Post pics of your builds....

[Shosta]

I take the basic design from Tangent. it's basically a PIMETA with OPA627 and two 634 buffers per channel.
Power is two 9V batteries in series (18V)

almost finished


amp&buffer 'section'


Reversed view - i'm not very good soldering - Thanks to tyre's photos i used wires to connect a lot of pins.


Into the cards box (I like this box. Look at the picture, they must be the girl's parents and look at the way he look at she. )


Front view


Testing with Richter


Firsts impressions:
If I noticed an improvement coming from my previous cmoy (OPA134) when compared to the standard headphone jack of the Marantz Amp, now the improvement is more noticeable. Bass are extended and controled, mids are liquid and warm and treble is cristaline. But the most important improvement comes from the separation of instruments. A lot of air between instruments, a lot of space.
And the improvement it's very, very important with HD600s. The grado 225s are good headphones but now i know why HD6X0s are so praised. The bloated bass they exhibit with the standard headphone jack is lost now.

In near future I plan to bias the opamps in class A. But for now I'm going to enjoy with the music.

[luften]

Originally Posted by ~n00beR

Isn't the maximum continuious output current for the 634 250mA, and the short circuit current is 350mA.

The clipping is probably because you are driving it beyond the max cont current recomendations , you've done pretty well to get it to run at that level :basshead:

Just a thought

n00b

Actually, the clipping comes when the voltage swing cant go any higher. 300mW in 300ohm equals ~32mA, so the buf has a lot more to give.

I did not run this in to my headphones , it is a resistive load (300 ohm) used to test the power I could get out.

[luften]

I just built myself another one

This one is running on batterys, and is a lot smaller. I meant to use it with my laptop while being abroad this sommer.

Sideview:


Endview:


Insideview:

[~n00beR]

Originally Posted by luften

Actually, the clipping comes when the voltage swing cant go any higher. 300mW in 300ohm equals ~32mA, so the buf has a lot more to give.

I did not run this in to my headphones , it is a resistive load (300 ohm) used to test the power I could get out.

Oh, OK

Glad someone set me straight about that

Makes more sence now, lol

[MaxW]

Originally Posted by luften

I´m pretty new to this forum, but I thought I could post you some pics

To begin with, my OPA627 + BUF634 headphoneamp, built almost as the sample in the BUF634 datasheet.
Internal amp:

Hi Luften,
Very nice. Would you share the design files for your layout?
I ask because I was never happy with my layout for the DIP version of the BUF634: http://max8888.orcon.net.nz/preamp.htm
and yours looks nice :allteeth:

[luften]

Originally Posted by MaxW

Hi Luften,
Very nice. Would you share the design files for your layout?
I ask because I was never happy with my layout for the DIP version of the BUF634: http://max8888.orcon.net.nz/preamp.htm
and yours looks nice :allteeth:

Thank you for your kind words! I´ll drop you a pm.

:600smile:

[Onix]

Originally Posted by Shosta

I take the basic design from Tangent. it's basically a PIMETA with OPA627 and two 634 buffers per channel.
Power is two 9V batteries in series (18V)

The box is beautiful. Felicidades.

[pburke]

Here some quick pictures of a recent project. This is a pretty modified DDDAC1543 (16 instead of 8 parallel DACs), sporting custom power regulation for the XO clock, as well as several other circuit modifications over the original design. The most obvious one is the direct headphone output (i.e. the headphones are directly driven by the DAC, no opamps, no tubes, nothing but a pair of blackgates beween the DAC output and the Neutrik jack. There's also a stepped attenuator that is outside of the signal path, which doubles for headphone and line-out volume control. The DAC is essentially a passive preamp for the digital sources, although it's a little loud for that right now - I will need to add a toggle with a single high grade series resistor to match my amps better. That'll be in the next build which will also have a modded M-Audio USB input inside the box. The thing plays for well over 18 hours before you need to recharge (8 hours for a full recharge). Just about all the components used are highest grade available: Silver wiring, Stillpoint ERS paper lining, Auricaps and Blackgate N/Nx caps, etc.

Sorry for the big pictures - there'll soon be a web page with more info and with big images linked from thumbs

Finished DAC:


Inside:


The Elma switch 24-step stereo attenuator - just because it looks so cool


Backside - top left are the main battery and charger connections. The weird plug below came with the enclsosure and powers the fan only. Inputs are toslink and SPDIF via proper 75 ohm Neutrik BNC connector.


18ah SLA battery with smart charger: you'd never know this thing runs on batteries. Portable? No


This is the batch I built for a few head-fi'ers - no, there are currently no plans to do this again. This thing isn't cheap (over $600 in parts alone), and the time that went into each of them.... don't ask.


Anyway, folks with AKGs need not apply - this thing won't drive them. Works fine on Sennheiser 650s and Grados and other less difficult to drive headphones.

Peter

[steinchen]

awesome

what kind of enclosure is this ? looks like the case for an external harddrive.

[jerb]

those were my thoughts aswell it defiantly looks liek an external hard drive but ive never seen that particular model