R/E/P Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1]   Go Down

Author Topic: another step to perfection.....geting rid of hum/buzz/noise  (Read 2463 times)

Red Mastering

  • Newbie
  • *
  • Offline Offline
  • Posts: 9
  • Real Full Name: Filip Pietrzykowski
  • online mastering studio
another step to perfection.....geting rid of hum/buzz/noise
« on: November 10, 2011, 02:47:11 pm »

Hi everyone!
I thought it could be good place to ask for a solution.
I have passive speakers in my system, my amp is a valve/tube power amp.
I have a few analog devices in my studio connected via patchbay.
Now the problem I have is a little hum/buzz I got in my monitors.
before I start, I don't know how to 'measure' this noise/hum,
please don't curse me for being not precise, explaining amount of noise for example,
so I will use non professional descriptions as - 'unnoticeable' or 'dead quiet' or sth. similar:)
if you advise me how to measure it - I'll do it
so the story of hum:
It's almost unnoticeable when only power amp is on (also it's much less when it's solid state amp instead of valve one - and it's obviously valve has more sensitive input),
I can't hear it until I put my ear into the speaker - so there's no problem, but obviously I need few more devices to work - then just power amp,
I used to have a hifi dac with rca outputs (just to inform my both power amps valve and solid state have rca hifi standard inputs) and this dac was completely 'dead quiet' when connected to power amp,
0 noise
I've noticed that hifi dac has a power supply not utilizing ground loop (that's what I think, but there's no way to find it- maybe I need to contact constructor?) - so maybe that's the answer, I dunno...
I noticed that every gear I have adds some minimal amount of noise to the system - I did checking using RME's digicheck software - it's brilliant;
Thermionic culture vulture LE is on top of the list - bypassed, then is TFPRO P9, P8 and diy SSL4k - the latter is dead quiet.
Since I plugged mytek 96dac into my system as a last monitoring dac, the hum/buzz noise became an irritating issue. When mytek was close to my PC (around 1 m) I could hear my HD in monitors...and many 'extra' noises, when I moved mytek and also plugged it in another power socket - it's much better. I can't hear the noise until I listen to classical music - then I can hear it and it makes me mad...
My room is ultra quiet, that's one of the reasons i can hear it.
It's not ground loop I think, as it's much more quiet then ground loop (I used to have ground loop issue before), it's i think mixture of EFM and hell knows what else all together
I also solder temp cables for checking new dacs and adc, so I used klotz cables - I noticed when I connected dac with belden (xxx1695 - sorry don't remember right now) - it was much less noise...
any ideas where to start and what to do ?
A week ago I went almost mad trying to find what cause the trouble and I unplugged every, EVERY cable in my studio...power, line, analog, digital...all of them:(
I switched off fridge, and all devices in kitchen:) - didn't help either..
apparently, when I moved power amp plug and dac plug into another power socket - it helped a bit (which is strange as all my devices were connected from same power socket- as they supposed to)
I thought about soldering proper (now it's good question - will it help?) power cables,
like this ;
http://diyaudioprojects.com/Power/diyMains/
but then read on Internet that it's all snake oil, etc...:
http://www.empiricalaudio.com/computer-audio/technical-papers/myths-and-snake-oil

any ideas how to approach this problem ?
I noticed this hum is not recorded when I go through analog chain,
it's only (!) monitoring issue

thanks for help in advance

Thomas W. Bethel

  • Sr. Member
  • ****
  • Online Online
  • Posts: 310
  • Where your dreams become reality
Re: another step to perfection.....geting rid of hum/buzz/noise
« Reply #1 on: November 11, 2011, 07:00:26 am »

Trouble shooting hum and buzz can get complicated very quickly.

