No crackling sound

[John V]

That’s correct, you can see that it is connected to the AC receptacle
and line fuse holder. Output of the supply, red wire, plugs into the HV mixer.

[hpfish10]

Hi John, from your photo where is the bias supply? Is it the gray/white rectangular shape unit to the right of the bias control?

[John V]

HI,

Correct, directly from the SL factory, speak to Connie and she’ll be able to fix you up.

Replacement is not difficult although it does entail soldering a few connections. Take a look at the pix. below, that should give you a pretty good idea. You’ll need to replace the bias control, included with the bias supply, also.

John

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[hpfish10]

Hi John V., where can I get the new bias supply? From SL factory? How easy to replace them?
My A1 is around 2001.

Update: i have crank up bias to max last few days, the right speaker has very low crackling noise and while playing music emitted some pop sound so I had to reduce the bias, but the left one no crackling BUT they both play loud enough.

[bk12]

When I had this issue in a past set of SLs, it turned out to be a panel issue fwiw. Dr. West and company will be a great asset in helping you get to the bottom of your issue.

[yoshi]

Hello:

The Dr. knows best…

IMO, Probably not the bias pot.
The bias supply may be tapped out due to a panel issue.

If it works and sounds good, turn up the bias control and see if these is some discharge over the next several days, or with a change in higher humidity/ weather low pressure. This may show you are close to a reasonable bias is level. Then enjoy.

Or,
A speaker turnaround return will take time and based upon repair and inevitable updates will run you some funds. you should then consider updates all things considered.

[John V]

You could try replacing both bias supplies with the newer version to see if that resolves the issue.
Also, the new bias supplies are regulated so line voltage variations no longer affect the bias level.

How old are your A1’s?

John

[hpfish10]

I have A1 with Toroidal (I think it is Toroidal I not II) upgrade. When I turned the bias control to max there was no crackling sound on one panel, i swapped backplates the issue did not follow the backplate so sound like backplate was not the culprit. Now both panels have no cracking sound. I emailed Dr West he think might need panel rebuilt.
Music still play fine in both panels. Could it be the bias pot not working and need replaced or should I just forget about it and enjoy music. I feel that i need to crank up volume more though.
Thanks for any input and advise.

[Author]

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