question for Luxman L-590AX owners

Yes, some toroidal transformer cores consist of a very long and thin metal strip that is wound up (like a spring) in a large circle rather than exist of lots of individual metal parts. A cross-section of the core:

https://diyaudioheaven.files.wordpress.com/2013/08/o-cores.png

Noted.

One can see the laminations quite clearly here on a stock E-I model.
https://www.ec21.com/product-details/EI-Transformer-Lamination-Magnetic-Core--10623566.html

I’m still curious about the construction of toroidal cores.  Are they built up with very thin "doughnuts" of laminated steel stacked on top of each other?

@twoleftears 
The power transformer in the Luxman is a EI type and not a toroidal transformer.

https://6moons.com/audioreviews/luxman4/6.jpg

@imhififan This is fascinating.  So is a toroidal core like a spool of one continuous sheet wrapped around itself, or is it built up of an accretion of concentric circular sheets, each one slightly larger in diameter than the previous?

The Luxman power transformer core is constructed by stacking layers of thin laminated steel sheets. The transformer is magnetically excited by an alternating voltage and current so that it becomes extended and contracted twice during a full cycle of magnetization. Transformer noise is caused by magnetostriction: means that if a piece of magnetic sheet steel is magnetized it will extend itself, when the magnetization is taken away, it goes back to its original condition.

Each laminated steel sheet with an induced magnetic field. That magnetic field acts between the adjacent plates stretching and squeezing the adhesive and insulation between them. Over time that adhesive starts to break apart and the laminated layers separate from each other slightly. That is the humming noise that you heard. It’s always present, but once the adhesive starts to break it gets louder. These micro-fractures in the adhesive may not be visible to the naked eye.

Maybe this is the cure:

https://www.youtube.com/watch?v=WW-QRar2RQ8

The more current draw through a transformer (class A amplifier) the larger the induced magnetic fields, and thus the louder the transformer hums.

One problem for me, like any other internet forum, is evaluating the answers that are offered. If it was my area of expertise, that would be great, but it's not. Are there differences in the design requirements for transformers between Class A, AB, etc. Is the heat of the Class A an issue? Are there other differences? I'm talking amps with similar output, of course.
Thanks

Lot of this has been covered. This exact integrated amp has been dead quiet since I've owned it, which has been 3-4 years, up until a couple of months ago, when the hum started. It's been plugged into the same outlet since day one. I just now checked the voltage at the wall, 121.2-121.6VAC. Tested several other outlets in the house, all in the 120-121V range. The panel is 10 years old, professionally installed. The PUD service drop is new, although the line feeding that is pre-existing. Same with my shop, with the exception that I wired it. Same service drop to parallel feeds into a 400A meter base, one set of feeds serve the house, the other set serve my shop. The amp has been powered up in both buildings with no difference, so unless the power company has a new issue, I'm ruling out our power.
I'm leaning heavily towards an issue with the transformer in the amp itself, or so it seems to me.
I'd feel more comfortable taking it apart if I could find a service manual.

@builder3    Can we go back to basics?  Would I be right in assuming that you've had other integrated amps or power amps in the same house that, when plugged in, didn't hum?

We also have reports of exactly the same model humming in other people's houses, and also occasionally examples of the same model with no hum.

From this I conclude that it's either:
-an interaction of the design of the amp with the power supply; some feature of the design makes it susceptible to hum in many but not all situations;
-a QC issue of many (but not all) examples of the transformer used in that model.

Yeah, no kidding. Seems like a solvable problem to say the least. C’mon Luxman, figure it out!

That’s why I really wish I knew how prevalent it was. 5% of units? 20%? 50%?

Helpful if others who have the units and have never had any buzz/hum issue post up as well. Maybe it is a very small minority? Fact that some users who've had multiple generations and all hummed could mean more widespread, or could me line issues if all happened in same house, or combo of both.  But if Luxman dealers actually admitting it is an issue, then that is more telling.  Dunno

@builder3 

I'd be interested in hearing your thoughts, jjss49.

i don't know what to say really...  saying class a amplification is an unavoidable factor in creating transformer hum is a new one to me, and i think it is a pitiful and lame excuse - i have had class a amps from pass and others they do not hum - and it has been a few years since i have had a luxman amp in house

hum can be caused by low line voltage as others have mentioned... maybe check your line voltage?  

otherwise, if you can try to see if the retaining bolt(s) to the major transformers in the unit are as tight as possible... sometimes with age, transport, movement, they can loosen...

good luck

From the posts on this thread and the other one linked to above it appears it is an issue that tends to develop after years.

I took a look at the Luxman class A release history to try to guess when the new versions of class A integrateds might be released, in hopes that perhaps this issue gets addressed. But if the issue goes back to past generations, who knows if having such hope for correction is even warranted??

Anyway, near as I can tell:

L590A was released in 2005
L590Aii was released in 2010
L590AX was released in 2013
L590AXii was released in 2016

Would seem that a new release should be soon if past is prologue, given that we are now into 2021.