The best way to proceed would be to pull out the input leads to the power amplifier, make up some adapters that short the tip and sleeve of the input jacks together (one for each channel) and have a listen to the speakers. If you still hear hum then it is in the amplifier itself. There maybe a hum adjustment on the power amp and you can rotate that for minimum hum. Some amplifiers used DC for the filaments and there is no hum adjustment, other manufactures just did not provide a hum adjustment and you amplifier maybe one of these. AC on the filaments can cause hum. Also leaky power supply caps can cause hum or a power supply that is not filtered correctly can cause hum. Once you have quieted the amplifier, replace the input leads and have a listen. You will have to work backwards from known to unknown until you find the source of the hum. You will know when you have identified the source of the hum because it will get louder when you hook the piece of equipment up.

A star ground system is good for a recording/mastering studio and you can find references for that on the WWW. In a star ground system basically all equipment is tied together to a central ground and all the connections between the equipment is  grounded at the patchbay but not tied to the grounds on the pieces of equipment. (Best to read about this solution in depth and follow it).

Maybe others have ideas as well.

Best of luck! :)
Logged
Thomas W. Bethel
Managing Director
Acoustik Musik, Ltd.
http://www.acoustikmusik.com/

Doing what you love is freedom.
Loving what you do is happiness.

Celebrating 22 years in business in 2017

Red Mastering

  • Newbie
  • *
  • Offline Offline
  • Posts: 9
  • Real Full Name: Filip Pietrzykowski
  • online mastering studio
Re: another step to perfection.....geting rid of hum/buzz/noise
« Reply #2 on: November 14, 2011, 05:38:35 pm »

Hey Thomas!
thanks for input, I think I don't understand what you mean for shortening tip and sleeve?
I have xlr out of dac (mytek96) into rca power amp.
Amp itself gives almost nonexistent hum, there's something but you need to fit your ear into monitor and stop breathing for a second to be sure:)
When mytek is plugged (all equipment out of power socket - there's is hum/buzz described above.
Interesting when I use hifi dac, with rca out (I dunno if it got anything with this noise) - there's no noise, even less then just a minimal noise from amp (only power amp powered)
it's completely dead quiet;
It's not amp issue as I swapped 2 amps and the other one gives me same buzz, bit quieter as it's solid state amp. but it's there

Thomas W. Bethel

  • Sr. Member
  • ****
  • Online Online
  • Posts: 310
  • Where your dreams become reality
Re: another step to perfection.....geting rid of hum/buzz/noise
« Reply #3 on: November 14, 2011, 09:34:30 pm »

What kind of inputs does your amplifier have? Phone, phono. XLR, or ????. Thanks!
Logged
Thomas W. Bethel
Managing Director
Acoustik Musik, Ltd.
http://www.acoustikmusik.com/

Doing what you love is freedom.
Loving what you do is happiness.

Celebrating 22 years in business in 2017

Red Mastering

  • Newbie
  • *
  • Offline Offline
  • Posts: 9
  • Real Full Name: Filip Pietrzykowski
  • online mastering studio
Re: another step to perfection.....geting rid of hum/buzz/noise
« Reply #4 on: November 15, 2011, 10:43:48 am »

amp has rca/phono inputs (-10dB hifi standard) - maybe that's the issue, as all my tools in audio chain are balanced, and all cabling - balanced, except power amp

Thomas W. Bethel

  • Sr. Member
  • ****
  • Online Online
  • Posts: 310
  • Where your dreams become reality
Re: another step to perfection.....geting rid of hum/buzz/noise
« Reply #5 on: November 15, 2011, 01:16:52 pm »

Did you look up Star Grounds and have you implemented it?

