EQUIPMENT FORUMS >> TORII MK IV >> Hum in a transformer

Message started by jsm71 on 12/08/13 at 16:13:41

Title: Hum in a transformer
Post by jsm71 on 12/08/13 at 16:13:41

Just in the last couple of weeks I've starting noticing an audible hum that I can only attribute to a transformer.  I can hear it in the left channel.  If the right channel is doing it also it is so faint that it is not a bother.  I swear that when new the amp was totally dead quiet when turned on.  This has just cropped up.

I know I need to call Steve and I will this week, but I was wondering if I should expect it to go away with time (since it is only recent) or if anyone else is experiencing this.  This is my first Decware piece and I don't know what is normal with this gear.  My listening room is very quiet and I can hear the hum across the room, albeit at a low level.  Naturally when the music starts it doesn't matter, but it bugs me.


Title: Re: Hum in a transformer
Post by Lonely Raven on 12/08/13 at 17:50:40

Can you lessen it by putting your hand on it? Is it a physical hum or electrical hum?

I'm just curious really, I don't have any solutions for you.

Title: Re: Hum in a transformer
Post by jsm71 on 12/09/13 at 16:12:12

I'll try tonight to see if touching it has effect but it sounds like a classic transformer hum, similar to the sound flouresent light transformers emit.  I have also determined that the sound is cumulative from both channels, not heavy on one side as I first thought.  I have also tried swapping rectifiers and that didn't change anything.

It is a minor annoyance but I need to know how much I should be concerned.  My question stands to all Decware owners; do you hear the transformers on your amp?  Honestly, I've never seen a transformer that didn't generate some hum.  It's just a question of degree.  If it is normal for tube amps to have this ok, I can accept that as part of the deal.  If they are supposed to be dead quiet than I have an issue.

Title: Re: Hum in a transformer
Post by Lonely Raven on 12/09/13 at 17:30:27

Electrical hum is usually dealt with in the design stage. If the layout of the transformers is good, you shouldn't hear that fluorescent ballast buzzing. That's Amp Building 101, layout of the transformers, and I'm sure Steve has that down. So unless there is an issue with the transformer it shouldn't be a problem.

Now, you could still have physical vibration simply from the current flowing through those parts. If you put your hand on it and can make the noise go away, something simple like a physical damper for the transformers is an option. Something like the Herbie's SuperSonic Stabilizer can help.

Once you know more and can accurately describe the problem, call Steve, I'm sure he's got things you can check to possibly solve this.

In guitar amps I've had failing tubes or other parts cause an electrical imbalance that makes transformers resonate, so don't put it off as it could be a small issue that could turn into a bigger one.

Title: Re: Hum in a transformer
Post by jsm71 on 12/09/13 at 19:00:32

Thanks for the ideas.  I will definately try to see if physical damping helps.  That would be an easy fix, not that I should have to, but I won't complain if that is the remedy.

Title: Re: Hum in a transformer
Post by Lonely Raven on 12/09/13 at 21:40:46

I agree, you shouldn't have to; that's why I feel once you narrow it down a bit more and feel you can describe it, give Steve a call. There are so many things that can cause transformers to make noise...I'm betting even bad power (harmonics in the 120v line) could cause noise in the transformers! That's not something an amp builder would be responsible for (as an example)

As with all issues, divide and conquer till you narrow down what the issue is.

Title: Re: Hum in a transformer
Post by will on 12/11/13 at 01:28:58

Power can definitely contribute, but if it was consistently quiet before, and now consistently noisy...this looks like a pointer that something changed. It could be your utility power that changed though...right.

But the fact that it is strong on one side is another pretty good pointer.

It is not only the rectifiers that could cause a 60 cycle hum...I would trade channels on each tube type, one at a time and see if it changes sides. Might be a bad tube, besides rectifiers (that seem fine) especially inputs and power tubes, but I would check the VRs too if it is not the power or inputs.

Title: Re: Hum in a transformer
Post by jsm71 on 12/11/13 at 13:36:39

I have discovered that the hum is not coming just from one side.  It is cumulative.  I was confused because of the power up sequence.  I always turn on the right channel first, then the left.  When I tried doing it in reverse order now the right channel seems to add the hum.  Reality is that both are generating some noise and it just gets louder when I turn on the second channel.

