View Full Version : Tube amp Hum/ground loop - good solutions?
Hello,
I struggle with a hum/buzz from my valve power amp...
It was so annoying that I at the end removed the ground/mass plug ( I know - big nono...) but I spent dozens of hours literally crawling on my knees, plugging and unplugging cables in my system (it's not hifi audio, it's a little home/based studio - so there's a lot of cables).
On some point I plugged only balanced cables, to avoid ground problem - still nothing...so I unplugged damn ground bolt from the plug ..
Well, strangely enough, it still sometimes gives me delicate noise and buzz, even without mass:(
so I did some research and found that hum isolator could be the nice solution.
http://www.google.co.uk/products/catalog?num=50&hl=en&q=art+isolator&cid=8182762875635119520&os=reviews&ei=Ix6MTuvEM56z-Qam4plX&ved=0CAYQ9AI
http://www.orchid-electronics.co.uk/dual_isolator.htm
http://www.amazon.co.uk/Behringer-MICROHD-Hum-Destroyer-HD400/dp/B000KUD2G4/ref=pd_sxp_f_pt
http://www.google.co.uk/products/catalog?q=EBTECH+Hum+Eliminator&oe=utf-8&client=firefox-a&cid=10273380025661229246&os=reviews&ei=Zx-MToLRGMmO-Aa81dmSAQ&ved=0CAYQ9AI
I know...b-ringer and art..don't have a very big esteem in audio market, but some folks say it does the job;
I don't want to introduce a box which takes my audio bandwidth away, so here's a question to any of you had any experience with above?
Please advise - not to mention that my budget is almost non existent atm:(
hence b-ringer and art here..
thank you in advance
WOStantonCS100
05-10-2011, 18:23
I use an Ebtech Hum X on my tube phono and line stage preamps. I originally purchased them for my guitar rig. I found they are equally as useful with my home playback gear. Small and passive.
http://www.ebtechaudio.com/humxsplashbanner.jpg
us hum is 60Hz, when here in Europe we got 50Hz...
so it won't work here
and I'd really want to know if anyone use it before an amp ?
and what about SQ ?
WOStantonCS100
06-10-2011, 01:35
us hum is 60Hz, when here in Europe we got 50Hz...
:o Oooops. Forgot about that. Shame really, works a charm here. Hopefully, someone will chime in with a good solution.
Stratmangler
06-10-2011, 08:44
If you've removed the earth connection from a valve power amp you need your head examining.
These things are lethal, kill you and hurt beyond your imagination for every second that it takes you to die lethal.
Reconnect it immediately.
However, your problem does indeed sound like a ground loop issue, and lifting the ground connection is the solution.
Just not at the power amp :doh:
Filip,
Has it always hummed or was it ok at one point and then became noisy?
You say the noise is coming from the amp - Is the noise coming through the speakers (likely to be ground loop related) or from the amp itself (likely to be tube related).
You don't say what amp you are using but I know from experience that harmonics from tubes can cause really annoying noise. I had some of this with my Croft 25R preamp until I finally hit on using a Quad of vintage NOS RCA 12AX7's (very low noise) and a single GE A2900. It still hums a little but nowhere near as bad as before. The Croft power amp hums a little but I think it's transformer related.
Oh and by the way - put the earth lead back in he loop :harp:
Steve
WOStantonCS100
06-10-2011, 18:24
Even if it doesn't kill you, the shock from a discharging cap of a valve amp, that earths through you, can be life changing (maimed). Anything that can weld a screwdriver to a chassis, in an instant, should be treated with much respect.
A preamp valve with a spiral filament should be quieter that one without, especially when gain is increased.
Tried the ART one, waste of time. Did pretty much wipe out the ground loop hum, but what was left sounded fuzzy/distorted and pretty horrific.
