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Old 15th September 2012, 02:19 PM   #8001
Salas is offline Salas  Greece
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Quote:
Originally Posted by RCruz View Post
Now another point: Why did you choose 47nF for interstage ? Can I use 100n ?

In the output... is 4u7 too much ?
Because for 47nF is getting even same cap as Riaa's one to do less part types sourcing, and VLF roll off is better predetermined for output cap and line preamp random combinations. What is the input impedance of your preamp?
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Old 15th September 2012, 02:48 PM   #8002
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I am using 10k pots in my DCB1.
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Old 15th September 2012, 03:53 PM   #8003
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In that case you can afford 100nF C3 and 4u7 C4 as you probably got in hand.
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Old 15th September 2012, 04:02 PM   #8004
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See also how RIAA when looked very up close turns with the above C3,4 values to 10K DCB1 when 2M2 R6. R9 1M is only a termination against C4 referring to nowhere to avoid pops. With real life impedance of usual line preamp 10K to 100K maybe you want to see again about your initial 1M4 choice of R6 for voicing.
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Old 15th September 2012, 08:02 PM   #8005
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Incredible acuracy... almost 0.05dB between 40Hz and 20kHz.

Anyway, the differences are slight and it is up to the builder to experiment.
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Old 15th September 2012, 08:04 PM   #8006
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Old 15th September 2012, 08:25 PM   #8007
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Old 15th September 2012, 08:33 PM   #8008
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Old 16th September 2012, 09:10 PM   #8009
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Default Simplistic NJFET RIAA

Salas,

You are the man.
I finished the first two parts of my phono pre amp. I am tickled, it sounds great!

I used your Regular MC schematic (56db). I used your SSLV1.1 regulators (one for L & one for R) with a pot to adjust voltage to get a 38V rail. And I have your B1 (Mesmerize) as the source selector.
It has plenty of gain for a F5 amp and 90 + db speakers.

The last part is my 24db per octave 2 way electronic crossover using B1 type buffers between sections. This board is stuffed.
I will use 2 Hypnotize (L & R) boards to power the buffers (8 B1's per channel).
But I haven't stuffed the Hypnotize boards yet.

I had asked about grounding in another thread. So I will mention there isn't any hum (at least not yet). I used a separate box for the 2 transformers (needed 2 different voltages) and used a 4 wire speaker cable to bring the DC voltage in.
That is one ground, +16vdc, -16vdc, +50vdc.
I wasn't sure how this would work, but it does work, so far.
I brought the ground to a central point on a PC board that I also used for the input and output RCAs. Then the Mesmerize has one ground from the in put to the power supply, all the input and outputs to the Mesmerize are 2 wire (L & R), no ground connection. The phono has the input RCAs floating and the only ground is from the central point to the input ground to the shunt regulators.

I thank you for all the help,

Rush
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Old 16th September 2012, 11:40 PM   #8010
Salas is offline Salas  Greece
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Ooops! Another one baby. Look at those lights! Very nice job that you won hum in this combo. Plus you say you like it, so only remains I wish many nice & relaxing vinyl sessions.

P.S. What TT, cart, speakers?
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