Analog sound from Digital source. Possible?

Extreme_Boky

Member
2003-12-07 11:57 am
I had great pleasure last couple of weeks playing with Audiomeca Mephisto II CD transport unit. This is the best sounding transport unit I modified so far with completely analog-like sound. Very natural, fast, detailed - It sounded NOTHING like digital source. I used it with Pedja's NOS 1541A (S1) DAC with 50MHz asynchronies reclocking. SUPERB!!!!

The long search for digital audio Nirvana has ended for me (now I have to find a way how to get this CD transport for a reasonable price, the cost is US$7000 !!). Actually, I would implement design ideas only, try to source similar cd mechanisms and use MUCH better digital servo PCB and power supply (power supply implementation is quite honestly - SHOCKING - however, the sound is SOOOO GOOOOOD!!!!)

I would like to hear what other people think about using the acrylic and heavy plastic as a solution to obtaining analog sound from digital sources?

In my opinion, the reason for such an analog sound coming from this CD transport is the fact that cd mechanism is fully potted in plastic / acrylic. It is also FULLY suspended via large acrylic plate in which the mechanism is mounted. The BASE of the whole unit is lead-loaded to lower the centre of gravity. The whole thing is VERY similar to large and heavy acrylic turntables that sound SO GOOD! Is this the secret to obtaining good quality sound from digital sources?

The rest of this CD transport is NOTHING special at all. However, this plastic material was extensively used. The bottom plate has very heavy lead-loaded "base" to lover the gravity.

Has anyone experienced these transport or played with similar materials?

Regards,
Extreme_Boky
 
this plastic material was extensively used. The bottom plate has very heavy lead-loaded "base" to lover the gravity.

Thats why i made a sandwich of mdf / lead and acryllic sheets for my home made 4 dacs parallel non-os 1541A cd player, and the CDM 2-0008 stands on home made rubber stand-offs and is dampened with lead and rubber sheets... but the player isn't finished yet, lack of time.
Nevertheless experienced that mechanism quality is very important to benefit sound-quality: crowdy parts in music are better followed, and gives a more relaxed sound overall.:)
 
I became to transform the KSM of a rotel in top-loader with acrylic base ,it sounds good with a 1543 .

Here is the first step :



now i will machine a larger base (about 420x230mm) , and i'll hook the motherboard on .
 

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Analog sound from Digital source? Possible!

Extreme_Boky said:
In my opinion, the reason for such an analog sound coming from this CD transport is the fact that cd mechanism is fully potted in plastic / acrylic. It is also FULLY suspended via large acrylic plate in which the mechanism is mounted. The BASE of the whole unit is lead-loaded to lower the centre of gravity. The whole thing is VERY similar to large and heavy acrylic turntables that sound SO GOOD! Is this the secret to obtaining good quality sound from digital sources?

I think you're right. I never experienced that 'fully potted' cdm2.0 transport, but I can can confirm that using acrylic or similar materials in suspending, or rather in mounting the cd mechanism, works very well. The first time I saw and heard that approach was with the Audio Research CD2, a reallly analogue sounding player, and to my ears better than most other cdp's at the time (compared to f.i. to Wadia 301, Bow and Meridian cdp's). The rather cheapish looking Philips VAM x cd-rom drive (if i remember well) was mounted on a thick slab of acryl or something like that.
Since then i experimented that approach, combined with making the overall base much heavier (yes, also with lead :) in two succesive transport projects with good results: Philips CDD882 (with cdm1 mkII) and the Studer A727 (with the superior cdm1). As a base i used a Corian plate; harder, stiffer and much heavier than acryl, but also useful in tuning those resonances (i also use Corian as an armboard for my modded Rega RB300). Of course wood, mdf and other materials do all have there sonic impact, so in the end its a matter of (fine) tuning -- as ever.

BTW interesting background information on the Audiomeca cd mechanism and design philosophy can be found here
Although i never heard the Mephisto (wow, what a name!) i guess the real secret in this case wil be the state-off-the-art vinyl/turntable expertise of Pierre Lurné, combined with the dito Philips/René Boonen engineering....

Extreme_Boky, could you elaborate a bit more on the construction of that cdm2.0? It looks rather like a cdm12 than a Boonen designed cdm4 or 9! Can't you post some pictures?

groeten
Lourens
 
Extreme_Boky said:
The long search for digital audio Nirvana has ended for me (now I have to find a way how to get this CD transport for a reasonable price, the cost is US$7000 !!). Actually, I would implement design ideas only, try to source similar cd mechanisms and use MUCH better digital servo PCB and power supply (power supply implementation is quite honestly - SHOCKING - however, the sound is SOOOO GOOOOOD!!!!)

