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Old 28th September 2010, 05:46 AM   #5031
le´flu is offline le´flu  Germany
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Hello Salas and all the others,
sorry for asking again, but i can´t find the adequate posting.
Could someone again please give a resume for best ground-
layout with ptp-soldering on tagboard please.
There were some hints a time ago but i can´t find it.

Greetings ulf
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Old 28th September 2010, 05:56 AM   #5032
Salas is online now Salas  Greece
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Either a copper buss bar from start to finish, grounding after last stage to PSU ground terminal, or a star to PSU ground terminal. Started building it?
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Old 28th September 2010, 06:06 AM   #5033
le´flu is offline le´flu  Germany
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Unfortunately not caused by long illness within family.
Two more questions please:
Salas, best are IRFP 9519 and 9540 in PSU right?
And voltage-drop across each 3 led-chain is 6V ?

Greetings Ulf
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Old 28th September 2010, 06:11 AM   #5034
Salas is online now Salas  Greece
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IRFP9240 is the classic V1 choice and mellow tone. You can try IRF9610/9620/9520 CCS and IRF9540 shunt for TO-220 also. Faster tone. You can tune your C3 to your HF response best system match from 15n1 to 15n5 with 15n33 midway tone too. Leds 5.4-6V.
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Old 28th September 2010, 08:38 AM   #5035
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Finally my phono is working like a charm. :-D I'm so happy and obligated.
I tried 15nF and after an additional 470pF but i dunno i need more hearing experience and some burning time for the components i guess. i have an r-core structured Tx with 4 pair wires and two of them in company provides ~37V so i can easily set Vout to DC 37V in shunt. I will measure voltage you asked for further biasing but i was impressed at least with the music i got. That is why i went to buy some good lp to our fleamarket. 50th anniversary with a lot of good stuff for cheap price.
Hence the week passed with listening.
Examining the phono pcb location and trying to rotate an move it , i find a place where i got only a very low hum. But after it will be on a box and grounded properly i hope hum will fall dead. Next is to make up a good collection of brand of capacitor for riaa stage and coupling caps and order it.
I will post further progress and measures that i will made.

Thanks for your (Salas and the Riaa troops :-)) help.
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Old 28th September 2010, 02:44 PM   #5036
Salas is online now Salas  Greece
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Nice! I am sure you are going to discriminate the HF Riaa capacitor steps after acclimatized more. They are not trivial. We will expect to see your final boxed build and system pictures. Happy vinyl sessions senior.
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Old 29th September 2010, 09:39 AM   #5037
le´flu is offline le´flu  Germany
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Hi Salas,
At postin 4141 you calculates schematics for my Lyra dorian.
At the weekend i measured a lot of sk170bl and i thought of
building the circuit you postet in 4945 instead ´cause it´s simpler.
Will this work too? I think so.
I chose jfet-pairs as follows:
8,16/816
8,45/8,50
8,23/8,20
8,39/8,37

for Q7 and Q2 at PSU i´ll use 6,61 Pairs

Do you see any advantages or should i just stick with circuit from
4141?
And i measured like 30 3mm green LED´s. They are 1,99V each

Greetings Ulf
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Old 29th September 2010, 04:03 PM   #5038
Salas is online now Salas  Greece
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You asked for 6.6mA back then. Now you got more jfets around 8mA? Both will work. The special one owes to be a bit more quiet. R11=2.7K on the 4141 its a correction.
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Old 29th September 2010, 07:59 PM   #5039
le´flu is offline le´flu  Germany
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Hi Salas,
you´re to kind...thanks. But still some questions.

Okay, i´ll stay with circuit 4141 for 6,61mA fets.
Will the 8,16mA pair be a good match for Q7?
Do i need any matching for bc550c?
Should i stay with the PSU you recommended in posting 4141?
Cause the psu at 4945 is slightly different what about use of Q2.
BF245A instead of 2sk170gr 2,94 and 2,98mA IDSS at PSU 4141?
As i understand, shunt reg (with irfp9540) has to be as close as
possible to the circuit. What about the CCS (irfp9510) part?

hopefully last question: how many VA for the transformer?

Greetings and thanks a lot

ulf


And...do you have a picture of PCB downside from Picture at Posting 4628?
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Old 29th September 2010, 08:33 PM   #5040
Salas is online now Salas  Greece
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Yes it can be good for Q7.

+/- 20 hfe between channels will suffice as for 550C.

Yes stay with that PSU, BF245A is there on the general because of dissipation its going to impose on its BJT underneath when over 40V, yours is 36V, hence less total dissipation and more mA from 2SK load is beneficial.

There is 4 wire remote sensing depicted, if you are not to use it, only then the shunt portion has to be near the consumption nodes. The reg must be tightly laid out as a whole though.

50VA.

Photo from a doubled Jfet 58dB (4628). The little caps and one resistor are to bring some values to 100% nominal & matching. The whole phono is 100% matched everywhere. Active & passive parts, plus THD, Riaa curves and gain. Much work, crazy left over volume for Jfets and Riaa caps.
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