Dear all,
I thought I share some experience with the the Dual DD motors from the 1000 series.
When the Dual CS 701 came to market I was lucky enough to be working for the Dutch Dual importer.
I have repaired there numerous Dual and Perpetum Ebners , PE was around that time acquired by Dual.
For me it was a great move when Dual finally stopped making record changers and moved on to single disc players.
The changers where good but required a lot of maintenance and adjustment.
One of their main problems was the main bearing that was hollow in order to control the record stack mechanism.
More rumble from this type of bearing was unavoidable.
So very happy Dual dropped that for the CS701 and CS601.
Later I looked at the other DD motors from Dual and had high hopes for the CS704 which I bought many years ago but it does not compare favorably to the EDS 1000`s.
Not so much in construction but more in torque.
My first Dual CS 701 was sold a very long time ago , it had served me very well with an EMT TDS15 glued into its head shell.
The early EDS 1000 motors where problematic because the platter would move up and down while running, this was very quickly corrected although I do believe some made it to the market.
There was also a problem with the hall sensors that would go bad.
Had to repair quite a few of those which was not easy to do as the whole motor has to come apart in order to do that.
The newer EDS 1000-2 never had those problems and featured silicium transistors instead of germanium.
Recently I thought to do some service on my EDS 1000-2 motor, mainly the electrolytic capacitors as I thought they would have been aged so they would need replacement.
However when I had three of them out and on the meter it turned out quite different.
They where all like new and perhaps even better than the new ones I had bought, quite shocking in fact.
I tested them for ESR, capacity and V loss.
I did replace them anyway but a good lesson was learned.
A few words on the bearings of the EDS 1000-2 I have I did try a few different oils like the thicker oil (Renotack I think) Dual used and later some van den Hul zirconium doped bearing oil but none made it run better.
Reflecting on this I believe the bearings which are sintered bronze don`t need lubrication unless they stick.
A final note, the Dual CS701 platter sounds better than the one from the CS721, it is quite a bit heavier.
Have a good Sunday you all, regards Veeren
I thought I share some experience with the the Dual DD motors from the 1000 series.
When the Dual CS 701 came to market I was lucky enough to be working for the Dutch Dual importer.
I have repaired there numerous Dual and Perpetum Ebners , PE was around that time acquired by Dual.
For me it was a great move when Dual finally stopped making record changers and moved on to single disc players.
The changers where good but required a lot of maintenance and adjustment.
One of their main problems was the main bearing that was hollow in order to control the record stack mechanism.
More rumble from this type of bearing was unavoidable.
So very happy Dual dropped that for the CS701 and CS601.
Later I looked at the other DD motors from Dual and had high hopes for the CS704 which I bought many years ago but it does not compare favorably to the EDS 1000`s.
Not so much in construction but more in torque.
My first Dual CS 701 was sold a very long time ago , it had served me very well with an EMT TDS15 glued into its head shell.
The early EDS 1000 motors where problematic because the platter would move up and down while running, this was very quickly corrected although I do believe some made it to the market.
There was also a problem with the hall sensors that would go bad.
Had to repair quite a few of those which was not easy to do as the whole motor has to come apart in order to do that.
The newer EDS 1000-2 never had those problems and featured silicium transistors instead of germanium.
Recently I thought to do some service on my EDS 1000-2 motor, mainly the electrolytic capacitors as I thought they would have been aged so they would need replacement.
However when I had three of them out and on the meter it turned out quite different.
They where all like new and perhaps even better than the new ones I had bought, quite shocking in fact.
I tested them for ESR, capacity and V loss.
I did replace them anyway but a good lesson was learned.
A few words on the bearings of the EDS 1000-2 I have I did try a few different oils like the thicker oil (Renotack I think) Dual used and later some van den Hul zirconium doped bearing oil but none made it run better.
Reflecting on this I believe the bearings which are sintered bronze don`t need lubrication unless they stick.
A final note, the Dual CS701 platter sounds better than the one from the CS721, it is quite a bit heavier.
Have a good Sunday you all, regards Veeren
I think i found it:
You asked for 701 but the above schematic is for 721, which uses the EDS-1000-2 motor. Now you have all schematics for both models.
Thank you all for your replies and help.
I do believe the coils and magnet structure is the same for both motors.
One bit of advise, don`t turn any preset pots without a service manual and scope.
These motors were hand tuned to their respective coils.
B.t.w. the replacement part price of the EDS1000 was 850 guilders!
Another thing, some of the pertinax pc boards can be very fragile, they will break in your hands so be very careful!
I suggest you stay with the original op amps nothing to gain here with tweaking a perfectly good designed motor.
Same applies to all capacitors replace same with same, especially around the speed control section, this motor`s speed is stable as is.
I do believe the coils and magnet structure is the same for both motors.
One bit of advise, don`t turn any preset pots without a service manual and scope.
These motors were hand tuned to their respective coils.
B.t.w. the replacement part price of the EDS1000 was 850 guilders!
Another thing, some of the pertinax pc boards can be very fragile, they will break in your hands so be very careful!
I suggest you stay with the original op amps nothing to gain here with tweaking a perfectly good designed motor.
Same applies to all capacitors replace same with same, especially around the speed control section, this motor`s speed is stable as is.
Veeren, I also know those motors well, and they are, for their time, and even today, excellent designs.
I overhauled my neighbor's 701 last year - it's in prisine cosemetic condition, not even a scratch on it.
And it runs far better than any of those "new" turntables of today.
Exactly my thoughts at the time i owned one of these motors. But then a better bearing would also make sense...
