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Hum problem with LP125m SE

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ronenash
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Hum problem with LP125m SE

Post by ronenash » Thu Jun 22, 2017 6:44 am

Hi all,

Thought someone might help with a fresh thought on this problem I am having. Since I built my new listening room and completed connecting all my gear I am getting fairly laud hum from my LP125 power amps. This is not super laud and when music is playing at reasonable volume you can not hear it but it still bothers me as hell and I did not have this problem in the past.
This is definitely coming from the power amps as it does not change with volume and it exists even when the interconnects from the preamp are not connected.

Any ideas?

Thanks, Ronen
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Re: Hum problem with LP125m SE

Post by admin » Thu Jun 22, 2017 8:00 am

If you still hear it without the preamp connected it "shouldn't be" a ground loop. However, "same setup in a new room" makes me think ground loop issues. Get a long extension cord, plug the amp into an outlet on a different circuit of the house and see if it still happens. Maybe try rotating the tubes. If that doesn't solve the issue then you probably have to look inside the unit for the issue.
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Re: Hum problem with LP125m SE

Post by roberto » Mon Jun 26, 2017 10:17 pm

Hola. Do you have any AC line 120V, crossing or next to the speaker cables? Remember that having a cable with a proximity to AC Line or AC cables, could get contaminated with 60Hz too. Make sure the speaker cables are not touching anything but the floor, from the amp to the speaker connectors. If you still have 60Hz hum, could be a bad capacitor at the power supply of your amp. Try to use another power amp, and try...get it from a friend for testing. What bugs me is that both amps have the same problem. It looks like its from the outside of the amps. Looks like an induction problem. Please, tell us more about it.
ML CLX speakers, BF-210 sub, Classic One Twenty SE amp. ET-7 C-J pre. Exasound E-32DAC, Mac Mini i7, Anthem MCA-3 power amp, Anthem AVM-60, Oppo BDP-103. ML Stage X Center, Motion 4, BPTSignature 3.5 Plus condiciones.

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Re: Hum problem with LP125m SE

Post by ronenash » Mon Jun 26, 2017 10:58 pm

Haven't had the time to do some more testing. I will try to float the ground in one of the mono blocks to see if that helps. Not a good permanent solution but might help steer me in the right direction. Will update soon.

Thanks for the ideas his far.
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Re: Hum problem with LP125m SE

Post by Big Dog RJ » Thu Jun 29, 2017 1:54 am

G'day Ronen,

Ah those typical issues with monoblocks... been there, had them and done them!

I have tried so many different kinds of power systems, such as voltage stabilizers, magnetic field stabs, AC isolators (industrial standard) nothing helped, even though my wiring and cables were dedicated runs and everything kept very neatly and tidy at the back, unlike what I've seen- cable fruit salads/spaghetti ...

Then my dear friend from Manley Labs herself, Eve Anna Manley (president of Manley Labs) advised to simply run a dedicated AC line direct to the system with a separate IC breaker. A line having 10 to 15amps is more than adequate for HiFi no matter what the system comprises of. After all these are "domestic" systems and not industrial welding machines... Some completely over-do it by getting massive 10awg power lines with 30amp circuits and rows of AC line connections to power each unit, definitely not required. If you can afford this, and then is the ultimate form of AC conditioning.

What she also told me is that most AC circuits in the typical home share other outlets, such as the fridge and your kettle... I can clearly remember when I had the Quads, the Rega phono stage was picking up some annoying high pitch buzz from somewhere and was being reproduced from only one channel. I later figured out it was the dam fish tank air pump making the slight buzz. Since I cannot turn off the air pump, due to the little fishies running out of air, I simply got an electrician to install a dedicated 10amp circuit for the system, and vola! no hum, buzz, unwanted noise whatsoever.

I was assuming since you had monoblocks and those wonderful Amati's, you may have already installed a dedicated AC line for the entire system... perhaps or maybe not, I cannot recollect your exact system config. Eve Anne also mentioned that if you must and want total piece of mind, acquiring a separate dedicated AC line just for the power amps alone, will be the ultimate AC conditioning and all that is required. I actually did this with my previous very powerful Manley 350's, and that was indeed very well delivered!

