Bottlehead Forum

Bottlehead Kits => BeePre => Topic started by: crgolfer on November 12, 2013, 06:30:14 AM

Title: Buzzing
Post by: crgolfer on November 12, 2013, 06:30:14 AM

I need some advice on tracking down a source of buzzing.  I have been get buzzing from one channel after about 45 minutes of use.  Today the buzzing started, as usual, at the 45 minute mark but was only intermittent.  It would last for about a minute and then go away.  I am now at 75 minutes of use and all is now quiet. 

I have switched tubes and reheated all solder joints but no luck.

Title: Re: Buzzing
Post by: Grainger49 on November 12, 2013, 06:33:20 AM

If it is only one channel swap the 300B tubes and see if it moves.

I'm betting it is some electrical appliance that is putting noise on the AC line.  But what do I know?

Title: Re: Buzzing
Post by: crgolfer on November 12, 2013, 07:03:03 AM

I have tried switching tubes but no luck. The unit has been on now for about 110 minutes and I now have a steady and louder buzz in the one channel.  Could it be caused by a transistor getting too hot?

Title: Re: Buzzing
Post by: johnsonad on November 12, 2013, 07:10:46 AM

Try cleaning your pins and socket contacts. You may also want to try tightening them.  I had the same thing happen to one pair of tubes.  It drove me crazy and I couldn't get it to stop.  I put in new tubes and didn't have a problem.  Hopefully you can solve your problem with less.

Title: Re: Buzzing
Post by: Doc B. on November 12, 2013, 07:20:32 AM

Have you rechecked your voltages?

Title: Re: Buzzing
Post by: crgolfer on November 12, 2013, 07:38:07 AM

I have tried different sets of tubes but no luck. 

I think that I may have found the source of my problem.  While listening to the Beepree, without an input signal, for buzzing and watching tv I noticed that the buzz went away when I switched channels.  I had the Beepree plugged into the same outlet as my tv and now plugged into another outlet there is no more buzzing. 

I didn't think of that being the problem as I was feeding the Beepree through a Foundation Research power line which has a dedicated line conditioner; so much for noise filtering.  What was probably happening was distortion from the tv getting into the Beepree and gradually building up to higher and higher levels. 

Title: Re: Buzzing
Post by: Paul Birkeland on November 12, 2013, 08:27:01 AM

This a pretty timely topic - I was doing some noise testing on a BeePre today and noticed that it was picking up noise from a battery powered flash about 3 feet away...

In any event, excellent work tracking down the source of the noise!

-PB

Title: Re: Buzzing
Post by: crgolfer on November 12, 2013, 10:09:35 AM

I wish that I would have noticed the source of the problem sooner.  I can't guess how many times over the last 6 months  I have had the Beepree apart trying to track down a non-existent soldering problem.  I never thought of the power connection being a problem because I had a Foreplay with the same connections and no problems.  The Beepree must be more sensitive to AC quality.

I just ran the Beepree from a different outlet for about 2 hours with no buzzing.

Title: Re: Buzzing
Post by: Paul Birkeland on November 12, 2013, 10:24:18 AM

Quote from: crgolfer on November 12, 2013, 10:09:35 AM

I wish that I would have noticed the source of the problem sooner.  I can't guess how many times over the last 6 months  I have had the Beepree apart trying to track down a non-existent soldering problem. 

At this point, you may have the most solidly soldered BeePre out there ;)