Simplistic NJFET RIAA - Page 918

Salas · 27th January 2013, 09:43 AM

Quote:

Originally Posted by buzzforb

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.

Salas · 27th January 2013, 09:55 AM

Quote:

Originally Posted by buzzforb

.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.

buzzforb · 27th January 2013, 10:12 AM

Thanks for the comments Salas. Degeneration is an option, but i have discivered i like as little as possiblle. Have you tried with none?

Salas · 27th January 2013, 10:22 AM

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.

buzzforb · 27th January 2013, 12:23 PM

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.

buzzforb · 27th January 2013, 11:11 PM

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?

Salas · 28th January 2013, 12:44 AM

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.

Salas · 28th January 2013, 12:47 AM

Connect PSU ground and reg ground, and reserve one cable in the umbilical to connect chassis to chassis.

buzzforb · 28th January 2013, 01:03 AM

Thanks.

buzzforb · 30th January 2013, 03:39 PM

I messd around with RCruz calcultor, and from memeory, it does very good job approximating the values.

27th January 2013, 10:12 AM	#9173
buzzforb diyAudio Member Join Date: Oct 2010 Location: Burlington, NC	Thanks for the comments Salas. Degeneration is an option, but i have discivered i like as little as possiblle. Have you tried with none? __________________ \|F6 Kit/Trasnformer GB Sign up sheet Closed,\|Primrose GB Sign Up sheetClick Here ...Shape the sound , Man!

27th January 2013, 12:23 PM	#9175
buzzforb diyAudio Member Join Date: Oct 2010 Location: Burlington, NC	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. __________________ \|F6 Kit/Trasnformer GB Sign up sheet Closed,\|Primrose GB Sign Up sheetClick Here ...Shape the sound , Man!

27th January 2013, 11:11 PM	#9176
buzzforb diyAudio Member Join Date: Oct 2010 Location: Burlington, NC	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? __________________ \|F6 Kit/Trasnformer GB Sign up sheet Closed,\|Primrose GB Sign Up sheetClick Here ...Shape the sound , Man!

28th January 2013, 01:03 AM	#9179
buzzforb diyAudio Member Join Date: Oct 2010 Location: Burlington, NC	Thanks. __________________ \|F6 Kit/Trasnformer GB Sign up sheet Closed,\|Primrose GB Sign Up sheetClick Here ...Shape the sound , Man!

30th January 2013, 03:39 PM	#9180
buzzforb diyAudio Member Join Date: Oct 2010 Location: Burlington, NC	I messd around with RCruz calcultor, and from memeory, it does very good job approximating the values. __________________ \|F6 Kit/Trasnformer GB Sign up sheet Closed,\|Primrose GB Sign Up sheetClick Here ...Shape the sound , Man!


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

27th January 2013, 10:22 AM	#9174
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	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.

28th January 2013, 12:44 AM	#9177
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	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.

28th January 2013, 12:47 AM	#9178
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Connect PSU ground and reg ground, and reserve one cable in the umbilical to connect chassis to chassis.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read