Updated:
25-Nov-01 23:41
Welcome to the DDDAC Column!
#6
"New DAC project, PHONO
stage ready, project: SUBWOOFER, Audio Visits and Site update"
Major Site Update (again...)
Indeed, it was about time to do something on the site. It might have looked, if I
have not been hobby-ing. Well I did! as you will read on all the new pages and new
projects. Why is it always so difficult to keep a WEBsite up to date?? I really don't
know. Probably because it might seem to be more fun to actually do things than write
about it....... I must admit, it is an awful lot of work to do this, but when I am sitting
down to make all this nice stuff, I do enjoy it. Well lets not get too philosophical.
What's new? I REMOVED all the pages on the "want to build the DAC?". I had some
response, but too little to really combine something. Better not too disappoint people. I
realized, that for most people, finding their own way in collecting the parts is part of
the DIY fun. Plus, nobody wants to wait for more to come. So what the heck? Now there is
place for my new project: de DDDAC 2002, read all about ! Since the beginning of the year,
my audio equipment has changed quit a lot, so I also updated the "listening"
section. New setup, I try to give a more relative picture, so comparison might make more
sense than just meaningless points, we so often see at the audio magazines..... Check the
rest for your self and enjoy ! Oh yes, I am building a MASTER SUBWOOFER, a what? read all
about it.........
The DAC strikes back..... my new
project the DDDAC 2002
The real fans of my site (are
there any?) know why I originally started the DDDAC project: My LINN/Ortofon combination
was so good, I did not enjoy anymore my CD music from the (standard) Marantz CD10. It is
always good to some luxury problems, eh? So I designed and built the DDDAC 2000. Actually
this DAC was so good, it could cope with the LINN combination and beat it some segments!
So I played less vinyl. Oh oh oh, not good at all! So I designed and built the DD PRE
2001. Recently this no compromise PHONO-LINE stage saw the light and after final tweaking
and solving some irritating HUMM problems, it is now playing the stars from heaven, so now
I play less CD
and..................................................................................
AHAAA ? You got the point? Great ! There is truly no other reason than this, to take the
next challenge: building a DAC with a modular design, so I can build in ANY digital filter
and ANY DAC chip set I like quickly and without completely redoing the lay out / PCB /
chassis. All selectable, through a bus structure (the DD-BUS) from the front panel for A-B
comparison or for selection of any Receiver/Filter/DAC combination you think fits best to
the music being played. I will start using latest technologies and latest design ideas,
trying to beat the LINN again........ Read all about it the project description at the new
pages!
Finally ready, the DD PRE
2001.......
This was almost a little drama, I could not get rid of the HUMM problems. Finally
it came out to be a bad combination of microphonic 6SL7's and a more than normal vibrating
Transformer. And here the solution only arrived because of the good spirit of other AUDIO
Lovers: Triodedick and Wil Blauw. Wil, because he immediately sent a new transformer
without discussions. This may sound normal, but believe me: IT IS NOT. I have some
problems with a spare set of AVVT 300B's which are now for the second time out of spec and
you won't believe the trouble I am going through to get a replacement. Still pending, so
in the next column we will see a positive or negative report on AVVT Warranty........
Sorry side step.... Triode dick heard about my humming problems and sent me a set of 5961
to check. The combination solved my problems and the DD-PRE 2001 is now playing the stars
from the sealing....... read about on the Tube portal ! Dick and Will, thanks !!!
New Project, the Master SUB
You might think I am out of my mind, didn't I have already subwoofers in my speaker
set up? and what the hell is a master sub??? This idea
was born, when I was trying out my new PC Function generator in combination with the
digital scoop. I noticed that the active Subwoofers, which are an integrated part of my
speakers system, refused to give any audible output below 35Hz and already start rolling
off below 45Hz. Grrrrrr.... I did the obvious thing for a real Audi Hobby-ist: I decided
to construct a MASTER SUB Woofer, to only support the last octave......
Again: this would not have been a good kick off without the help of, yes again, the help of another audio lover: Tony Gee (check his great Loudspeaker WEB Site at : http://home.hetnet.nl/~geenius/index.html ) specialist on everything which has to do with speakers. He really helped me in making the right decisions, which is not easy in the loudspeaker world !!! so many choices to make, unbelievable. Tony thanks !!!