Here are some articles http://www.aikenamps.com/StarGround.html

http://www.geofex.com/article_folders/stargnd/stargnd.htm

http://www.diyaudio.com/forums/chip-amps/115698-understanding-star-grounding.html

and from the WWW

Star Ground
    A type of grounding scheme used in some studios to prevent ground loops. It requires isolating each piece of gear from AC ground (using a ground lift adapter) and running a separate ground wire from the chassis of each piece (including the racks themselves) back to the main studio ground (we call this "Technical Earth"). This "Tech Earth" gets connected back to a main AC ground, and/or a large copper rod driven 18 feet into the ground. Thus every piece of gear still has AC fault protection, but no earth grounds are tied together. Technically limited ground loops can still exist in the studio signal wiring, but the path length differences are minimized to an extent that it isn't likely to be a problem. Star Grounding is a time consuming and complex wiring scheme, but is generally very effective at preventing ground loops and works great in conjunction with other measures such as telescoping shields. Occasionally you'll still find some piece of gear that requires audio transformers to eliminate ground loops. Generally you'll find that with today's equipment, you really don't have to go as far as all this. Telescoping shields, balanced lines, and careful consideration to signal cable wiring with today's equipment is often good enough.

Let me know if I can give you any more help. It sounds like you have a problem that could be solved by using a star grounding scheme.

Best of luck! 8)
Logged
Thomas W. Bethel
Managing Director
Acoustik Musik, Ltd.
http://www.acoustikmusik.com/

Doing what you love is freedom.
Loving what you do is happiness.

Celebrating 22 years in business in 2017

Red Mastering

  • Newbie
  • *
  • Offline Offline
  • Posts: 9
  • Real Full Name: Filip Pietrzykowski
  • online mastering studio
Re: another step to perfection.....geting rid of hum/buzz/noise
« Reply #6 on: November 16, 2011, 01:59:19 pm »

Thanks Thomas!
I will look into it for sure, but I think it's not a ground loop issue...
I noticed for example- when I moved mytek converter further from pc - the noise gets smaller - hence it has to be some sort of RF noise or internal power supply generates EMF,
maybe I am wrong, and for sure I will try what you suggest first:)
thanks again

Thomas W. Bethel

  • Sr. Member
  • ****
  • Online Online
  • Posts: 310
  • Where your dreams become reality
Re: another step to perfection.....geting rid of hum/buzz/noise
« Reply #7 on: November 16, 2011, 02:08:57 pm »

Most computers use switching type power supplies and they can have an RF component to them. Most audio equipment has what is called a brute force power supply and "usually" does not produce RF components. This RF hash would normally be perceived as noise not hum. The other possibility is that something in your wiring/setup is producing a strong magnetic hum field which is being picked up by your analog equipment but that probably would not be too likely. I still think you have a grounding problem.

Best of luck!
Logged
Thomas W. Bethel
Managing Director
Acoustik Musik, Ltd.
http://www.acoustikmusik.com/

Doing what you love is freedom.
Loving what you do is happiness.

Celebrating 22 years in business in 2017

djwaudio

  • Moderator
  • Full Member
  • *****
  • Offline Offline
  • Posts: 223
  • Real Full Name: Dana J White
Re: another step to perfection.....geting rid of hum/buzz/noise
« Reply #8 on: November 18, 2011, 12:00:39 am »

apparently, when I moved power amp plug and dac plug into another power socket - it helped a bit (which is strange as all my devices were connected from same power socket- as they supposed to)


This looks like a place to start, checking the integrity of the grounding in the building (Some power conditioners have a simple tester/monitor built in).

If you're getting hum with just the Mytek and Power amp, can you swap either of those components with a known quantity? 

I have a Mytek DA and have interfaced with unbalanced signals successfully, but there is more noise since it's not getting the benefits of common mode rejection. 
Logged
Respectfully submitted,

Dana J White
Specialized Mastering
www.specializedmastering.com

scott2000

  • Newbie
  • *
  • Offline Offline
  • Posts: 1
  • Real Full Name: Scott Savageau
Re: another step to perfection.....geting rid of hum/buzz/noise
« Reply #9 on: June 17, 2017, 02:45:45 am »

I agree with the above tests...I know things can get goofy if the interconnects aren't wired correctly when going from balanced to unbalanced gear. Some balanced outputs use different methods than others. I know the Apogee I have needs to have pin 3 tied to ground if feeding unbalanced gear. I'm not sure the Myteks do.

OOPs...Pretty old post...

Sorry...New guy here...
Logged
Pages: [1]   Go Up