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  »  New  Ultimate Turntable..  Techdas Designer Hideaki Nishikawa R.I.P...  Analog Playback Forum     220  1337266  05-31-2004
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  »  New  A turntable platter as a turbine?..  A turntable platter as a turbine?...  Analog Playback Forum     0  16765  10-27-2010
12-16-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #: 51
Post ID: 3309
Reply to: 2019
Micro double-deck, a flywheel = bye-bye bass.

Today I concluded what I suspected from the beginning:  in the double-deck configuration I lost some bass. I know that Micro did some heavy mass stabilizers for their TT and some other companies did the same. People clamed that sound got “better”.  I always had suspicions about it and what I made my double-deck where the second deck acted effectively a stabilizing flywheel for a playing platter I felt that the effect was not as dramatic as people proposed. I might accept the upper mF range become very minorly smoother but the degree was warring with the forth of the belt. The lighter tension of the bell the less effect and at “normal” tension there is no effect from the “flywheel”. However what I did detect also that with the “flywheel” I was slightly close up at the very lowers bass. It was not major change, in fact it is very-very minor but it was there. Then I was looking at the installations of the guys who commented positively about the flywheel benefits… and I discovered that none of their speakers even were able to care lower bass. Well… this answers  the things...

Anyway, it is still might be becose the “specific belt” , or the belt's force or the motor,, or zilions of other resosns... but for now I use my double-deck TT one deck per time, switching a single belt from one platter to other when I need… (Thanks the layout and positioning of my motor allows me to do it)




"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-17-2006 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #: 52
Post ID: 3312
Reply to: 3309
The part of the belt
I am interested to determine from further reading if by "rubber" belts you mean anything as springy as rubber tubing or stapled bicycle tubes suggested by others.  It has been my own finding that the older pro-quality recording tape is as good as anything for driving a TT, and even silk or dacron thread works better than any sort of bungee-type belt.  I suppose that among other things this gets down to traction versus spring, and I am pretty sure that too much of the latter is always a bad thing in this particular application.

As for belt length, I have tried longer belts in order to move a drive motor away from the arm/cartridge, and I have listened to some 2-motor set-ups that used long belt free spans.  None have worked well, IMO, with diminished bass being the most obvious problem, and a loss of coherence a less obvious but no less important problem.

I have the non-scientific impression that drive belt length is best kept to a practical minimum, and I have jumped to the wild tentative conlusion that a longer belt can develop a strong-enough-to-matter harmonic resonance and even, at times, a resonance-within-a-resonance, a sort of ocillating resonance, if that makes sense.

Not that I would care if it sounded OK; but it doesn't.

But then, I have not yet heard what I would term a successful installation of a giant motor driving a 100 lb. platter, either.

Best regards,
Paul S
12-17-2006 Post does not mapped to Knowledge Tree
George
Posts 26
Joined on 03-23-2005

Post #: 53
Post ID: 3313
Reply to: 3312
Belt Creep
Here are some quotes from AA that I found interesting:

Rubber transmits vibration poorly, that's why it's used. Unfortunately this also means that it creates speed variation, mostly due to belt creep (NB I do NOT mean belt slip).

The motor is also coupled to the TT through its mountings and attempting to reduce noise transmission along this path is fraught with perils.

Flywheels offer advantages but these are often offset by the increase in belt creep that the extra couplings entail. This is so application specific that generalisations are worse than useless.

In my opinion the "one true path" is to ensure that the motor is as quiet as possible (cogless DC) and then reduce compliance in the transmission path as much as possible. Everything else is putting make-up on a pig.

and

The problem is that belt drives must lose speed around the drive pulley to work - there can be no transmission of force unless the tension difference in the belt is transferred to the drive pulley. Since the belt is elastic the tension difference must create a length difference. In turn this means the belt creeps against the pulley so the speed at which the belt is "taken up" is greater than the speed at which the belt is "let out". This speed difference depends on the torque demand from the table so any torque modulation creates speed variation. The simplest model of torque variation is that the torque reflected to the drive belt from primary stylus drag diminishes as the torque arm shortens across the record. This leads to an easy test - measure the speed with the stylus off the platter then cue the stylus at the lead in groove. Modulation drag is harder to estimate but will be proportional to the variability caculated by this method so it remains valid.

