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Old 27th January 2013, 09:43 AM   #9171
Salas is offline Salas  Greece
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No worries. Amps lab has some. I'll just get the there, although I do have a question. I believe you said a single 369 beat dual 170's. what about distortion? I would think dual 170's would have better linearity than single 369.
The 369 will beat them below 300Hz only. Gate capacitance is roughly the same for one 369 and two K170. You will lose 1.5dB gain with the single 369 in this circuit.

P.S. Having two positions already its easy to check one or the other config.
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Old 27th January 2013, 09:55 AM   #9172
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.I knew it would be susceptable to hum. I am taking big donut over there today. It may not help much, but the hammonds hummed right out of the box.
Use distance.
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Old 27th January 2013, 10:12 AM   #9173
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Thanks for the comments Salas. Degeneration is an option, but i have discivered i like as little as possiblle. Have you tried with none?
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Old 27th January 2013, 10:22 AM   #9174
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I had double and triple matched 369s without any Rs and they had instability tendencies due to capacitance and gain. Small Rs tamed them. Lends some more linearity also. Although the swings in first stage aren't anything that demanding.
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Old 27th January 2013, 12:23 PM   #9175
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I am going to be getting some TX2575 resistors for the 47K signal path spot as well as some 220R for the DCB1. Anyone interested, PM me Sorry Salas, not trying to turn this into buying thread, just thought RCruz and others might like a shot.
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Old 27th January 2013, 11:11 PM   #9176
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Salas,
redesigining everything and working on the PSU. I am going to have the Toroid in a seperate case, with shielded umbilical bringing the secondary voltage into the main case. I am unsure of how to ground the main case to earth. I will bring earth in the umbilical so the case can be grounded. Just wandering if I just run a wire from the prereg ground to earth ground, sperated by dual diodes. Any suggestions on wire up for quiet ground?
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Old 28th January 2013, 12:44 AM   #9177
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No don't run AC umbilical, run DC only to the phono box to achieve best results. Move the bridge diodes in the Tx box and connect to the filter cap remotely as it will be left alone on the reg board.
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Old 28th January 2013, 12:47 AM   #9178
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Connect PSU ground and reg ground, and reserve one cable in the umbilical to connect chassis to chassis.
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Old 28th January 2013, 01:03 AM   #9179
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Thanks.
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Old 30th January 2013, 03:39 PM   #9180
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I messd around with RCruz calcultor, and from memeory, it does very good job approximating the values.
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