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Old 11th July 2002, 04:35 AM   #1
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Default DOZ headphone amplifier

Has anyone built the headphone amplifier? ..have any images to share?

What does it cost to build one of these?
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Old 11th July 2002, 06:48 AM   #2
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Default Good project.

Will not cost much.
It is standard components.
If you have lot of money
you could waste it on some "exotic" stuff,
like cables for $500
Capacitors for $50, still it will just add capacitance.
Connectors in solid gold, $799.99 - sound is the same, yet

regards
"not a money waster" Groman
like money, if it is mine!!!!!!
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Old 11th July 2002, 12:42 PM   #3
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Gomer,

Check out this thread:

http://www.head-fi.org/forums/showth...?threadid=8443

There's a link to pictures of the DoZ Headphone amp I built there. I think I estimated cost to be around $80 but I used a lot of surplus components for everything except the PCB components
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Old 11th July 2002, 07:01 PM   #4
paulb is offline paulb  Canada
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Hey Sidney, good to hear your report. It makes an interesting contrast with this one:
Quote:
Originally posted by morsel
The Doz has a bipolar input, which is much lower impedance than a FET input, and a poor choice. It has capacitively coupled output instead of direct coupled output, a total nightmare for quality audio. The output impedance is too high for low impedance headphones. Real world headphones have impedances ranging from 30 to 600 Ohms. A quiescent current of 330mA, gah. I could go on and on, but basically, it is not a great headphone circuit. If you are insistent on discrete design, at least look at Kevin Gilmore's class a amp.
See http://www.diyaudio.com/forums/showt...=gah#post41397

Enjoy your amp. I think I may build one too. Sometime.

Paul
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Old 11th July 2002, 07:28 PM   #5
The one and only
 
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You can build a fine headphone amp with a single
transistor and about 10 passive components and run
it off a 13.8 volt battery, and it will drive any dynamic
headphone I've seen. No need for 3 gain stages at all.
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Old 11th July 2002, 08:02 PM   #6
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Default Hi Paul

Since the headphone amplifier, I've built a full power version DoZ Amp as a cube (basically 12" x 12" x 2" fin natural alum. heatsinks as sides with quality perforated aluminum top with red oak trim and a red oak face plate). Transistors used are the Motorola BC559 equivs, NTE 373 drivers and MJ15003's on the outputs. (IMHO, after much listening and swapping in and out, you should use the 2n3055's on the headphone version and MJ15003's on the full power version for the best sonics). Also has dual matched cap multipliers. Power supplies for both were oversized.

I won't comment on technical interpretations of suspected design shortcomings of this type of amp, all I know is I am extremely pleased with both versions I've built. I recently got my speaker placement just right and when my wife looked into the room I was sitting there with a grin from ear to ear! It's just a great sounding amp!
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Old 11th July 2002, 08:23 PM   #7
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Default You are right Nelson

The voltage gain needed for a headphone
driving circuit is not high.
This is even more true for low impedance Headphones.
They need a little more current.

An alternative to consider is a high quality OPamp
for raising the voltage somewhat, followed
by a buffer to deliver enough current.

The buffer may be included in feedback of
circuit or not.

Many different solutions work alright.
If you want to use an output capacitor
put the money there.
My choice would be OSCON, parallelled if needing
low roll off.

The high quality Sennheisers have 300 and 600 ohms impedance.
Need not so much current 50mA is enough.
6-12 dB voltage gain is alright,
depends a little on what kind of music-recordings
you listen to.

See this thread of discussion of a low power buffer.

BJT Buffer Circuits?

groman
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Old 11th July 2002, 08:54 PM   #8
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Groman,

Your writing style is nearly poetic. Have you considered
posting your comments solely in Haiku?
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Old 11th July 2002, 10:06 PM   #9
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Default I have my way.

Glad if you think it is amusing in any way!

I have had thoughts on writing a book, sometime.

I like expressing myself in writing.
It fullfill creative needs.
so does constructing designing amplifiers, too.

groman
likes to be creative
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Old 12th July 2002, 02:46 AM   #10
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Default haiku for groman

sun beats on my skin
must I design these circuits
in sweaty clothing?
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