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Simplistic NJFET RIAA
Simplistic NJFET RIAA
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Old 15th September 2008, 03:01 AM   #91
Salas is offline Salas  Greece
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Old 15th September 2008, 03:03 AM   #92
Salas is offline Salas  Greece
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Old 15th September 2008, 03:22 AM   #93
Salas is offline Salas  Greece
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Default Tracking the trax

Listened for many hours with the stripped 0.25mV Ortofon. This RIAA sounds hideously correct. I have put a lot of effort in details that don't stick out when you see the schematic. Don't change it if you make it!
The 7.5mA Idss 2SK170BL is used in my modeling because I have seen that the majority of them is 7-8mA. They are matched per stage and side of course. See that you read roughly the same Voltages on JFET drains per stage. Trim the corresponding Rs if some Vd is off the median for a JFET. There is no NFB so that is your ticket to L-R balance. I used a Telarc Omnidisc and I measured the balance from cartridge to line out for L&R. OK.

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Old 15th September 2008, 11:41 AM   #94
nicoch58 is offline nicoch58  Europe
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VERY GREAT WORK Salas!

IF you feel that you can live withot a tube is a time to order better part because are so sensitive ....


PM if joint with me for order
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Old 15th September 2008, 02:21 PM   #95
Salas is offline Salas  Greece
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Thanks nicoch46. I have to see what happens with the Steve Bench tube circuit and compare so to finally decide. Also to set up the Denon DL-160 too. As it is, there is good synergy for tone between parts. No nastiness anywhere. The good thing with the Russian capacitors is that they have great value for money. The polystyrene and mica of the Soviet army can really sing. Some can prove dodgy though. Ebay stuff, you know. I will keep the Salas RIAA of course and will be listening to it. If I decide its best maybe I will scrutinize parts. What is your experience so far? What parts are best for you in RIAA, coupling, PSU bypassing etc?
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Old 15th September 2008, 02:38 PM   #96
kevinkr is offline kevinkr  United States
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Hi Salas,
Cool and a good result.. For safety though I strongly recommend a fuse at the battery and before the 10,000uF cap in the event of an inadvertent short circuit. I don't think you want to see what will happen.. Wire melting so fast your head will spin, batteries venting, and plates buckling, worst case a burning battery. (Yes I have seen this happen with SLA batteries.)

Your comments about battery impedance echo mine exactly, note also that batteries are not as quiet as many believe, although at the low operating currents of this pre-amplifier it is probably not an issue. Apparently the chemical reactions going on between the plates and electrolyte generate measurable LF noise. (Probably see it best with a very good 24 bit sound card and any of the extant FFT based audio analyzer software.)
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Old 15th September 2008, 02:46 PM   #97
Salas is offline Salas  Greece
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Thanks Kevin. True, if not properly decoupled, they can even cycle pump the woofers! Good for no fields if in same box and nice sonics at low current consumption though. Yes I will fuse soon.
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Old 15th September 2008, 03:32 PM   #98
Salas is offline Salas  Greece
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Default Greg Ball is cool!

I must credit Greg Ball of SKA, Australia. We had a very fruitful discussion and opinions exchange about the JFET peculiarities and design approach. He is very knowledgeable, practical and open. No wonder his kits have an excellent fame.

Thanx Greg!

SKA-Audio
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Old 15th September 2008, 03:34 PM   #99
nicoch58 is offline nicoch58  Europe
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is I have read that alkaline are better ,but.... some info

big step when I change metal Rdrain and 200mf muse for dale-2200mf mundorf

signal mundorf are very good but I use in bypass with claritycaps to lower the cost.... s/o are very sweet...

for riaa you are correct polystyrene or mica ,for now i use vishay MKP 1837 but I can buy some siemens polystyrene ......

need try vishay nude - caddoc- tamtalum -AB
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Old 15th September 2008, 03:35 PM   #100
nicoch58 is offline nicoch58  Europe
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Yes THANKS GREG !!

in my previous dac i/v for my hear riken better than kiwane ,kw alot better than no name metal
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