[mdlover]

it sounds good to my ears. i have added an active I/V stage too and is better than passive version in terms of clarity and dynamic.

would like to know what tricks you have done for the treble.

cheers

 

[IpsilonSound]

Quote:

Originally Posted by mdlover would like to know what tricks you have done for the treble. cheers

Not added yet, still waiting for my TDA1543 chip to arrive. The treble fix I found is passive and includes using a coil and capacitors to create a resonance in the high-frequency area thus compensating for the roll-off. Will post the results when put everything together.

Here's the schematics:

 

[mdlover]

yes, i have the sinc correction sch. too but not added yet.

cheers

 

[rickcr42]

ah yes

thorsten's circuit !

makes a world of difference

honest

 

[IpsilonSound]

Quote:

Originally Posted by rickcr42 ah yes thorsten's circuit ! makes a world of difference honest

Why not? Simple solutions often DO make a world of difference

.

A little simplification would be the first step toward rational living, I think.
Eleanor Roosevelt

and another one...

Reduce the complexity of life by eliminating the needless wants of life, and the labors of life reduce themselves.
Edwin Way Teale

 

[setmenu]

Hi IpsilonSound
How is your dac coming along?
I have just completed my second model.
This new version uses Riken carbons rather than Audio Note Tants and also
has some revised receiver cap values [Black gate N] with reversed polarity
as per Peter Daniels advice.
Well I was none too confident about the difference this would make..
But I have been pleasantly surprised

The sound certainly seems more open with a top end closer to what I am used too.[I look forward to extended listening to really get the measure of this new device..]
It is interesting that using the MK1 dac I found that my Beyer DT931 could be listened to without added source impedance to tame them.
With the MK2 dac they again benefit from a little added source resistance as
before.
Doing a back to back comparison with my CD23 output the NOS dac does have less HF [and a bit less overall V out] and also some reduction in the very
lowest frequencies but overall compares very favorably, but no doubt measures awfully in terms of tech spec....

Mysterious things these little NOS dacs

I look forward to reading about yours.


Cheers

Setmenu

 

[ppl]

Since the DAC is going into a ppa portable have you considered the current Draw. The old TDA1541 and related chipset will typicaly consume about 100 mA add to that the about 120 ma of the ppa and then consider the 800 MAH of the Battery board. Also alot of the non oversampling DAC's paralell severial DAC chips to get the Current output needed to drive a cable so as to eliminate the I/v convertor op amps. also a good non oversampling DAC is
http://www.ack-industries.com/

 

[setmenu]

My 1543 based portable dac consumes 80ma at 9v.
Also Nimh cells seem to be going from strength to strength, it is now
possible to purchase 800mah AAA and 2200mah AA cells quite readily.
It will be interesting to see how much more they can squeeze out of this
cell chemistry...



Setmenu

 

[ppl]

yes like 2000MAh out of AAA. I use the aos DAC and the first version consumes 40 mA with the AKM receiver chip and about 75 mA with the DIR1703 receiver chip. http://focus.ti.com/docs/prod/folder....html#features
The AKM4117 receiver chip http://www.asahi-kasei.co.jp/akm/en/...17/ak4117.html

the Run time difference just between these two receiver chips in a PPA with the 18 cell AAA 800 MAh NI-MH is about just over one hour. when the total runtime is only 5 Hours this is an importent difference

 

[IpsilonSound]

TDA1541 is probably a worse candidate for portable PPA+DAC setup, compared with TDA1543. It requires gain stage to output enough current for line-out, at 100k the direct unamped output from the becomes very distorted. It has, however, better THD and smoother sound compared to TDA1543, as some reported. I'd like to try out the TDA1545 as well, but cannot find the chip except one website in Germany. Ack-industries uses this chip in its setup.
Several folks at diyaudio.com tried 2-4 TDA1543 chips in parallel to increase dynamics and ouput loudness. The drawback of that was losing some focus and coherence in details.
The current required for the chip per se is 50-60mA, and like Setmenu said the complete DAC draws about 80mA, which isn't a big problem IMO. After all the battery board can be re-built for AA 2200mAh cells.
I ordered a few of TDA1543 and TDA1541 chips from MCMelectronics but haven't received them yet

, more than 10 days already... Can't wait to start prototyping.

Also, another issue... i received my SMD 3300pF and 220nF from DigiKey, extremely small multilayer ceramic caps, they come in tape and are almost impossible to be soldered by a human being. Any recommendation for replacing those with thru-hole quality caps?