My New TT : The Cello from Scheu Analog

[G401fan]

Thanks, Asit, for the clarification.

The 6moons review spoke of the Scheu manual recommending optimal string tension, as against the string tied too tight. String tension does affect speed in any case, and since they expect the customer to tie the string, there could be scope for inaccuracy. Guess you might have to use a strobe disc after all(sometimes you can monitor it with any bright light). Set the speed accurately, check the sound again, and then get it to drift maginally in case you prefer the sound the faster way.

Since the motor is DC, there must be some electronics to convert AC to DC, and that should take care of voltage fluctuations which are otherwise the cause of speed variations.

regards,

 

[Asit]

G401fan,

Thanks for the recommendation. What you say makes very good sense. Actually one is not supposed to have the string too tight around the platter. Now in my case, I do not know if the string is too tight or not. Jochen actually made a string for me, but while installing, the knot came off and my wife then made a knot with the same string. I have to discuss this with Jochen and take it from there. I'd think we should make another string which is slightly less tighter than the one I am using now, and see the differences.

About the motor and voltage stabilization: I use a high quality Krykard 3 KVA servo stabilizer (bought from Alacrity, Chennai) for all my AV needs. The Cello uses a power cord (to be connected to the foot containing the motor) that has a small power brick and that goes into the female power socket, AC to DC conversion is taking place in the brick. It takes 100-240 V, at 50/60 Hz and gives out 12V DC. It says "switch mode power supply" on the box for the brick. After about 3 hours of operation, it does not get hot at all, I checked.

Regards.

 

[anm]

nice suggestion G401fan. It is sometime so obvious that we miss it. On Technics, I always set pitch when a record is playing - but not all TTs have the markings on platter so important in that case.

 

[Thad E Ginathom]

Actually one is not supposed to have the string too tight around the platter. Now in my case, I do not know if the string is too tight or not. Jochen actually made a string for me, but while installing, the knot came off and my wife then made a knot with the same string. I have to discuss this with Jochen and take it from there. I'd think we should make another string which is slightly less tighter than the one I am using now, and see the differences.

One one of the links you gave (or maybe I surfed to) it mentioned something like just tight enough to move the platter.

With something like a drive belt on a machine, one might have guidance like being able to easily push 1/4 inch in the middle of the belt. Any such thing given here?

What sort of string is it? Is the material/diameter specified? What sort of knot are you using to tie it with? Isn't it fiddly, frustrating and difficult to tie. Is the "lump" of the knot going to upset a purist?

Your turntable is beautiful, but that string has stimulated my curiosity

 

[quad]

I am not very comfortable with the strobo, because I am not sure which lamp to use. I do not have a strobo lamp.

Assuming you have a 50Hz strobe disc, here's a simple strobe
lamp - look for a neon indicator which looks like the middle one in
the image below, available at your local electrical store.
You can put it in a plastic switch box, and run it directly off your
household mains. A bit unwieldy, but you'll only need when setting up
the speed.

 

[Thad E Ginathom]

The pattern disc thing should work under an ordinary lightbulb. The card is marked to look as if standing still at 50hz --- and all out electric lights are 50hz strobes!

 

[quad]

Agreed, but a neon has some advantage, as it emits distinct pulses of light
due to it's non-zero strike voltage.
Also, CFL lamps will not work, as they typically have an internal circuit board,
and run at a higher frequency.

 

[Asit]

Great discussion, Thad and quad, on the strobe light. I am learning all the time. Thanks to both of you.

Thad, the string is made of nylon. There is no specification given by Scheu, but they give a full bobbin of this string, and they say the bobbin-length should be good enough for the life-time. They also recommend a length that should be cut from the bobbin and then a tiny knot should be made at the two open ends. The string is very thin and hence a knot is almost invisible and the claim, I suppose, is that it is certainly not more than the tolerance of a rubber belt. I also worried about the knot when I first heard about the string, but in practice, I do not notice any irregularities with the best recording I have (last night I had Itzhak Perlman playing Bach Sonatas). They are using the same string even in their very expensive TTs. The thinness made a problem for me though, to tie the knot, because I have +7 near sight lenses. Next time, if I am making a knot by myself, I will do it against a dark (preferably black) background.

I am quoting from the Cello Operating Manual:

"For the drive belt, a piece of string about 1100 mm long should be cut off. The two ends should then be placed together and tied with an ordinary knot (Fig.).

When threading the string over the turntable and the driving pulley of the motor, it may be determined that the string is too long. One or two more knots then need to be tied in the string to make it short enough to just fit over the turntable and pulley with a small amount of tension."

Now regarding the tightness and tension in the string, obviously, there has to be enough tension in the string and therefore the string should feel tight enough. On the other hand, if the string is too tight, it will slip on the pulley and not on the platter, because the platter is rough and the pulley is very smooth. As a result, the pitch of the music being played will change intermittently when this occurs. Jochen says that, if this happens, just try another string longer by a few mm only, not more than that.

