Startup sounds for a BeePre and Paramounts

[Bryce]

I'm curious about the sounds that I hear through the initial warm-up phase of the preamp and amps.  After building the systems and basking in the accomplishment of it both working and sounding amazing, I am left with another curiosity...

System:
BeePre with Paramount mono blocks (300b); Orcas with Dungeness subs

Basic procedure:
1) turn on source
2) turn on BeePre (300b)wait (anywhere from 0-30 sec depending on paying attention)
3) turn on Paramount mono block (300b)(L&R)
4) enjoy music
5) reverse for shutdown
6) repeat (on another day)

Observation:
After switching on the power to the amp, after 15 seconds there is a static sound that builds then crescendos with a squeak.  Oddly, the left channel is louder than the right.  I have tested this without the pre-amp connected, with a 10k test plug, swapping the 300b tubes, but not the 5670's yet. After the squeak that occurs in each channel, the background is very quiet.  Playing music appears to be completely unaffected and they operate normally.  At first, I thought that this was a new tube issue, but now that I've put on weeks (<4+) of daily use (>2hr), the warmup sound is unchanged. 

I will try to find a place to post the sound bites captured with my hi-fidelity phone... in .mp4 (AAC) format held by hand at a distance of about 6 inches from the speaker/driver. The only format that I can seem to post audio files in an audio forum is through attaching the files within a microsoft .doc format...

Is this sound something that I should be concerned with? Is this a normal startup sound (albeit, louder in one...)? Is it something that I can repair- i.e. just a bad part (cap) or solder connection?

Thanks,
Bryce

[Doc B.]

It's perfectly normal.

[Paul Joppa]

Normally I would expect the soft-start to suppress the squeak - do you have that, or (equivalently) the v1.1 Paramounts?

[Bryce]

Paul: Yes- I have the v1.1 Paramounts with the soft start. I hear the squeak in both Paramounts. It is just louder in the left channel.

Doc: It is reassuring though to know that the sound is normal. 

[Doc B.]

The squeak is just a slight oscillation. PJ is right that one would think that it would be suppressed by the soft start, at least the first time you turn the amps on after being off for more than 20 minutes. At any rate I've had amps that squeak at startup and others that squeak at shut down. It's not a problem unless it doesn't go away with warmup.

You could double check the solder joints around the soft start board and the 5670 sockets.

[Grainger49]

I've had amps that made, well, farting sounds on startup.  That is why we Bottleheads turn on from source to amp and off from amp to source, all with a 10-30s pause in between.

[Bryce]

 
It doesn't seem to matter if the delay is 30 seconds or more even if the system is turned off overnight. Again, it is reassuring that this squeak is normal.