Hello to all. I am new to the forum, and starting this thread is not without some trepidation. As indicated in the heading the subject I'd like to discuss or re-discuss is the matter of hum in the power transformers on the Torii MKIV.

I have had my Torii in operation for a little over a year now. I love the sound, but became more and more distraught with power transformer hum/buzz.  I had talked with Steve on three different occasions, in an attempt to figure out what I was dealing with, and if it was just me or if there really was an issue. I noted that I was not the only one having issues like this as the forum suggests.

Between the second and third contact with Steve, who led me to the belief that it may well be a "dirty power" issue, I searched the net for solutions and for possible reasons for transformer hum/buzz. There of coarse is a difference between buzz and hum. Hum is a 60 cycle issue, and buzz is 60 cycles plus harmonics, or just a lot of trash on top of the 60 Hz.  Both can be an issue in power transformers for a variety of reasons. Mine fit the buzz category.  My Torii was loud and annoying, and became louder the more it warmed up.  It was frankly irritating and needed fixing. I tried tightening the bolts that hold the covers/plates together. I tried padding under the amp. I tried sound deadening material. I tried changing tubes. I even have an isolation transformer  between the equipment and the power line. Nothing helped.

Some of the causes talked about on the internet are: loose windings, or loose plates in the transformer, dc in the power line, and dirty power (i.e. other frequencies on top of the 60 Hz), all of which have been addressed here and on other forums. Some manufacturers pour various tars, plastics etc. around their trannies in cans to mechanically dampen the vibration. Others dip the tranny in various varnishes and other goop  to quiet them down. Some suggest taking the transformer apart and varnishing the plates etc. - a fast track to ruining a warrantee I'm sure .

One of the thoughts concerning what is happening in the transformer is that dc in the power line pulls the plates in the tranny to one side, skewing them, and thus causes the plates to vibrate. This I considered a real stretch - pardon the pun. But I was desperate to find a cure, so on a whim, I got some magnets and tried placing them in different places around the power transformers - I was going to pull those plates back . I placed them around the tubes and everywhere I could think of. I used magnets of every variety.  I was holding a magnet that came out of a dc motor of some kind, over one of the OA3s and it accidentally slipped out of my hand and wedged between the OA3 and the right channel power transformer and lo and behold that transformer got quieter. So as not to scratch the paint on the amp, I wrapped the magnet in plumbers Teflon tape and began moving it around on the tranny. I found the best (quietest) spot and proceeded to do the same on the other power transformer. Same result. I was elated and flabbergasted. It changed the buzz into  what I would consider a normal transformer hum, that was audible at 2-3feet or so from the amp, but not from 6- 8 feet away as it hand been.

Now here comes the coup de gras;  the sound of the amp improved by a bunch. The high end was sweeter, the bass was cleaner and tighter. Was I dreaming? Was I experiencing some sort of self delusion?  I then tried other configurations and placements, and found by ganging two round dc motor magnets together, and placing them such that they spanned the distance between the power transformers on the front side behind and in line with the OC2s, I got the best results. And, rotating them even a little would make a difference.

In a roundabout way, I sort of pulled a "double blind" on myself. I sat down to listen to some music one night and found the sound to be less appealing for some reason. In fact it sounded bad- strident, with poor sound stage and lackluster bass. What now? Then it dawned on me that I had removed the magnets because we had company over and I didn't want ugly magnets hanging from my beautiful amp. I put them back on and once again had good sound. I called Steve the next day and expected to get laughed off the planet. But he was very thoughtful, and simply said, "You may be on to something." He also suggested that I put this out on the forum to see what everyone else had to say. So here it is.