Audioman
11-10-2011, 11:53
I hope you've reconnected that earth Filip ! The ground loop is likely caused by components connected to the amp. Try connecting ground between casings assuming your valve amp is earthed. Also hum eliminators (transformers) can be bought that split the phono leads - can be expensive solution.
hi,
Thanks for info lads...
well, I am worried now more then before, as I simply can not put the ground plug, as the hum don't let me use monitors to work:(
maybe someone is happy to look into amp for some money of course?
it's old power amp. push-pull 4xel84
all tubes are brand new nos, from russia, military standard, made in 1970 - reflector,
amp is Edison HFA12
12W, amp, which was designed by Erik Andersson (who used to have a company here in UK, in Brighton)
it was sold as a diy amp, for my knowledge -it was case and amp separate, so you have to solder it yourself (? - not sure about it)
I bought it from second hand shop, it was without a plug, so maybe I mess with plus and minus ? when I solder plug here at home
amp is extremely sensitive (at input)
it is something with this amp since day one, and I think it's a matter of maybe old components, maybe some dodgy soldering job...( I did open it to swap tubes, and it looks like 10 years old kid did soldering job, it's really messy there....)
I think it's a good timing to ask someone for help, and proper check with tools, what is inside not working wright.
If anyone here is able to help with it - please let me know, I'll start collecting money..
atm, I have some quiet hum from time to time, even with ground plug off...
it could be src2496 (b-ringer's power supply)
Filip,
Has it always hummed or was it ok at one point and then became noisy?
You say the noise is coming from the amp - Is the noise coming through the speakers (likely to be ground loop related) or from the amp itself (likely to be tube related).
You don't say what amp you are using but I know from experience that harmonics from tubes can cause really annoying noise. I had some of this with my Croft 25R preamp until I finally hit on using a Quad of vintage NOS RCA 12AX7's (very low noise) and a single GE A2900. It still hums a little but nowhere near as bad as before. The Croft power amp hums a little but I think it's transformer related.
Oh and by the way - put the earth lead back in he loop :harp:
Steve
the hum was always there,
and it was really bad at the beginning when I had my old pc plugged into system, I could hear like someone put microphone inside my pc!
noise and buzz, hd motor buzz, when I moved mouse - noise,
plus ground hum....just terrible
the thing is, I am not hifi user, it's in my studio, where there's many tools and boxes, and many cables connections;
bum come out of speakers, it's not amp hum...just hum and buzz in monitors
i did try many things - all connected to 1 socket, star connection, all cables balanced, etc..
no way to find it...
anyway, seems this is more serious problem then I thought-
I need to resolve it asap, please direct me to someone who can hep here in uk
cheers
Stratmangler
11-10-2011, 12:43
This company can't be far from you http://www.tube-electronics.co.uk/ , contact them and see what they can do for you.
Then there's this chap http://www.stevesamps.co.uk/wp/
For goodness sake don't run that amplifier without an earth connection.
StanleyB
11-10-2011, 14:29
For goodness sake don't run that amplifier without an earth connection.
A warning that MUST be observed with valves. Ignore it and you could get the Grim Reaper paying you a visit.
all right I got it; no need for any reaper,
grim or not;
please lads connect me with reliable person,
also, I can not afford to pay 30UK/h....
Ali Tait
11-10-2011, 16:54
Filip, you could try contacting John Caswell on the World-Designs forum. He's in Wokingham and there's not much he doesn't know about repairing valve amps.
vinylspinner
11-10-2011, 17:01
I would recommend John as well, he services most of my valve gear, good rates too.
Nigel
Thank you very much Gents!
Mighty Ant
11-10-2011, 17:40
You could try EFG, excellent service at reasonable prices. Should be close to you also.
EFG (London) ltd
EST 1948
9 The Vale, Acton, London, W3 7SH, UK
Tel 020 8743 2727
Anthony
You could try EFG, excellent service at reasonable prices. Should be close to you also.
EFG (London) ltd
EST 1948
9 The Vale, Acton, London, W3 7SH, UK
Tel 020 8743 2727
Anthony
appreciate your help,
thank you!
great forum
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