Cheap upgrade for michell gyro

[gwernaffield]

with 100% feedback world wide, i think they work well enough

[struth]

To be fair, Peter has plenty of people who have got sets of them and are all happy. Thats what counts.

[gwernaffield]

thank you grant ,
as i said i have only ears to test these, not a computer that says no ,,,,
test equipment is fine in the lab but useless in the home,,, when the washing machine, the kids , the dishwasher and tv are all adding to the vibration in the house,,,,
the design came out of the need to try and get a better wider sound stage ,after reading on PFM that the gyro and orbe where a bit thin on the sound stage, the mid range can be a bit lost , the problem being the original design of the gyro and the design of the transrotor delight , the delight is sat on springs , in the same position ,
Michell changed it to a suspended design , will no doubt change it again,, but how and what too i do not know,,

it just seems if you want to get a head with something in HIFI , be it a cable or a piece of hardware some one will always have a go, as it was not their idea , quote all kinds of technical data ,web sites, and every thing they can throw at you ,,,

these are my sons and not mine, he pays the TAX , and has to do a lot of other things, i gave him the design ,

as it seems not good enough for the professors who constantly want to put their pennies worth into these forums, and forget it is a Hobby and not a class room, i just have to throw this open to debate off them ,, all will rubbish the idea in the first place ,
the people who have them can always contact us and get their money back at any time with in the first 6 months of use,

regards
pete

[YNWaN]

Well, you asked and I explained; if you don’t like the explanation then don’t ask. IMO, if Michell really want to improve on what they have they should reconsider the motor mounting, get a more accurate drive belt made, reduce the tension of the drive belt and rethink the suspension (possibly also the suspended mass). At present it seems that the lateral frequency is too low and, for whatever reason this is causing the suspension to deflect and this is causing small speed fluctuations - stiffening up the suspension reduces this but it will also reduce isolation - there is an element of inevitable ‘swings and roundabouts’, one compromise versus another.

[YNWaN]

i hope this helps i no these will end up getting rubbished, as there are far more knowledgeable people them my self , but as long as i have made some people happy , i am happy with that,,

You hope that what helps? Honestly, I’m really not sure what point you are trying to make with regard to ‘Solidair’, or even exactly what you are complaining about. I don’t want to be the ‘grammar police’ but your post is really difficult to interpret.

[gwernaffield]

i am sorry for my short comings in English and the way i was taught in the education system ,

i am sorry you have problems with my grammar ,it is not meant to upset any one, ,, the meaning of them being rubbished ,, some one will come up with a reason on not to use them ,,, so far every thing has been personal , like the grammar comment

which is fine by me, The i hope bit ,,, was to explain the back ground in engineering , ok it may not be in this industry,,

[struth]

keep it non personal please....

[BendBound]

I agree that isolation from all vibration is paramount. Some manufacturers, Rega for example, goes with light, and low resonant materials. Other manufacturers go with massive platters and other suspension cures. I could simply sell my Michell and try one of the other options. Instead, I've been working for some time to figure out how to isolate my TT from external vibration and to minimize the effects of resonant frequencies within the the TT itself. Removing the spring and using the lattice bridgework castlenut system Peter designed helped immensely on the internal sources of vibration.

In addition to that replaced suspension, I use an acyrlic toroid under my armboard, separated by 1/16" large washer of Herbie's Audio Grungebuster, a platinum curried silicone material that is terrific at absorbing vibration. The entire armboard-toroid system is mounted on hard rubber spacers too, to isolate the tonearm from the chassis, using also a 1/16" small washer of Grungebuster to interface with the toroid. The turntable sits on a 4" thick maple block. But under each of the three Michell feet I have a 1" diameter turned brass lamp shade ring (LSR) into which is a 1" diameter disc of 1/8" thick Grungebuster. I use Grungebuster with an adhesive side and that side is up into the LSR so that the finished side would be down on the shelf. Since the LSR has a hole in the center, the adhesive side of the Grungebuster is exposed. The Michell sits on that adhesive bit, finished side of Grungebuster on the shelf, and the Michell feet do not touch the LSR, making the TT completely stable from movement on the maple block.

For outside of the TT, I have my turntable mounted on a 4" thick Mapleshade Samson maple block. That block is supported by three particle dampers. All of that is on yet another thick maple shelf. I can tap on the lower shelf and nothing comes through my TT. I can rap on the 4" thick maple block and it does not pass through.

All of this has incrementally added to a very low external and internal vibration control of the TT. While still not perfect, folks who hear it in my house say they have never heard a system that sounded that good. When I play vinyl, folks are astonished that I'm playing a vinyl record because it is so quite, the detail is awesome and the soundstage is terrific.