Just to knock two things on the head; Yes such small changes are perceptible, no no amount of platter mass can "fix" the energy lost due to belt creep, it just slows down the rate at which the speed changes. This will help with modulation drag indiced pitch change but not with drag induced rhythm changes.

============

I have not read about "belt creep" any where else. You can find more by searching "belt creep."




12-17-2006 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #: 54
Post ID: 3314
Reply to: 3313
Slip, creep, belts, platter mass and idler wheel

I do not know if I agree, or take seriously belt creeping. Belt creeping is applicable for the systems where the speed or tension a variable. However, in the case of TT, where the speed and tension are constant the amount of belt creep is constant also. If so, then the belt creep as well as the belt slip are all equalized and “included” after a platter have reached its cruse speed. Not to mention that in context of platters large mass I think all contribution of all belt related issues become negligible. I think people build those theories about slipping and creping for defend type of transmissions – like power transmissions. In TT it would be a typical relatively-powerful motor driving some kind of 3 pounds acrylic platter. In this setting the torch on the motor is co-measurable with the torch of platter. However, if you have a very low torch motor and large mass platter then, I think, all bets off. I kind of always with irony look at the turntables when you turn motor on and the platter practically instantaneously hits 33prm. To me it is an indication that platter-motor coupling is wrong. I think the only “correct” coupling is possible if a motor and the belt can not drive the platter. You should turn motor and the platter should stay still. Then you push the platter with your hands and only then the motor and belt can stabilize it at 33rpm…

BTW, in largest Micro Seiki turntables are made exactly like this – motor could not start platter. However they resolved the problem, making it friendly, with very elegant solution. When you turn the “largest” Micro motors they begin to speed very violently with 10-20 times more speed then necessary. Usually it’s enough to give to a platter the initial “kick”. Then the Micro’s torch-sensor comes to play and it detects what contra-force the motor experience. if it detects that the platter is spinning with near-necessary speed then it drops torch monitoring, stabilize low voltage in motor and let it be. On my motor the voltage of the initial “kick” is 15V and the voltage of the “cruse” operation is about 4-5V. I think it is very elegant and very friendly solution. I never push my platter with hands…

Anyhow, another thing that I’m contemplating now in order to make both of my platters spinning is to drive one with belt and to drive another via an idler wheel. I think if I find a large enough, soft enough idler wheeland mount it on a proper arm then it might be an interesting to try. Now I need to find in garbage some kind Studer A810 and pull out of it the idler wheel arm assembly… :-) Here is how I visualize it…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-02-2007 Post does not mapped to Knowledge Tree
tokyo john
Narashino, Japan
Posts 36
Joined on 01-31-2006

Post #: 55
Post ID: 3423
Reply to: 2777
say, is that an Audio Note cart?
I think you also mentioned that you were involved with the Voyd (which for a Pink Triangle user as I was back then, looked very charming). I recall Voyd being recently acquired by Audio Note UK; are you affiliated with them?

Anyway, I actually wanted to ask you something else. I need another TT to accomodate my mono cart (some people are not as lucky as Romy to have 8 arms hooked up to one TT!), and was interested by your comments on the SP10. Since I already got a Micro (mid-level model but can't lift anything heavier, my poor back), may as well try a DD I thought.

Any advice on what to watch out for when I browse through Yahoo Auction Japan for a SP10? Do you have any experience with the very popular Denons and Yamaha 2000GTs? Thanks very much.
01-02-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #: 56
Post ID: 3425
Reply to: 3423
Mono cartridges: please not here.

John, I had nothing to do with Voyd or Pink Triangle, I also not a big fan of Audio Note UK.