Hi Extreme_Boky

According to this review the Audiomeca cdm2.0 is "(...) licensed to a few select manufacturers building state-of-the-art players themselves."
Do you, or anybody else know which players are meant here?

groeten,
Lourens
 
analog sound

my TDA1541 nos dac which have amplitude equalizer and steep LPF is much much more analoge sound than the Benchmark DAC-1,comparing two days ago.

My NOS DAC can express music emotions,DAC-1 cannot in compring.

this is my post on the other forum a week ago

http://www.diyhifi.org/forums/viewtopic.php?p=6107&sid=3d86a3332fb13ab1a39ab2401c64519d#6107

PS:I am busy in improve my TDA1541 NOS DAC.I spent 6 months for that,I had tried Zanden's Filter (I found Zanden's theory is wrong!) ,K. Y. Wang's filter, 3th and 5th LC filter.Using the steep LPF and amplitude equalizer,I got the excellent sound now, much much better than before. maybe I had know the reason why Jocko don't like the sound of NOS DAC.

www.hifidiy.net/dispbbs.asp?BoardID=2&id=4499&replyID=4499&star=21&skin=0

[IMGDEAD]http://www.hifidiy.net/UploadFile/2005-6/2005613135349130.jpg[/IMGDEAD]

I have post the the chinese thread which explain why I use amplitude equalizer and steep LPF :

http://www.hifidiy.net/dispbbs.asp?boardID=2&ID=12780&skin=0

If i have time,I will post that thread in English on here

goodluck

X.G. from China
 

Extreme_Boky

Member
2003-12-07 11:57 am
BTW interesting background information on the Audiomeca cd mechanism and design philosophy can be found here
Although i never heard the Mephisto (wow, what a name!) i guess the real secret in this case will be the state-off-the-art vinyl/turntable expertise of Pierre Lurné, combined with the ditto Philips/René Boonen engineering....
According to this review the Audiomeca cdm2.0 is "(...) licensed to a few select manufacturers building state-of-the-art players themselves."
Do you, or anybody else know which players are meant here?

I am not sure which players use this CDM2.0 mechanism.

The material used to fully pot the mechanism is not acrylic but very dense black in colour "heavy" plastic. This is one of the main reasons for such a wonderful sound coming from this mechanism. The potted mechanism itself is bolted to a plate of approximately 350 X 350 X 8 mm (8mm being the thickness) which is suspended at 4 points on to 4 springs. There are 4 alen / imbus screws to make the whole suspended plate with mechanism levelled. The plate is of the same material as one in which the mechanism is potted (i think). Unfortunately, I did not take any photos and the unit is back in Melbourne.

However, there is another very good point to remember - the wiring between cd mechanism and PCB is soldered at cd mechanism end and has connectors only at the PCB end. I have modified some CD players where I removed the membrane ribbon cable and used fine silver wiring which I soldered at both ends with excellent results.

Back to Audiomeca's mechanism - I can suggest a quick and easy mod to the pickup itself. There are two power supply decoupling low profile capacitors located on the little PCB on the lens assembly. Those two have to go out and make place for two 0.1uF / 50V NX type Black Gates. I have carried-out modifications in steps - this being the first one out of many. The result was excellent - dark background, better detail retrieval, more natural piano.

One should seek to use only Cast Acrylic, which is superior in all ways to common extruded acyrlic.
I'd like to see this cast acrylic. I'll search the net and see if there's more on this material.

I'd also like to remind everyone that I used very good DAC with asynchronous reclocking. I spent at least 2 weeks trying to get basic DAC to sound excellent. I added the reclocking board AFTER I was fully satisfied with the sound of "basic" DAC.

There's no doubt in my mind (especially now - a week after I sent the unit back to Melbourne when all the impressions and thoughts have settled in my head) that the plastics used extensively in Audiomeca Mephisto II transport are to blame for analog - like sound.

Regards,
Extreme_Boky
 
acryl

I'd like to see this cast acrylic.

Me too! Especially when it could be moulded (DIY), for instance filling all those spaces on a cdm1 platter to get both a really smooth surface and better damping....

Maybe widely available epoxy or polyurethane resins are an altenative??

There's no doubt in my mind (especially now - a week after I sent the unit back to Melbourne when all the impressions and thoughts have settled in my head) that the plastics used extensively in Audiomeca Mephisto II transport are to blame for analog - like sound.

I will explore this futher. Starting with a cdm1...
 

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Filled the hollow spaces of disc clamp from CDM-2 with a mixture of polyvinylcellulose (woodglue) and sharp bird-cage sand, just like Focal: they fill their woofercones with tiny glass balls to reduce resonances. You have to fill the spaces a few times and let it dry, the woodglue crimpes every time when drying, and the sand sinks a little to the bottom of hollow spaces. After drying cut off too much glue/sand with sharp knive. Before procedure grind off the hollow spaces for good adhesion. After last gluelayer: a layer of matt black paint on it to adhese some loose sands. When ticking on the clamp it has now a really "dry" and a fast decay of sound, and therefore much better dampened!
Cheap diy and simple mod with good result.
 

