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Old 24th May 2010, 12:34 AM   #521
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John, I read on your other DAC thread that you have changed your approach to regulators. I recall that the 1541a requires more regs than the 1543. Based on your current versions of the 1541a and 1543 dacs, how would you and others describe the differences in SQ as through your ISD Player?
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Old 25th May 2010, 06:13 PM   #522
brubeck is offline brubeck  Netherlands
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Hi,
I own the two first editions of Ec-design's 1543DAC and 1541ADAC. I feed them I2S from a modded and batterie feeded Squeezebox reciever. So not the sd-card as source, but maybe you are interested in my experiences about the SQ between these DAC's.

With the luck to be Dutch, in this case ;-), i often discussed SQ issues with John and followed every step/tweak/update of the 1541A DAC circuit until the 1541A reached then MKII status now.

Personally i am a fan of the sound of NOS DAC's in particular the TDA1543. The EC-design single chip version with honeycomb I/V resistors Performs very well. I had more 1543 based DAC's at my place and they al sound nice. The exceptional approach of filtering al source lines to the chip increased the upper detail level a lot compared to other 1543 DAC designs. The disadvantage of using 1 single chip is imo a lack of dynamic power and articulation in the mid's and lows. I personally would say, it sound a bit soft. In the basic design i was not complete satisfied with smoothness of the high's. Hard voices became a bit glassy and therefore not natural. Recently i tried to bypass the 7805 regulator and injected the chip and I/V resistor direct to the 6 Volt lead accumulator i use, with one serial diode. That reduced the glassy high's. The 1543 is a musical miracle. The natural and musical character is amazing. While listening my foot keeps tapping :-)

I also bought the first edition of the 1541DAC. With the feed of 3x12 volt batteries, the first impression was positive as i wrote earlier in this thread. More dynamic resolution and, what i would call, more 'emotional impact'. Looking back now with all the experiences of the last month the sound had not the overall natural performance in the whole spectrum as the 1543 DAC. After a couple of days playing with the 1541A DAC, i experienced an annoying noise in the tweeters when the DAC chip got warm. In between John already told me about this issue. I had to do with the DEM injection circuit. That was the start of a cumbersome route. When i received the DAC back after modification, the sound had not the same impact on me and i was disappointed. Then the difficult part started. How to describe and indicate this change of perception? The updated DEM injection (and some other little mods) where from a technical view better then the first solution John told me. It took weeks of modifications by Ec-Designs to identify the internal chip effects versus the audible perception with different DEM injection methods. This resulted in the current and final DEM-circuit that sounds excellent. The most important issue is that John now fully understands why it is like it is. At this stage the 1541DAC performed very satisfactory. In spite of several other new little updates to the circuit the overall 'sonic' performance still wasn't equal to the optimized (and direct DC feeded) TDA1543. Piano attacks, as an example, did not have the beautiful decay/resound as the 1543. I argued this with John, but the fact that we play with difficult configurations and PSU made it hard to value. 2 weeks ago I got a surprising email with the announcement of complete changed and simplified output stage with one single Jfet. Less is more? Yes, less is more in this case. The output change is now comparable with the simplistic 1543 output. The expected result of this is that the character of the sound has to be equal, and it is! With the single Jfet the overall 'sonic' performance equals the 1543, but WITH the advantages of the 1541chip design, like more accurate details, more dynamic and more high details. After some time of happy listening i detected the same issue as i heard with the 1543DAC with regulator. Loud upper high's still have a very little irritating edge. Yesterday i did the same trick as i did with the 1543 and bypassed the 7805 regulator for the PS of the I/V honey's with success.

I personally think that the 1541A MKII DAC now hits the ceiling for what we can expect from a TDA1541A DAC chip. For all you people that wants to know the secrets and schematics while this is a DIY forum, i would suggest that you buy a DAC from John to support his R&D costs en commitment. Not only the circuit, but also the print is very sophisticated and uses a lot of SMD components.

(Hope my English is sufficient?)

Last edited by brubeck; 25th May 2010 at 06:34 PM.
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Old 25th May 2010, 10:56 PM   #523
a333bt is offline a333bt  Slovenia
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Hi Brubeck,
thanks for review of latest DACs.
I think it would be sonic quality upgrade, if you connect to EC SD transport. It is different use, but for critical listening cant be beaten.

My experience with latest (before mkII) EC TDA1541 is really another level, before DI4T and other earlier versions with DAC1543.
When i connected "last" version of DAC1541A is absolute transparency, natural sound, nothing irritating, classical music sounding exactly like it is recorded, instruments are placed in their positions (John said mkII version is even better in fokus positions).
Averal feeling is that like listening VERY good record player (friend has very good vintage system).
But as you said they are some isues with instability of DEM, now it fixed in mkII and even simpler output stage. I like simplicity more and more.

I could said also about EC bridge balanced amplifier: now i using them already few months and i am complitly satisfy with them. Cant find any critic about sound quality. Transparency, natural sound, pure sound.

