ARC VS60 hum in speaker - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th October 2010, 10:00 PM   #1
diyAudio Member
 
Join Date: Oct 2010
Location: NYC
Default ARC VS60 hum in speaker

I have a brand new ARC VS60. When I connect my Focal 1027 Be speakers to them, I have a very soft 60hz hum coming from them. I tried disconnecting the input of the amp and hum still remains. I also tried lifting ground and the hum is still there.

The hum is not loud at all but I am concerned if this is a defective amp. Should this amp be dead silent at the speaker or is a small amount of hum normal? For what it's worth, I upgraded from a solid state Arcam amp and that amp was dead silent.
  Reply With Quote
Old 20th October 2010, 10:19 PM   #2
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Have you tried it with the inputs shorted? The Focals are not high sensitivity, so yes, it should be completely silent.
  Reply With Quote
Old 20th October 2010, 10:22 PM   #3
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
considering what's written on their web page ARCDB - VS60 , I think that's time for you to call your dealer

don't do anything , because of warranty .

with this :

Quote:
Hum & noise Less than 0.2mV RMS - 100dB beow rated output (IHF weighted, input shorted).
Power supply energy storage Approximately 166 joules.
there must not be any hum
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 20th October 2010, 10:23 PM   #4
diyAudio Member
 
Join Date: Oct 2010
Location: NYC
Quote:
Originally Posted by analog_sa View Post
Have you tried it with the inputs shorted? The Focals are not high sensitivity, so yes, it should be completely silent.
No. Just unplugged. I've been told the Focal 1027 Bes are high sensitivity at 91db. Is this low? or high?
  Reply With Quote
Old 20th October 2010, 10:24 PM   #5
diyAudio Member
 
Join Date: Oct 2010
Location: NYC
Quote:
Originally Posted by Zen Mod View Post
considering what's written on their web page ARCDB - VS60 , I think that's time for you to call your dealer

don't do anything , because of warranty .

with this :



there must not be any hum
I have called them and waiting for Calvin to call back.
  Reply With Quote
Old 20th October 2010, 10:34 PM   #6
diyAudio Member
 
Join Date: Oct 2010
Location: NYC
After a quick search on "hifi strereo tube amp hum", this problem is not uncommon at all. Vast amounts of tube amp seems to emit a soft hum in the speaker from what I read. The hum is quiet and only noticeable when I put my ear to the speaker. However, I'd like to correct this if possible. I'll test it with the inputs shorted and see what's up.
  Reply With Quote
Old 21st October 2010, 06:25 AM   #7
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Quote:
Originally Posted by GeneJazz View Post
No. Just unplugged. I've been told the Focal 1027 Bes are high sensitivity at 91db. Is this low? or high?

Speakers which are above 100db sensitive are known to make hum problems a lot worse. 91db is just above average.

Unless you actually measure the hum with the inputs shorted it will be hard to say anything for certain. And to what end? Is it worth shipping the amp back for a minute amount of hum? Not sure if ARC would be able to do much about it anyway.
  Reply With Quote
Old 21st October 2010, 12:14 PM   #8
diyAudio Member
 
Join Date: Oct 2010
Location: NYC
I did just that. I took the amp to my bench and measured the hum with the inputs shorted. The published spec states 0.2mV IHF weighted.

I measured on the right channel, 0.25mV and on the left channel, 0.7mV. Nearly 3 x more hum. I did notice the left channel hum to be louder so I wanted to confirm. It is not the tubes as I swapped the R and L channel tubes and still got the same measurements.

I think there is something wrong with this amp and will call ARC for an exchange or repair. A brand new amp shouldn't have 3 x more hum in 1 channel, I would think.
  Reply With Quote
Old 21st October 2010, 12:37 PM   #9
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Quote:
Originally Posted by GeneJazz View Post
I measured on the right channel, 0.25mV and on the left channel, 0.7mV. Nearly 3 x more hum.


A friendly advice: unless you intend to listen exclusively on headphones, ignore the hum. I don't believe it can actually interfere with yours or anyone else's enjoyment of music.

As an academic exercise it is certainly interesting to analyse the source of it. Without knowing anything about the circuit i would venture that it is most probably a design oversight, rather than a defective component. As HT and heater supplies are common you can remove the PS as a culprit. Which mostly leaves poor ground layout or inductive coupling as possible sources of hum. Not likely ARC will fix either of those but a good technician, after investing some time and effort might.
  Reply With Quote
Old 21st October 2010, 01:23 PM   #10
diyAudio Member
 
Join Date: Oct 2010
Location: NYC
Quote:
Originally Posted by analog_sa View Post
A friendly advice: unless you intend to listen exclusively on headphones, ignore the hum. I don't believe it can actually interfere with yours or anyone else's enjoyment of music.

As an academic exercise it is certainly interesting to analyse the source of it. Without knowing anything about the circuit i would venture that it is most probably a design oversight, rather than a defective component. As HT and heater supplies are common you can remove the PS as a culprit. Which mostly leaves poor ground layout or inductive coupling as possible sources of hum. Not likely ARC will fix either of those but a good technician, after investing some time and effort might.
VS60 is a power amp so for headphone listening, I would leave it off. You are right with your insight. From a practical point of view, the hum is not too objectionable.

On the other hand, my tech interests wants to get to the bottom of this. Who knows, it might be as simple as using a chopstick and shifting some wires a bit.

I'll speak with ARC again. Perhaps they can send me another one and if that one is good, I'll do an exchange. These amps aren't cheap and I don't think one channel should be so out of spec.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Linear power supply causing mains hum at speaker cmhadley Power Supplies 5 18th April 2009 02:43 PM
Ground loops, speaker hum and buz steevo Solid State 15 31st October 2008 09:58 PM
Power trans coupling with speaker, causing hum slowpogo Parts 0 15th January 2007 01:59 AM


New To Site? Need Help?

All times are GMT. The time now is 12:05 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2