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Old 1st September 2013, 08:55 PM   #10001
evanc is offline evanc  United States
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I'll look through th thread to check on any info already discussed.
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Old 1st September 2013, 08:58 PM   #10002
Salas is offline Salas  Greece
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You can ask Merlin directly about any hints and experiences, he is frequent here.
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Old 1st September 2013, 09:10 PM   #10003
Salas is offline Salas  Greece
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Quote:
Originally Posted by AndrewT View Post
the BOM shows two R1.
I think one of them should be R11.
Yes, there is a typo there indeed. Thanks for picking that up. I am arranging for the print on solder mask to have a Q3Y and Q3Z in the main circuit not to confuse with the Q3X in the regs also. So I will be editing a final refresh of the text when all is ready. I will let people know then.
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Old 2nd September 2013, 02:31 PM   #10004
Salas is offline Salas  Greece
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Default Update

Minor details fixed.

PCB
There are Q3Y and Q3Z designations on the PCB print now.
(Q3X, Q3Y previously for the alternative cascode transistor types).
So to avoid any possible confusion with the Q3x JFET in the regs when populating the board. (Tnx Rush).

Guide
Q3Y, Q3Z designations correspondingly listed and explained in notes.
R11 was R1 BOM typo fixed. (Tnx Andrew).
"Gain" topic in notes got better detailed.
R6x in the reg's schema went to its correct position (I only saw that bug ).

So its recommended you discard the previous guide downloads to keep this one which is up to date. #9980
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Old 2nd September 2013, 03:24 PM   #10005
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Is it possible to switch the gain somehow?
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Old 2nd September 2013, 04:02 PM   #10006
Salas is offline Salas  Greece
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Quote:
Originally Posted by vdi_nenna View Post
Is it possible to switch the gain somehow?
No. You build with a certain gain in mind. Its possible to modify for using another output level cartridge by changing a couple of things as described in the guide but not on the fly. Its not a loop feedback design to flick some op amp gain resistor, its open loop SE so its about about re-fixing it.
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Old 3rd September 2013, 06:41 PM   #10007
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Many thanks to Salas for making his Folded NJfet RIAA design compatible with MM cartridges.

I'm still using his first version of the 'Simplistic' for my Nagaoka MP20 and I'm happy with it. But I am heavily tempted to try the new folded simplistic pcb, so I would like to ask a few (newbie) questions.

I suppose R1 is the cartridge load impedance. This is specified as 47K. Is it OK to increase this value to make it compatible with a different cartridge load, say 68K?

If in future I opt for a low o/p MC, does this necessitate a change in the values of Rx1-Rx4?

Regarding the Elcap, is this the bi-polar type or will the usual 105 deg. aluminium electrolytic type do?

Thanks for any clarification to my newbie questions.
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Old 3rd September 2013, 07:01 PM   #10008
Salas is offline Salas  Greece
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The input load R1 is arbitrary, your choice in other words. The use of JFETS with their very high natural input impedance allows that.

Rx1-Rx4 can be high like 3.3k 10k 20k 33k to achieve intermediate values for evaluating MM and high MC carts or left unpopulated when you are sure of just one optimum value that you can use for R1. Or just put capacitor loads in some of those positions to select.

Later if with MC cart you can populate/replace with what is best load range for that cart.

Elcap for regs termination can be your choice electrolytic either polar or bipolar 50V-100V, any type not characterized as "Low ESR".
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Old 3rd September 2013, 08:30 PM   #10009
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Is there any problem with building the folded phono and dcb1 into the same chassis with a separate chassis for the raw psu's?
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Old 3rd September 2013, 09:19 PM   #10010
Salas is offline Salas  Greece
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No problem in combining if you will not insert AC secondaries cabling in the main "audio" box.
High MC and MM level sensitivity is naturally less affected by hum pick up due to less gain, but better avoid AC fields there for all types of phono build.
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