F5 Headamp ?

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#22
EUVL said:
The F5-HA already has JFET input and hence high input impedance (essentially same as a complementary JFET source follower).
There is no need for any additional buffer (of which the so called B1 is on of many).

In my listening test, I use a 10k stereo pot between DAC out and F5-HA.
No problems whatsoever.


Patrick
Click to expand...
The Buffered output would be in parallel to the headphone output ?
The he/she can plug into one, or both, outputs without having to disconnect the other.
Especially if the Pre-amp, volume control, headphone amp is near the listener and all the other gear is one shelves in other parts of the room/in another room.
 
#25
If you :

1. accept a bit more noise and a bit more distortion
2. have well matched pairs with low Idss (6mA or lower preferred)

Then you can go back to the original F5 feedback arrangement.
Performance is still very decent (~ -75dB THD at 5Vrms out into 50 ohm).


Patrick

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#27
EUVL said:
How does it sound ?
Fast, clean, have plenty in reserve, background dead quiet.
I'll let someone else listen and give you his subjective review. 🙂

Patrick

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Click to expand...

Really looking forward to hearing more.

This is very opportune for me. I built Tortello's 'zen-like headphone amp' some years ago but I was never very happy with it...particularly the top end. last week I decided to rip the amp boards out of the case and was casting around for another suitable circuit to put in and found this thread. So you've got my full attention!
 
#28
If you have a lab supply. you can knock a couple of these in a few hours.
So why wait for someone else to give you his subjective view?
In the end you have to like it, not us.

Especially if you build the one in post #25, it does not cost anything.
The JFETs and the MOSFETs all cost much less than 1 USD each.
You don't even need to match to make it work, just trim R3, R4.
And when you are then happy with the results, you can rebuild again using properly match devices, good resistors, ....., etc.
It can only get better.

I actually have a fully designed PCB layout on my computer.
This includes everything from transformers, fast recovery diodes, super regulators,.... to cross feed, volume control, etc.
i.e. everything I would want in a head amp.

But then I just finished my DAO. Which is a different story. 😉


Patrick
 
#35
EUVL said:
This seems to be a good deal ?

Toshiba Original 2SJ74GR 2SK170GR Matched Pair 0 05 MA | eBay

Disclaimer :
I do not know him. Have not bought from him before.
But he has good feedback ratings, and price is market value (i.e. realistic).
You need to increase drain resistor values for GR grade, without saying.


Patrick
Click to expand...

I just placed an order from this seller. I plan to build this head-amp when I get back from vacation!

Steve
 
#37
Patrick,

Thank you for the offer of your time. I know how hard tinker time has been for you to come by as of late. I also ordered some j511 diodes to complete the second channel of my DAO V1 that I started YEARS AGO! I too have a hard time finding the time to tinker.

When I get the two finished I will compare them.

Steve
 
#38
The DAO has a lot more power and (shall I say) authority, but no gain.
It is also intrinsically linear with no feedback.
So it is not a fair comparison.

But both have very high bandwidth.
Which was why I used the words "fast & clear".

Hope you like them also.


Patrick
 
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