I do need to talk to Steve.  Maybe some further line treatment is needed.  I don't put the amp through any conditioner.  I have a PS Audio Quintet which is super for my sources and preamp, but I have always read to not use one for the amp.  I go straight into the wall.  Odd however that this seems to have just started a couple of weeks ago.

Putting my palm on the transformers had no effect.  This is internal electrical hum.

Title: Re: Hum in a transformer
Post by Lon on 12/11/13 at 14:17:33


I have always read that about conditioners too. But I think the Duet, Quintet and the regenerators from PS Audio are different. I have Duets, and had a P300 (well, still have it inoperable) and a Power Plant Premier and all give benefit to an amp plugged in to them, and does not restrict dynamics, etc. So I would say feel free to plug it in and try it. I'm not certain that it WILL quell the hum, but you're not imo going to restrict the sound by doing so. I've always found these products to improve the sound. Your mileage may vary, of course, but well worth a shot. They do make the sound different. . . and when I adjust and then compare I consider it a valuable improvement

Title: Re: Hum in a transformer
Post by Lonely Raven on 12/11/13 at 16:56:07

Yeah, not all power filters/conditioners/regenerators are the same.

The first point is that the device first needs to be able to handle the constant current of your amp, but the key point is that it need to be able to handle the amps sudden current demands, and do so without being sluggish about delivering that inrush of current. That's where the power device can and will effect the sound.

PS Audio seems to have a grasp of this, and it can't hurt to try it assuming the device can handle the constant current. It would also let you see if that filters out the problem!

Title: Re: Hum in a transformer
Post by jsm71 on 12/11/13 at 19:09:20

Thanks for the encouragement.  I no sooner posted my last response that I thought, hey, why not try it?  It clearly cleaned up the power for everything else.  The Quintet also has a marked outlet just for the amp.  I don't know if that really means the outlet is wired differently or if it is just "labeling".  PS Audio seems to know what they are doing however.  

My prior amp put out 900 watts/ch @4 ohms and had a regulated power supply, very unique and designed specifically for varying impedance swings.  The manufacturer was clear about not using a conditioner for this amp.  I think Steve's voltage needs may not be so severe.  It is certainly worth a try.  That will be on tap for tonight.  Before trying that I think I may also just try swapping outlets or using the amp on a dedicated outlet with nothing else.  It shares an outlet currently.

Title: Re: Hum in a transformer
Post by Lon on 12/11/13 at 19:30:41

I know you'll update us. . . .

Title: Re: Hum in a transformer
Post by Lonely Raven on 12/11/13 at 20:58:54

Yeah, I'm super curious to hear what your further testing shows up!

Also, I believe those outlets on power conditioners and such that say they are OK for amps, I think they have *less* filtering so it doesn't muck with the current draw of the amp. But *some* filtering might be just the right amount for you.

Title: Re: Hum in a transformer
Post by jsm71 on 12/12/13 at 13:31:03

I played around with different power outlet options last night.  Good news and bad news.  The bad news is I couldn't eliminate the hum.  It would likely not be noticable or less so in a larger room, but my space is small and very quiet.  

The good news is I now have the amp plugged into the amp outlet on my Quintet.  That helped the sound quite a bit.  I didn't think the degree of transparency could rise any more but it has.  The bass has also tightened noticably.  One advantage of this problem is I never would have tried the conditioner based on my prior thinking.  Nice lift.

I was listening to John Mayer's Gravity on his live Where the Light Is 4 LP set.  This is a super engineered recording, heavily center focused on many of the numbers.  Simply amazing realism and I highly recommend this if you like Mayer's music.  The set was $80 for the 4 180 gram LPs, but worth it.  I was guilty of audiophile focusing on the sound more so than to the music.  So clean, clear, and in the room, it was scary.  I could live with the hum I guess, but I know its there.  Talking to Steve will be the next step.  

Title: Re: Hum in a transformer
Post by Lon on 12/12/13 at 13:35:19

Glad you checked out using the amp with the Quintet! I was pretty sure it would be a positive step.

