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Bias setting on Pristine 2 - Feedback from members (Read 348 times)
Yoshi
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Bias setting on Pristine 2 - Feedback from members
Mar 24th, 2017 at 3:22pm
 
Pristine 2 bias control:  I have owned my panels for over 20 years, and had them updated with the copper diffusion ring, new Mylar and a power supply.

Had some arcing on the panel screws to the frame for a while, but backed off the bias and clean the electro-static dust off between the screw heads regularly has mitigated the effect.

I now have the bias control set around 2-2:30 on the dial.  There is more headroom on the dial, and when rotated past 3:00, I will get an audible discharge noise.

Is this a regular occurrence for olde models, to have the bias turned up at this level, without noise discharge?  I would like to turn it up more, for higher efficiency, but I more concerned about any damage that may arise from setting the Bias at around 3:00.  Is this a sign of any issue for me address, or is there an update that is resonantly priced? 

Like to get some feedback on this form other pristine, dealer or SL owners.

I am running them with a fully modified VTL 220t , el-34 based, hard wired triode mono blocks that I have had for a very long time.

My set up is on Canuck audio, see Yoshi, for member systems.

Look forward to a comment and devise or experiences.

Ps:  still would like to turn it up the bias...

Ken
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HJP
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Re: Bias setting on Pristine 2 - Feedback from members
Reply #1 - Mar 24th, 2017 at 11:19pm
 
Ken,

Everything you have said sounds normal, more or less the same as my experience with my U-1's over many years.  Here's the way I recommend setting your bias for maximum sensitivity.  However, you should know some say a slightly lower bias level sounds better (less aggressive and harsh).  But try what I'm about to suggest and then back it off a little and decide which you prefer for yourself.

Slowly advance the bias control until you begin to hear some gentle "pops" and light "ticking" sounds that occur a few seconds apart.  These are very light and cannot be easily heard unless you listen in a very quiet room close to the speakers.  They will not be heard at all over even very soft music.  If you go too far, you will hear a constant "rushing" noise that resembles the sound of frying eggs.  This is too high and must be backed off to the level of the light ticks.  This will be the maximum safe bias level.  These light ticks are not harmful however, I strongly recommend you leave the speakers unplugged when not in use.  Continuous application of high voltage, especially the extreme high voltages that Sound Lab uses, is harmful to many materials over time.  Left that way for long enough virtually guarantees deterioration.  I have personal experience with this although not with Sound Labs.  Since your updated panels will reach full charge in a few seconds, there is no advantage to leaving them plugged in.  Word to the wise.

That's it.  Hope this helps.
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Yoshi
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Re: Bias setting on Pristine 2 - Feedback from members
Reply #2 - Mar 25th, 2017 at 4:52am
 
Thanks for your quick reply and comments.

For other potential respondents to this issue, are there any downsides from having the bias control running at approx.3:00 o'clock on the bias dial, to achieve optimal panel efficiency? 

If this is the bias setting where the panel efficiency is optimum, does it indicate any determination of the power supply or other voltage deliver system to the electrostats?

Look forward to your experiences and comments.

Thanks for reading ,

Ken



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Re: Bias setting on Pristine 2 - Feedback from members
Reply #3 - Mar 25th, 2017 at 9:37am
 
Yoshi wrote on Mar 25th, 2017 at 4:52am:
Thanks for your quick reply and comments.

For other potential respondents to this issue, are there any downsides from having the bias control running at approx.3:00 o'clock on the bias dial, to achieve optimal panel efficiency? 

If this is the bias setting where the panel efficiency is optimum, does it indicate any determination of the power supply or other voltage deliver system to the electrostats?

Look forward to your experiences and comments.

Thanks for reading ,

Ken





Ken,

The specific position of the bias control, whether 3:00 or any other location, has nothing to do with a maximum sensitivity setting.  There are many other things that determine where a given control on a given speaker winds up including relative humidity in your house at the time you adjust it.  This is why Sound lab provides the ability to adjust the bias in the first place.  What determines the maximum safe bias setting is the noise you hear as you advance the control.  You want the control as high as you can get it short of the "frying eggs" sound, just light ticking.
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Re: Bias setting on Pristine 2 - Feedback from members
Reply #4 - Mar 25th, 2017 at 10:43am
 
Thanks for your feedback and advise.

Will give this a go.

K

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