I tried (and using) 3 segment honeycomb chokes for crossover of SR60.
Difficult to make, but for high resolution of microdetails is a must. Yes, it make big difference in sound, it makes sound (more) natural.

If someone search natural sounding speakers i sugest SR60 of John. It is omni approach, which most people are not used to. But when you listen and get used to, you dont want get back to direct sounding speakers, which has some mistakes in sound reproductions.
Maybe can someone who has visit Johns place, wrote some experinces.
When i finish One box solution ISD player, i will demonstrate here also.

So as you could think, i am thankful to John, for his support and finaly hear pure natural sound out of TDA1541A.
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Old 26th May 2010, 03:34 PM   #524
brubeck is offline brubeck  Netherlands
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Quote:
Originally Posted by a333bt View Post
I think it would be sonic quality upgrade, if you connect to EC SD transport. It is different use, but for critical listening cant be beaten.
Perhaps, i am not sure. Without doubt the SD-transport is very good. I heard it at John's place. The Xilinx processor and the CPU in the SB are both batterie feeded, Lan is connected through external Wifi and there is a seperate batterie driven reclocker between SB and DAC. The Xilinx is clocked by the Superclock.
I can't invent relevant negative effect's against the SD-card is this config. Modding the SB is this way is not easy, but i like the benefit of streaming. In the future i plan to add the sd-card player as second option. Then a A/B comparison can be made.
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Old 26th May 2010, 05:23 PM   #525
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Hi there.

I honestly got lost about what versions people are talking about.

Johns products are obviously "work in progress". 5 people talking
about five different build states as it seems.

I hope that one day John clearly states "That's it" - and that should stay this way at least for a year or so.

He should introduce a proper revision handling, introducing a changelog and upgrade options.

I had received one of the "early" 1543 SD-players for testing. And I listened
also to an earlier 1541A at a friends place.

I just won't comment on these, because the comments would be for sure pretty misleading and wouldn't reflect the latest build state, which can be - as we can read - a day and night difference.

I honestly wouldn't be able to judge "from remote" the statements recently made about the experienced SQ.

Just my two cents.

Enjoy.
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Old 26th May 2010, 10:03 PM   #526
brubeck is offline brubeck  Netherlands
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Quote:
Originally Posted by soundcheck View Post
He should introduce a proper revision handling, introducing a changelog and upgrade options.
Not necessary. Ec-Designs will exchange sold MKI DAC's for the MKII version for free as a service. Updating the 'old' version is not possible with optimal results. While i have some little more experience with the circuit now, i can say the the DAC-circuit has three important core circuit elements which are together head-responsible for the performance. It's the Superclock, DEM injection and output stage. PSU, and jitter-reduction parts are the creme on the dessert. The first Superclock was allready proven, the current DEM injection is final (no variables) and the output stage is so remarkable simple that it can't be modified even if you should want it.
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Old 27th May 2010, 01:01 AM   #527
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Hi John,

I visited your website and realized you do not have the transport module in stock....
Have you any idea when it will be? If you can take PayPal, I intend to buy one SD transport module and conect it to my DAC project, based on SRC4192/PCM1794A.
Thanks in advance..

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Last edited by Hisatugo; 27th May 2010 at 01:05 AM.
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Old 27th May 2010, 07:05 AM   #528
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Quote:
Originally Posted by brubeck View Post
Not necessary.
This is your opionion. I've seen several MK1s and problably even an MK2.X?

I consider it necessary. I honestly would have problems to buy that equipment otherwise.


And the key element of the SD player is the SD Transport first of all, not the DAC, clock or output stage.

There are a hundred well done 1541/1543 implementations out there, which are not much worse, if they are worse at all - by just looking at the DAC module.

I honestly have issues with single dac-chip solutions and related to it, the low output voltage, low current capabilities and the high impedance.
You need to find a perfect matching amp to squeeze most out of it. After my tests I very well understood why John decided at a certain stage to prepare a DAC/AMP solution. Only here he can guarantee best sound.

Two posts earlier you mentioned that it needs a battery to get most out of it.
D'accord!

I am not sure if the coupling cap chosen by John is the right choice. This single part has a major impact on the overall sound.

BTW: Try the Squeezebox Touch as transport. With a little tweaking it'll beat the Duet on all aspects.

Cheers
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Old 27th May 2010, 08:09 AM   #529
jonners is offline jonners  United Kingdom
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Quote:
Originally Posted by Hisatugo View Post
Hi John,

I visited your website and realized you do not have the transport module in stock....
Hisatugo -

I suggest you contact John via his website. He was able to produce my SD player very quickly.
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Old 27th May 2010, 12:30 PM   #530
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Quote:
Originally Posted by jonners View Post
Hisatugo -

I suggest you contact John via his website. He was able to produce my SD player very quickly.
Oh, thanks for advice. I though would be short to reach him here.

regards...


Hisatugo
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