Threshold S/1000 optical bias??

RobertS61 · 2018-02-21 5:38 pm

Dear fellow diy's

This Threshold amplifier is not suppose to exist as far as I know and understood from it's designer Nelson Pass.
SA/1 optical bias yes S/1000 only Series I & II.
http://www.diyaudio.com/forums/attachment.php?attachmentid=663964&stc=1&d=1519234649

Any thoughts, not real?

Eric M · 2018-02-21 8:28 pm

I have a pair. I purchased mine about 1 year ago from The Music Room. It is a Series II but not Optical Bias.

Zen Mod · 2018-02-21 8:29 pm

if Papa doesn't know , who else ?

RobertS61 · 2018-02-21 8:41 pm

Eric M said:
I have a pair. I purchased mine about 1 year ago from The Music Room. It is a Series II but not Optical Bias.

Yes I had a S/1000 Series II also but an optical bias version is as far as I know never produced.

Eric M · 2018-02-21 8:42 pm

Where did you find the picture?

RobertS61 · 2018-02-21 10:51 pm

Eric M said:
Where did you find the picture?

Audiogon

RobertS61 · 2018-02-22 12:18 pm

Eric M said:
I have a pair. I purchased mine about 1 year ago from The Music Room. It is a Series II but not Optical Bias.

Hi Eric,

Did you get the needlepointer of the VU meter fixed?

Eric M · 2018-02-22 1:03 pm

No, not yet. There is a place that can do it. I need to send both meters in and they will replace both needles, so they match. It's on the to do list, but keeps getting pushed further down.

RobertS61 · 2018-02-22 1:36 pm

According to Nelson Pass these are Modutec Mustang series
http://www.diyaudio.com/forums/attachment.php?attachmentid=664120&stc=1&d=1519306320

These were mine S/1000's Series II from 1984:
http://www.diyaudio.com/forums/attachment.php?attachmentid=664121&stc=1&d=1519306485

Yours are from 1986.

Eric M · 2018-02-22 7:46 pm

Thanks,

I wonder if I could repair the meter myself?

RobertS61 · 2018-02-22 8:17 pm

No idea. I think you should take it to the professional you already found.
Maybe Jon Soderberg of http://www.vintageamprepair.net/: knows a solution.
Modutec is now Jewel as far as I know.

They're great sounding amps and as a bonus they look great too!
Happy listening!

Eric M · 2018-02-23 5:36 pm

But this is DIYAudio! I gotta give it a try.
I think I'll probably send them in. Swapping components I can do, I'm not even sure where to find meter parts, how to calibrate, etc. But for now the amp sounds the same even with it's stubby little needle frantically swing back and forth at the top of the meter.

RobertS61 · 2018-02-23 5:55 pm

I did swapping the large Mallory cans, Spectrol one turn biastrimmer for a multiturn Bourns, electrolytic on the frontend and a faulty powertransistor bulbs and meterperpex with real glass. That was not really DIY like cloning an amp but better than nothing...
Those meters is a specialist job I reckon. You can't just glue on the missing part it seems to me.
http://www.diyaudio.com/forums/attachment.php?attachmentid=664312&stc=1&d=1519408856

Nelson Pass · 2018-02-23 6:21 pm

Perhaps you will appreciate these 1985 brochure pages, which
is all I have on the amplifier.

Eric M · 2018-02-23 6:51 pm

Mr. Pass, could I ask you to take a glance at the preamp board here:

Need help identifying Threshold preamp

I'm trying to figure out what it is. It's a Threshold factory upgrade on an NS-10.

Thanks,

Eric M.

Nelson Pass said:
Perhaps you will appreciate these 1985 brochure pages, which
is all I have on the amplifier.

RobertS61 · 2018-02-23 9:57 pm

Nelson Pass said:
Perhaps you will appreciate these 1985 brochure pages, which
is all I have on the amplifier.

Yes I know I have them too but how about a Threshold S/1000 optical bias as depicted in my first post?
I'm almost sure that there wasn't a optical bias version of the Threshold S/1000 only of the SA/1, that is to say with the Thresholds that had VU meters.
Do you concur with that or did Threshold make S/1000 optical bias upgrades with a complete new frontplate (probably as expensive as the 1000VA Fischer & Holden toroid it had) as well?

Thanks for the highres scans though

RobertS61 · 2018-02-23 10:02 pm

Eric M said:
Mr. Pass, could I ask you to take a glance at the preamp board here:

Need help identifying Threshold preamp

I'm trying to figure out what it is. It's a Threshold factory upgrade on an NS-10.

Thanks,

Eric M.

Looks like a FET10 I once had
http://www.diyaudio.com/forums/attachment.php?attachmentid=664368&stc=1&d=1519423347

Eric M · 2018-02-23 10:08 pm

Did your FET 10 have the same layout on the PC board? I've found a few pictures on-line of the FET 10 board, but none are even close to mine.

Thanks,

Eric

RobertS61 said:
Looks like a FET10 I once had
http://www.diyaudio.com/forums/attachment.php?attachmentid=664368&stc=1&d=1519423347

RobertS61 · 2018-02-23 10:34 pm

Eric M said:
Did your FET 10 have the same layout on the PC board? I've found a few pictures on-line of the FET 10 board, but none are even close to mine.

Thanks,

Eric

No probably not. I just looks like an Threshold pre-amp from that era.
It has probably more in common with the FET 10e or 11.
The pre-amps that were sold in the era of the Threshold S/1000 Series II were the FET One and Two Series II designed by Eric Lauchli

Eric M · 2018-02-23 10:44 pm

RobertS61 said:
It has probably more in common with the FET 10e or 11.

FET 11? Is that a misprint or was there a FET 11??

Threshold S/1000 optical bias??

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