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EAR 834P mod - help identifying components
EAR 834P mod - help identifying components
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Old 26th July 2018, 09:46 AM   #31
spaceistheplace is offline spaceistheplace
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EAR 834P mod - help identifying components
Default EAR 834P mod - help identifying components

Can you clean up what you have and post?

220k may be reduced to account for the JFET?

There’s a difference between cheap and stupid. There’s a reason for it.
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Last edited by spaceistheplace; 26th July 2018 at 09:52 AM.
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Old 26th July 2018, 11:29 AM   #32
Herr Grau is offline Herr Grau  Germany
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I'll post it as soon as I get home and have a minute. I'm certain there's a reason for the reduction of the load resistor to 220K. But I don't think there is one for constructing it of 6 cheap smaller MFRs except "practical reasons".
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Old 2nd August 2018, 04:35 PM   #33
Herr Grau is offline Herr Grau  Germany
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Here's what I have. The part between V2 and V3 and the RIAA are obviously already changed to the modded version, as are the PSU capacitors and their bypass. I didn't bother to change any of it back, because the board is true to the original schematic there (first page, first post). The main thing is the input stage, and this I think is halfway acurate. The one resistor I couldnt properly identify by the color codes and also readings on the meter changed towards bigger values. Maybe it's 330k, maybe it 440k, maybe its even more.
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Old 2nd August 2018, 05:22 PM   #34
hottattoo is offline hottattoo  United States
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IIRC check out GoodSoundClub - Romy the Cat's Audio Site. This is Romy the cat's site and look up "end of life phono stage" i believe he modded an EAR unit to max performance. Perhaps you can find some good info.
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Old 8th August 2018, 10:51 PM   #35
PRR is offline PRR  United States
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The JFET should not be critical(*). Most any JFET will give a noise-figure at 1mA lower than the 2.2K source resistor, which is not large compared to the pickup noise impedance. 2.2K will also swamp-out JFET transconductance variation. I'd just use the same type and lot for both side of a stereo.

(*) That last plan can not be right. Assuming high voltage supply (over 70V), it runs the JFET at half the supply voltage. So for 200V supply, 100V, across a device rarely rated much over 35V. A 330K:68K divider might be OK for lower B+. 330K:33K may be even safer. There's no reason for more than a few volts across the FET.
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