I thought about buying a power conditioner of some kind. But, what kind? The only ones that make any sense to me are the kind that change the line ac into dc and then back into ac. But those are expensive. I had a chat with my brother-in-law who is an audio engineer and owned the classical radio station here for many years (I trust what he has to say), and he said placing magnets around transformers would change things in the tranny - flux, plates etc. He provided me with a "Sniffer" which is a coil you would find in the rf section of radios, and a small battery powered amplifier. If you hold the Sniffer up to a light dimmer for example, you can here the hum it makes. This hum (and lots of others) gets into the power in your house and ultimately into your amp. Now a well designed amp like the Torii is in and of itself a power conditioner. And true to Steve's design, I get no unusual hum in my speakers (90 db sensitive). But I do get the awful tranny buzz. Using the sniffer, I found that my breaker box has hum coming from several breakers (not all) and their associated wires. One breaker feeds our WiFi extension device which is very noisy and happens to be on the same circuit as the hifi equipment.

I became rabid in my pursuit of solving  the cause of my problem. I decided to run a dedicated line straight from our service box to the stereo equipment ( no small task in a flat roof adobe with brick floors). This reduced the buzz in the transformers  somewhat, but not all of the time, and on occasion, I still had to use the magnets to quiet things down and to make the sound better. I can not explain why things sound good without the magnets one time and then sound better with the magnets at other times. It still may be dirty power coming from the power grid or being created by my equipment.

There are a couple of things to warn readers about. First, you can over do the size of the magnets. I have been told that the magnetic field introduced can cause the field around the transformer to kind of "seize up", perhaps by saturation, and thus cause the windings in the transformer to see a short and potentially burn up. I have not tested this theory . I have used only two magnets at a time and have experienced no abnormal temperature rise in the transformers. Second, it is a good idea to wrap the magnets in Teflon tape or some other protective coating so as not to scratch or mar the amp. Try to run "blind" listening tests, but I know you will notice the difference in any event. Will it help the sound on amps that have no abnormal hum? I don't know.

I know this all sounds crazy, but I hope those of you who are having this problem will experiment with this and relate your findings on this thread. I have no idea why this works, but the magnets must somehow "smooth" the field around the transformer, or  somehow "throttle" them back, or in fact pull the plates back and keep them from vibrating, or perhaps just let them do what they are supposed to do.  One last thing, I have noticed that I  have less hum in my turntable motor since running the dedicated line. It was well worth the trouble running the new line. Is the next step a power conditioner?

Further research has led me to discover an issue known as DC offset. It happens in the main power line because of all the gadgets we have. For example, the switching transformers in our computers have half wave rectification and this pulls the line voltage up or down because of an imbalance  and this is seen by your audio equipment as a DC voltage or rather a shift in voltage up or down on the main line AC waveform. In a transformer, the current follows the voltage 90 degrees behind and therefore is out of phase with it. Audio equipment is designed with this in mind, but if there is a shift of voltage on the main line, say upwards of a half  volt or more, then the current is out of phase a different amount than the usual 90 degrees. This can be major source of distortion, and may well be what is causing the excessive hum and poor sound I am experiencing. It can also lead to an increase in temperature and or saturation in the transformer.

I have recently come upon a DC offset correcting device made by Emotiva called the CMX-2 that supposedly blocks the DC offset. The little gadget works. It has made the hum in the trannies less and has made the sound better.  I no longer need to use the magnets to get good sound. In fact if I use the magnets, it sometimes degrades the sound now. The trannies are louder than with the magnets in place, but the sound is good. Perhaps the magnets can be a diagnostic tool and nothing more?

I look forward to others comments.


Dan
 

We use these magnets at work, they might be the ticket.
Strong, strong, strong.
They are way smaller that the picture!

http://www.amazon.com/CMS-Magnetics%C2%AE-Holding-Neodymium-Countersunk/dp/B008H...

 Interestingly, since the transformer produces a magnetic field just by it's very nature, I hadn't about 'balancing' it, or in some way focusing it. I  Might try it, but for the time, my amp is waaay ahead of me sound wise, and I had better just sit back and enjoy it.

Very interesting but I am curious if the use of these magnets could also cause unintended problems.  My knowledge of magnets is rudimentary. It seems to make sense that the magnet would be able to counteract or hold back some of the emf/rfi. In the manual it says that the transformers on the Torii IV are original to the amp and are not used on any other Decware amp.