I think yes, call Steve. Just be sure you don't talk to him more than a few hours and delay his getting to Stone and Raven's (hey some sort of diabolical law firm?) ZMA builds. ;)

Title: Re: Hum in a transformer
Post by Lonely Raven on 12/12/13 at 15:50:24

I think yes, call Steve. Just be sure you don't talk to him more than a few hours and delay his getting to Stone and Raven's (hey some sort of diabolical law firm?) ZMA builds. Wink

You just earned plus two in cool factor with me. Thinking of our ZMA amps first, and coming up with a cool and diabolical company name!

J- I'm starting to wonder if maybe your just hearing the inherent tube noise that comes with tube amps...they aren't dead quiet, and if your room is super quiet, you can actually hear that slight buzz of the current going through the tubes come out of the speakers. My 2 watt, 15 year old Zen amp used to have a lot of that, but is much, much quieter with new tubes and Steve's circuit mods (I had a big tune up done on the old amp). If that's what it is, I personally feel it's just nature of the beast with very transparent, single ended tubes.

Title: Re: Hum in a transformer
Post by Lord Soth on 12/12/13 at 16:14:03

I confirm that my Torii MK4 is dead quiet and Hum free.

I always turn on my MK4 and let it cook for 30 mins before my audio sessions.
There is no tube hiss too.

Title: Re: Hum in a transformer
Post by jsm71 on 12/14/13 at 15:08:35

Well, I solved the problem the audiophile way.  After talking to Steve and hearing that the faint sound was inherent, I decided to take the only sensible path left.  Upgrade to the ZMA!  Steve and I worked out how that will happen.  Don't worry, I'm at the back of the list. ;D

This actually solved another dilemma that was eating at me.  I've been holding on to a monster SS amp as an insurance policy if the MK IV proves too weak when I get a bigger listening room.  Selling the SS amp will more than cover the cost of the upgrade and I will have an amp with enough power for any room.

I should have pulled this trigger as soon as the ZMA was announced, but the MK IV sounds so damned good I was nervous.  I will now have visions of meters and big ass caps dancing in my dreams during the cold months ahead.


Title: Re: Hum in a transformer
Post by Lon on 12/14/13 at 15:27:04

Awesome Scott! An elegant way to solve your problem. . . I hope the ZMA doesn't have that hum!

I'm sure someone will take that IV off your hands if it's not part of a structured deal with Steve. And you will be able to give valuable comparisons between the two amps.

Title: Re: Hum in a transformer
Post by tgarden on 12/14/13 at 16:24:02

It's interesting about the hum of Scott's MKIV.

I had hum issues from time to time with my MK II and III.  Once I started using a Running  Springs Audio Haley (latest version) on my MK III, it became dead silent. I was previously using a a PS Audio Quintet, and before that, PS Audio Power Plant Premiers (one of the first 100 built and a later replacement, both self-destructed).  

Now that I've converted my MK III to a MKIV, it's still dead silent.  No transformer hum. I can hear the rectifier tubes if I put my ears close to them, but that's it for amp noise.

Mike in Seattle area

ps  I should mention I'm using a PS Audio Duet in my second system (ZSM's with Jupiter caps), and they are dead silent.

Title: Re: Hum in a transformer
Post by Lord Soth on 12/15/13 at 00:30:25

I do hope that Scott's problems are solved with the new ZMA.

In my audio (and home theatre) system, I'm using a simple Belkin Surge Protector with some EMI/RFI filtering.

Nothing fancy or expensive.

I leave the final AC power cleanup job to the Torii MK4's VR tubes! ;)

Title: Re: Hum in a transformer
Post by jsm71 on 12/15/13 at 15:11:31

I want to be clear about what I was hearing so anyone reading this thread isn't confused.  The sound through my speakers is dead quiet.  Steve's design is great.  What I hear is a very faint electrical hum from the transformer's windings.  I know enough about electricity to know that current running through wires will generate this sound.  You can hear power lines as well if you are close enough.  Experimenting with my power conditioner was beneficial and yielded better and cleaner sound through the speakers, but physics still prevail with the transformers.  I had a hard time believing this noise was in the signal path.  A number of designers use covers over their transformers if not not the whole amp, and if not this issue would likely be discussed more.  I like the open design however.

