CDM 4/11 vs CDM 4/19

Hello all,

First off, like a good boy, I have searched. But I have still not gotten all the information I need.

I here today asking about the differences between the 4/11 and 4/19 CDM mechanisms.

From my research here, all I can tell is that the 19 is the 'standard' version while the 11 is the 'hall motor' version. Can anyone tell me what 'hall motor' means? Is this a better motor?

If someone could point out any other differences, I would be most grateful.

Cheers! :)
 
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Hi adhoc,
The /XX is the option code, as you have mentioned. A hall motor is one where the disc motor has no brushes. The coils are energized in sequence from the rotor position. Hall effect elements provide the position information.

These motors are the ones you see where the rotor sits just over a small circuit board. It's a very flat assembly, but wide.

-Chris
 
anatech, thank you for your reply.

My research here has indicated that 'brushless' motors make for superior transports due to their better mechanical characteristics. Am I correct? Would you happen to be able to elaborate on these 'better mechanical characteristics'?

Cheers! :)
 
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Joined 2004
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Hi adhoc,
That is a question that has many variables. It depends on the number of poles for one. It's true there are no brushes to wear, but I see more bearings gone anyway.

I have a deep distrust for anything Philips makes. They are usually very inexpensively constructed. So I will not comment any further.

-Chris
 
Adhoc, a Philips player with CDM4 *can* make excellent transport. I use one with CDM4/25 (? -- no sticker). But I also have CD650 with CDM2/10 which is clearly much worse. Both have hall motor... Now I bought same player as first one, but with CDM2 mechanism, so I'll compare them. The thing is that the radial bearing of the rotor on these motors isn't very good or durable, one has to select, which is not too expensive.

"I have a deep distrust for anything Philips makes" -- same for me, except for those swingarm transports and tda1541 ;) But this is history.
 
The on the CDM-2 is not that bad. I have played 18 years (!) with a CDM2 in CD640, it still plays. Every Philips (standard) CDM after its predecessor became more flimsy every time. CDM-0 & 1 has roll bearings on arm, Cdm 1 is from alu. CDM 2 has all features of 0 and 1 but single ball as bearing and more plastic as base, though this is quite rigid glass fibre filled polyester. Imo the CDM 4 is the last reasonally good CDM, but there are exceptions: CDM-4/25 is not as good as other CDM-4's with lower suffix #.
My current project has a modified CDM2-(00081 as suffix#) This diy player weighs about 8 kg's allready.
 
adhoc said:
anatech, thank you for your reply.

My research here has indicated that 'brushless' motors make for superior transports due to their better mechanical characteristics. Am I correct? Would you happen to be able to elaborate on these 'better mechanical characteristics'?

Cheers! :)

Brushless motors do radiate far less RF. In (for example) a TEAC T1 I can measure that at the SPDIF output. 2 capacitors solve a lot of these problems.

best
 
I think the CDM4/25 is older than CDM4/19, even older than CDM4/11. It has just different laser head than CDM2 or CDM4/11, the rest seems equal. Re the bearing, is there a reversible way to take away the platter from shaft? This would allow a bronze bushing or the like and new life for these plastic chassis, better than new.
 
I just read a article, Alte Helden, in german magazine "Audio". They discussed the Philips CD650, which on photograph of interior the same CDM4-25 i have in a Magnavox player.

I don't know if the plastic disc can be removed off shaft. Never tried.

I modified the white Glass filled Resin CDM-2 base (where laser-arm is assembled on) whith a lead and rubber sheets, glued them on. The resonance freq. of it substantially dropped then too. I replaced foam dampers in springs, they were'nt elastic anymore. The whole bounces very good now, and is rests still fairly quick then after.
The guide pins of drawer are replaced by new ones, no play anymore.
The outer base is resting on 3 self made rubber suspensions. The black
clamp is filled with woodglue and sand mixture. An added teflon sheet reduces wear on spindle, it runs very smooth now.
Listening with stethoscope shows a very good decoupling from player and ground around it.
Now finish the 4 paralleled dac, and eventually i can listen!

http://img135.imageshack.us/my.php?image=cdm25iv.jpg
 
Great problems I have to find out differences in detail between the exist CDM-4 versions. Easy to find out are the versions without brushless motors like CDM-4/19 and CDM-4/31 with integrated servo board. Even Justone Schnepel seems to be to fight with this problem - go to
http://www.ersatzteil.justone-schnepel.de/html/philips_cdm-4-25_cdm425.html.
In the moment I want to know the differences between the version CDM-4/11 and CDM-4/25 and CDM-4/27.
According the attached images the only difference between CDM-4/11 and CDM-4/25 I note on the turntable resp. disc pulley (due different centering units of the pressure unit resp. clamp unit from loader). But the CDM-4/27 (used in Revox B-126) uses the same servo board - thus here also only a different disc motor pulley from the brushless spindle motor.
Are my estimates right ?
Thanks for any advice.

P.S.: this threads don't provide the right hints:
https://www.diyaudio.com/community/threads/cdm-4-laser-compatibility.70702/
https://www.diyaudio.com/community/...problem-disc-rubs-not-spinning-freely.353625/
https://www.diyaudio.com/community/threads/quot-cdm-4-36-quot-and-quot-cdm-4-industrial-quot.118290/
https://www.diyaudio.com/community/...i-cdm-4-pro-laser-makes-whining-noise.282779/
https://www.diyaudio.com/community/threads/any-docs-for-cdm4-31.12389/page-3
https://www.diyaudio.com/community/threads/philips-cdm-4-21-4-25.220022/
 

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  • CDM4-25 loader-.jpg
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  • CDM-4_11 Loader closed.jpg
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  • CDM-4_11 Loader open.jpg
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Last edited:
CDM-4 mechanism to replace two different CDM-2 versions

In the attachment are the associated instructions so as the description of differences.
Code "4822 691 20464" is for CDM-4/11 (turntable for mechanical disc hold down, for replace CDM-2/0501)
But to which CDM-4 version does the code "4822 691 30205" belong (turntable for magnetic disc hold down for replace CDM-2/0503) ?
 

Attachments

  • data change philips_cdm2-0500-503 and cdm4.pdf
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