JD

Hello Rick and all,
There are a couple of DC blockers that I know of out there. There may be more. One is the Emotiva CMX-2 and the other is the RPD-15 by Blue Circle. I purchased the CMX-2 as it was $100 less ($89.95 on Amazon including shipping), and it was after all an experiment. Which is better I can not say, but I am pretty happy with the CMX-2, and it physically looks better than the RPD-15. I have taken the isolation transformer out of the loop for now as well. I do plan to get some neodymium mags, like Will did, and experiment with them as well. As for now, I am only using the DC blocker and am pleased with the sound.
Cheers,
Dan

Good news Lon.

I have the ones on the plate sides of the transformers about 1.25 down from the top corner, centered between the covers, and across from each other. No idea but I thought this was better than offset with one side lower and one higher. The ones on the outside covers of the outputs are pretty centered.

Since we don't really know what is happening, and preconditions vary place to place, it may be worth trying more or less in a given setting, and explore placement. I like mine where they are so much better than without, I have not searched further. I did like these plate side locations to start with though for some reason. Can't remember why.

Pictures please. I'm swiping some magnets from work tomorrow and I want to see where you all are sticking them.
I did leave that kind of open ended didn't I?
You can all tell me where to stick em!

I guess I don't do them either.

By the way, connect about four of those cute little magnets together and hold them over the rectifier, regulation and output tubes on the Torii. You can feel the magnetic fields interacting, vibrating your fingers. And hear noise through the system.

I have heard "veils" of noise stripped away when I got my PS Audio Premier, then more with the P5, then more with the PowerBases and now these magnets have found another silky layer to remove. . . .

Hi Rick,
When I installed the CMX-2, I could hear a lowering of the tranny hum,(not as much as with the magnets) but more importantly, the sound definitely improved. Question: Are you still using the isolation transformer? I took mine out of the loop so as to not have too many variables. I also put a ferrite on the power cord that came with the CMX-2 ( ie at the CMX-2 end of the cord). I also made up a shorter power cord and found it degraded the sound as apposed to the stock cord. Do try the magnets. As stated before, the ones I started with were circular rings that are 1.8" diam.X1"thick, and have 8 magnets around the inside of the ring. Placing it across the gap between the 2 trannies on the front just behind the OA2s would quiet the trannies a bunch. Also check to see what other electronics are on the circuit you amp is on, and eliminate them for diagnostic purposes. Try plugging only the amp into the CMX-2. And this sounds crazy, but by giving it  3-4 days of use- the transformers get quieter with time.

BTW, I found some 5/16 neodymium mags at Harbor Freight for $2.99 for a pack of 10. I fiddled with them about 4 hrs today and found a sweet spot centered on top of the plates and forward against the cover plate of each tranny. I Scotch taped them to some thin plastic fingers so I could move them around without marring the paint. Definitely a difference with and without.

And Lon, I had to move my Von Scheikerts  farther appart to get the sound stage back. You are spot on with your observation that the mags move the sound stage. Why???  Cheers, Dan

Dan,
I have th CMX2 RMA # and was going to ship it back tomorrow but I'll try it again for a few days and see what it does. Yes I did bypass the isolation transformer and didn't see any change so we will see what happens.
Thanks,
Rick

First I checked the date of the first post...04/04. Cool. I`ve ordered some 20 magnets. I dont have a Torii but am going to start by.......

On second thought, I had some lower profile rare earth magnets (1/2 inch donuts, 1/8 inch thick) that fit between the transformers and large caps on my ZMA.  I tried to follow Will's placement as I understood it.  I put one on each side of each transformer, 1 1/4 inch down from the top of the transformer to the center of the magnet and centered side to side.  In addition I put one on the front cover of each of the output transformers in the center of the cover.  I also put them on the sides of my CSP3 and ZP3 transformers.

I can't describe in detail what I hear but I think I've picked up some clarity.  It takes me too much time to put them all in place to do a meaningful A-B comparison.  I'll leave them on unless someone thinks they could harm things.  I have a suspicion that when I make a change like this I tend to listen more carefully and the "Improvements" that I hear may just be me really digging my equipment.  