So Peter in my humble opinion has advanced the discussion on how to solve a rather serious design flaw built into the Michell GryoDec. SME uses a somewhat similar approach to thwart vibration issues in their products. SolidAir has a completing product, and I would expect them to attack Peter's design simply to protect their own niche. Michell is not going to adopt Peter's solution because of "not-invented-here" syndrome, and the fact that to do so now, means that they have no better ideas but to adopt what someone else has done. Gert Petersen has a solution too.

So I applaud Peter for his tireless work toward making the GyroDec a better turntable. And I look forward to seeing what the next generation of designers come up with for the final cure.

[AJSki2fly]

Turntable isolation generally relates to two planes of movement, lateral and vertical. Ideally, a turntable should be equally well isolated in all planes but achieving such is a lot easier said than done. Look at the isolation systems that Minus K build (https://www.minusk.com/).

the system of springs in extension that Michell use gives a very low resonant frequency but this means that the suspension is very soft and easily deflected. The motor sits outside of the suspension and so errors between the drive and the chassis can easily upset the suspension and therefore alter the tension of the drive belt - this will directly impact upon speed stability. Stiffening the suspension will, no doubt imbue the suspended mass with added stability, but it will also raise the resonant frequency of the suspension. The design balance comes when one has to weigh up whether it is better to have increased isolation or increased stability. In general, I am not keen on motoring analogies applied to audio, but I will have a go anyway. On the one hand you have a motorway cruiser with a suspension designed to glide over uneven road surfaces - however, it wallows when asked to go round tight corners at speed. On the other hand you have a sports car with a much stiffer suspension, the body remains flat under hard cornering but the suspension transmits every ridge and bump of the road surface. Unless the whole drive system is reinvented, there is no free lunch here.

Mark, you are partially correct but using springs is a very tricky thing to do on any mechanical device. A spring itself has its own resonant frequency, as you point out, and if you hit the frequency or get close when the spring is used it can result in unexpected isolations. For example I have spent many hours trying to tune Morgan sports car suspension(notoriously tricky to get right) and an old MR2 hill climb car, the balance of the spring and how it is damped is very important to get the desired result, damping is predominantly done in this situation with shock absorber and bump stops.

For me the lack of damping in the Gyrodec suspension is probably a key issue here, effectively it has none or is minimal, so as you say when the platter turns it will impart forces on the springs, and the result will be wow/flutter or instability. This movement in itself will cause some level of noise and vibration, even though you will not hear it.

There other some other serious issue IMO, the direct coupling of the feet to the suspension towers is a great way to transmit vibration into them and ultimately into the springs, and also the chassis, this is especially true on the Gyrodec. The Orbe has a double spider in an attempt to decouple the feet from the chassis. There is another added factor which is the chassis IMO has a bell like character, Michell have obviously recognised this and tried to limit ringing or resonance by using a heavy putty like material to dampen it. The issue here is that if there is resonance and vibration entering the chassis then it will ultimately get to the arm and probably through the bearing to the platter. If you are to dampen something then it needs to be done so that you don't just move the vibrations or resonance to another frequency which has a different but just as bad and effect.

I have actually measured vibrations on the platter using a simple accelerometer before and after making modifications to feet and pylons, and this supports the above as after making the changes the vibrations are lessened dramatically. I used to work in the Wolfson Unit Sound and Vibration Lab many years ago so have some practical experience in this area.

From my personal experience the new pylons from Peter do make a significant improvement in the end result from a Gyrodec, this is because they have be developed and designed to to limit rotational movement of the chassis and at the same time give the chassis better damping, albeit in a stiffer spring (rubber o-rings). The result is an immediate improvement in the clarity and openness of the sound stage and as a result more detail.

Other areas that can be simply and cheaply addressed to limit feedback into the chassis are to replace the metal feet, see my earlier post, this results in at least a 50% decrease in vibration reaching the platter(measured). Another area the can be addressed to to try and de-couple the arm mounting from the chassis, not easy to do, but by using a silicone rubber gasket between the chassis and the arm board an improvement can be made. I have not experimented greatly in this area but 2mm off silicone rubber to my ears does result and more detail from the reproduction.

[YNWaN]

I should add that I am not saying that Peter’s ‘Pylon’ mod does not work and I’m certainly not arguing that springs are the best solution for a turntable isolation (not metal springs implemented as Michell do). I’m just saying that there is a trade off at work. In the case of the Michell it appears that the weakest link is the spatial relationship between the motor and the chassis/platter and the ‘Pylon’ mod seems to address this whilst maintaining sufficient low frequency isolation (I’m going off my experience of SME decks and working with O rings). Another consideration with isolation is what vibration you are trying to isolate your equipment from and at what amplitude - for example, is it noise from the motor, vibration from the speakers, or vibration in the building and/or footfall.