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Message started by Steve Deckert on 09/07/19 at 02:28:53

Title: TRANSFORMER HUM HOW TO ELIMINATE
Post by Steve Deckert on 09/07/19 at 02:28:53

Quote:

Hi Steve!

You’ll be interested in the latest developments with my very noisy Torii Jr transformer. First of all, except for a 60 watt solid state amp made by a mad scientist (this guy very much reminds me of you) in Great Britain that I bought a couple of years ago, I have used tube gear exclusively for the past 30 plus years, and most were the SET variety. Unfortunately, every tube power amp I’ve owned had very noisy transformers, but none quite as loud as the big transformer on my Torii Jr. Many years ago I considered purchasing a PS Audio Humbuster, thinking that it might solve my possible DC-on-the-AC-line problem, but I didn’t want to take a $350 chance, and, I was still feeding 3 hungry teenagers and finances were tight.

With your suggestion a few weeks ago that I might have a DC offset problem, I decided to check out Emotiva’s website to see if their $129 CMX-2 DC offset eliminator was currently available. It was, so I ordered one a week or so ago. It has been sitting on the floor in the box since last Monday because I’ve been afraid to try it thinking that it would do nothing to solve my noisy transformer problem. I finally took it out of the box today and hooked up my Torii Jr to it.

After the Jr had been on for about 30 seconds I started to panic, thinking that some new
problem was occurring, because the amp was absolutely dead silent. Well, it has turned out that I had a severe DC offset problem, as the amp operates flawlessly now with no vibrating, humming, or buzzing—literally, none at all. If I put my ear within an inch of the transformer, I can hear a faint buzz, but I’ve gone from being able to hear the noise from 30 feet away down to barely hearing it at 1 inch. Here’s the other thing; it became instantly clear when I began playing music that the DC issue was causing numerous other problems........significant distortion, very weak and unstable bass response, veiled treble response, what I can only describe as compression of the music, and even more issues that I would have difficulty describing.

I am now having 2nd thoughts about selling the Jr to buy a Mystery amp, as the Jr now appears to have far more power than I previously thought. Maybe I should simply have your 25th anniversary mods applied to the Jr to match my CSP3-25.

So, that’s where I have landed of today. I will be plugging the CSP3 into the Emotiva unit later today. Who knows....maybe I’ll see another big improvement in sound. I’ll let you know.

Thanks for everything!

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Lonely Raven on 09/10/19 at 00:33:31

Ha, just reading the title before I clicked on the thread, I'm thinking to myself this sounds like DC riding on the AC and wondering where it might be coming from...then I open the thread and I'm like Ha! One point for the Raven.

It's good that the device eliminated that DC, but I'd like to find the source. IMHO, I usually find it's coming from a cable connection. Disconnected the main coax line to the house and suddenly your problem goes away. The hard part is getting them to fix it!

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Lon on 09/10/19 at 01:09:18

I've found the cable to be the culprit as well in the past. You can buy a transformer to put in the cable line that eliminates it and does no harm. Several make them, Jensen makes a nice one, amazon sells these type of things.

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by dank on 09/10/19 at 14:05:25

Don't know about all digital multi-meters, but mine will read any DC that is on the AC line. Just set it to DC volts and plug the leads into the AC socket, being careful not to electrocute yourself of coarse :)

The higher voltage ranges, 40 and 400, work fine. The lower range, 4, reads "over" all the time. The way to test is with a hot air gun, or a hair dryer. My hot air gun puts .34 vdc on the line in low and 1.7 vdc in high. My cheap $5 Harbor Freight meter also works, but does not read 0 when there is no DC, but rather flickers between 0, .1, and .2 (200v scale which seems to have the least flicker) so you might interpret this as a false positive.

Audio by VanAlstine (www.avahifi.com) also makes a DC blocker, the HumDinger, that sells for $140. They have sold quite a few and have had very few, if any, returned under their 30 day money back satisfaction guarantee.
https://avahifi.com/collections/used-demo-and-quick-ship/products/humdinger-dc-line-blocker

Dan

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Geno on 09/10/19 at 15:26:54

I have a Zstage in my phono setup that still has just enough hum to be aggravating. It gets worse the more I increase the volume. I've done all manner of troubleshooting, but cannot get rid of it.

I wonder if this product would help with that?

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by dank on 09/10/19 at 15:55:49

Correction: The hot air gun puts much more DC on the AC line when its in LOW. Typically a diode is used to to block half the AC to the heater in low and this causes a large imbalance and hence the large DC component on the AC line.

Geno: Try plugging a hair dryer in the same circuit as your Zstage and turn it on/off. You can use a long extension cord to get the hair dryer in another room if its too loud. If your hum changes noticeably as the hair dryer is turned on/off it will tell you that your Zstage is sensitive to DC. If there is no change in hum your Zstage is relatively immune to DC and the blocker probably won't do much good.

Dan

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Geno on 09/10/19 at 16:31:45

Thanks, Dan. I'll try that and see what happens.

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Doug on 09/14/19 at 15:37:45

So, I’m the guy that had the DC offset issue for years, and that’s my note that Steve posted a few days ago. Over the years, I tried several possible solutions, really thinking that the problem was anything other than DC on my AC, although, the DC offset issue was always in the back of my mind. Installation of dedicated AC lines, heavily shielded AC power cables, shielded IC cables, careful positioning of all equipment and cables, weights on transformers, using isolation transformers that themselves hummed, even attaching clamps directly to transformers and tightening them down, were some of the things I tried. Some had some affect, but none solved the problem.