Regards.

 

[Hiten]

Sorry for late reply. Was out of town yesterday
@ Asitda, vasu, Joshua Thanks. Yes looks like there are two manuals for ortofon rm30 cart and I miscalculated some figures. The aim is to have safe upgrade area boundries. Definitely measured numbers are always preferable. Those turntable pictures are

From the technical details provided by the TT owners in your thread, it is pretty sure that TT is a different ball game.

That's what make analogue source interesting, One can try various things for best SQ.

Actually one is not supposed to have the string too tight around the platter

One of the easiest way to make sure is put a finger on motor pulley top surface lightly and move the acrylic platter with hand. The thread should not slip on pulley if it slips the belt is loose. The belt is too tight if it takes good amount of finger pressure to stop pulley from rotating if one moves the platter. Other way is measure exact diameter required with normal thread with length marked with marker pen. And make required nylon thread belt a little less say approx 1c.m. less.

 

[sachu888]

Great discussion, Thad and quad, on the strobe light. I am learning all the time. Thanks to both of you.

Thad, the string is made of nylon. There is no specification given by Scheu, but they give a full bobbin of this string, and they say the bobbin-length should be good enough for the life-time. They also recommend a length that should be cut from the bobbin and then a tiny knot should be made at the two open ends. The string is very thin and hence a knot is almost invisible and the claim, I suppose, is that it is certainly not more than the tolerance of a rubber belt. I also worried about the knot when I first heard about the string, but in practice, I do not notice any irregularities with the best recording I have (last night I had Itzhak Perlman playing Bach Sonatas). They are using the same string even in their very expensive TTs. The thinness made a problem for me though, to tie the knot, because I have +7 near sight lenses. Next time, if I am making a knot by myself, I will do it against a dark (preferably black) background.

I am quoting from the Cello Operating Manual:

"For the drive belt, a piece of string about 1100 mm long should be cut off. The two ends should then be placed together and tied with an ordinary knot (Fig.).

When threading the string over the turntable and the driving pulley of the motor, it may be determined that the string is too long. One or two more knots then need to be tied in the string to make it short enough to just fit over the turntable and pulley with a small amount of tension."

Now regarding the tightness and tension in the string, obviously, there has to be enough tension in the string and therefore the string should feel tight enough. On the other hand, if the string is too tight, it will slip on the pulley and not on the platter, because the platter is rough and the pulley is very smooth. As a result, the pitch of the music being played will change intermittently when this occurs. Jochen says that, if this happens, just try another string longer by a few mm only, not more than that.

Regards.

Some people find audio cassette tape better than rubber belt or nylon string.
You can also try that.

Regards,

Sachin

 

[Asit]

Sorry for late reply. Was out of town yesterday
@ Asitda, vasu, Joshua Thanks. Yes looks like there are two manuals for ortofon rm30 cart and I miscalculated some figures. The aim is to have safe upgrade area boundries.
Definitely measured numbers are always preferable.

Yes, Hiten, there seems to be two brochures of Ortofon giving 35 and 25 as the value for the cart compliance. Actually I first took a look at the site of the German distributor ATR-AudioTrade - Super OM 30 . They actually give the number 25 too. You can also get, from the same page, the Technischedaten (clickable to produce a pdf file containing technical data of the cartridges). But as you have said, the actual measurement should produce the closest to the real value. I also have noted your previous comment on the performance of this arm-cart combo at high volume with low bass music. So far I have not seen even a hint of any problem with the music I have played, but I should try perhaps all kinds of music. There is no problem with bass with my amp-speaker combo, it can be very fast and deep, but you have to remember I very seldom use recordings of anything other than acoustic instruments. However, I do not anticipate any problem with playing low bass music, nothing goes down significantly below 20 Hz or so. The cantilever resonance at sub-7Hz frequency can be induced only with movement of macroscopic objects (from floor, wind etc). In Indian households, because of mostly concrete floors in metro cities, floor vibrations can almost be ruled out; the wind is there though, but that too can be controlled in a room environment. Anybody knowledgeable in this subject, please give inputs.

OT: The address of the German distributor brought back some memory. My first public music performance in Germany was in the same town (Muelheim an der Ruhr) in 1989. There I met a German born Indian boy who later accompanied me in most of my performances in Europe.

One of the easiest way to make sure is put a finger on motor pulley top surface lightly and move the acrylic platter with hand. The thread should not slip on pulley if it slips the belt is loose. The belt is too tight if takes good amount of finger pressure to stop pulley from rotating if one moves the platter. Other way is measure exact diameter required with normal thread with length marked with marker pen. And make required nylon thread belt a little less say approx 1c.m. less.