This one is much better then the Emotiva.

http://www.avahifi.com/products/humdinger-dc-line-blocker

A lot of folks with Decware do say their amps are dead quiet. I gather Steve might associate some of the minor hum for those of us with it, with DC offset. Not sure how the amp companies you are referring to deal with that, but presumably they have in some way if they are all quiet with most all power.

Copying a little of what I gather some DC offset setups do, I have added small, relatively high voltage, non-polarized caps, with AC ratings, across the AC at the IEC coming into my pre and amps. Helping hum and subtler clarity, to me this is likely corroborating that I had some DC offset. I also added a cap in the Torii, similar to that in the CSP3, from IEC ground to amp ground, and that cleared the sound up some. Interestingly, the cap used can be heard even in these applications...not all sounding the same.

Crossing the AC with a cap seems to me to be a risky mod, and I did not take it lightly, doing a fair bit of research before making choices and trying it. Finally I reasoned that with my surge limiting power regenerator before, with care in cap choices and application, it should be OK. I hope I am right!

The magnets are very interesting to me. You can use more or less, bigger or smaller, and move them around to achieve subtle sound preferences, while also adjusting for a wider soundstage and/or a deeper one...wild.

I hope Steve will notice your post and concerns and comment more clearly than I!

Check it out online, DC offset is not the amp, but can cause an amp to hum.

Hello SB,

Taking pictures is easier said than done for me. My amp is in a cabinet with the shelf above pretty close, and the magnets spread around transformers and chokes. I would have to pull it out and take a lot of pictures to show you them all.

Luckily, this method is best done by sound anyway.

This was years ago, and the only time I asked Steve about this...we were on to many subjects so did not focus on this. I casually asked why the magnets worked at some point, and the slightly exasperated sounding way he said "I don't know," I don't know if that meant he didn't believe it, or didn't know, or didn't really want to go there at that point....but he did not tell me not to do it. Not a good answer I know, but all I have.

Noisy tubes can definitely cause more or less hum in my system. I have found rectifiers can be quieter, louder, and in-between, as well as power tubes and inputs... I can't recall exactly, but I am thinking especially rectifiers, and perhaps to a little lesser degree, power tube induced hum can increase transformer hum. And either of those, and inputs can cause greater or lesser hum at the speaker.

It is interesting that the Emotiva did not do much for you. Don't they have general filtering as well as a DC offset repair circuit? Perhaps you are not dealing with DC offset, and more ground loop or other noise issues the filters help some with but don't solve.

Before getting into magnets:

1) What do you call "significant?" How far from the amp can you hear hum?

2) You can also get hum from your other gear broadcasting airborn noise, and/or power noise back into your system. For trouble shooting, have you tried unplugging everything but the Torii? Not just ICs, but power?

3) Is your power strip filtered? Is it Star grounded?

4) Have you tried plugging the Torii into a different circuit to see if the transformer hum improves?

5) Is your amp new or did it come with a checkup and warranty transfer?

I am thinking the magnets may not do loads to fix whatever is happening in your case. The way I have used them, they are more about sound refinement, though meaningful at that. But Dan, at the beginning of this thread, using big magnets, heard a notable change. Then he ended up liking the Emotiva a lot, which to me would indicate DC offset in his case.

Quote:


No, Decware doesn't consider transformer hum normal, nor do any of our transformers hum when they leave or return here. Literally you have to put you ear up to it to tell if it's even energized. Most customers who have experienced it always found a reason for it in the end that was not the amplifier.  DC offset is a common issue.  Something as simple as using a hair drier on low can inject DC into your AC grid. It can even be a neighbor sharing the same transformer on the telephone pole.  

Steve

Safe,

Sorry you are having troubles with your new amp. I feel for you, and agree, tubes can be challenging at times. But mostly they just work for me, and small idiosyncrasies are easily overwhelmed by the beauty. I hope, and suspect, that once you get this solved, your love of tubes will be restored

More thoughts on troubleshooting:

-Has the other gear you mention been quiet in this same system and with the same power and cables?

