[HarleyMYK]

Has anyone auditioned the Le Amp 3's?  If so, can you post, link, or PM?  Thanks...

[yeldarb]

I'd love to see a review, too.  And I would encourage M. Barnes and company to get a pair to TNT for a review. 

[GRacer]

hi guys

im a newbee here

i got my new le amps 3 arrived today and just finished 1-hour music listening session with them

compare to my yamaha m-70 power amp, my initial thought is the le amps has more details, more accurate and has a good wide staging. bass is very smooth, yet still deep and fast, just the way i like it  . i'm no audiophile nuts nor crazy hifi freaks, but i know a bit or two about sounds 

but one thing that strike me the most, is that both amps are humming  . one is louder than the other. my m70 is quiet as a mouse compare to these le amps.

i'm sure that these amps are NOT suppose to hum, correct ? it reminds me of my tube amp, but my tube amp doesn't hum as loud as these le amps. luckily the humming doesn't get louder when you crank up the volume.

i have emailed namphung about these problems and awaiting for his reply now.

*******
related equipments used on this session were :
- paradigm reference studio 60 speakers
- harman kardon avr-8500 reciever (used as a pre-amp)
- yamaha m-70 power amp
- pioneer dv-989avi
- pioneer pd-s904

[tecrench]

I have read other threads talking about a hum in some of them

Also how long did it take for you product to ship -I waiting on speakers and an amp

[GRacer]

from thailand to nz from time of shipping confirmation to arrival is about 4-5 days ?

good service i'd say on the shipping

yeah, it's just frustrating for me that the hum exists on both amps although the performance of the amp itself is brilliant

hopefully namphung respond to me soon

[sas]

i'm sure that these amps are NOT suppose to hum, correct ?

No, these amps are NOT supposed to hum.

This was one of the big problems with the Le Amp2 (i have a pair), and I would have thought that nOrh would have done everything possible to prevent this happening again. They said at the time that they were testing their amps through a stabiliser, and when shipped out to people who don't use a stabiliser they hummed.
My LA2's had hum, and I tried various stabilisers and only managed to reduce it. In the end I think the problem was that the LA2 used a switchmode PSU that was far too noisy. The hum was not that bad, but not acceptable. In the end I ripped out the SMPS and amp board, made my own lower wattage class A amp and put in a linear supply.

However the LA3 uses a linear supply, which should be easier to make hum free than an SMPS.

Do a google search for hum troubleshooting, there may be an obvious solution (like eliminating a ground loop). For example, does it hum when the input is disconnected?
Otherwise, unless you are diy minded I would advise you send it back.

[GRacer]

No, these amps are NOT supposed to hum.

This was one of the big problems with the Le Amp2 (i have a pair), and I would have thought that nOrh would have done everything possible to prevent this happening again. They said at the time that they were testing their amps through a stabiliser, and when shipped out to people who don't use a stabiliser they hummed.
My LA2's had hum, and I tried various stabilisers and only managed to reduce it. In the end I think the problem was that the LA2 used a switchmode PSU that was far too noisy. The hum was not that bad, but not acceptable. In the end I ripped out the SMPS and amp board, made my own lower wattage class A amp and put in a linear supply.

However the LA3 uses a linear supply, which should be easier to make hum free than an SMPS.

Do a google search for hum troubleshooting, there may be an obvious solution (like eliminating a ground loop). For example, does it hum when the input is disconnected?
Otherwise, unless you are diy minded I would advise you send it back.

Exactly what I thought ! When an amp is humming, they are considered one of those cheap and nasty ones in the market, and i'm sure that this is NOT the image nOrh is trying to achieve with their amps or products in general. Like I said, my good old yamaha m-70 is completely NOISELESS, no hum no nothing, quiet like a mouse.

After 2 days listening to them, they do sound a lot worse in my ears now    . I can practically hear the hum clearly from 4.5m away (where I sit) especially on quiet scenes or when I pause the player or mute my receiver.

I have also used stabiliser in my system and that definitely doesn't do anything to the hum. The amp I use for the right channel is significantly humming worse than the one I use for left channel. I have tried swapping the RCA pre-out, and it didn't do anything, the one I use for the right previously still signifinicantly louder than the other one. This amp also click a bit louder when turned on compare to the other one.

I have not tried disconnecting the input line, I will give it a go tomorrow.

