DOZ headphone amplifier

gromanswe

Disabled Account
2002-07-08 8:42 am
North
www.google.com
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!!!!!!
 

paulb

Member
2001-06-01 4:53 pm
Calgary
Hey Sidney, good to hear your report. It makes an interesting contrast with this one:
morsel said:
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/showthread.php?postid=41397&highlight=gah#post41397

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

Paul
 
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!
 

gromanswe

Disabled Account
2002-07-08 8:42 am
North
www.google.com
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.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=2744

groman