DIY Audio Projects Forum
http://diyaudioprojects.com/Forum/

4S Universal Tube Preamp Project (12A*7)
http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=4628
Page 29 of 35

Author:  Chris65 [ 17 May 2017, 18:43 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

Suncalc wrote:
Alex Q wrote:
Can i used 6CG7 for this preamp?
The reason for this amp is to allow the use of a series of tubes. However, the 6CG7 (6SN7) is a different beast. Here is a design for a 6CG7/6SN7 version which, coincidentally, will also make use of your 100kΩ Alps potentiometer.

We did discuss this tube a while back when suggesting other 6V heater tubes:
http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=4628&hilit=6cg7&start=140

Author:  Suncalc [ 17 May 2017, 18:50 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

Thanks Chris! :thumbsup:

I had totally forgotten about that whole series of posts. Another good reasons to go back through these threads from time to time.

Author:  Alex Q [ 17 May 2017, 20:05 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

Suncalc wrote:
Alex Q wrote:
I have a spare 100K ALPS Blue Velvet POT can i used this for the 4S
Unfortunately, 100kΩ is too small to use in this design as is. However, if you replace the 250kΩ pot in the design with just a 250kΩ resistor, you can put the 100kΩ pot on the front end and it will work fine.
Alex Q wrote:
Can i used 6CG7 for this preamp?
The reason for this amp is to allow the use of a series of tubes. However, the 6CG7 (6SN7) is a different beast. Here is a design for a 6CG7/6SN7 version which, coincidentally, will also make use of your 100kΩ Alps potentiometer.

http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=3266&start=99


Hi Matt,
I will get the 250K instead i still need to order some parts anyway,This 4S is to drive the Headphone amp that you designed by the way the more i listened to this amp the more i like it to my ears it is comparable to the kit that i got which the kit is 3X more expensive.Thanks again!

Alex

Author:  Alex Q [ 17 May 2017, 20:07 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

Chris65 wrote:
Suncalc wrote:
Alex Q wrote:
Can i used 6CG7 for this preamp?
The reason for this amp is to allow the use of a series of tubes. However, the 6CG7 (6SN7) is a different beast. Here is a design for a 6CG7/6SN7 version which, coincidentally, will also make use of your 100kΩ Alps potentiometer.

We did discuss this tube a while back when suggesting other 6V heater tubes:
http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=4628&hilit=6cg7&start=140


Thanks for the INFO!

alex

Author:  Alex Q [ 20 May 2017, 14:19 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

Do i need to isolate the Transformer from the chassis?

Thanks!
Alex

Author:  Suncalc [ 20 May 2017, 14:41 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

Alex Q wrote:
Do i need to isolate the Transformer from the chassis?
Nope.

Power transformers are all HI-Pot tested these days and transformer microphonics is practically non-existant in modern units. Personally I always make sure I have a good ground between the chassis and the transformer end bells. This just makes shielding that much better and provides a guaranteed ground path in the event of catastrophic transformer failure. The industry chassis ground bonding standard is 2mΩ.

Author:  Alex Q [ 20 May 2017, 17:39 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

Suncalc wrote:
Alex Q wrote:
Do i need to isolate the Transformer from the chassis?
Nope.

Power transformers are all HI-Pot tested these days and transformer microphonics is practically non-existant in modern units. Personally I always make sure I have a good ground between the chassis and the transformer end bells. This just makes shielding that much better and provides a guaranteed ground path in the event of catastrophic transformer failure. The industry chassis ground bonding standard is 2mΩ.


OK Thank You!

Alex

Author:  Alex Q [ 02 Jun 2017, 22:01 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

I just started working on the amp and realized i don't have enough solid core wires the local supplier only have 20 gauge stranded wires, is there advantage on using a solid vs stranded,Which type of wires(Solid or stranded)do you guys used for your build?Thanks!

Alex

Author:  mwhouston [ 03 Jun 2017, 05:04 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

I use solid core only in the audio path. Usually wire-wrap wire which fine copper wire with a silver plating. Or more recently solid core Cat5. I never use shielded wire for interconnects or in wiring amps and preamps.

Author:  Alex Q [ 03 Jun 2017, 13:30 ]
Post subject:  Re: 4S Universal Tube Preamp Project (12A*7)

mwhouston wrote:
I use solid core only in the audio path. Usually wire-wrap wire which fine copper wire with a silver plating. Or more recently solid core Cat5. I never use shielded wire for interconnects or in wiring amps and preamps.


Ok Thanks!

Alex

Page 29 of 35 All times are UTC - 6 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/