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Old 20th September 2013, 06:35 PM   #10151
Salas is offline Salas  Greece
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Much Miller, clipping.
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Old 20th September 2013, 06:40 PM   #10152
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So the only solution is a third stage if we want more gain (like 70dB).

I do not like a MC prepre (prefer a sut), but a third stage in the end might be better.
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Old 20th September 2013, 06:42 PM   #10153
Salas is offline Salas  Greece
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70dB will bring hiss. More gain should be done in the line level. There is a stages gain ratio for allowing the head amp to dominate the SNR. In the original design its kept.
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Old 20th September 2013, 06:44 PM   #10154
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Thank you again.
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Old 20th September 2013, 07:37 PM   #10155
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Quote:
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You recommended to use RG174 coax for signal wires.

I also have a question about RG179 coax. Is it a good choice for Phono and MC?
I have plenty of it, and I do not have GR174. I thought I might use it instead.

Thank you.
RG174 vs. RG179 for signal?
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Old 20th September 2013, 07:50 PM   #10156
Salas is offline Salas  Greece
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The only things I care for about those signal cables regarding the audio band its they are thin, flexible, well shielded and widely available.
Their impedance differences will be interesting only in RF and instrumentation in long lengths. Use either. If you want audio marketed types, keep them short, thin to be flexible, well shielded also. Me I used 174 that I had and I am happy. Now if I tell you its copper clad STEEL core cable you may shrug or look for oxygen free pure copper alternatives.
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Old 20th September 2013, 08:54 PM   #10157
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Quote:
Originally Posted by Salas View Post
The only things I care for about those signal cables regarding the audio band its they are thin, flexible, well shielded and widely available.
Their impedance differences will be interesting only in RF and instrumentation in long lengths. Use either. If you want audio marketed types, keep them short, thin to be flexible, well shielded also. Me I used 174 that I had and I am happy. Now if I tell you its copper clad STEEL core cable you may shrug or look for oxygen free pure copper alternatives.
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Old 21st September 2013, 09:42 AM   #10158
AndrewT is offline AndrewT  Scotland
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Originally Posted by alexkosha View Post
.........

I heard that some people uses only central wire to connect all signal point and braid is connected to ground on one end only to avoid a loop........
Each input is a circuit. That circuit MUST have a Flow and a Return.
That Flow is commonly referred to as Signal, or Hot.
That Return is commonly referred to as Ground (very ambiguous), or Signal Ground, or Cold (generally only in balanced signalling).

The connection from the cartridge to the RIAA Pre must be a two wire connection to form that circuit. If you use a shield as the Return part of that circuit you MUST connect the shield at the cartridge end and at the RIAA Pre end.

If you use a twisted pair for the connection then again it is a two wire connection. Both the Flow and Return must be connected at both ends to complete the circuit.

If you use a shielded twisted pair, or shielded star quad (microphone cable), again these are part of that two wire connection. The Flow and Return are connected at both ends. The Shield is connected to Chassis at the point where the cable enters the Chassis, NOT at the PCB inside the Chassis. If there is a Chassis around the cartridge, or cartridge wiring, then the shield should be connected to that enclosing metalwork, eg the arm tube and headshell.
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Old 21st September 2013, 03:46 PM   #10159
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Each input is a circuit. That circuit MUST have a Flow and a Return.
That Flow is commonly referred to as Signal, or Hot.
That Return is commonly referred to as Ground (very ambiguous), or Signal Ground, or Cold (generally only in balanced signalling).

The connection from the cartridge to the RIAA Pre must be a two wire connection to form that circuit. If you use a shield as the Return part of that circuit you MUST connect the shield at the cartridge end and at the RIAA Pre end.

If you use a twisted pair for the connection then again it is a two wire connection. Both the Flow and Return must be connected at both ends to complete the circuit.

If you use a shielded twisted pair, or shielded star quad (microphone cable), again these are part of that two wire connection. The Flow and Return are connected at both ends. The Shield is connected to Chassis at the point where the cable enters the Chassis, NOT at the PCB inside the Chassis. If there is a Chassis around the cartridge, or cartridge wiring, then the shield should be connected to that enclosing metalwork, eg the arm tube and headshell.
Thank you again for such detailed info.
How about RCA connectors returns? Do you connect them together at the MM OUT?
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Old 21st September 2013, 05:09 PM   #10160
AndrewT is offline AndrewT  Scotland
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if one connects the returns at the Source and one also has the returns connected somewhere downstream, then one has created a very long loop. That loop is very likely to have problems with picking up interference.
Recently I can across a dual coax with the screens in contact. That would be one way to minimise the loop area of that long loop.
I have never seen any project describe how to avoid this stereo source to stereo receiver loop.
There are a couple of papers that describe methods of reducing the current in these loops.
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Last edited by AndrewT; 21st September 2013 at 05:23 PM.
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