If the discussion presents dissent as well as assent, yes. Assent only, not so useful.Agree entirely Jonathan. Keep it coming :^)
Regards
Henry
A Copernican View of the Turntable System
Once again this site rejects my long posting so I need to post it via this link to my 'Systems' page
HERE
HERE
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Dear Halcro: Regarding what I think is the overall point of your post, I agree that everyone has and should have the freedom to listen to the sound that they like. Regarding the Olympos, I should point out that the Titan-i is the more neutral, better-performing cartridge, but it is more demanding of setup, and it is more demanding of partnering equipment. >If you've ever heard what room 'volume' can do for your sound, you'd select that over most other parameters I believe. I have friends and business associates that I visit frequently, with big listening rooms that are acoustically shielded, structurally solid, and receive electricity from dedicated, 3-phase power lines. I agree that room volume is good, but past a certain point, I prefer proper mechanical, acoustic and electrical setup, and I prefer close listening proximity to the speakers (and a speaker that allows this). The air between your ears and the speakers is a great sound absorbent (filter), and you can tell a lot more about the faults of your system and components if you can listen from within, say, 1.5 meters from the speakers (although I try to stay closer). >The greatest changes I've heard to my sound over the last 2 years is in fact in the reduction of distortions from the turntable. If you use a DD motor and you don't have much moment-inertia in the plinth, you will be creating a form of noise which is somewhat similar to the background noise of an LP (but is a separate, distinct phenomena). FWIW, Sansui designed a couple of contra-rotating turntables specifically to combat this distortion without requiring so much moment-inertia in the plinth. If you have a tonearm mount that allows relative movement between the LP and tonearm pivot, you are also creating distortions. And if the turntable shares the same acoustic space as the speakers, without structural and air-borne isolation, you will again be creating measurable, audible distortions (although the magnitude of the problem depends on how much acoustic or structure-born energy the turntable receives). You can quantify the difference by making a high-bit recording of your turntable without the speakers playing, and with speakers playing at your customary listening levels, and compare the two files. If you put the two files through a program such as DiffMaker by LIberty Instruments, it is possible to extract the difference component and listen to it as a distinct "distortion" track. There are reasons why I said that some of the posts suggested that the poster wasn't hearing distortions that were almost certainly present, and should be quite measurable and audible. >major reduction in analogue distortions to my ears, has been the switch to MM cartridges over LOMCs. My experience is that MM vs. LOMC is largely a phono stage and tonearm issue. LOMCs need a good phono stage, they need as few electrical contacts between themselves and the phono stage as possible, and the low-compliance types need a suitable tonearm that can sink a lot of mechanical energy without becoming perturbed. I have heard (or own) some MMs that I rate fairly highly, but they still leave me somewhat wanting. OTOH, I do believe that MMs or MIs have more performance potential than most previous efforts have been able to demonstrate, and in the future, I hope to be able to design an MM or MI cartridge that shows this to be true. >Now you obviously do not hear these distortions so I'm not sure that a meaningful discussion between us on that topic is achievable :^( It would be more accurate to say that I hear other distortions from MMs or MIs that annoy me even more (^o^). >I find far greater differences in cartridges than in drive type and I admire those who claim to hear those differences. Interesting, because I've designed and built various turntable power supplies, control systems and drive amps, and I assure you that the difference between topologies and components (semiconductors, capacitors, rectifiers etc.) is quite audible. And that is without changing the particular motor or drive system under test, let alone the drive type. >I can't stand the distortions I hear in digital reproduction yet most here, can happily live with them? I hear a different set of distortions from digital than I do analog, but both have audible distortions. Open-reel tape has audible distortions, and recording microphones do, too (smile). FWIW, my experience is that the transport, DAC and line preamp all have a significant effect on the reproduced sound quality from digital audio. My present digital system is capable of playing back 384kHz 32-bit studio master-grade recordings, and the transport is a dedicated solid-state device that runs in synchronous clock mode with the DAC (effectively eliminating or at least drastically reducing jitter). At this level, digital doesn't sound so bad (^o^). >We all are different and all our experiences are valid. When it comes to subjective preferences, everyone is free to choose whatever they like (and for whatever reason). But let us also keep in mind that not everyone who dissents is an armchair critic, Sunday designer, or lacking in the experiences that make others go ga-ga. >This is a 'discussion' Forum and the more we have.....the more we can possibly learn. If the discussion presents dissent as well as assent, yes. Assent only, not so useful. kind regards, jonathan |
