Meet Lizi,on the paper

Leolabs · 2nd December 2005, 02:47 PM

Here she is,on the paper,any comments are welcome

MikeB · 2nd December 2005, 03:16 PM

Hmmm, unless you use cascoded jfets in input it is very unlikely to be functional at all ? Or am i wrong ?

Mike

mastertech · 2nd December 2005, 08:00 PM

i cant see it very well being turned vertically,very symmetrical,
did you come up yourself?, you know my friend jean... said
two things are important for top sound, wideband and symmetry
well i jean.. didnt know that! thanks jean

looks good should sound good

cheers

anatech · 2nd December 2005, 08:17 PM

Hi Leolabs,
I can see your feedback resistor getting warm at high levels. Guess inductive types are not recommended?

-Chris

rtarbell · 2nd December 2005, 08:26 PM

Howdy! Let me ask: In your second voltage gain stage with the BJT's (just before the MOSFET outputs), what is the purpose of your two 10k resistors to ground?

Leolabs · 3rd December 2005, 02:01 AM

Yes,I came up Lizi by myself,and she isn't well tuned yet,as she's still on the paper.

I dont see that cascoded JFETs are necessary to be used at the input stage,but I maybe wrong.

The resistors might get warm at high levels,just wondering half watt resistors might do the job or not.

The two 10k resistors at the second stage are local feedback resistors,which are rarely seen.

And I wish that DIY audio topic of year 2006 will be"Lizi vs Gainclone"

Tim__x · 3rd December 2005, 02:12 AM

The input stage is unbiased, the amplifier will have massive uncorrected crossover distortion.

Either use JFETs, as MikeB suggested, or add some bias through diodes or emitter followers.

Overall I think you'd be better off with a more standard topology.

P.S. The 10k resistors merely reduce open loop gain, for local feedback they should be connected collector-base .

MikeB · 3rd December 2005, 10:07 AM

Quote:

Originally posted by Tim__x
The input stage is unbiased, the amplifier will have massive uncorrected crossover distortion.

Either use JFETs, as MikeB suggested, or add some bias through diodes or emitter followers.

Overall I think you'd be better off with a more standard topology.

P.S. The 10k resistors merely reduce open loop gain, for local feedback they should be connected collector-base .

To show the problem/biasing i attached a sim-shot. By using jfets the circuit becomes functional at once, but the jfets needs cascoding because they would not withstand the 40volts.
The 10k resistors are typically a good thing, they flatten openloop bandwidth and reduce zout of the vas.

Leolabs, you might consider getting a sim software, it is the best tool to learn a lot about electronics.

Mike

Leolabs · 5th December 2005, 01:29 AM

Here is another look of her:

Leolabs · 5th December 2005, 01:41 AM

The first stage is around 5mA,and the second stage is around 10mA.

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
Lizi final	Leolabs	Solid State	1	1st February 2006 02:39 AM
Another look of Lizi	Leolabs	Solid State	4	7th December 2005 02:49 PM
amorphous paper or Mu-metal paper can use for D/A chips for shielding or not????	siu sin man tho	Digital Source	0	17th March 2004 12:31 PM

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


	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

2nd December 2005, 03:16 PM	#2
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	Hmmm, unless you use cascoded jfets in input it is very unlikely to be functional at all ? Or am i wrong ? Mike

2nd December 2005, 08:00 PM	#3
mastertech Banned Join Date: Mar 2005 Location: Australia	i cant see it very well being turned vertically,very symmetrical, did you come up yourself?, you know my friend jean... said two things are important for top sound, wideband and symmetry well i jean.. didnt know that! thanks jean looks good should sound good cheers

2nd December 2005, 08:17 PM	#4
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Leolabs, I can see your feedback resistor getting warm at high levels. Guess inductive types are not recommended? -Chris

2nd December 2005, 08:26 PM	#5
rtarbell diyAudio Member Join Date: Sep 2005	Howdy! Let me ask: In your second voltage gain stage with the BJT's (just before the MOSFET outputs), what is the purpose of your two 10k resistors to ground?

3rd December 2005, 02:01 AM	#6
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	Yes,I came up Lizi by myself,and she isn't well tuned yet,as she's still on the paper. I dont see that cascoded JFETs are necessary to be used at the input stage,but I maybe wrong. The resistors might get warm at high levels,just wondering half watt resistors might do the job or not. The two 10k resistors at the second stage are local feedback resistors,which are rarely seen. And I wish that DIY audio topic of year 2006 will be"Lizi vs Gainclone"

3rd December 2005, 02:12 AM	#7
Tim__x diyAudio Member Join Date: Jun 2004 Location: Edmonton area, Alberta	The input stage is unbiased, the amplifier will have massive uncorrected crossover distortion. Either use JFETs, as MikeB suggested, or add some bias through diodes or emitter followers. Overall I think you'd be better off with a more standard topology. P.S. The 10k resistors merely reduce open loop gain, for local feedback they should be connected collector-base .

5th December 2005, 01:41 AM	#10
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	The first stage is around 5mA,and the second stage is around 10mA.

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