6SN7 pre-amp - Page 6

Andersen · 20th April 2007, 03:05 AM

Quote:

Originally posted by ocha

Hello Andersen!

I am interested in this topic very much. My 300B SE amp copied Sunaudio schematic. I manage to assemble preampli by Tango NP126. I hope that I could see and listen to your system because I am also a fan of Altec. Please contact me by lg2y of YM.
Thanks a lot!

Hello ocha

You're welcome. I live in HCMC and do not use YM. You can email via hvdinh@hcm.vnn.vn.

Can you share your pre schematics and what is the progress so far?

Andersen · 20th April 2007, 06:15 AM

According to the below schematics of Tango NP-126, should I ground pin #8 (S).

Thanks.

Andersen · 10th August 2007, 06:25 AM

Hello

I've just got a few questions relating to the attached schematics. Can anyone tell me the difference between using 0.22uf/630V capacitors and 0.47uf/630V ones in the position of 1uf/630V, and can I use 100uf/16V in the position of 470uf/25V, which one is better?

Thanks a lot.
Andersen

MartinV56 · 14th September 2007, 05:32 PM

Hi, the cobra 2 line preamp circuit is similar Sun Audio preamp stage used in 300B, 2A3 and VT-25 amps

dungaudio · 12th July 2011, 12:31 AM

Quote:

Originally Posted by Andersen

Thanks for your advice.

My next project is the ultrapath pre-amp and after that is a pre-amp using 45 tubes.

dungaudio · 12th July 2011, 12:41 AM

Quote:

Originally Posted by Andersen

Thanks for your advice.

My next project is the ultrapath pre-amp and after that is a pre-amp using 45 tubes.

made in sg VN

krivium · 12th July 2011, 01:48 AM

Hi Andersen,

this circuit is a SRPP design. You can find general information about this kind of circuit here and even more infos in this article from the same author.

To answer your question for the 100uf it should not modify too much the behavior but i'm not sure about V rating, 16V should be ok but 25V is specified on schematic so better to stand with it.

For the 1uf it's a different problem as SRPP is designed with a defined load Z at target and changing this cap with a different load Z than the one specified for this circuit can alter the BW. EG: 0,47uf with 10k load is about 34hz.

Beware your heater must be 'elevated' at some 60v or so (depend on your B+) for the circuit to behave correctly (see anode to heater limit in tube datasheet).

dungaudio · 17th July 2011, 06:00 PM

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14th September 2007, 05:32 PM	#54
MartinV56 diyAudio Member Join Date: Nov 2006	Hi, the cobra 2 line preamp circuit is similar Sun Audio preamp stage used in 300B, 2A3 and VT-25 amps

12th July 2011, 01:48 AM	#57
krivium diyAudio Member Join Date: Oct 2009	Hi Andersen, this circuit is a SRPP design. You can find general information about this kind of circuit here and even more infos in this article from the same author. To answer your question for the 100uf it should not modify too much the behavior but i'm not sure about V rating, 16V should be ok but 25V is specified on schematic so better to stand with it. For the 1uf it's a different problem as SRPP is designed with a defined load Z at target and changing this cap with a different load Z than the one specified for this circuit can alter the BW. EG: 0,47uf with 10k load is about 34hz. Beware your heater must be 'elevated' at some 60v or so (depend on your B+) for the circuit to behave correctly (see anode to heater limit in tube datasheet).

17th July 2011, 06:00 PM	#58
dungaudio diyAudio Member Join Date: Aug 2005 Location: Sai gon - HCMC- 97 Truong Dinh- Q3	- My Photo Gallery

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