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Old 4th August 2014, 03:57 PM   #2431
nar is offline nar
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Seems your caps don't block DC ...
"... Audio needs the thinnest wire ..." Rowan McCombe ... I hear it !!!
"Just 'cause they can't hear or sense it themselves doesn't mean you can't !" Allen Wright Allen was right ...
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Old 4th August 2014, 04:03 PM   #2432
Siberia is offline Siberia  Lithuania
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Due to holidays and heat waves the investigation stalled.
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Old 4th August 2014, 04:36 PM   #2433
wayne is offline wayne  United States
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You could try removing the coupling caps between the stages as an experiment.
Do you have a scope to look at it? The input stage is sensitive to temperature and air currents the thermal sinking and cover will help.
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Old 4th August 2014, 05:22 PM   #2434
Siberia is offline Siberia  Lithuania
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Thanks for suggestions. Yes, I do have a scope.
Covering helps. But DC levels after the output caps seems too high.
My next move intended was to check behavior and voltages under standard gain settings.

Seasonal heat waves and 93F at home.
So I'm not uproaching my soldering iron at the moment.
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Old 30th August 2014, 10:40 PM   #2435
Geosto is offline Geosto  Netherlands
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Hi everyone,

I was looking for a new phono amp to use with my high output MC Benz Glider. The phono i wanted needed some more gain than a regular MM stage and of-course it should be better as my current phono stage the Phono Dude.
Of course my search ended with the Pearl2 witch seems to have what it takes.
And because it is DIY i wanted to change the standard boards designed by Wayne a bit.
The connections for the in and output needed on one side of the board so the wiring stays clean, short and simple. Also like to use the Salas shunts so the power regulators are not needed. And also the first and the second stage have there own shunt so the positive power rail needs to be in two sections.
The next thing was to fit it on a 10x10cm board.
I came up wit this design.
My question is now concerning the 2SK170, i have a batch here of 180pcs from the BL type and 40 of the GR type. I can make a set of 8 in the GR range with in the 0.26mA, from 5.52 to 5.78 or i can make a set of 8 with in the 0.03mA in the BL range, From 6.81 to 6.84.
What is the best option here, use lower value with in the 0.26 or use the higher idss type in a closer range of 0.03?

Wayne thank you for this nice peace of work.
Hopefully it sounds as good as your project is documented.
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File Type: png Pearl 2 Pass Back final.PNG (70.6 KB, 269 views)

Last edited by Geosto; 30th August 2014 at 10:48 PM. Reason: Wrong attachment
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Old 31st August 2014, 01:35 PM   #2436
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Awesome !!

Are going to do a group buy?
Blaue Leuchtdioden machen blöd. (hb)
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Old 31st August 2014, 03:02 PM   #2437
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I would go with the BL because of the tighter matching. My quads have Idss ranging from 9.26-9.36. I changed R21-R24 to 20R to get the current down to something like 5.5mA. With Idss around 6.8 you might not need to make any changes.
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Old 31st August 2014, 03:11 PM   #2438
6L6 is offline 6L6  United States
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I agree, use the BL.

I like your board, and I love the idea of the Salas shunt regs as well. You should have a truly fantastic phonostage when you are done.

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Old 31st August 2014, 03:11 PM   #2439
AVWERK is offline AVWERK  United States
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Since your in the planning stage of your pcb, why not incorporate a 2 or 3 gain switch and or loading dip switch arrangement ?

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Old 31st August 2014, 07:37 PM   #2440
Geosto is offline Geosto  Netherlands
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Oké the BL range it will be.
I am not planning on setting up a GB. I don't think it is fair to sell this boards while mr Pass is still selling his original boards. Bud thank you al for the compliment.

I am already left the planing stage and the boards are produced and on ther way to me. Bud to make a gain switch you can make a bypass with a switch and different resistors. I was thinking to make this like you suggested with dip switches bud since I am not planing on swapping a lot with phono cartridges it is better to change the resistor and set the gain with a fixed value.
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