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Old 23rd December 2012, 01:07 PM   #51
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Quote:
Originally Posted by EUVL View Post
A version of the DAO as it is will do 11Vrms and 150mA.
It will be described in Part 2b of the article (after Xmas).
So I consider the AKG 600 covered.

The HE-6 I also now considered solved, at least in simulation, using 5 active devices per channel.
The driver device is still an LU1014, cascoded by a higher power MOSFET.
The trick is then to get the LU1014 to work in triode mode at a bias of ~500mA.
In simulation, at full +/-25V swing into 50 ohm load, 2nd harmonics is -85dB, 3rd -100dB, 4th -105dB.
Bandwidth -3dB is 2MHz.
That is respectable performance, even only in simulation.

The changes are not minor, so we need new PCBs as well as a substantially revised case design.
But since headphone is not our main interest, I doubt we should invest 1300 USD to buy one of these just for testing.
Unless of course there is a huge interest (so far only you ?).
2
But i'm interested in lower voltage, higher current to drive 25-80 ohm HPs only.
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Old 23rd December 2012, 01:54 PM   #52
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In the spirit of DIY, have you considered figuring it out on your own, following EUVL's wealth of given info.
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Old 23rd December 2012, 02:21 PM   #53
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How do you define "high" current ?
Is 200mA Class A insufficient ?

The original DAO was designed for the AKGK701 at 62 ohm, which is about the middle of your mentioned range.
On top of that, I have not finished published all parts of the article.
For example, in Part 2b, higher current and higher voltage versions would be dealt with.

The HE-6 is a special case.
I do not know any other headphone that needs 6W, other than maybe the electrostatics.
That is why it needs special treatment.

Maybe a bit more patience, and your "problem" might be resolved automatically.

Merry Christmas,
Patrick
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Old 24th December 2012, 06:15 AM   #54
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Some more reading material for Christmas.




Patrick

.
Attached Files
File Type: pdf DAO SE Public Part 2b 121224.pdf (447.9 KB, 458 views)
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Old 24th December 2012, 12:42 PM   #55
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I don't have any problem
Good reads I have for Xmas day.
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Old 28th December 2012, 09:32 AM   #56
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I have been asked to show a simulated FFT plot of the HCLI (High Current Low Impedance) version as described in Part 2b.

Here it is, with 22V p-p output into 40 ohm.
I consider harmonics < -80dB at such output levels to be very respectable for a headamp.
Especially achieved just by a JFET source follower with ZGF.


Patrick
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File Type: png DAO HCLI THD 40R 22Vpp Public.png (40.3 KB, 906 views)
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Old 29th December 2012, 02:20 PM   #57
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And for those interested in the high power version for the HE-6, here is a plot of the 500mA triode cell.


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File Type: png LU1014 Triode Cell 500mA.png (20.6 KB, 847 views)
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Old 6th January 2013, 11:36 AM   #58
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Quote:
Originally Posted by EUVL View Post
I have been asked to show a simulated FFT plot of the HCLI (High Current Low Impedance) version as described in Part 2b.

Here it is, with 22V p-p output into 40 ohm.
I consider harmonics < -80dB at such output levels to be very respectable for a headamp.
Especially achieved just by a JFET source follower with ZGF.


Patrick
Hmmm
Can you post a plot with 4V output?
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Old 6th January 2013, 02:20 PM   #59
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It is only simulation.
Better wait for real measurements.


Patrick.
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Old 20th January 2013, 03:33 PM   #60
EUVL is offline EUVL  Europe
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Part 3 of the article, plus a couple of finished PCBs.
In case you wonder why the amp PCB has not been shown, I have been waiting for PRP resistors from the US for 2 months !!!!


Patrick

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File Type: jpg 130120 DAO PSU s.jpg (180.3 KB, 693 views)
File Type: jpg 130120 DAO Cross Feed s.jpg (98.4 KB, 692 views)
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File Type: pdf DAO SE Public Part 3 130115.pdf (413.4 KB, 297 views)
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