No buzz with my L-590AXII. Something is wrong with the unit or the mains power supply if there's a buzzing sound from the amp.

I'd be interested in hearing your thoughts, jjss49.

My dealer and Luxman said that. My dealer emailed them and the chief engineer said because they are class A they buzz when in idle.

seriously? omg you have got to be kidding me

maybe they need to hire nelson pass on a contract engineering assignment LOL

snapoli, thanks. I've came to the same conclusion, although certainly nothing that I can prove. Mine's quiet enough that I can't hear it from a couple feet away, and certainly not when there's music playing. It still peeves me, because it's a recent thing with it.
Appreciate everyone's input, thanks.

I'll add this post, for anyone that's interested.
This afternoon I disconnected everything from the amp, my intent being to test it on another circuit. First, I took it downstairs and plugged it in there, mostly because it was on the way to where I was going. No change, still a low hum.
After that, I lugged the thing down to my shop. It's a modern building, 70 years newer than the home, and on a parallel drop with our home service. After the meter, the house and shop are two separate feeds. I shut off every breaker in the shop, other than one 20A circuit that the outlet was on. No lighting, no heat, etc. The amp still had the same hum. I'm not an electrical engineer, so I'm unsure as to how flawed this test might be. Obviously, it eliminates everything in my home. It seems to me that all it really leaves is the initial service from the power company, and the amp itself. I'm still thinking the transformer in the amp.

I know, kren, hard to keep everything straight, lol.
I read about the DC line blocker a bit, sounds like a coin toss. If the transformer has an issue, it's not going to magically eliminate the problem.
I'm not looking for Luxman to come clean on what they know, or don't know, I'd just like a reply on having it repaired. Or, for that matter, a response of any kind.

Haha, erik_squires suggested the same device halfway up the thread.

Dang the whole issue is troublesome though. I was seriously considering targeting an L590axii for my main system and an L550axii for my secondary because I know the SQ is up my alley with my Spendor speakers but now I just don’t know. This doesn’t sound like an isolated incident.

That said, I wonder how prevalent it is? Does it affect 5% of units or 40%? It’s a rhetorical question since probably only Luxman knows and sounds like they’re not talking, also troubling.

Anyway, I’ll continue to follow here and hope that tweak works out for you OP.
If other Luxman class A integrated owners have also experienced the hum, post up!

Thanks, jjss49, I think I'll give that a try.

I was the same, until a couple months ago. I'd like to have the newer AXII, even though I choke at the money, but a couple guys here say theirs have the same hum. I bought this amp used, it's immaculate, think it was $4300. Not sure what I'm going to do, it's eating at me, lol. Might be nice to hear something from Luxman, too, obviously.
Thanks to everyone for the input.

I guess I must be lucky then. Zero hum or buzz on my AXII even if I put my ear right next to it. 

Even though I used the same word, it's not really a buzz. It's a hum that I have to be within a foot to hear, and have nothing playing. Still bothers me though, the idea that it's not dead quiet.

I might have to live with it, I guess. I was considering buying the new AXMarkII, sounds like that would just be a very expensive crapshoot. I don't think it has a thing to do with any outside factor. I think it's the transformer. I can't hear mine unless I stick my head right beside it.
I emailed LuxmanUSA probably 3 weeks ago. Actually went through their page to request information on a repair. Crickets. Hey, if your customers are a bother, just ignore them, they'll go away.

I just got my L590AXII. and also I hear the hum. My L509x is dead quiet.
Using SR Power cord and SR Powercell.
age est 5-6 years old.  

I have email Luxman USA. awaiting for answer.

Yuck it up, erik. Mine had zero buzzing as well, until about 2 months ago, lol.
Btw, if anyone is interested in complete dead silence, all you need to do is email Luxman USA. Kind of a joke.

All I can say is I love the sound of the 507ux and the complete lack of buzzing. :)

Yes, plenty of space around the amp. It only happened twice for the past 6 months of use.

Nothing here is about the L-509X, which is an entirely different piece.
I own the L-590AX. There's no version that was ever called a MkI, throwing weird names in the mix won't help clarify anything.
On a side note, I'm inclined to think that your amp shutting down is indicative of a problem that needs addressed. Do you have plenty of room around the amp? They need to have good ventilation.

So the OP has the mk1 version of the L-509X. Just to clarify that my L-590AXII does not show any hum. Very silent and no issues whatsoever except that it automatically shuts down by itself, occasionally, after prolonged listening sessions at moderate to high volume levels. Guess the protection circuit feature of the amp is working fine which is a good thing!

But OP the thread title is for L590AX, not the Mk II version that I’m asking about.

Or are you saying you have the L590AXii. ???

