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Old 30th July 2011, 08:13 PM   #11
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Hello Nelson,

thanks for the quick reply!

The schematic doesn't match, unfortunately. On the other hand it was pretty helpful as it's similar, input stage is identical (I suppose..).

The board has an opto coupler 4N37 plus one transistor PN 4250A not contained in the drawing and I can see only one thermistor.

Any idea?

Cheers, Gerhard
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Old 21st August 2011, 11:32 AM   #12
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Gentlemen, I have upgraded the big power supply caps on my SA-2's so far. I wanted as well to update the rectifiers but am challenged as to what the best solution here should be. Fast, slow - and with the upgraded capacitance in the power supply would anyone have experience with a specific model of rectifier? Thanks in advance
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Old 21st August 2011, 11:37 AM   #13
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Quote:
Originally Posted by nailzgun View Post
Gentlemen, I have upgraded the big power supply caps on my SA-2's so far. I wanted as well to update the rectifiers but am challenged as to what the best solution here should be. Fast, slow - and with the upgraded capacitance in the power supply would anyone have experience with a specific model of rectifier? Thanks in advance
Nelson prefers the slow ones.
I've upgraded my SA/1's from the stock 29,000 uF Mallory's to 68,000 uF CDE's.
The rectifiers are attached to the bottomplate so I reckoned they cool down enough so I kept the ones that were already in. I did not encounter any problems with them as far as I know.
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Old 21st August 2011, 11:43 AM   #14
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Quote:
Originally Posted by SL10User View Post
Hello all,

recently got a S/500. It had DC offset 3 V in one channel and distortions at higher levels.

Found defective device 2N5566. Have ordered replacement already, hope it will work...



I noticed that these both previously posted schematics (Thanks, Nelson!) doesn't match with the PCB in my S/500. A matching schematic would have been very helpful. So I had to find the defective device by swapping with the good channel...

Does anybody (Nelson?) have knowledge of this specific version? Seems to be an early version (or stripped down)?

Here is a picture:

Thanks
It looks like the optical bias version to me because there's a blue thermister that pokes into your heatsink. The black one is for the thermal shutdown provision.
The last Schematic Nelson supplied is from the Series II versions.
The first one he supplied is the most correct one because it has the IC's and thermistors on them.
I will also attach a frontendboard from a SA/1 optical bias version which seems the same to me as your version.
Attached Images
File Type: jpg Opticalbiasboard 2.jpg (135.2 KB, 225 views)
File Type: jpg Opticalbiasboard.jpg (45.1 KB, 211 views)
File Type: jpg Opticalbiasboard 3.jpg (76.2 KB, 209 views)
Attached Files
File Type: pdf attachment.pdf (65.3 KB, 60 views)

Last edited by RobertS61; 21st August 2011 at 11:56 AM.
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Old 24th August 2011, 10:53 PM   #15
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Hi SL10
This must be the right one:
It's a drawing from a S/300 but the frontend is the same as all the SA and S Series with optical bias before the 'E' series of 1989.
Attached Images
File Type: jpg Threshold Optical bias version 1988.jpg (97.4 KB, 200 views)
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Old 11th December 2011, 03:01 PM   #16
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Quote:
Originally Posted by BrianEno View Post
Hi SL10
This must be the right one:
It's a drawing from a S/300 but the frontend is the same as all the SA and S Series with optical bias before the 'E' series of 1989.
Ok, so I am enamoured with capacitors these days having just finished updating the cross-overs on my speakers for a second time. This time using Mundorf and Obbligato capacitors instead of the basic generic caps that can be had at one of my local speaker parts stores. I could not be more surprised and pleased at the results of replacing the caps of these speakers which for the mid 80's were considered to be upper echelon in quality. This makes me wonder how much of an improvement can be had by updating the front end caps on my SA/2 with a couple of today's "Supercaps" like a V-Cap or a Dueland.

My question then is this. Which of the front end caps would be sensible to replace. The silver pF caps I would think should stay. The tantalum seems like it would be eligible as would the Mylar and Polyfilm caps. The 47uF aluminum also seems a good candidate likely where a Blackgate would have gone, but has anyone tried to shoehorn a film cap here?

I am looking for bang for the buck here, so if a single change makes a big sonic difference then this would be a place to invest as opposed to changing all.

Lastly has anyone added bypass caps to the main big cans and if so what would experience recommend?

Thanks!
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Old 11th December 2011, 03:48 PM   #17
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Default Thanks!

Hi BrianEno,

read your post today.

Yes, that's it!

Thank you very much and

Kind regards,
Gerhard

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Old 6th December 2012, 11:26 PM   #18
wsjoe is offline wsjoe  United States
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So what is a good market price of a pair of Treshold SA2?
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keep those balls on the fairway...
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Old 7th December 2012, 12:29 PM   #19
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Wink Marketprice Threshold Stasis Series

Based on my 30 year experience with Threshold gear buying and selling this would be my best estimation for near mint Threshold Stasis designs.
I have not much experience with the last 'e' Series (SA/3.9 ~ SA/12 and S/450 ~ S/1600) so I did not provide listings for these ones.
The once graced with meters (Stasis 1, S/1000 and SA/1 are particurlary wanted)
The Stasis 1 is pretty rare and the only offering in the US I ever saw was from Nelson's long time associate Joe Sammuth.
My favorites: SA/3 (because Nelson likes it so much ) the S/500 and the SA/1.
Upgrades are for 90 percent in the frontend section.
When ever I bought a Threshold I immediately swapped all the lytics (big cans also) and I would start a so called stowed away or not used for a long time with a Variac. Nelson did not employ any sofstart relays with these models in so far I know so you won't burn out the rushincurrent limiting resistors.

- Stasis 3: $700.00
- Stasis 2: $1000.00
- Stasis 1: $5000.00 (pair)

- S/150: $450.00
- S/200 Series II: $600.00
- S/200 optical bias: $700.00

- S/300: $700.00
- S/300 Series II: $800.00
- S/300 optical bias: $900.00
- SA/3: $900.00
- SA/3 optical bias: $1000.00

- S/500: $1000.00
- S/500 Series II: $1150.00
- S/500 optical bias: $1350.00

- SA/2: $2250.00 (pair)
- SA/2 optical bias: $2500.00 (pair)

- S/1000: $3500.00 (pair)
- S/1000 Series II: $4000.00 (pair)
- SA/1: $4500.00 (pair)
- SA/1 optical bias: $5000.00 (pair)

Last edited by RobertS61; 7th December 2012 at 12:33 PM.
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