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Simplistic NJFET RIAA
Simplistic NJFET RIAA
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Old 9th March 2013, 01:20 AM   #9381
Siberia is offline Siberia  Lithuania
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Quote:
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Yours are Spendor S100 if I remember well? At 89dB/W/m as measured by Atkinson they should be much more comfortable than SHL5 with a circa 50W amp. Current delivery and damping factor from just a couple of drain out Mosfets in a low negative feedback amp won't be spectacular but your speaker does not dip impedance too violently. You will evaluate in time.
Yes, it's S100. That's why to VSSA or to TSSA is the question.
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Old 9th March 2013, 03:02 AM   #9382
Salas is offline Salas  Greece
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Simplistic NJFET RIAA
Piece of cake. VSSA class A/B in the bass TSSA 1.6 class A in the mids & highs. Both diminutive and SMD, both same power-same tone, you set their gain the same and you go biamp to push the 12 inchers better.
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Old 9th March 2013, 09:05 AM   #9383
Siberia is offline Siberia  Lithuania
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Ha, ha. That's quite a heroic piece a' cake to me. And after its finished, I would need some Salas DCB2 pre! While staying in a dreamworld, I thought, I could build on of them and if it turns out a bad marriage with S100, I would ditch them for some potent DIY ones.

SMD keeps me at bay, but as LC says, there has to be a first time someday.
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Old 10th March 2013, 03:42 AM   #9384
The Space Egg Corp is offline The Space Egg Corp  England
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Old 10th March 2013, 10:39 PM   #9385
Tea-Bag is offline Tea-Bag  United States
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Simplistic NJFET RIAA
Here is my stash of 60- 2SK369-BL measured at 9V for 20 seconds each.
These were purchased at AMPSLAB. The deviation seems similar to 2SK170BLs.

9
9.3
9.5
9.5
9.7
9.7
9.7
9.8
10
10.3
10.5
10.5
10.5
10.5
10.6
10.7
10.7
10.7
10.8
11.1
11.4
11.4
11.4
11.5
11.5
11.5
11.8
11.8
12.1
12.2
12.2
12.2
12.4
12.4
12.5
12.5
12.6
12.8
12.8
12.8
12.9
12.9
12.9
13.1
13.1
13.1
13.3
13.3
13.9
14
14
14
14.4
14.4
14.5
14.7
14.7
14.9
15.1
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Old 10th March 2013, 10:46 PM   #9386
Salas is offline Salas  Greece
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16 pcs from 10.5 to 11.5 already and pairs on every higher step. A very usable stash.
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Old 10th March 2013, 10:56 PM   #9387
Tea-Bag is offline Tea-Bag  United States
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Simplistic NJFET RIAA
Quote:
Originally Posted by Salas View Post
16 pcs from 10.5 to 11.5 already and pairs on every higher step. A very usable stash.
And the rest is not suitable for our purposes correct? or can the source resistor be raised to use higher IDSS pairs?

Last edited by Tea-Bag; 10th March 2013 at 11:09 PM.
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Old 10th March 2013, 11:07 PM   #9388
Salas is offline Salas  Greece
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It can. But the smaller it stays the less it adds its own small noise. There is some good bunch around 12.5mA +/-1 also in yours. If others will report some stashes too we will have some statistic so to fix the IDSS spec to what will be expected as easier to chance on.
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Old 10th March 2013, 11:14 PM   #9389
Tea-Bag is offline Tea-Bag  United States
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Another thought Salas is my measurement time. These are slightly higher numbers, because the higher the IDSS, the more they tended to drift up in IDSS. 20 seconds seemed to be the time where it settled, or just rose much more slowly.
Should we be measuring the first number we see, or standardize on a timeframe? I can remeasure if we all agree on a certain standard.
It looks like a 25 percent yield on a stash, so expect to order possibly 4x what you need. Of course based on my current results.
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Old 10th March 2013, 11:18 PM   #9390
Salas is offline Salas  Greece
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High transcondutance Fets tend to drift up noticeably because the warmer they get the easier it is to gain enough more current. We will say 20 secs time for all.
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