Resistor upgrades for Eros?

mwaller · 2600

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Offline mwaller

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on: May 12, 2016, 08:21:49 AM
I've read a number of posts indicating that various resistors can be replaced for improved sound. 
Many people swear by the TX2352 resistors...
Which resistors are most critical to the sound, and what components are considered the best replacements?
Thanks,
Mik



Offline mwaller

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Reply #1 on: May 13, 2016, 07:36:58 AM
I've read that the 47K input load resistor and 47K (2W) output tube plate load resistor are critical to the sound. 
How about the 27K (1W) resistor attached to the cathode of the output tube?
Thanks,
Mika



Offline Paul Joppa

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Reply #2 on: May 13, 2016, 10:01:30 AM
The 27K is bypassed with a large electrolytic, so the resistor has little effect. That cap will have more effect. The 75K and 10.5K in the RIAA filter are probably important. We have used good quality metal film resistors, so effects will be small.

Paul Joppa


Offline mwaller

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Reply #3 on: May 16, 2016, 01:13:31 PM
The 27K is bypassed with a large electrolytic, so the resistor has little effect. That cap will have more effect. The 75K and 10.5K in the RIAA filter are probably important. We have used good quality metal film resistors, so effects will be small.

Thanks for the reply!  Regarding that 100uF /160V bypass cap - what voltage rating is actually required in this application?  Is a 50V cap ok, or do you really need the 160V rating?
Thanks,
Mika



Offline Doc B.

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Reply #4 on: May 16, 2016, 01:31:49 PM
I'll suggest studying the schematic if you are going to make these modifications. From the schematic you can see that the voltage at the cathode of the 6922 is 27174 ohms x .0038A = 103V.
« Last Edit: May 16, 2016, 01:50:00 PM by Doc B. »

Dan "Doc B." Schmalle
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Bottlehead Corp.


Offline mwaller

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Reply #5 on: May 16, 2016, 01:52:16 PM
I'll suggest studying the schematic if you are going to make these modifications. From the schematic you can see that the voltage at the cathode of the 6922 is 27174 ohms x .0038A = 103V.

Thanks for the explanation. I'll have a closer look.
Mika



Offline mwaller

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Reply #6 on: May 16, 2016, 04:22:30 PM
The 27K is bypassed with a large electrolytic, so the resistor has little effect. That cap will have more effect. The 75K and 10.5K in the RIAA filter are probably important. We have used good quality metal film resistors, so effects will be small.
What brand / type is the stock 100uF 160v cap?  Mine doesn't have any mfg markings.  Thanks!
Mika



Offline Doc B.

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Reply #7 on: May 16, 2016, 04:26:29 PM
We use Nichicons.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.