If you plan to have monoblocks in the system down the line or at least for a while (couple of decades) I would highly recommend dedicated AC lines running directly to the amps alone and nothing else to share that circuit with.
Let us know how it goes, cheers
RJ

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Re: Hum problem with LP125m SE

Post by admin » Thu Jun 29, 2017 8:08 am

I think what Big Dog RJ is saying is really important. When I built my home theater room I ran 3 separate power lines into the room. Not because I needed the power, but because of the contamination of the line by other equipment or devices. You definitely don't want to share the line with any kind of electric motors, they typically produce a lot of noise.
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Re: Hum problem with LP125m SE

Post by roberto » Thu Jun 29, 2017 11:01 am

Hola. Reading this guy who has one of the best DACs on the market today, wrote this article regarding the noise...its very interesting what he is saying...
http://www.lampizator.eu/AC%20FILTER/SILK/FILTER.HTML

Happy listening!
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Re: Hum problem with LP125m SE

Post by admin » Thu Jun 29, 2017 12:15 pm

roberto wrote:
Thu Jun 29, 2017 11:01 am
Hola. Reading this guy who has one of the best DACs on the market today, wrote this article regarding the noise...its very interesting what he is saying...
http://www.lampizator.eu/AC%20FILTER/SILK/FILTER.HTML

Happy listening!
Interesting read about the AC filter in the article. Makes me want to build one just for the heck of it (even though I don't currently have an noise issues in my system).

Is there are 110v version schematic?
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Re: Hum problem with LP125m SE

Post by roberto » Thu Jun 29, 2017 10:56 pm

Well, all that I know is that perhaps using the same value components, being at a half ot the voltage that they were made, might work right. Its not an active components, so I do think that it might work. You can experiment yourself and tell us your findings.

My history is about the same. I thought that my AC line was clear and was not contaminated by any noise coming from the Mains AC. Because the noise its not part of the music, we can and we do it, mentally filter this unwanted noise really at a micro level, where the heart of the musician(s) are.
Hi resolution form analogue or digital gear is fantastic, and even more when you clean this unwanted noise that your brain is cancelling. Believe me, its there!. When a set up my BPT Signature 3.5 Plus, a big wow! came out of my. Its the most revealing tweak. Now my brain is only getting music, the musician(s) playing for me, there, in my Bat-Cave. My room is small, but I hear big stages, BIG! And all the dirt had gone. I getting goosebumps more often, listening to such wonderful musicians playing great music!, no matter the type of the music, or the instruments, they are here, in my batcave.
By the way, just came out a review of the new Classic One Twenty SE... http://www.enjoythemusic.com/magazine/e ... fined.gbpl
The reviewer express better what I meant to say about it!...it is a wonderful new power amplifier. A jewel to listen to...


Also, the Shun Mook Monks made the Cable Jackets to capture this unwanted contamination from EMI (Electro Mechanical Interference).
https://www.stereophile.com/features/69/index.html
http://www.positive-feedback.com/Issue1/tweaks.htm

Regards,
Roberto.
ML CLX speakers, BF-210 sub, Classic One Twenty SE amp. ET-7 C-J pre. Exasound E-32DAC, Mac Mini i7, Anthem MCA-3 power amp, Anthem AVM-60, Oppo BDP-103. ML Stage X Center, Motion 4, BPTSignature 3.5 Plus condiciones.

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Re: Hum problem with LP125m SE

Post by ronenash » Thu Jul 20, 2017 8:08 am

A quick update. Floating the ground on both mono blocks completely solves the problem. I am not very comfortable with this solution but when doing so the amps are 100% silent. Next step would probably be to route a dedicated line from the breaker board to the listening room.

Currently I am using a Torus Power AVR15 for supplying power to the power amps and a PS Audio P600 to supply power to everything else so I do get clean power but a dedicated line might help with the grounding issue.
ronenash
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Power:CJ LP125m SE, Beard P100, McCormack DNA500, Krell FPB300
Pre:CJ ACT2.1, Pr14, Pr15
Analog:VPI Classic/Falcon/SoundSmith Denon 103R, Lenco L75 rebuild
Digital:J.River-->Chord 2Qude
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Re: Hum problem with LP125m SE

Post by admin » Thu Jul 20, 2017 8:13 am

Ground loop issues can be frustrating. You may want to try turning off some of the circuits in the rest of the house to see if you can isolate some noise contamination. It's a long shot, but you never know and it may be more easy to turn off the circuit to the washing machine then run a new line.
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Re: Hum problem with LP125m SE

Post by roberto » Thu Jul 20, 2017 4:23 pm

I was going to suggest to you to use an AC cheater plug. Yup, ground loop issues are sometimes very difficult to solved too.

