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Old 8th February 2013, 06:46 PM   #9241
Salas is offline Salas  Greece
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3-5ma
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Old 8th February 2013, 06:58 PM   #9242
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Originally Posted by Tea-Bag View Post
I am going to start hoarding K369BL
You are going to enjoy a very noticeable reduction on noise. Not only it refers to ground but uses much less current through the cascode BJT which brings it to better current noise and linearity region. Also 2 K369BL are ideal for LMC since the extra capacitance won't bother the bandwidth with such low coil resistance carts. The penalty is the more defined input overload margin (VPP after first stage gain x100 plus) given the RIAA 20dB rise and vinyl hitting over 0dB modulation its something to know how to handle when matching carts and gain. A 58dB single K369BL with 0.9mV cart did not manage to go clipping with dynamic 45rpm reissues is my harder real life test up to now.
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Old 8th February 2013, 07:03 PM   #9243
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Salas,
As a side note, the Bf245A is difficult to source, stateside, but the 245C, which is availalble, needs to be degenerated by about 35-40 homs. I have 33 and I think it reduces current to 6-7mA. Might be noteworthy to future builders of the folded version.
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Old 8th February 2013, 07:21 PM   #9244
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Its everywhere in EU, I could find it in local stores even, maybe harder in the US? A BF245B can be degenerated with less resistance also. A K117GR is acceptable also. Any low noise low capacitance circa 5mA JFET in other words. See if there is something under 20nVrtHz J series American chopper JFET for there is another guide. Those who gonna make SSLVs for it gonna have K117GR spares nonetheless. Since it only takes shorting s&g pins which are sequential in most pin outs when the IDSS is right unaided by degeneration, using several types should be a breeze.
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Old 8th February 2013, 07:24 PM   #9245
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3-5ma
Yep
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Old 8th February 2013, 08:40 PM   #9246
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Originally Posted by Salas View Post
Its everywhere in EU, I could find it in local stores even, maybe harder in the US? A BF245B can be degenerated with less resistance also. A K117GR is acceptable also. Any low noise low capacitance circa 5mA JFET in other words. See if there is something under 20nVrtHz J series American chopper JFET for there is another guide. Those who gonna make SSLVs for it gonna have K117GR spares nonetheless. Since it only takes shorting s&g pins which are sequential in most pin outs when the IDSS is right unaided by degeneration, using several types should be a breeze.
OK. I was unsure of how important that specific part was to performance. Does the degeneration add noise?
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Old 8th February 2013, 09:36 PM   #9247
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Sorry, exactly Ricardo have five 7.8mA and four 7.7mA K170, could I use?
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It will not go too far off I suppose.
Wich is the best position for each Idss, or is the same?

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Old 9th February 2013, 10:36 AM   #9248
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OK. I was unsure of how important that specific part was to performance. Does the degeneration add noise?
Yes but insignificant when talking low ohms in that position. Mainly the Jfet needs be medium impedance to match the Leds own for better PSRR and their 1mF cap to be good in shorting the noise and hum.
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Old 9th February 2013, 10:37 AM   #9249
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Originally Posted by merlin el mago View Post
Wich is the best position for each Idss, or is the same?
Same.
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Old 9th February 2013, 10:46 AM   #9250
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Yes but insignificant when talking low ohms in that position. Mainly the Jfet needs be medium impedance to match the Leds own for better PSRR and their 1mF cap to be good in shorting the noise and hum.
New version gets fired up today. Got dual 175VA instead of 50VA. It will all be cased up, with seperate psu. Also have some 369 coming for comparison.

One quick question. In main pdf, you spec SSlV 1.5. Does this outperform 1.1 which i am currently usiing?
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