VO-BB - 20 YEARS OLD!

Dan-O · The Gates of Troy Joined: 17 Jan 2005 Posts: 1638

Hi All,

In the middle of a session today, my engineer alerted me to a sudden increase in my noise floor. After hunting it down, my Avalon 737 become the culprit. I quickly switched over to my trusty Focusrite Voicemaster Pro to finish the session. Can anyone help me eliminate the noise or should I just send it in for repairs?

(EDIT: SAMPLES NO LONGER AVAILABLE>)

Here are some trouble shooting steps I have already taken:

Noise is still generated with Preamp Gain off and even when I barely increase the Output Gain.

All tubes are still functioning (EH-6922)

Any help would be great.

Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

Look in your Avalon manual for a reference to a ground attachment (I think they refer to it in the troubleshooting section) that you may not need, and that could be the cause.

Of course, be sure that you don't need it before removing it.

I have gotten weird noises from time to time, but it usually has been a problem with my converter (Apogee Duet).

Mike Sommer · Posted: Wed Dec 16, 2009 8:18 pm Post subject:

It could be a tube.
Next a capacitor.
After that the Opto unit for the compressor.

Try a new tube.
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Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong.

Dan-O · The Gates of Troy Joined: 17 Jan 2005 Posts: 1638

Rob, thanks for the suggestion. I couldn't find my manual, so I tried Mike's suggestion, first. And...

Mike did it, again...kinda

Through process of elimination by removing one tube and replacing it with a new one; I found the third of four tubes was bad. (Good thing I ordered an extra one.) But, then the problem became evident again ten minutes later.
And then I was happy, again, because it came back down. Very strange.

Mike Sommer · Posted: Thu Dec 17, 2009 12:19 am Post subject:

It could be a leaky electrolytic capacitor.

Keep and eye on it for a few days and see what happens. If it starts up again, it might be best to send it out for service; no sense in fooling around blowing perfectly good tubes.

(If I had a schematic and knew which tube it is, I could possibly boil it down for you. I would not rule out the Opto unit for the compressor either, sometimes when they go out they can create a lot of hiss.)

Keep us posted.
_________________
The Blog:
http://voiceoveraudio.blogspot.com/

Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong.

Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

Dan-O,
Here is the page in the manual that refers to the ground link:

Mike Sommer · Posted: Thu Dec 17, 2009 8:31 am Post subject:

I'm hearing floor noise/hiss, indicative of a bad tube, a ground hum or buzz would be louder and undeniably obvious.

One other thing- you could be having a pin connection problem with the tube socket. Plastic sockets are notorious for this.
_________________
The Blog:
http://voiceoveraudio.blogspot.com/

Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong.

JTVG · Backstage Pass Joined: 21 Jun 2007 Posts: 433

Dan,

Noticing the exact same thing with mine but I didn't think much about it until I saw your post. It was brand new only about a year ago. Just seemed like the hiss was more noticeable in the last few months. I gate a little but even that was letting more noise through than what's normal.

Maybe I'll pick up some new 6922's and troubleshoot.

One other thing -- I was able to bring the noise floor down a little by reducing the output drastically and counteracting that by increasing the input. Since I don't use the compressor, it sounds pretty much the same either way. The higher that output level, the louder the hiss, regardless of where the input level is set.
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Joe Szymanski
http://www.joethevoiceguy.com

Dan-O · The Gates of Troy Joined: 17 Jan 2005 Posts: 1638

Your solution is right on, Joe. According to Mike at Avalon, the optimum settings for low noise is to set your Output Gain in between -4 and -6, then set your Preamp gain at 0, then adjust the Preamp Gain to your acceptable level of noise. Use your mixer to adjust volume once you have your preferred settings. Since, the amp uses class A tubes, which are at full power at all times, you receive the "Avalon Sound" at any level of output.

JTVG · Backstage Pass Joined: 21 Jun 2007 Posts: 433

Interesting. I appreciate the call today too, Dan. I looked at my output and it was right about -6 so I'm right in the ballpark.

I've always had a suspicious that cranking the input did not, in fact, drive the tubes harder as people say. Other than being louder and leading to distortion, there was no noticeable tube difference to my ears.

Keep us all posted!
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Joe Szymanski
http://www.joethevoiceguy.com