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Doug Self Elektor phono preamp: SA1085 substitute?
Doug Self Elektor phono preamp: SA1085 substitute?
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Old 23rd September 2013, 01:37 AM   #1
tcpip is offline tcpip  India
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Default Doug Self Elektor phono preamp: SA1085 substitute?

I am thinking of building the phono preamp from Doug Self's Elektor preamp circuit. I intend to buy the PCB which Elektor sells, use the components in the official parts list (may replace NE5532 with LM4562, maybe even not do that) and make my own power supply and case.

But his MC pre-preamp seems to use SA1085 which are not available any more. Any idea whether they are still being manufactured, and if not, then what can I use as substitutes? I need pin-compatible substitutes, since I want to use the same PCB.

Many thanks in advance.
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Old 23rd September 2013, 06:41 PM   #2
tcpip is offline tcpip  India
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Any suggestions?
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Old 23rd September 2013, 06:57 PM   #3
Mooly is offline Mooly  United Kingdom
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Doug Self Elektor phono preamp: SA1085 substitute?
What is an SA1085 ? IC ? or transistor (2SA1085)
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Old 24th September 2013, 11:00 AM   #4
tcpip is offline tcpip  India
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Oops... 2SA1085, not SA1085.

Sorry.
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Old 24th September 2013, 11:05 AM   #5
tcpip is offline tcpip  India
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I tried looking in digikey; they don't have it. I tried findchips.com, and I was pointed to RS Components; none of the other resellers have it. On RS Components, I found this (screenshot attached). It's not that the transistor is not in stock -- it is a discontinued product.
Attached Images
File Type: png 2SA1085.png (54.2 KB, 481 views)
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Old 24th September 2013, 11:15 AM   #6
Mooly is offline Mooly  United Kingdom
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Doug Self Elektor phono preamp: SA1085 substitute?
OK

Well in many ways its just a generic PNP used in numerous commercial applications, however as Doug will no doubt have chosen it for some preferred characteristics such as noise etc (I'm assuming its in the front end) then perhaps he may be the best to ask on a replacement. Even something as run of the mill as the 2N5401 is probably OK.

Why not ask here and link to this thread,
http://www.diyaudio.com/forums/solid...mp-design.html
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Old 24th September 2013, 05:02 PM   #7
tcpip is offline tcpip  India
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Quote:
Originally Posted by Mooly View Post
(I'm assuming its in the front end)
Yes, the extreme small-signal stage at the input of the MC pre-preamp

Quote:
... then perhaps he may be the best to ask on a replacement
I was so hoping he would comment, but he's not said anything.

Quote:
Why not ask here and link to this thread,
http://www.diyaudio.com/forums/solid...mp-design.html
Actually I discovered an earlier thread, more than a year old now, which had been started with exactly the same requirement as mine, and I'm getting some suggestions there. But Doug Self is silent.
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Old 24th September 2013, 05:22 PM   #8
Mooly is offline Mooly  United Kingdom
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Doug Self Elektor phono preamp: SA1085 substitute?
Try asking the question on the thread I linked to
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Old 24th September 2013, 06:46 PM   #9
Mark Johnson is online now Mark Johnson  United States
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Doug Self Elektor phono preamp: SA1085 substitute?
The Elektor article states that 2SA1085 is Mr. Self's second choice; he actually prefers the 2SB737 but these are out of production and difficult to source. The Signal Transfer Company happens to sell the 2SB737, see their "Price List" web page.

Both are TO92 with ECB pinout.
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Old 26th September 2013, 12:11 PM   #10
quadtech is offline quadtech  India
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Here's an interesting article here comparing a BC560, 2SA1085 and a BF423 - and
some surprises....

Common-mode distortion.
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