Rerurn to Romy the Cat's Site

Analog Playback
Topic: Background

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Posted by rom661 on 11-29-2022
Hi.  I acquired and spent a lot of time on this guy over the last few months. I've installed a Dynavector 507 MK II tonearm and a Dyhavector XVS-1 cartridge.  I read Romy's comments that in his experience with the 8000 the belt doesn't affect the sound.  I bought some of the aramid fiber string and made a belt but have trouble keeping the speed consistent.  Not varying, just dropping down to almost half and staying there.  Bought a $20 "replacement" belt that seems to cause static, which I don't understand.  Now I'm seeing the SF-1 belt, some new, which is fiber.  I don't have a preference, just something that works reliably and sounds good.  I didn't even know the fabric one existed.  If anyone has suggestions, with sources, they are very welcome.  Thanks

Posted by Romy the Cat on 11-30-2022
 rom661 wrote:
Hi.  I acquired and spent a lot of time on this guy over the last few months. I've installed a Dynavector 507 MK II tonearm and a Dyhavector XVS-1 cartridge.  I read Romy's comments that in his experience with the 8000 the belt doesn't affect the sound.  I bought some of the aramid fiber string and made a belt but have trouble keeping the speed consistent.  Not varying, just dropping down to almost half and staying there.  Bought a $20 "replacement" belt that seems to cause static, which I don't understand.  Now I'm seeing the SF-1 belt, some new, which is fiber.  I don't have a preference, just something that works reliably and sounds good.  I didn't even know the fabric one existed.  If anyone has suggestions, with sources, they are very welcome.  Thanks

 
rom661, Reading what you are saying I do not think that your problem is with belt or with a type of the belt. I do not know what setup you are running and what are your expectations but on this type of the tables the type of the belt is kind of irrelevant at least when the platter has reached the cruise speed. the fact that you report that your platter drops speed in half is indication to me that your suspension most likely not good. the RX-5000 has boll suspension which is most likely has 40 years old oil. Also, if the turntable was shipped a lot or heavy handled then the bottom plate under ball rolling might be warped. each in signal 5000 that I've seen had this problem and you need to reverse the plate and serve new oil. I think the idea to put instead of the steel plate under the ball some kind of contemporary ceramic material would be else not bad. I have written about it in this site in the past, you can search it.

Posted by rom661 on 11-30-2022
I don't think I made myself clear.  The only time the table ran slow was with the thread belt.  Speed is very constant with the rubber belt.  If you spin the platter with no belt it continues for several minutes. The table hadn't been moved for 35 years prior to my picking it up.  It belonged to an old friend who left it to me upon his death.  I hope it does not require the work you mention because I'm now visually impaired (not blind) and I would have to find someone to do the work.  However I wanted to make clear that a rubber belt works fine in general.  I did assume that choice of belt was of at least some concern.  The one on it is decades old and it seemed prudent to replace.  Thanks

Posted by Romy the Cat on 12-02-2022
 rom661 wrote:
I don't think I made myself clear.  The only time the table ran slow was with the thread belt.  Speed is very constant with the rubber belt.  If you spin the platter with no belt it continues for several minutes. The table hadn't been moved for 35 years prior to my picking it up.  It belonged to an old friend who left it to me upon his death.  I hope it does not require the work you mention because I'm now visually impaired (not blind) and I would have to find someone to do the work.  However I wanted to make clear that a rubber belt works fine in general.  I did assume that choice of belt was of at least some concern.  The one on it is decades old and it seemed prudent to replace.  Thanks

rom661, 

it is not the subject if you are blind of not. It is always a good idea to flip they turned table unscrew 4 screws, that covers the bearing and to inspect the bottom plate. if you discover any indentations at the bottom plate then just make the actions. The bottom contact of ball supposed to be absolutely horizontal surface without any indentations. I personally open perhaps 5 or 6 RX500 turntables and all of them had slightly used or indented bottom plates.
 
If your platter spins a few minutes after you drop the belt then you most likely you are OK. if you use a standard rubber belt then be advised and the belt should not be tight. the proper tension of the belt that it should just slightly hang on platter and to be extremely loose. it is normal as the platter reaches cruise speed the belt my move across the platter very slightly, it is indication that belt tension is good. The strength of the belt between motor and platter constitutes a second order mechanical filter and when you change belt tension you are moving Q of this filter. you want to have as low possible tensions for a given belt type in order to keep the queue of the filter as much as possible to 1st order.
 
Now, we are entering the wonderful world of not rubber belts. I experimented a lot with it, using anything from different type of magnetic tapes from real to real machines two different type of the strings, included external stabilizers. it is all about balance between retention and slipperiness of your given type of the belt. some people use baby powder in order to increase the strength grab-ability of the plotters. I remember I had one configuration with magnetic tape when I need to start the platter by the hand and then wait probably 3-4 minutes and still the speed was stabilized. Can I report that change of the interface between motor and platter make difference? Yes I certainly do but the heavier player you have The lower Q of your mechanical system and add the level of RX500 it is practically negligible. my main turntable is RX800 and with it I did not detect any difference in type of the belt I used. Well, the difference might exist but it exists on the level proving of concept of purely audio self-entertainment but I feel that and the level of changes which make difference for music the difference is irrelevant.

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