I'm very very tempted to send these amps back as I don't think I could live with this annoying humming noise ! **ARRGHHH** 

Namphung still has not replied to my email (from the previous email, I think they were in the middle of moving office)

I was really expecting these Le Amps 3 amps to be way better than this

[sas]

...some suggested reading that may help you eliminate the common causes of hum...

http://www.perreaux.com/troubleshoot.php
http://www.decware.com/paper41.htm
http://www.audioholics.com/tweaks/connecting-your-system/ground-loops-eliminating-system-hum-and-buzz/
(PDF file): http://www.passlabs.com/downloads/articles/ground-loops.pdf

hope that helps, and keep us posted.

[GRacer]

RIGHT............

i have set up the amps side by side and to make it easy, i will call the amp on the left AMP-1 (connected to LEFT RCA cable) and the one on the right AMP-2 (connected to RIGHT RCA cable). so far AMP-2 is humming like crazy compare to AMP-1.

I think i got them sorted. What I have done to get to the bottom of this problem :
- as suggested above, I did disconnect the RCA cable from my receiver, which acts as a pre-amp, turned on the amp and voila, NO humming ! Connect the cable back on, there was the HUM again.
- switched to another high quality interconnect and switched it back on, still HUMMING.
- switched the RCA cable from the pre-amp around, LEFT RCA to AMP-2 and RIGHT RCA to AMP-1, turned it on, and AMP-2 was still humming. so far i have eliminated the possibility of faulty output on my receiver as well as faulty cable/interconnect.
- switched power cables around between AMP-1 and AMP-2, and AMP-2 was still humming. Eliminated the possibility of faulty power cables.
- i was really really frustrated on this stage, was about to throw the amps in the "BIN" then i accidently stumbled around an IEC power cable with NO ground (2pins only).
- i thought to myself, WTHell i got nothing to loose, might as well try this cable.
- hooked this un-grounded 2pins cable to AMP-2, turned it on and VOILA.... HUMMING drastically reduced to almost non-existant !! AMP-2 also doesn't click as loud as before when it's being turned on now.
- i disconnected the ground on my receiver and used the original power cable on AMP-2, turned it on, AMP-2 was humming again. so this eliminated the probability of ground problem in my receiver.
- put the 2pins power cable back on, turned the amp back on and the humming noise is almost to non-existant. infact, it's quieter than the AMP-1 now.
- i grabbed another 2pins power cable and connected it up with AMP-1, turned it back on and i noticed reduced humming noise very very slightly, it wasn't as noticable & drastically as with the AMP-2.

i'm happy now with the amps... but i can't help but wonder WTF went wrong with them ? both connected to the same power board, both power cables are the same, supplied by nOrh. also tried with other 3pins iec cables and result was still the same, AMP-2 hummed really loud.

anyone care to shed some lights for me ?? i'm not very technical person when it comes into electronic stuff, so explanation in simple english (not technical jargons) would be much appreciated

happy but confused...

[GRacer]

btw, to this day, i haven't heard or received any reply from Namphung. Not sure if this is an acceptable form of communication at their side after a customer's complaint?  hmm..

[Early B.]

It's not unusual at all for amps to hum when connected, then the hum is virtually eliminated by removing the ground. Lots of reasons for it, but the problem is not the amps itself.

Glad you're enjoying your amps.

[KKM]

I have the LA II's and my original set had hum but they had a fixed and sent another pair that was fine. I think they put some kind of filter.

[GRacer]

It's not unusual at all for amps to hum when connected, then the hum is virtually eliminated by removing the ground. Lots of reasons for it, but the problem is not the amps itself.

as kkm mentioned above, i tend to think that there's something wrong with the amps. i have done many process of eliminations and always went back to the amps.

if the problem is not the amps, would you care to elaborate what could possibly the cause ?

i have even tried to connect them up straight from the wall, with the supplied 3 pins power cable, and it's still humming badly.

[Early B.]

It's not unusual at all for amps to hum when connected, then the hum is virtually eliminated by removing the ground. Lots of reasons for it, but the problem is not the amps itself.

if the problem is not the amps, would you care to elaborate what could possibly the cause ?

Read the links provided in reply #7. In particular, read the decware link, second paragraph and beyond. 

[sas]

It's not unusual at all for amps to hum when connected, then the hum is virtually eliminated by removing the ground. Lots of reasons for it, but the problem is not the amps itself.

Agreed. If there is no hum from the amps when they are switched on but no input is connected, that means the amps are not the problem. Bear in mind that in a system a ground loop is a general problem, not something that you can blame on a particular component.

Judging from your process of elimination, sounds to me like a stubborn ground-loop problem. The solution of using ungrounded power cords is not a long term solution either -- can be unsafe and maybe even illegal, depending on your local electrical regulations, or void insurance in the event of a fire. Using a 'high quality' interconnect will not make a difference either.

