6V6 line preamp - Page 252

Salas · 5th February 2014, 10:31 PM

Quote:

Originally Posted by JimT

Thanks
Jim

We possibly crossposted.

gtoro · 8th April 2014, 07:18 PM

Hi folks , a question about a hum noise in buffer circuit with a simple crc+ 2last separate rc for each channel. I'm no surprise for litle noise with this kind of supply, but the noise go down a lot at maximum volume without and song is very clear the change of level...
Could somebody light me about?
Thanks a lot for any answer ...

fdegrove · 8th April 2014, 07:45 PM

Hi,

Not sure I understand but are you certain you have the volume control wired up correctly?

Ciao,

gtoro · 8th April 2014, 08:16 PM

I think Was right i Can control level simpy the noise when the pot is in position without attenuation go down somebody db at my (not only) ear

Salas · 9th April 2014, 01:27 AM

The pot needs its body grounded also. Revisit the grounding scheme.

gtoro · 9th April 2014, 07:59 AM

The pot is an blue alpls, the cover is mainly in plastic i have to ground the upper side? I'll try this evening thanks a lot!
the sound it's very good! I'll try with SE EL34 and with a little T-amp and result was fantastic gain in deep, detail and "body" of sound..., I'm thinkng to separate in two cabinet pre and supply for give him in future the chance of better supply based on your circuit.

Salas · 9th April 2014, 08:19 AM

The Alps face plate is metal. It usually grounds when mounted to a zero referenced chassis. When not like that, use a collar and a ground wire.

Salas · 9th April 2014, 08:22 AM

P.S. About the sound congratulations. It will be even better when you will finish with all the build details. Better PSU is always a plus also. Post us some pictures when done.

buzzforb · 11th April 2014, 04:43 PM

Salas,
Time to rebuild the 6v6 preamp and I had a couple of questions. If I wanted to have balanced out, would it be smarter to use a unity gain phase splitter like the one found in the impasse, or a transformer? Would a standard 600: 600 transformer work on the output or would it cause issue? Lastly, have you had a chance to listen to the Amtrans Carbon Film?

Salas · 11th April 2014, 04:58 PM

Such Tx would load down the gain version's higher than 600R Zo. Better an active splitter, or step down 5k primary Tx instead of resistor anode load with balanced secondary. Given that your system gain allows 1:3 gain loss at the pre. Line noise will go down accordingly as microphony also nonetheless.

*No use of Amtrans yet. BTW they have given good feedback on it in the phono thread but they ultimately preferred the very low ppm foil and the non inductive ww very low ppm too. But in no power demanding locations.

8th April 2014, 07:45 PM	#2513
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	Hi, Not sure I understand but are you certain you have the volume control wired up correctly? Ciao, __________________ Frank

11th April 2014, 04:43 PM	#2519
buzzforb diyAudio Member Join Date: Oct 2010 Location: Burlington, NC	Salas, Time to rebuild the 6v6 preamp and I had a couple of questions. If I wanted to have balanced out, would it be smarter to use a unity gain phase splitter like the one found in the impasse, or a transformer? Would a standard 600: 600 transformer work on the output or would it cause issue? Lastly, have you had a chance to listen to the Amtrans Carbon Film? __________________ ...Shape the sound , Man!

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8th April 2014, 07:18 PM	#2512
gtoro diyAudio Member Join Date: May 2012	Hi folks , a question about a hum noise in buffer circuit with a simple crc+ 2last separate rc for each channel. I'm no surprise for litle noise with this kind of supply, but the noise go down a lot at maximum volume without and song is very clear the change of level... Could somebody light me about? Thanks a lot for any answer ...

8th April 2014, 08:16 PM	#2514
gtoro diyAudio Member Join Date: May 2012	I think Was right i Can control level simpy the noise when the pot is in position without attenuation go down somebody db at my (not only) ear

9th April 2014, 01:27 AM	#2515
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	The pot needs its body grounded also. Revisit the grounding scheme.

9th April 2014, 07:59 AM	#2516
gtoro diyAudio Member Join Date: May 2012	The pot is an blue alpls, the cover is mainly in plastic i have to ground the upper side? I'll try this evening thanks a lot! the sound it's very good! I'll try with SE EL34 and with a little T-amp and result was fantastic gain in deep, detail and "body" of sound..., I'm thinkng to separate in two cabinet pre and supply for give him in future the chance of better supply based on your circuit.

9th April 2014, 08:19 AM	#2517
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	The Alps face plate is metal. It usually grounds when mounted to a zero referenced chassis. When not like that, use a collar and a ground wire.

9th April 2014, 08:22 AM	#2518
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	P.S. About the sound congratulations. It will be even better when you will finish with all the build details. Better PSU is always a plus also. Post us some pictures when done.

11th April 2014, 04:58 PM	#2520
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Such Tx would load down the gain version's higher than 600R Zo. Better an active splitter, or step down 5k primary Tx instead of resistor anode load with balanced secondary. Given that your system gain allows 1:3 gain loss at the pre. Line noise will go down accordingly as microphony also nonetheless. *No use of Amtrans yet. BTW they have given good feedback on it in the phono thread but they ultimately preferred the very low ppm foil and the non inductive ww very low ppm too. But in no power demanding locations.