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Old 28th August 2008, 02:51 PM   #21
Dxvideo is offline Dxvideo  Turkey
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This is my headamp. Its my own design and using for over one year...
Click the image to open in full size.
Its DC coupled but I've never measured over 4mV on outputs. It can drive both 32 and 64R headphones. Its 100mA biased and works in Class A. Now it works for an Ultrasone DJ1. And I am very happy with its sound!
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Old 28th August 2008, 02:58 PM   #22
lineup is offline lineup  Sweden
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good and low cost!

nice DIY circuit

will work like a charm

thanks, Dxvideo, for your schematic
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Old 28th August 2008, 03:00 PM   #23
Dxvideo is offline Dxvideo  Turkey
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You welcome..
Caution: Its a bit warmblood friend.. You will need a good heatsink..
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Old 28th August 2008, 03:02 PM   #24
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Sorry Lineup, I should have been more specific. I am going to build a MOSFET based amp as opposed to an OP AMP cct.


zekeres Driver headphone amp

Also, I (stupidly) posted the wrong link for the first PSU. It should have been this one.

http://www.maplin.co.uk/Module.aspx?...96864&DOY=28m8

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Old 28th August 2008, 03:09 PM   #25
lineup is offline lineup  Sweden
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Quote:
Originally posted by zebra100
Sorry Lineup, I should have been more specific. I am going to build a MOSFET based amp as opposed to an OP AMP cct.
zekeres Driver headphone amp
Also, I (stupidly) posted the wrong link for the first PSU. It should have been this one.http://www.maplin.co.uk/Module.aspx?...96864&DOY=28m8
i know .. maybe you havent even read my 2 posts above ????????????
http://www.diyaudio.com/forums/showt...36#post1594136
shame on you!
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Old 28th August 2008, 08:23 PM   #26
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Sorry,

I was having a dumb moment.
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Old 20th September 2008, 07:06 PM   #27
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Well, I finally have one channel working and it sounds awesome. Very detailed and clear. I can't comment on soundstage yet as I only have one channel. The other channel shouldn't take too long to do because I ironed out all the issues on the initial build. It doesn't go very loud. I am using a cheap 100k pot and some old Sony MDR-CD280 headphones (24 ohms/ 98dB). When I finish the other channel, I will get some better specification headphones to test it with.

I have used a modified cct from the original design. I went with a 13.8v psu for now and used an LM317 as a ccs with 250mA. The MOSFET does run quite warm, but not too hot.

Thank's for all the information guys.

Can't wait to get it finished.............
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Old 20th September 2008, 08:57 PM   #28
lineup is offline lineup  Sweden
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You could try to lower the 250 mA current supplied from the LM317.
0.250 Ampere (1,25V/5ohm ) where two paralleled 10 ohm make one 5ohm.

As I recall it, IRF510 (or IRF610) works quite well at around 100 mA. And this level is well more than what 16 or 24 ohms or 32 ohm Phones will need. ( And of course even if impedance is higher, like 100 ohm )

Using the LM317 and two parallelled 22 Ohm/0.25Watt metalfilm resistors, will give you 1.25V / 11 Ohm = 113.6 mA Class A current.

I have designed/built one HP-amplifier for 32 ohm.
I set the Class A current in output ~90 mA in my prototype.
It it worked very well. I used one bipolar BD139 (TO-126) for my output. With a very small heatsink.
This amp have similar power supply = 12.0 Volt DC. Regulated by one 7812 3-pin IC.
To make it very clean supply.
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Old 20th September 2008, 10:08 PM   #29
Archwn is offline Archwn  United Kingdom
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You could try the simple design. This sch. with good opamp like LME49860 would match or at least very close to top class headphone amp (you name it) with 32R headphone.

I recommend using NiMH battery and forget about the bias for now.

If you got too much hiss, try 1k/5k or even 100k/500k (or something between) instead of 250R/1K
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Old 20th September 2008, 10:23 PM   #30
lineup is offline lineup  Sweden
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It will work.
And be real hi-fi

When using CD-Player output and Gain=5, like you do
with your LME49710, LME49720 or LME49870 or LME49860
this would suit most anything between impedance 32 - 300 Ohm

32 Ohm phones, like Grado Hi-fi http://www.gradolabs.com/
and phones with 300 Ohms impedance
For example Sennheiser HD600, Reference Class
http://www.stereophile.com/headphones/408/
http://www.sennheiserusa.com/newsite...transid=004465
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