Well, its nice to know that now you have again a clean sound!
Happy listening!
ML CLX speakers, BF-210 sub, Classic One Twenty SE amp. ET-7 C-J pre. Exasound E-32DAC, Mac Mini i7, Anthem MCA-3 power amp, Anthem AVM-60, Oppo BDP-103. ML Stage X Center, Motion 4, BPTSignature 3.5 Plus condiciones.

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Re: Hum problem with LP125m SE

Post by Joe Appierto » Fri Jul 21, 2017 8:20 am

Both my Premier 11A and 140 had hum problems and I had to resort to a cheater plug in each case which promptly solved the issue. For whatever reason, I haven't had that problem with my CA200.

Glad you were able to find a solution, Ronen.
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Re: Hum problem with LP125m SE

Post by Big Dog RJ » Sun Jul 23, 2017 8:11 am

G'day Ronen,

Good to hear that you have sorted out that hum issue, and whatever caused it mate.

In the long run, it will be far better to have a dedicated line just for the audio. Especially in high-end systems where the slightest nuance/detail of excessive noises are picked up...

I remember the good old days of low-end or entry level gear, just plug in and hit play! Cords, cables and interconnects were all over the countryside, it was a mess behind rack systems. Not to mention the dust build up... Music was all that mattered and now we get too fussy if there are unwanted noises, dust or finger prints on the panels. Sometimes, I tend to wonder if we have a serious cause of OCD- the wifey thinks definitely so.

Oh well, the cleaner our systems are, the clearer they will sound for sure, and this will obviously bring in more joy no matter how lofty our systems are. Whether entry level or ultra highend, the music must be reproduced unhindered and within the best signal path possible.
We just finished off the plans to the house and electrical layout last Tues, I have ordered a dedicated 10AWG with a 10amp rating to the main board with a separate circuit breaker switch. This only cost a few 100 bucks, definitely a good idea for a long term solution rather than using alternatives.

I strongly believe, that since we have invested quite a lot of hard earned money into our systems, and especially CJ gear, might as well give it the best possible AC power from the main board, and nothing is better than a dedicated line.
Most electricians will charge a reasonable cost for doing this. If you are not happy with their work and charges, perhaps a DIY project could also be looked into. It's not rocket science nor is it too difficult to source the material required, it's actually quite straight forward once you know how. Safety is the main key and also remember to get it checked by a qualified electrician just to make sure all boxes are ticked.

Cheers mate, RJ

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Re: Hum problem with LP125m SE

Post by Coppy » Fri Aug 04, 2017 8:44 pm

Hey Ronen,

Much as i dislike it, I've always had to float the grounds on my c-j Amps to eliminate the hum. Both the big SS stereo P350 and the LP140 monos. Of course, mono's are notorious for making these little noisy back currents. I installed a dedicated 20 amp circuit for the total system with it's own, unshared ground system this spring hoping something would change, but unfortunately not. Let us know if you find a solution.

Best,
Coppy

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Re: Hum problem with LP125m SE

Post by plurn » Sat Aug 12, 2017 1:16 pm

ronenash wrote:
Thu Jun 22, 2017 6:44 am
... it exists even when the interconnects from the preamp are not connected.
ronenash wrote:
Thu Jul 20, 2017 8:08 am
Currently I am using a Torus Power AVR15 for supplying power to the power amps ...
ronenash wrote:
Thu Jul 20, 2017 8:08 am
A quick update. Floating the ground on both mono blocks completely solves the problem. I am not very comfortable with this solution but when doing so the amps are 100% silent. ...
Hi Ronen,

Just wondering if you have tried this set up:

- not using the Torus Power AVR15, and
- not floating the ground

So basically just plug in the power amps to the wall outlets (perhaps also disconnecting the interconnects for the test). I wonder if that would also fix the issue. Sometimes power conditioning can be detrimental.

Anthony

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Re: Hum problem with LP125m SE

Post by ronenash » Mon Aug 14, 2017 11:27 pm

Hi Anthony

I have not tried this. Might try it some day but everything sounds so good right now that I am not very motivated to make changes.

Ronen
ronenash
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Power:CJ LP125m SE, Beard P100, McCormack DNA500, Krell FPB300
Pre:CJ ACT2.1, Pr14, Pr15
Analog:VPI Classic/Falcon/SoundSmith Denon 103R, Lenco L75 rebuild
Digital:J.River-->Chord 2Qude
Speakers:SF Amati Futura

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