Do you really like to bring here all the useless "guru" type discussions over here from other sites? People do whatever they want in life .If Leonardo Da Vinci would have been the only scientist allowed to do science , we'd all be his Monalisa models today... So thank you but no thans you for your kind words! By the way...those who don't make any mistakes are usually the most prone to learn nothing new.I do mistake after mistake for decades already and i hope i won't lose the taste for making more mistakes! Only death is perfect.Those Dual EDS1000 motors don't need any modding.
All the WANNABE TECHS want to get their STICKY FINGERS in things like that motor that are already perfected and documented as excellent performers.
Abut alas, some insistent people just don't want to listen to REASON.
Yes, if it ain't broken, fix it until it is !
Unless there's some issue with these direct drives, there's no need to do anything beyond the usual maintainance. As said before, those phenolic boards are prone to fail, especially if someone does unneccesary solderings on them. IF the AC188k Germanium transistors may fail some day, one can decide an upgrade to the 721's EDS 1000-2 design.
No need for substituting the venerable 709 opamp by some modern low-noise and high-speed one. You won't hear it!
Best regards!
!Unless there's some issue with these direct drives, there's no need to do anything beyond the usual maintainance. As said before, those phenolic boards are prone to fail, especially if someone does unneccesary solderings on them. IF the AC188k Germanium transistors may fail some day, one can decide an upgrade to the 721's EDS 1000-2 design.
No need for substituting the venerable 709 opamp by some modern low-noise and high-speed one. You won't hear it!
Best regards!
Thanks Kay Pirinha and wiseoldtech.
Any "improvements" on these motors is futile.
If you have a CS701 or CS721 be sure to replace the Rifa cap inside the transformer box, they short circuit in time from age!
They will take out one 110V winding from the transformer putting 230V
over the remaining 110V winding!
Replacing this T-former with a small 9+9V toroidal is a good idea in my view.
While in there replace the now hardened grommets that hold the box in place
with new or sorbothane ones, you will notice the difference.
To compare servo vs non servo listen to a SL1200 and a CS701-721.
If you cant hear the difference than it does not matter to you.
A better bearing, why the ones in there are fine, have a look at the CS601 platter bearings for comparison or a Ariston RD 40 etc.
Regards,Veeren
Any "improvements" on these motors is futile.
If you have a CS701 or CS721 be sure to replace the Rifa cap inside the transformer box, they short circuit in time from age!
They will take out one 110V winding from the transformer putting 230V
over the remaining 110V winding!
Replacing this T-former with a small 9+9V toroidal is a good idea in my view.
While in there replace the now hardened grommets that hold the box in place
with new or sorbothane ones, you will notice the difference.
To compare servo vs non servo listen to a SL1200 and a CS701-721.
If you cant hear the difference than it does not matter to you.
A better bearing, why the ones in there are fine, have a look at the CS601 platter bearings for comparison or a Ariston RD 40 etc.
Regards,Veeren
Indeed, Veeren, when I did service on the 701 last year, I of course changed those trouble-prone Rifa caps - I do it as standard procedure with all the Duals I service.
I also upgrade the main power supply filter to 1000uF also.
Any rubber gets attention too, as well as that "pimpel".
I believe in thorough service for these beauties - they deserve it.
I wish it were that simple
You'd be comparing lots more than servos.My experience with DD drives is limited as i have only listened long term to a cs701, an L07 and an SP10 mk2. The 701, obviously replinted and with a real arm, and the SP10 were indeed excellent. I have also listened casually to many others and they have generally sounded much worse than a proper belt/rim drive. With the notable exception of the GP Monaco 2.0 which was just unbelievable. If it wasn't for these three i would have thought DDs were only suitable for dj-ing.
Hi analog_sa, a fellow countryman.
Boa tarde!
Just curious, what real arm did you use on the 701?
In a way my comparison is simple but just listening how the music flows on both gives a clue.
I had a SP10MK2 on a makeshift plinth with a SME 3012 that to my ears did not flow properly everything technically speaking was there just not the music.
I had the same experience with AJ van den Hul`s SP10MK2 when I visited him in his atelier.
Once I had a repair job at the neighbors of the recording studio I was working in, they had a SP15,
same experience, no music.
I also had a Scheu with a 5cm thick acrylic platter and a outboard DD motor with string drive.
Same experience, no music just sound, sold it in a months time.
This is where my servo- non servo remark comes from of course simplified as a Rega RB 300 can also sound
off.
Going back to the eighties when I was still involved with a Dutch audio magazine Audio en Techniek
there was some talk between John van der Sluis en Peter van Willemswaard about a certain record player
a JVC or Pioneer, I cant remember, where Peter had removed the servo and that made it sound good.
I could not verify as I did not have that table and the details of what he exactly had done were missing.
All subjective and only applicable to those who hear it.
Boa tarde!
Just curious, what real arm did you use on the 701?
In a way my comparison is simple but just listening how the music flows on both gives a clue.
I had a SP10MK2 on a makeshift plinth with a SME 3012 that to my ears did not flow properly everything technically speaking was there just not the music.
I had the same experience with AJ van den Hul`s SP10MK2 when I visited him in his atelier.
Once I had a repair job at the neighbors of the recording studio I was working in, they had a SP15,
same experience, no music.
I also had a Scheu with a 5cm thick acrylic platter and a outboard DD motor with string drive.
Same experience, no music just sound, sold it in a months time.
This is where my servo- non servo remark comes from of course simplified as a Rega RB 300 can also sound
off.
Going back to the eighties when I was still involved with a Dutch audio magazine Audio en Techniek
there was some talk between John van der Sluis en Peter van Willemswaard about a certain record player
a JVC or Pioneer, I cant remember, where Peter had removed the servo and that made it sound good.
I could not verify as I did not have that table and the details of what he exactly had done were missing.
All subjective and only applicable to those who hear it.