Biasing pre-amp problem

HOMER_PT · 25th November 2005, 06:49 AM

Hello everybody,

I’ve get a pre-amp recently and I would like to improve it (if possible).

I’ve checked some voltages and I think the tubes aren’t perfectly matched or the diagram is not correctly designed.
Regarding the voltages I think the first stage is working with a very low current. Some authors refer that the 6922 tube don’t work very well in these conditions. On the other hand, the second stage seems to be working at very high current.
What is your advice? I’ll appreciate if you could help.

Cheers,

HOMER_PT · 26th November 2005, 08:14 AM

No comments till now.

No problem. Just one more question.

In the original schematic, the resistor R1 doesn’t exist. I’ve added it trying lowers the gain but it still continue being too high. How can I lower it?

Cheers,
Homer

Tube_Dude · 20th February 2006, 09:41 PM

Ola Homer

Why don't you wired the pot as a volume pot and not as a trimmer pot , as in the schematic

rlaury · 20th February 2006, 10:58 PM

Hi Group!
This is an interesting looking circuit.
Who was the original manufacture or
is this a DIY amp? I would like to know more about it.

Thanks!

RonL

20th February 2006, 09:41 PM	#3
Tube_Dude diyAudio Member Join Date: Mar 2002 Location: Aveiro-Portugal	Ola Homer Why don't you wired the pot as a volume pot and not as a trimmer pot , as in the schematic __________________ Jorge

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

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Differential filter circuit: biasing problem	Alex M	Tubes / Valves	4	5th May 2009 09:44 AM
Biasing	fauxpas	Tubes / Valves	4	3rd January 2008 08:06 AM
SWR biasing need help...	spirus	Instruments and Amps	4	23rd November 2006 08:58 PM
low-biasing or high biasing in Class-AB amps	Workhorse	Solid State	124	18th October 2005 04:45 AM

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

26th November 2005, 08:14 AM	#2
HOMER_PT diyAudio Member Join Date: May 2005 Location: Lisbon	No comments till now. No problem. Just one more question. In the original schematic, the resistor R1 doesn’t exist. I’ve added it trying lowers the gain but it still continue being too high. How can I lower it? Cheers, Homer

20th February 2006, 10:58 PM	#4
rlaury diyAudio Member Join Date: Sep 2005	Hi Group! This is an interesting looking circuit. Who was the original manufacture or is this a DIY amp? I would like to know more about it. Thanks! RonL

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)