Mono cartridges is good, in fact I feel that Mono Cartridges IS A MUST for anyone who do analog more of less serious. Defiantly a second arm is more convenient then a second TT…

Anyhow I would like do not go into details about Mono cartridges as this is not the thread about cartridges. Very briefly juts to reply your question.  I had 4 Mono cartridges:

Denon 102
Ortofon  CG 25Dia
Ortofon  SPU MONO Ellipticalh
Ortofon  SPU MONO Conical

The cartridges are listed in the order of my preference in descending order with the best at the bottom. I do not know about any other mono cartridges.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-03-2007 Post does not mapped to Knowledge Tree
tokyo john
Narashino, Japan
Posts 36
Joined on 01-31-2006

Post #: 57
Post ID: 3426
Reply to: 3423
sorry I meant to respond to Guy Sergeant

with his photo and comments on his Technics SP10.
Inexperienced imbecile that I am in participating in thread discussions, my question went into limbo (and thank you for responding to it).

And thanks to you, I bought the SPU Mono some time back and now looking for a TT to permanently house it Smile

01-03-2007 Post mapped to one branch of Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #: 58
Post ID: 3427
Reply to: 3423
Adding a second tonearm vs. a second TT

 tokyo john wrote:
Anyway, I actually wanted to ask you something else. I need another TT to accomodate my mono cart (some people are not as lucky as Romy to have 8 arms hooked up to one TT!)...
John,

it was always my sentiment that it is much better (comfortable and functional) to have two tonearms then two turntables. If you have one turntable that you fell comfortable with, then it is always possible, with no expiations, to add a second arm. Yes, it might screw up the turntable cosmetic or resale value (if you care about such a thing) but a comfort of lowering a second arm without any hassles really overcomes all other considerations. I do not know what TT you have buy I defiantly would NOT go for a second TT - only if I need to put a Mono arm into the game. Even if you have the smaller “rectangular TT” then it is always possible to hard-attach an extra surface along with the top long side of your TT and use this new space as an arm-base for a second arm. Going for a longer arm in this setting is a most reasonable solution….

The problem that I see with two TT (and I commenting from my own experience) that you need to lift a record and put it on the other platter. I find it annoying. In my setup my right platter is my main platter and it has my most beloved arms and mono/stereo needles. This platter does over 95% of all play and I go for the left platter only if I would like to have “intentionally different sound”.

Frankly speaking using the double deck TT for a while (the same I presume would be for a second TT) I do not find the idea worth duplication. It is too much hassle for too little actual gain. If I were an audio professional why do listening and audio assessments for living (although those assholes do their audio evaluations by listening CDs over a telephone!!!)  then I see some justification for setting up multiple playback opportunities. But for music listening I feel 2, maximum 3 arms are enough. More is worse. I never understood why people have multiple turntables with zillion arms and now after years of using the multiple turntables with zillion arms I understand it even less.

So, John, do not let yours to slide into the irrationalism of multiple platters: juts “glue” a second Mono arm to you TT and it will be it.

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-03-2007 Post does not mapped to Knowledge Tree
tokyo john
Narashino, Japan
Posts 36
Joined on 01-31-2006

Post #: 59
Post ID: 3428
Reply to: 3427
octopussied
Dear Romy,

Thank you for the advice.

Yes, I believe I can hard-attach another arm to my current TT if I sacrifice the dust cover. I am going to have to give it some serious consideration.

I think many people end up with multi-TTs with a zillion arms because we have a soft spot for tone-arms and cartridges. I should be happy with two (stereo and mono), but sometimes I cannot go to sleep thinking about all the arms and carts I need to collect before they go out of production. Yes, it is some kind of sick-ness....

Again, thanks for the advise and for running the most useful, interesting and brutally honest website in audio. If my business does well in 2007, I ought to send you a Ikeda long arm as a present!