Edit: sorry didn’t read closely enough your last post. I guess you are saying you have the original version (not mk ii ). Got it thx

Wow, I'm an idiot, lol. Hadn't read that entire thread that twoleftears linked, just did look at everything, the last post on it was mine from two years ago, good grief.

kren, I went and dug up the original receipt for my amp. I'm the 3rd owner, but I have the paperwork. My amp is 5½ years old, and I'm pretty sure this just started. You'd have to hear it for yourself, but I can only hear it with my ear down next to the unit when I turn it on. Still irks me a bit, since it used to not be there. On the newer MkII, who knows? Maybe in 5 years, it may show up in some pieces, I don't know. Personally, if I auditioned the piece and liked it, I wouldn't let it be a deal breaker. Hope this helps.

I used to own the 590AX2 and it was dead quiet. But my unit was new and I sold it after a few months to go to tubes, but still one of my favorite Integrated.

Interesting thread. Have never heard of this issue with reference to the current version L590axii, but since that amp is on my radar I’d like to know in advance if that model is also susceptible. 

Anyone know if Luxman corrected the issue with release of the L590axii, or does the hum issue arise there as well?

Now I can reasonably say my amp didn't originally have a hum. The original owner stated as much in the above link in twoleftears post.

Thanks, guys. Essentially, it's a near non-issue for me, other than the fact that I'm quite sure it never was there before. I'll do some more reading.

Reports of Luxmans with hums go back at least five years, probably further.
https://forum.audiogon.com/discussions/luxman-class-a-integrated-slight-buzzing-noise/post?highlight=luxman%2Bhum&postid=78228#78228

The hum issue seems to be fairly common with Luxman integrateds.  I have a 507ux and it also started humming a few years after I bought it.  The amp itself is dead quiet-no sound from the speakers-just from the unit itself.This issue has come up a few times online.  Some people say you need to tighten or put insulation under the transformers.  I have been meaning to write to Luxman about it but haven't gotten around to it since it is doesn't affect my actual listening experience.  Very disappointing though!The new Luxman distributor seems like a much more helpful guy than the previous one.  Hopefully they will offer some suggestions that don't involve Bulgarians.

Here is another such product, about $150 :

https://avahifi.com/products/humdinger-dc-line-blocker


Of course, more expensive solutions are to use a balanced power transformer, which are themselves subject to mechanical hum without enhanced circuitry. :-)

I do want to point out that yes, any lights with little wall warts, especially those with built in dimmers, may introduce DC.  The best way to diagnose this is to turn off everything in the house except your amp and see if it goes away.  Then start flipping breakers back on until the hum reappears.

What happens is that these devices only take power from one side of the AC line, but not the other. This lack of symmetrical power draw causes DC to appear, and then the mechanical hum.

Best,

Erik

I don't have any hum through my speakers, gryphongryph. The piece you linked may be great, but the idea of buying something from halfway around the world for $1000 and seeing if it makes things better isn't overly attractive to me. When my car has an issue, I don't just start replacing parts at random. There has to be a method to the madness, at least for me.
L.

I have this one, made my Hi-Fi sound better with blacker background and the hum I had from my class A power amp trough my speakers disappeared, mine is with 8 outlets, beautiful made.
https://harmonydesign.se/produkt/dct-90/
The guy behind the company (Mattias) is very friendly and competent, answered a lot of my questions.
Why not shoot him a mail, sure he can help.

No hum but I’ve trigerred the protection circuit several times now as the amp automatically shut down by itself. The system was played continuously for several hours, sometimes above 10 hours in a day when it happened. At least I am aware the protection circuit feature of the amp is working and the unit is protected from the heat that it produces.

It sounds magnificent by the way.

I have smaller brother... Sister..?  The 550ax2 and a class as well. No hum I've noticed but I'm in a city with good supply and 230v here (which may be a reason) 

As for heat mine gets warm to touch but I can still hold hand to case after hours. A bonus in fact for cold Scotland 

Hey, guys, thanks to you all for taking the time to help. Your answers give me some food for thought. We have one dimmer in the house, on a light that's seldom used, I don't think that could be it. Two things come to mind, after reading your replies. Number one, we have a lot of Christmas lights and decorations up at the moments, all indoors, most of it on timers, and controlled electronically, etc. Not sure if they are causing any issues, but they'll be gone within the week, so maybe I'll see a change. The second change is my wireless router. It's the same one for a few years, but I recently made some alterations, at the advice of the phone tech. Almost everything was hard wired, and I was having service issues. He told me the hardwiring was actually causing interference with the signal, and advised me to unhook everything and let it operate wirelessly (less the TV that's 3 rooms away). This was counterintuitive to me, and I was skeptical, but everything was definitely improved after I unhooked the cabling. My first step is wait and see if there's an improvement after the Christmas lights go away.
wahoostewjr, I would like to say I'm positive I never had the hum before, but can't. It's that quiet. It sounds exactly like the low hum in my heater/thermostat combo down in my shop. Nearly unnoticeable, unless there's not a lick of noise anyplace, and you listen very closely. My amp also runs pretty warm. From comments here about other pieces of equipment, sounds like some other stuff runs a lot hotter.
Thanks again!

Yes, I’ve got the integrated and, yes, I’ve got the low hum. Not really that noticeable. I wondered if it was a characteristic of a Class A amp since I’ve never had one before. It runs very hot.