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Old 24th November 2020, 08:08 PM   #21
Hans Polak is offline Hans Polak  Netherlands
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The proof of the pudding is ......
For little money you can get a confirmation, so why not try it ?

Hans
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Old 24th November 2020, 09:07 PM   #22
SMABB is offline SMABB  Denmark
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Allright then....

Just a quick note:
An Australian guy got hold of one. Here's what he wrote:

"First thing I did was substitute a more solid power supply. I liked that.
Then I upped the gain massively.
Then I changed the impedance match also.
These two changes were not resistor values you'd expect but it's sounding really good now. It's got good PRAT. It's quick and very musical. I think my transformer had better more solid tone and even better dynamics but this device is very clean, low distortion, very open and very musical. Musical is it's best attribute I think in my system."

He does explicitly mention benefits from a larger transformer, but focuses most on benefits from load matching and upping the gain. That comes as no surprise..
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Old 25th November 2020, 02:32 PM   #23
Kay Pirinha is offline Kay Pirinha  Germany
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Quote:
Originally Posted by SMABB View Post
Is the circuit inverting the input signal?
Meaning I will have to alter the wiring connector pins on the cartridge?
1st question: Yes, as stated above.
2nd question: Not necessarily. I doubt that the human hearing sense can discern between natural and inverted phase. On top of that, one ground pin might be tied to the catridge's case, so inverting the phase of this channel inevitably will introduce hum.
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Old 25th November 2020, 04:22 PM   #24
MarcelvdG is online now MarcelvdG  Netherlands
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As far as I know, double-blind tests have been done that show that humans can hear polarity changes on special test signals and even on music played back in mono in acoustically dead environments.
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Old 25th November 2020, 05:24 PM   #25
Kay Pirinha is offline Kay Pirinha  Germany
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I'd like to know and read the sources.
Best regards!
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Old 1st December 2020, 04:48 PM   #26
sgrossklass is offline sgrossklass  Germany
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This circuit is... well, I wouldn't say a waste of some perfectly good 2SB737s, but not exactly very good use of them either.

Where your average MC prepre tends to focus on low noise with linearity being less of a priority (levels are, after all, quite small), this one is quite the opposite, with the usual bad tradeoff between input impedance and input noise of an inverting circuit. I am not convinced that this set of tradeoffs has any practical benefits, quite the contrary, it makes the circuit quite complex while giving good performance where it doesn't matter all that much but mediocre performance where it does.

Possible the circuitry had been adapted from a full phonopre or something. In any case, this smells of design by agenda.
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Old 1st December 2020, 07:05 PM   #27
SMABB is offline SMABB  Denmark
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Thanks for chiming in....

I assume you are referring to basics, that resistors are exceptional sources of noise. Bigger resistors make more noise than little resistors.

Would you mind clarify further the trade offs as seen from your POV?
Electrical circuits are not among my strongest offerings coming from a base in the acoustical area.

What I can tell you by ear is, that the MC-2 is exceptionally low on noise and the sound (or music) is exceptionally beautiful.
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Old 1st December 2020, 10:32 PM   #28
MarcelvdG is online now MarcelvdG  Netherlands
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R1 sets the input impedance, so you can't make it arbitrarily small, so you can't make its noise voltage density arbitrarily small, and meanwhile it is connected straight in series with the input. That's the main disadvantage of this topology (another one is the inversion).
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Old 2nd December 2020, 07:52 AM   #29
Hans Polak is offline Hans Polak  Netherlands
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Quote:
Originally Posted by sgrossklass View Post
This circuit is... well, I wouldn't say a waste of some perfectly good 2SB737s, but not exactly very good use of them either.

Where your average MC prepre tends to focus on low noise with linearity being less of a priority (levels are, after all, quite small), this one is quite the opposite, with the usual bad tradeoff between input impedance and input noise of an inverting circuit. I am not convinced that this set of tradeoffs has any practical benefits, quite the contrary, it makes the circuit quite complex while giving good performance where it doesn't matter all that much but mediocre performance where it does.

Possible the circuitry had been adapted from a full phonopre or something. In any case, this smells of design by agenda.
Iím sorry, but I donít share your opininion at all and I fully reject your comment on using an inverting topology.
It may be that blind tests have shown that we can theoretically hear a difference but a difference does not automatically mean a worsened sound.

About noise production: a non inverting pre will always need a low value resistor in itís feedback loop, where in this topology you can discard the input resistor completely by just using the Cartís source resistance, so itís even superior noise wise.

My personal experience so far with virtual gnd pre-preís is very positive, in line with several test in Stereophile.
It has become my favourite topology.

Hans
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Old 2nd December 2020, 08:04 AM   #30
MarcelvdG is online now MarcelvdG  Netherlands
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An audible difference that shouldn't be there at least means a less realistic sound.
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