You probably mean the total length of the string, am I right? I have a question here: Is it a good idea trying to stop the pulley? Is it not going to put undue pressure on the motor to try keep it rotating? Isn't there a danger of motor-breakdown?

Regards.

 

[Hiten]

For accurate speed, this should be interesting.
New Digital Laser Photo Tachometer Non Contact RPM Tach | eBay
Approx. Rs. 600+shipping. A Digital laser tachometer. Very nifty I think.

 

[Hiten]

You probably mean the total length of the string, am I right? I have a question here: Is it a good idea trying to stop the pulley? Is it not going to put undue pressure on the motor to try keep it rotating? Isn't there a danger of motor-breakdown?

Yes 1cm less than total measured length. No I am not saying while turntable is on. Please don't do that. Without turning on the turntable manually rotate the platter and I am talking about only light finger pressure to feel the torque. I think measured belt method is safe.
Regards

 

[Asit]

Some people find audio cassette tape better than rubber belt or nylon string.
You can also try that.

Interesting idea, indeed. However, Scheu has to approve of it. You probably know, these TTs developed over a period of many years through DIY work of Thomas Scheu, the founder and designer (he died in an accident in 2004, and Frau Scheu has been running the company since). Herr Scheu used to sell DIY kits at good prices and people compared these with high end TTs. I have some documentation on that. They have tried a long list of stuff for a good enough belt and found this string to work best for their platters. The other thing is that the groove on the pulley is very narrow and would not accommodate the width of an audio or video tape.

Regards.

 

[sidvee]

Asit meant to ask you when I saw the beautiful photo of the TT - does it come with a dust cover? I experimented with Vinyl 4-5 years back with a Music Hall MMF9 and a sutherland phonostage and keeping the platter and of-course the records dust free was a constant battle, and this was in US. I would imagine here in India it would be an even tougher issue to deal with.
Cheers
Sid

 

[Bluu]

Sid, a dust cover is not part of the package and from what I remember Jochen mentioned that that getting a cover from Scheu is very expensive.

 

[Asit]

Asit meant to ask you when I saw the beautiful photo of the TT - does it come with a dust cover? I experimented with Vinyl 4-5 years back with a Music Hall MMF9 and a sutherland phonostage and keeping the platter and of-course the records dust free was a constant battle, and this was in US. I would imagine here in India it would be an even tougher issue to deal with.

Sid,
As Bluu has already pointed out, none of the Scheu TTs come with a dust cover. It has to be ordered separately, and like the VPI dust-covers, they are quite expensive too. I am not ordering a Scheu dust-cover, for sure. At the moment, I am keeping it covered by soft cloth. But soon I am going get a transparent cover made. These can be locally done, costs under 1K (INR) and has decent finishes. Both Pratim and Vasu are using such dust-covers respectively for their RPM4 and VPI Classic, neither of which came with a dust-cover.

Actually, as a rule, I cover all my electronics by pieces of soft cloth, when the equipments are not in use and cold. I do not do that with my speakers though, however grilles are on always. Still, once in a while I have to clean the drivers very very carefully with an used shaving brush. Yes, dust is a problem.

Regards.

 

[sidvee]

Sid, a dust cover is not part of the package and from what I remember Jochen mentioned that that getting a cover from Scheu is very expensive.

Thanks Bluu - I have seen a few custom made acrylic TT covers in the US for about $200-$250, but they should be cheaper to make here. Just food for thought Asit.
Cheers
Sid

Sorry Asit: I was posting as you posted. There you go, as I thought it should be very inexpensive here.

 

[sachu888]

Sid,
As Bluu has already pointed out, none of the Scheu TTs come with a dust cover. It has to be ordered separately, and like the VPI dust-covers, they are quite expensive too. I am not ordering a Scheu dust-cover, for sure. At the moment, I am keeping it covered by soft cloth. But soon I am going get a transparent cover made. These can be locally done, costs under 1K (INR) and has decent finishes. Both Pratim and Vasu are using such dust-covers respectively for their RPM4 and VPI Classic, neither of which came with a dust-cover.

Actually, as a rule, I cover all my electronics by pieces of soft cloth, when the equipments are not in use and cold. I do not do that with my speakers though, however grilles are on always. Still, once in a while I have to clean the drivers very very carefully with an used shaving brush. Yes, dust is a problem.

Regards.

Hi,
A good thread about DIY dust cover.
Make Your Own Acrylic Cover - AudioKarma.org Home Audio Stereo Discussion Forums

Regards,

Sachin

 

[Asit]

Sachin,
Thanks for the link. I am useless in DIY, but it will be peanuts for our resident expert Ali (magma) for this sort of things. The locally available ones used by Vasu have good finish too and looks quite decent.

Regards.