This may not be end-all info, but perhaps a good thing to note in your troubleshooting.

-Presumably you are using power cables and ICs known to be quiet?

-Have you tried changing cables, power and IC to the Torii?

-Is your dedicated line breaker in its own box, and with a good clean earth ground? I have no experience with mixing old power with new so can't advise, but hopefully someone more knowledgable will notice this and comment on best practices.



-Ringing is possibly a pointer...microphonics and noise can go together, but even without microphonic ringing, since you have replacement tubes, that would definitely be worth checking out.

-At the Speakers, is the hum uniform, ie, not more on one channel?

If mostly one channel, and you did not have replacement tubes, typical testing would be to methodically trade the right channel tubes to the left channel tube positions and visa versa, trading each tube type individually. If the noise moves, you will have identified a problem tube(s). In the case of having two tubes per channel, like your power tubes, if you want to get the exact tube, you would have to change them one at a time...like say, trade sides with the two outside power tubes....then the two inside. If speaker noise is different, you could try this method if you want for interest sake.

But since you have replacements, and likely a tube with some problems, you could replace one tube type at a time, listen, and see if you hear hum change as you go. This would identify noise making tubes....or show that the hum problem is not tubes.

I personally have never had a bad Voltage Regulator, so don't know if they will make noise as they go. But guessing not having OA3 replacements is fine for these tests.

Good luck!

My objective in magnet placement is to subtly, but meaningfully clarify what is already there without changing the tonal balance. What I hear with clarification is an increase in space, increase in fine detail and fine detail differentiation, and I go for increased density that does NOT compress the sound....So that added density enhances the positive things I am after rather than thickening, or overly concentrating the sound...

If the fine detail in space is better, there is more refined and complex density, and the rest seems to follow across the spectrum, direct notes more rich and complex, more speed and better harmonics....nice textures, and ambient information...from the player to the last of the decays.

Finally, late night, lights out, with less sensory distractions, I can hear with more clarity and discernment, so this is when I like to fine-tune for sonic attributes I like, AND for sound stage balance. Again, I try to go for what is there, a good balance side to side, and front to back, but with the magnets making soundstage saturation and the ambient space between players more clear. Improving ambient and spacial information makes it realer, helping define each player in the sound field, while also improving "room" feel, the spaces between supporting integrating the players and space into a whole musical experience.

That said, depending on magnet placement, one can use them for subtle adjustment of what is there....making the sound more dense and full, more concentrated and focussed...making the soundstage deeper and less wide, or visa versa. Just wanting to encourage playing with it, and if it is better in your system to use the magnets to adjust sound rather than focus on enhancement only...why not!

Also, your transformers look different from mine, boxier, and the center ones thicker, where mine appear all the same ...no idea how that might make magnet placements sound different, but it could! So a good idea to play with number and placement.

Here is a starting point based on my choices so far:

I use all 1/4 square Neodymium magnets, by the feel of them, some stronger (like 50 ish) and some weaker, maybe in the 40s. I have not played with these in years, until yesterday, so don't know where they will end up, but this is close to where they have been, and maybe a good start.

Looking at the amp top pic you posted, you have the smaller chokes in the back center (23 on them). They support your input transformers, rectifier, and beyond. On top of the chokes, I now have 2 near the back/top corner edge, and about 1" from the outside edges.

Coming forward, on the center, bigger transformers, I have one magnet on each side, from the right and left top corners, down the sides about 1 1/4". Both are near center on the sides front-to-back, but I prefer one to be offset a little toward the back, and on the other side, offset from center a little toward the front. So they are not directly across from each other. Also, on the inside sides, I have one mag above the others about a 1/4 down from the top of each transformer and a bit front of center...so two magnets on one side, and one on the other.

The outside transformers, are set up the same, one on each of the ribbed plate sides 1 1/4 down and a little off center, with the addition of one near the top on the front side, about a 1/4 down from the top edge.

