see if the hum goes away. I have yet to replace the rectifier, so it may happen again. I will report back tomorrow with my result. Thanks to all. You all have been a great source of knowledge. -Danny |
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Title: Re: Recent hum - Here is what I found... Post by will on 03/28/23 at 02:30:45 Hey Danny Boy, Didn't you say Steve was recommending 200 mA for that position in your amp now... apparently wanting more protection than the 500. I have had a few rectifiers with a mildly sparking cathode on startup that survive and continue to work for a time. But most times, seems once they start to spark, then flash, if they survive, it is not long. Hoping you might have a tube other than the one that caused the fuse to blow, like the stock one or something to try? |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/28/23 at 02:48:56 Yes, he did recommend the 200 mA fuses, and I plan to change to those. I am thinking the same thing for the rectifier. I will be replacing it soon, or it will just go on it's own. |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/30/23 at 20:24:25 I got myself some 200 mA fuses, and I'm back in business. If a rectifier tube gives you a flash near the bottom when the power is turned on, is that tube bad? I really don't know enough about the subject. |
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Title: Re: Recent hum - Here is what I found... Post by Lon on 03/30/23 at 20:27:25 Glad you are back in business! In general those flashes are not good signs for tube health. Sometimes hundreds of hours may still be available. Sometimes very few. Extra fuses and back up rectiifers are good to have. |
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Title: Re: Recent hum - Here is what I found... Post by CAJames on 03/30/23 at 20:50:07 Quote:
IMO Yes. If it were me I would put that rectifier out to pasture, better to replace it too soon rather than too late. But as Lon says it is possible it will still work for a while, maybe a long while. I guess the question is, do you feel lucky today? |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 03/30/23 at 21:05:05 Thank you, thank you. That was my thought as well. I still have the hum, but I believe the rectifier could have damaged the new fuse. I know, I know, that rectifier in question will be replaced. I'm not in the mood to pop the hood again to look at it. I will wait until I receive my new rectifier. When I looked at every fuse in my amp, I found a ceramic 6A (slow or fast-blow unknown), and 2-500 mA slow-blow glass fuses under the rectifier. At the plug, I found a 3.15A fast-blow glass fuse. Again, Steve emailed and said the 500 mA fuses are no longer installed, as they have changed to 200 mA fuses for their current production. He also mentioned the manual has not been updated. On a funny note, you should see me walk across the house carrying the amp in order to pop the top. My wife said I looks like I'm carrying a bomb that is about to go off. Ha. |
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Title: Re: Recent hum - Here is what I found... Post by will on 03/30/23 at 22:50:41 The hum could as easily be from the tube and not "under the hood." Being bad enough to start all this, it may be the main culprit with hum. |
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Title: Re: Recent hum - Here is what I found... Post by Kamran on 03/31/23 at 02:09:59 Speaking of hum…I went crazy for the past two days trying to isolate transformer hum on my Dennis Had amp. It was audible from 10 ft. At first I thought it was a faulty power cable—tried 3 different cords—nope — if anything it got worse with the stock PC. Then I thought it might be my beloved Sophia Aqua 274B rectifier (sweating bullets at this point). But nope—Dropped in a GE 5U4 and the same issue. Then I thought to change out my 6SN7 input tube and voila—-the hum dropped to almost negligible levels—normalcy restored. Didn’t realize a bad input tube (or going bad) could cause really audible transformer hum. |
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Title: Re: Recent hum - Here is what I found... Post by will on 03/31/23 at 02:13:24 I think Had amps and Decware are both so tube dependent and simple, that everything shows well, for better or worse. I am pretty sure I have had noisy 9 pin inputs before and noise apparently passes itself around in a simple circuit. |
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Title: Re: Recent hum - Here is what I found... Post by CAJames on 03/31/23 at 02:26:58 Quote:
A lot of times what happens is the filament gets loose and the AC heater current cause it to vibrate. The causes the hum. |
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Title: Re: Recent hum - Here is what I found... Post by Danny Boy on 04/30/23 at 04:58:05 Circling back to the beginning of this thread. I had a rectifier that was damaging fuses, and causing my hum problem. I got a bad Cryotone 5U4GB-WC, and it was certainly damaging fuses and causing the hum. About a week ago, I got a replacement rectifier, and actually got the correct one that I ordered months ago, which is the 5AR4-WC. I listened to the wrong tube for months before I realized it was a 5U4 and not a 5AR4. D'oh. The hum is gone, and if it ever returns, I will know where to look first. Thanks again to all for the guidance. |
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