You are using single ended interconnects (unbalanced, RCA), so try putting a jumper between pin 1 and 3 on the XLR (balanced) input on each of the amps (usually the holes on the XLR input are marker with little numbers if you look closely) -- like a piece of wire (do it while the amps are switched off). Then try it again with grounded power cables. That may work.

Regarding contacting norh, send a mail again copied to all of the following addresses, you'll be certain of getting a reply:
namphung at norhtec.com
namphung at norh.com
mbarnes at norh.com
yuths at norhtec.com

[sas]

I have the LA II's and my original set had hum but they had a fixed and sent another pair that was fine. I think they put some kind of filter.

The LAII's had an altogether different kind of hum problem. They hummed, connected and disconnected from a source. The problem was that to save materials cost and weight (shipping costs), Norh used a switch-mode power supply, which unless executed properly can be very noisy, rather than the traditional linear supply -- a heavy transformer, rectifiers and large filter capacitors. The LA2's have a class-A gain stage, which is very sensitive to dirty power, hence the noise. The fix involved putting an EMI/RFI filter at the mains input (less noise to be ampilified by the SMPS), and (i think) some filters and revised grounding in other places.
I have some LA2's (which had the fix), but which had a little hum that was impossible to totally eliminate -- fine with low sensitivity speakers but not with anything over 90db w/m. Apart from the slight hum, the sound was excellent -- very full, fast and dynamic. In hindsight, the hum was not really any worse than most other amps i've heard.... but being a tinkerer, I gutted the amp anyway and have put a diy-ed class A board (Nelson Pass Aleph design) and traditional PSU inside instead. I now have 20w pure class A per channel instead of 200w class A/B.

Being a traditional linear amp, the LA3 hum issue should be entirely different to the LA2 one. I suspect a ground loop, although if more investigation does not sort that out.... it could be poor board layout, soldering etc. In which case the amps will have to go back....

[GRacer]

You are using single ended interconnects (unbalanced, RCA), so try putting a jumper between pin 1 and 3 on the XLR (balanced) input on each of the amps (usually the holes on the XLR input are marker with little numbers if you look closely) -- like a piece of wire (do it while the amps are switched off). Then try it again with grounded power cables. That may work.

have tried this, and still humming..

[sas]

 

......more reading:
http://forum.ecoustics.com/bbs/messages/34579/180767.html
http://www.equitech.com/support/wiring.html
http://www.ebtechaudio.com/findloop.pdf
http://www.aqdi.com/groundloop.htm

Also, try the amps without the pre amp. Perhaps you have an Ipod or something else with a built in volume control, and a minijack->2xRCA cable. connect the ipod direct to the amps (connected with ground power cords to the same power outlet), turn the volume right down (!) and play, and see if there is hum. Steadily raise the volume to normal listening level.

- Read all the links above again, and try to go through a process of elimination once again.
- Also, send an email to all the norh people mentioned above, and point them towards this thread.

I think at this stage, if there is no solution, you will have to either:

a) open up the amp and start measuring with a good multimeter, photograph the insides, post here and get advice, and get ready to solder.... (none of which you should be expected to do with a commercial product)
b) send 'em back.

[guest1632]

You are using single ended interconnects (unbalanced, RCA), so try putting a jumper between pin 1 and 3 on the XLR (balanced) input on each of the amps (usually the holes on the XLR input are marker with little numbers if you look closely) -- like a piece of wire (do it while the amps are switched off). Then try it again with grounded power cables. That may work.

have tried this, and still humming..

Hello, My gut feeling says you have the RCA's grounded. On some circuits, the ground is "floating" that is not connected to the chassis. It depends on the type of RCA connector that Norh is using. The reason I suspect this is because when you pull the connector out, the humm is gone. So what you probably have is a ground loop between the chassis ground and the RCA connectors. There is that issue of the poor QC in how the soldering on the boards are done.

I might suggest that you contact Mike at:

mbarnes@norhtec.com

I talk to him every now and then. Let him know what is going on, and hopefully he will get back to you ASAP. I'm willing to bet this is a simple problem, with a simple cure.

Bottomline here is, you have to many items in the amp being grounded to the chassis.o

Ray

[GRacer]

have emailed all the people mentioned few posts above, only yuths had replied to me.

problem is still there.. i don't know what to do now. if i sent them back, who's going to cover the shipping back to them ? whenever i bought something new, i never expected to end up like this. i'm not trying to be difficult but i'm in the trade/business industry myself and whenever there's a faulty item supplied to me, my supplier always covered the shipping cost back them. not sure if this is going to be the same with norh, judging by only 1 person replied to me after i emailed them many times before that.
i bought the amps on good faith knowing all the good reviews out there and their reputation for good service they provided to their customers, but it's not happening in my case