Another refinement I have found very useful is damping the bottoms of the transformers. I use EAR ISODAMP from Michael Percy, "*SD40AL... .040" thick w/ 5 mil aluminum constraining foil for increased damping and flame resistance: 12" x 27"/$58.00 or 9" x 12"/$20.00”

This is the best stick on damping material I have tried for not altering the balance of the sound, and it works so well, I stopped looking. It depends of course on not overdamping, but when right, it gives sound refinement, without notable tonal alteration. I tried a lot of ways to damp the transformers when I was working on modifications, and finally settled on cutting little strips, about 1/8" h x 3/4" w, and placing one on each ribbed side of each transformer, near the bottom, centered and about 1/8" up from the bottom edge of the transformer. So two strips on each of the large transformers

I also use Herbie's Supersonic Stabilizers on my center transformers. I thought they helped some, but a thick/flat chunk of flagstone on top of them, bridging and weighing them down, seemed to make them a lot more effective here for quieting mechanical sounding hum. Not sure what would be an ideal weight solution, but weight can really help solve vibration induced noise.

Did you find anything out with your troubleshooting experiments?

Yes, it seems the weight works in cleaning up chassis vibration, and with  how feet absorb/drain vibration, different feet changing the effect of the weight, and different weight effecting foot sound.

I just ended up bridging the transformers because, with the Sonic Stabilizers right next to each other, the flat rock chunk was an easy way to get a lot of weight on the transformers in a fairly small space. I was wondering what the effects of the mineral composition and structure of the flagstone would have, but since it sounded good, never experimented further. This was years ago%^&*()_

When I first tested the Stabilizers, unlike some Herbie's things, I do remember thinking they had a pretty transparent effect, just not a whole lot of it in the case of my transformers. But with more weight on top of them, they seemed more impressive to me.

What I was referring to about the mineral composition and structure of the flagstone was relative to how different minerals and structural makeups seem to effect RF, EMI, and how effectively and transparently they absorb and dissipate vibration. But I get your point and can believe weight on the Sonic Stabilizers may well mostly just increase the "sound" effects from what the Stabilizers do. Interesting observation!

As with most weighting I have explored on components, if it works, generally more weight tends to have a resolving and solidifying sonic influence, and without notable tonal balance modification. And some places, the effects more subtle than others, overall, the sonic impact from micro vibrations, and from mitigating them, can sure can add up!

A lot of the Telefunken labelled 7DJ8/PCC88s are Siemens. If there is a straight/vertical copper wire rising to an O getter ring, it is most likely made by Siemens. Of that tube design, those with Siemens labels are generally less costly than those labelled Telefunken. There are a few other Siemens variations of PCC88s, the ones I have heard all nice tubes, but this is an interesting one, extended, solid, clear, and relatively powerful sounding. The only true Telefunken PCC88 I have personally has a smallish diameter O getter ring on top of angled sheet metal riser with a rib impression going up the middle. And as usual, it has a diamond on the bottom of the glass.

Glad you are getting into the magic.

Did the new inputs solve your hum and microphonics?

Great news on the improvements in hum and microphonics!

And good to check to see if your inputs are true Telefunken or relabelled Siemens, as these two tubes have pretty different sonic characters. Good to know for future reference in tuning.

Hey Geno,

I can summarize, but audio hum is a big arena! Based on your interests, I think if you take the time to carefully read this thread, it would probably be useful to you, and finally answer what you are asking and more about hum issues and possible solutions.

If you want a truncated version, particularly looking at your specific questions, at least my take on magnet use and placement, and touching on weight based in my and Lon's experience, you might start at post 37.

Somewhere in between, for more information about hum and solutions in general, maybe try starting at 26, where orangecrush links to a DC blocking tool, the page giving a simplified overview of that issue. Then post 27, begins the recent conversation with safebelayer's concern over hum coming with his new/used amp. And after it indeed did have hum, troubleshooting conversation pointing to more information related to hum, and leading to posts that I think probably collectively address a lot of your specific interests.

Does this help? If not, I can try and fill in blanks, or give a broad summary. Let me know.

Will