Current feedback headphone amp

peranders · 19th August 2005, 09:48 AM

What do you think of my SMD current feedback amp?

At the moment I have only pdf's but if you'll check my QRV-06 amp you will have all info about the amplifier itself.

Page 1
Page 2
Page 3
Page 4
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Page 6

Partslist

Solder layer
Component layer
Component print
Groundplane layer
Thermo pads layer

Workhorse · 19th August 2005, 10:46 AM

Hi P E R A N D E R S,

I liked your current feedback amp very much!

How about publishing the specs......It would be great to see your revelation......

Cheers and enjoy!
K a n w a r

anli · 19th August 2005, 11:00 AM

Try to move T12/T11 collectors to T13/T14 emiters respectively. Such way you will reduce AC part of Vce for T11/T12. Some resistors values rearrangement is needed, of course. The same idea may (must?) be applied to (pre)output stages.

peranders · 19th August 2005, 11:06 AM

Quote:

Originally posted by Workhorse
How about publishing the specs......It would be great to see your revelation......

Some hints can be found here .

peranders · 19th August 2005, 11:09 AM

Quote:

Originally posted by anli
Try to move T12/T11 collectors to T13/T14 emiters respectively. Such way you will reduce AC part of Vce for T11/T12. Some resistors values rearrangement is needed, of course. The same idea may (must?) be applied to (pre)output stages.

Yes, but I don't have much voltage and also _how_ much will I reduce?

In order to get good performance the R10 and R11 must be kept as low as possible, preferable zero ohms!

anli · 19th August 2005, 11:23 AM

Quote:

Originally posted by peranders

Yes, but I don't have much voltage and also _how_ much will I reduce?

In order to get good performance the R10 and R11 must be kept as low as possible, preferable zero ohms!

AC part of T12/T11 Vce will be virtually null. I don't see any reason to make R6/R7 (R10/R11) as low as possible. There isn't one :-)

Such way amp's Rin will be much linear (try with non zero Rout signal source) and input (preoutput) stage will have less THD.

peranders · 19th August 2005, 11:53 AM

R6, R7 is a part of the input buffer. Only R11, R12 is involved in the current feedback circuit.

anli · 19th August 2005, 12:14 PM

Quote:

Originally posted by peranders
R6, R7 is a part of the input buffer. Only R11, R12 is involved in the current feedback circuit.

For page 1 - R10, R11 probably? OK, they are inside FB loop. R6/R7 are beyond one.
And .. what? You have more reasons to make input stage (and amp's input impedance) more linear, I think

peranders · 19th August 2005, 12:30 PM

R10, R11 of course. How much more linear do you think it can be? Right now the THD is below 0.008%, below my soundcard.

anli · 19th August 2005, 12:44 PM

Try with, say, 30K output resistance signal source - as for input linearity and THD. And measure input buffer power dissipation deviation in both case - as for input buffer thermal distortions.

P.S. Of course, I don't insist on anything. No more rather "I would modified this topology this way".

19th August 2005, 09:48 AM	#1
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Current feedback headphone amp What do you think of my SMD current feedback amp? At the moment I have only pdf's but if you'll check my QRV-06 amp you will have all info about the amplifier itself. Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Partslist Solder layer Component layer Component print Groundplane layer Thermo pads layer __________________ /Per-Anders (my first name) or P-A as my friends call me

19th August 2005, 10:46 AM	#2
Workhorse diyAudio Member Join Date: Dec 2004	Hi P E R A N D E R S, I liked your current feedback amp very much! How about publishing the specs......It would be great to see your revelation...... Cheers and enjoy! K a n w a r __________________ It's a fruitless endeavor to try and educate a fool that rejoices in ignorance

19th August 2005, 11:53 AM	#7
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	R6, R7 is a part of the input buffer. Only R11, R12 is involved in the current feedback circuit. __________________ /Per-Anders (my first name) or P-A as my friends call me

19th August 2005, 12:30 PM	#9
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	R10, R11 of course. How much more linear do you think it can be? Right now the THD is below 0.008%, below my soundcard. __________________ /Per-Anders (my first name) or P-A as my friends call me

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19th August 2005, 11:00 AM	#3
anli diyAudio Member Join Date: Oct 2004	Try to move T12/T11 collectors to T13/T14 emiters respectively. Such way you will reduce AC part of Vce for T11/T12. Some resistors values rearrangement is needed, of course. The same idea may (must?) be applied to (pre)output stages.

19th August 2005, 12:44 PM	#10
anli diyAudio Member Join Date: Oct 2004	Try with, say, 30K output resistance signal source - as for input linearity and THD. And measure input buffer power dissipation deviation in both case - as for input buffer thermal distortions. P.S. Of course, I don't insist on anything. No more rather "I would modified this topology this way".

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