Extreme_Boky

Member
2003-12-07 11:57 am
The Audiomeca's website provides the real insight in to what makes the great CD playback possible (thanks Lourens for the link!):
http://www.audiomeca-hifi.com/page10.html
It puts the accent on mechanical aspects of well designed transport mechanism. I haven't touched my notes since I finished mechanical studies. My love for electronics and day-to-day involvement in electronics at work, and as a hobby, dragged me away from thinking "mechanics". However, Audiomeca's web site and their products show us not to forget an importance of the "mechanical" approach / thinking, to achieve really god results. Cutting the vibrations with right material and balancing the mass(es) is extremely important.

Obtaining the suitable CD mechanism and applying the right material is going to be the next step for me. The way my DENON loads the CD rom makes it impossible to do any mechanical deadening of the existing mechanism. However, I have played with different plastics for the last week or so. I applied this plastics on top and sides of the mechanism with very good results. The original copper-plated metal sheet was removed (forever!).

It is far from Audiomecas implementation, but the awareness, thinking and intention is there!

Regards,
Extreme_Boky
 
Re: analog sound

X.G. said:
my TDA1541 nos dac which have amplitude equalizer and steep LPF is much much more analoge sound than the Benchmark DAC-1,comparing two days ago.

My NOS DAC can express music emotions,DAC-1 cannot in compring.

this is my post on the other forum a week ago

http://www.diyhifi.org/forums/viewtopic.php?p=6107&sid=3d86a3332fb13ab1a39ab2401c64519d#6107

PS:I am busy in improve my TDA1541 NOS DAC.I spent 6 months for that,I had tried Zanden's Filter (I found Zanden's theory is wrong!) ,K. Y. Wang's filter, 3th and 5th LC filter.Using the steep LPF and amplitude equalizer,I got the excellent sound now, much much better than before. maybe I had know the reason why Jocko don't like the sound of NOS DAC.

www.hifidiy.net/dispbbs.asp?BoardID=2&id=4499&replyID=4499&star=21&skin=0

[IMGDEAD]http://www.hifidiy.net/UploadFile/2005-6/2005613135349130.jpg[/IMGDEAD]

I have post the the chinese thread which explain why I use amplitude equalizer and steep LPF :

http://www.hifidiy.net/dispbbs.asp?boardID=2&ID=12780&skin=0

If i have time,I will post that thread in English on here

goodluck

X.G. from China


Hi XG, Steep filters have a lot of ringing which is undesirable I think...
 
Re: Re: analog sound

Elso Kwak said:



Hi XG, Steep filters have a lot of ringing which is undesirable I think...

Yes,I see....thanks for your response,ELSO.

after reading some books and materials,I found that there are different opinions for the delay-time distortion,some say important,some say not, seems that dominate opinion is un-important....I believe my experience can tell me the truth ;)

by now,my conclusion is: the sound of TDA1541 NOS-DAC without steep LPFs is just good,the the sound of TDA1541 NOS-DAC with steep LPFs is much much better!

regards

X.G.
 
Me too! Especially when it could be moulded (DIY), for instance filling all those spaces on a cdm1 platter to get both a really smooth surface and better damping....

Hi Lourens

You can easily fill the spaces with acrylic. Chloroform can be used to dissolve small pieces of acrylic. The highly viscous solution created can then be poured into the spaces, this will take a while to harden. Alternatively you can:
cut pieces of 3mm acrylic to the general shape of the spaces on the CDM1,
cut a rectangular piece to the dimensions of the CDM, with a hole for the spindle and an arc for the laser.
Use some acrylic/chloroform paste to fill in any small gaps and to 'glue" the rectangular plate to the pieces in the gaps. This ensures a solid piece of acrylic.

The acrylic solution will mould perfectly to the gaps in the metal and if you don't like the sound you can just lift it off.

Work in a well ventilated area or you could end up with impressions of the CDM1 spaces on your face :).


Cheers

Richard
 
Hi Richard,

Thanks! Dunno if my alchemist competences are up to this. But i have a broken cdm1 at hand which i can use as a testbed, one day, after a deep breath of pure oxygen and a nice pair of safety glasses, and perhaps even a complete mask to protect my :eek:
Some more questions:
1. Did you actually carry out this mod yourself?
2.1 You say you can lift the moulded inserts off easily. So it does not bond with the metal surface?
2.2 Some glue will prevent unwanted resonances then, contributing to the dead silence we are aiming at, mechanically speaking, won't it?

groeten
Lourens