A fellow Nietzsche fan,
John
01-04-2007 Post does not mapped to Knowledge Tree
guy sergeant
United Kingdom
Posts 260
Joined on 08-03-2004

Post #: 60
Post ID: 3430
Reply to: 3428
SP10's etc
Hi John,

I was involved with the Voyd originally. I have no connection with AN UK now except that I use one of their UK made Io cartridges.

With regard to the SP10 Mk2 I like it very much. It removes any sense that a record is playing. I use a 10mm polycarbonate mat on it which to my ears gives a more natural presentation of lower frequencies than the supplied rubber mat. It is also ergonomically a joy to use. One of Arthur Khoubesserian's Funk Achromats would also worth trying if cut down to 293mm diameter.

If looking for one now, I would try to avoid ex radio station ones particularly if they have the additional pitch control electronics (unless you are an avid 78's collector). I'm not convinced by the overpriced Technics Obsidian plinth either. Mine is fitted to a Stirling Broadcast Corian plinth but I'm not sure these are still available now. Mine also has the magnetic brake disengaged. If you have any electronics capability it may be worth updating some of the electrolytic capacitors in the power supply purely for reasons of longevity although many of these machines that have been in regular use still seem to work perfectly well.

If you see the much rarer SP10 MK3 you should definitely consider that. It was possibly the ultimate expression of Direct Drive.
01-04-2007 Post does not mapped to Knowledge Tree
tokyo john
Narashino, Japan
Posts 36
Joined on 01-31-2006

Post #: 61
Post ID: 3432
Reply to: 3430
SP10 and the Japanese contribution to audio

Hi Guy,

Thanks very much for providing me your insights on the SP10.

I have to confess when I initially read your comments I could not help but be astounded that a person involved with a Brit belt driven, light weight, suspended turntable would be using a DD. (and with an unfashionable SME V at that!)

But then, 25 years ago I thought the Japanese were crazy with their SP10s, SPUs, pivoted arms, tubes and Tannoys. (back then, most decent folk in other parts of the world were either flat-earthers (Linnies) or Absolute Sounders)
Then tubes (esp SETs) became sexy again, then horns (obvious partners for those SETs afterall), and now I learn that DDs are not hopelessly flawed. Sure, the infamous Goldmund Studio was DD, but the Reference was belt driven. Come to think of it, I recall one of the TAS reviewers (maybe Dave Wilson before he sold so many speakers?) used a Denon DP100 monster DD in his playback.

Of course, not all the Japanese stuff was good, and brands like Kondo Audio Note and Final, from what I understand, played up the Japanese thing to a point  where their prices reflected more Geisha-lust than engineering. I suppose the stuff that the Japanese can truly be proud of are certain TTs, some arms, many carts, tuners and tape decks (there are lots of garage tube amp makers but not having owned them I have no idea how good they are). Romy had some nice things to say about Japanese drivers installed in boom boxes; incredible! (but then again, the Japanese dominate the up-stream of the consumer electronics industry through their strength in the materials industry; even Samsung is at their mercy)

But I am digressing here.

Thanks again, and let me know if I can do anything for you from out here in Japan (the offer also remains open to, yet unactivated by, Romy).

John
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   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Ultimate Turntable..  Techdas Designer Hideaki Nishikawa R.I.P...  Analog Playback Forum     220  1337266  05-31-2004
  »  New  My Analog Playback: the fat lady has sung..  My analog setup update....  Analog Playback Forum     9  119524  04-04-2006
  »  New  Maria Callas’s Glory Days: Available in Europe..  Here you are...  Musical Discussions  Forum     3  46636  08-26-2007
  »  New  Micro Seiki SZ-1T..  I guess it's my own fault....  Analog Playback Forum     2  36927  06-10-2008
  »  New  The Foolishness of Analog People..  Late to the discussion but cannot resist...  Analog Playback Forum     56  585283  01-30-2006
  »  New  A turntable platter as a turbine?..  A turntable platter as a turbine?...  Analog Playback Forum     0  16765  10-27-2010
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