Steve in fact told me (no surprise) that all transformers have this inherent hum.  I really expect that the ZMA may also give me similar behavior and if so that won't be part of the "mystery".  Sorry for the pun.  I really believe in a more open room this will all become moot.  Today the easiest remedy is lowering the stylus on to the record.


Title: Re: Hum in a transformer
Post by Lonely Raven on 12/15/13 at 17:55:50

Well said Scott!

I do think some companies have potted transformers. They are basically dipped in epoxy or some other tough material that can soak into the windings and keep them from vibrating in the current. Not that that is going to help you, just throwing that info out there.

Title: Re: Hum in a transformer
Post by Lord Soth on 12/16/13 at 14:47:04

For my Torii MK4, the closest I ever get to my amp is when I have to change the volume.

At that close distance, I still can't hear any external transformer hum emanating from my unit.

Title: Re: Hum in a transformer
Post by Lonely Raven on 12/16/13 at 19:36:50

LS - I think it's probably a local power issue. After this thread, I gave my Zen Amp's transformer a good listen to - I don't have to go up to change the volume since my Oppo has variable voltage analog outs on it, so it's been a while since I stuck my ear right up to it. Sure enough, I can hear the transformer humming...I was thinking how I never noticed this before as I got up to get a drink from the fridge (just one room over) and the hum of the fridge matched the hum of the Zen Amp's transformer EXACTLY.

Well, that solves that one for me. LOL

My noise floor in my listening room isn't that good, what with dogs rustling and cats pawing at stuff, and the fiance's laptop cooling fan going, traffic just outside the window, heat kicking in. It's a wonder I hear any micro-detail at all! So someone in a great listening room with really low noise floor (I can only wish), would probably notice details like this much more.

Plus, as stated above, it's nothing a needle drop doesn't take care of...or in my case a double click on the 24/96 or DSD file.  :D

Title: Re: Hum in a transformer
Post by Lord Soth on 12/17/13 at 02:01:15

Hi LR,

Yes, I agree with you and Scott.

My listening area is semi-open rather than a "man cave ".
So maybe the natural transformer hum is more pronounced in dedicated listening rooms.

The power lines in my residential area are also very clean.
I've never had any Hum issues with audio equipment both Decware or otherwise.

On a side note, I'm using an Oppo-95.
I belong to the religious (*) category of audiophiles who believes in using the max output volume of the DAC, hence I don't mind the "extra" exercise involved in changing the volume manually. :)

(*) I suppose this make me a Puritan then ;)

Title: Re: Hum in a transformer
Post by Lonely Raven on 12/17/13 at 02:58:51

LS - I've tried both ways (DAC full on or Amp full on), and I hear no difference. Granted, the Oppo is variable analog voltage, so I don't worry about losing bits turning it down - and as Steve reminded me, the volume pots on amps sound better the higher they are. If it was a different mix of equipment, it might be a different choice.

When my big amp shows up, I'm going to retry and see if my opinion and method changes. I am kinda stuck on this remove volume though, especially since I've been jumping tracks lately rather than playing an album from end to end.

Title: Re: Hum in a transformer
Post by Lord Soth on 12/19/13 at 01:36:30


I could not resist testing my equipment, must be a carry over of my tube rolling OCD. ;)

Late at night with minimal ambient noise, I turned on my MK4 and put my ears literally next to the transformers.
There was completely no hum nor any noise at all!
If it weren't for the fact that my tubes were glowing, I might have thought that the MK4 was turned off.

As for the Oppo's digital volume control , my settings are normally

Oppo 95 : MAX 100 Fixed volume
MK4: 9 turns volume

I then tested it with
OPPO 95 : Variable Volume 90-95
MK4: 11 turns volume

In my audio chain, with variable volume, there was something missing from my music.
I can't say for sure, I admit that it might even be Psychologically induced, but I felt less drawn by the music.

For this reason, I'll stick to my normal Oppo 95 settings and change the mk4 volume manually.
I'm using pure silver interconnects and speaker cables so my audio chain is really sensitive to the minutest changes made.
This could be the reason why the adverse effects of using an extra volume control are more pronounced in my audio chain.

Title: Re: Hum in a transformer
Post by ckc527 on 09/10/14 at 23:39:17

JSM, did upgrading to ZMA solve the transformer hum issue?


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