Audio Visits
Last weekend I took the opportunity to visit audio friends Dick van de Merwe and
Jan Deckers. Just to have a day of inspiring audio discussions and good food. (Actually I
go there only for the nice meals they always prepare for me, hehehehe..... but don't tell
further!). Great days at both friends, lots of Vinyl ofcourse and some nice CD. Any thing
interesting? ohhhhh yes, you bet! we did some comparison of DIY equipment and came
to some interesting conclusions:
Scratch and DD-PRE Phono stage:
These 2 stages has been built and upgraded recently and have a different way
the amp and the filters are set up (for details see our WEBsites). The thing they
have in common, is a filter network, tuned to the MAX, resulting in a very precise RIAA
reproduction. We first listened to the Scratch/CLEO 4 combination. No need to
mention this sounded very nice.... than the DD-PRE with Phono stage. Mmmmhh different
sound character. Not sure, are we listening to the phono stage or the line stage, in
regard to the difference? No problem, Scratch connected to the Line in, so A-B comparison
can be done. Now with the Scratch almost identical sound stage and character. So the
difference must be between the line stages. Will come back to that later. Listening to
both Phonostages, it was hard to tell the difference, they were both very spatial,
dynamic, sweet and very natural. May be from the Scratch could be said, that the highs
were a little (very little) less filigran. Something we know in the meantime will be
solved, when the right power supply is built. Dick was planning this already. Hell, what
can we conclude? As far as I am concerned only one thing: That a correct filter response
is the MOST important part of the RIAA stage. If this is right and you use good tubes and
a quality power supply, it does not matter any more, what capacitors or tubes you use.
This can still be done to tweak to own taste, but the major step is already done: the
filter. Needless to say, that the right T/M equipment is needed to check the filter.
Solutions where people claim, that the filter can be tuned by listening to it, I now
believe we can bring under at the section fairy tales......
Uhhh, the line stages. Yes, they were quite different in character, hard to say what was "better" here. Dick's Cleo sounds very smooth, very detailed, very filigran. He uses a lot of old stock Paper in Oil and the Philips B406 tubes. I use the triode 30 and ASC MKP in Oil. The DD-PRE has more bite, but less smooth. Both very spatial and natural, but different in the dynamics; is this the 30 and the capacitors? Conclusion? no conclusion on winners or looser, therefore they sound both too good, but inspiration to see if I can combine the dynamics with the smoothness! I still have a few Philips A406 on the shelf and 226. All DHT tubes. Time to start experimenting with these tubes !! If done, you can read it here......
DDDAC 2000 and the Tribute
At Jan's place we took the time to compare the Tribute DAC and the DDDAC 2000.
The interesting thing is, that both DAC's are quite similar. They both use the
PCM63 DAC, a 100 Ohm R I/V load and a step up transformer for H.F. filtering and
output buffering. The difference is in the Digital receiver and Filter. The Tribute is
using older generation parts (and therefore the DAC is extremely affordable, which is a
good argument to use these parts by the way) like the CS8412 and SM5813. The DDDAC uses
the CM8420 and SM5842. The DDDAC receiver does re-sampling and converting to 24 bits (8412
16bits). The 5842 is a Pentium 4 compared to a 486DX in terms of calculation power and
accuracy. For example the 5813 works with 16 bit input and accumulators and multiplicators
with much lower resolution than the 5842. But for 3 pieces of the 5842 you can buy a
complete Tribute DAC, so we need to keep that in mind. Never the less it was interesting
to hear the actual difference, which had to do with the digital filter/receiver
combination. We connected both DAC's for an A-B comparison and came very quickly to a
conclusion: The 8412/5813 is no match for the 8420/5842. The DDDAC was playing in a
different class. The 5842 showed very high accuracy in the stereo image making the whole
sound more clear and open. Dynamically, both were equal. The difference was really the
sound stage and micro level details. So, I guess, it will be time for an upgrade??? Not to
difficult as the 5842 is an evolution of the 5813.......
Just image all DAC's were like the
DDDAC 2002 already, just Plug and Play !!!!!!!!!
Happy Listening and Building !!!!
Doede Douma
IMPORTANT: The information provided on this page is intended as guide for DIY activities and therefore free to copy and or publish. If any one wishes to use any of the information from my WEB site, please make sure to refer and footnote to my URL Link as source! Doede Douma