The results of using the Emotiva CMX-2 DC offset eliminator go far beyond silencing extremely noisy vibrating transformers. Steve told me that it would be like listening to my Torii Jr for the first time, and of course, he was right! To my great surprise and delight, every aspect of music reproduction has improved! A huge perceived increase in power was immediately noted. The deeper bass and incredible control over my eight 15” OB woofers is simply hard to believe. I thought I had a very clean sounding system prior to buying the CMX-2, but only now do I realize that there was significant distortion. Treble sounds have completely opened up, as if I added tweeters to my system. Sound staging/imaging have improved too, but in unexpected ways—the apparent spaces and silence between instruments and singers is now spooky good. It’s all truly better than what I’m writing.....I just don’t know how to describe it. And here’s the biggest surprise of all; not only are all of these things true when driving my PAP Quintets with my Torii Jr, the improvements are even bigger when using my LFD solid state amp that has a huge toroidal transformer. This transformer was dead silent before using the CMX-2, so I was expecting little to no enhancement of sound. Man, was I wrong!

I will be purchasing another $129 Emotiva DC offset eliminator and plugging my CD player into it. Will I see more refinement in sound? Based on what has happened so far, my guess is yes, but if not, it’s only $129 and it certainly won’t hurt anything. I’ve read on various forums that DC offset filters cause overall compression of music reproduction, but my experience has been the exact opposite. There has been a substantial increase in dynamics, especially on the low end. My OB woofers now have as much tight slam as my corner bass horns (Klipsch copies) loaded with Altec 515B’s. I am one happy guy today!

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Archie on 09/14/19 at 17:56:51

Doug, your post reminded me to ask whether plugging my ZLC into a Emotiva CMX-2 would allow me to run all of my components off of just a single CMX-2 rather than using multiple units. I can't say I have a DC problem but based on your success, it might be worth trying one anyway.

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Doug on 09/15/19 at 22:30:33

Archie, I think that’s a question for someone with far more technical expertise than I possess, but my question is this. Are any of your larger transformers audibly vibrating/humming beyond your expectations? The smaller transformer on my CSP3-25 was nearly dead silent prior to purchasing the CMX-2, and I have been unable to sense any improvement in sound quality with it plugged into to the CMX-2. So, it seems to be the pieces with very large transformers that are negatively impacted by DC offset. Maybe Steve or the guys at Emotiva can give you some advice.

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Archie on 09/15/19 at 22:54:18

Thanks Doug. My ZMA transformers must be my biggest and they are very quiet. I was just trolling for an inexpensive improvement.

If your CSP3 didn't improve with the CMX-2, why do you think your CD player might? It was based on that idea that I thought it might be a magic pill. And if I could have it in front of everything, a cheap magic pill to boot!

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Doug on 09/19/19 at 12:23:42

Same thinking here......maybe it’s the missing link to creating the perfect chain!

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Lon on 10/25/19 at 12:40:37

I tried one of these Emotiva units and I'm not using it. . . . I primarily bought it to use it's line condition readout capabilities and it helped me identify an outlet that had the hot and neutral reversed. I'll put it up for sale soon as it didn't provide a sonic benefit for me, I don't seem to have a DC offset issue, but it's an impressive bit of kit.

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by maddog07 on 10/30/19 at 19:57:43

+1 on the Emotiva DC eliminator. I have kept one around for years - they work if/when you encounter the problem. I don't have a DC offset problem in my current setup/listening room. But I carry the CMX-2 around with me to my audio buds house in case we encounter that dastardly beast when swapping gear around. If you have DC offset, you can also see it displace the cones on your speakers drivers(mids and woofs) from their neutral resting positions when you hook your amp to the speakers.

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Carlsbad on 04/17/22 at 03:51:54

Well, based on this thread I thoroughly investigated DC offset and found no indication of it. I have a dedicated line from breaker panel. 10 awg.

So I opened it up. found the center fuse under the rectifier blown. I'll further investigate which pin on the rectifier goes through this fuse but it apparently still makes some very nice music without it. However it causes transformer hum. UPDATE: This tube has 2 anodes, this is one of the anodes out. So was running on 50% and unbalanced power. Yes, I think it regained some magic when I replaced the fuse.

Transformer seems to run much cooler now too.

I didn't have a 500mA fuse so I put in a 315mA. So far it hasn't blown and probably won't. but I'll order some 500mA for Monday delivery.

And I assume that wire by the on-off switch (bottom of photo) isn't supposed to be hooked up to anything. It comes from the transformer.

https://share.icloud.com/photos/042ASun4LEoEoqO7PzqP_-y3Q

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Nick on 10/29/22 at 18:58:01

I just wanted to thank Carlsbad for sharing his story. In my case, with a SE34I.5, I suspected a DC Offset issue, based on posts here on the forum, and I tried the iFi DC Blocker without any improvements and then I decided to check the fuses and one was blown (the one on the right). Once replaced the hum was gone. Too bad that there is no access to them via the bottom and you need to open it up. I hope this information will help others.

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Carlsbad on 10/29/22 at 20:38:21

I no longer have the SE34I.5, sold it and upgraded to a ZMA. (FYI, it is currently for sale on audiomart. Seller says he is going back to UFO, hooked on Decware).

If I still had the amp, I would replace these fuses with copper jumpers. I believe the fuses protect the transformers. But I'd be willing to replace whatever components might get damaged in eschange for power unencumbered by a fuse. We spend thousands of $ on power components and cables as big as our wrist, then we strain the electrons through a fuse with a filament the size of a human hair.

Jerry

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by Tony on 10/31/22 at 04:58:17

Ditto with Nick. I tracked down my hum in a Torii MKIV to a blown a fuse. Once replaced, no perceivable hum from the listening position.

Title: Re: TRANSFORMER HUM HOW TO ELIMINATE
Post by markmiller on 07/06/23 at 08:07:24

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