Dear Halcro, The Germans are not considered as having any sense for humour. By the Dutch in any case.But they produced this saying:'if theory and practice coincide then they are probable both false'. They were also the first to mentinon this 'unity between theory and practice' ( Marx if I am correct). Now I consider Jonathan as a genius designer (think also about his pres), a nice guy and as honest as 'Gold' as one says ( aka indisputable integrity). But his aims and intentions are impossible to fulfil without his own preferences or testes. His work imply both: the technical knowledge and application of this knowledge to reach some ends. For him this 'unity' of theory and practice must be self-evident. But we want a separation of 'objective' and 'subjective' aspects of the valuation process and can always attribute some of his propositions to his 'subjective valuation'. The same apply to Raul btw. Now this 'subjective valuation' is connected with our upbringing,culture, education, family infuences , experience etc, etc. Ie our whole brain is involved. To refer to all this as 'subjective' is of course very slim. But somehow in our discussions we are predisposed to talk about 'subjective' as something that is suspicious. Why are we so skeptical about those with whom we disagree? Regards, |
Dear John, You are obviously an atheist. Never seen a church from the inside? There is always a Podium in any that I know of and all of them claim to be the winner. However if the other members of my church prefer 'Podiúm' above 'Pedestal' who am I to disagree? As long as I don't need to kneel before some plinth...that is. Regards, |
Dear Jonathan, We all, I believe, value your contributions to these forums.......I know I certainly do. And I recognise that you must have vast experience in listening to audio systems of all types. You should appreciate that most of to us here, also have many years of experience in listening to various systems belonging to other audiophiles as well as those in dealer's listening rooms and also hi-Fi shows so that our 'hearing' is conditioned by all those experiences and also more importantly, live music performances. It is thus a little puzzling to think that you actually believe we are perhaps listening to distortions without somehow knowing it? I have listened during a period of 2 years to a Rockport Sirius III turntable with your own quite good Olympos cartridge :^) and over the last 4 years, have regularly listened to a Continuum Caliburn with Cobra and again.....your modest Olympos. I have heard hundreds of systems in rooms far far better than mine and have continually monitored my sound against all of these. My room is not ideally designed with regard to equipment placement as you quite rightly point out but some of us have no other choices without a dedicated listening room. One thing my room does have......is a wonderful acoustic volume with a ceiling raking up to a height of 18 feet. If you've ever heard what room 'volume' can do for your sound, you'd select that over most other parameters I believe. My point is that the sound emanating from my system is compared to that of the finest sources, amplification and speakers commercially available and I believe that I can detect 'distortions' as well as you or anyone else. The greatest changes I've heard to my sound over the last 2 years is in fact in the reduction of distortions from the turntable. Some of this results from the isolated armpods (I do still play the Raven AC-3 for comparison) but the major reduction in analogue distortions to my ears, has been the switch to MM cartridges over LOMCs. I can hear high frequency distortion in most of the LOMCs regardless of the arm, turntable or set-up. Now you obviously do not hear these distortions so I'm not sure that a meaningful discussion between us on that topic is achievable :^( Having said all that......there are those who prefer DD to Belt Drive and others who prefer Idlers. As I've said before.......I find far greater differences in cartridges than in drive type and I admire those who claim to hear those differences. I can't stand the distortions I hear in digital reproduction yet most here, can happily live with them? We all are different and all our experiences are valid. I've also learnt that 'blanket' statements regarding audio are commonly wrong? This is a 'discussion' Forum and the more we have.....the more we can possibly learn. |
In general, I try to avoid commenting on things that I have no hands-on experience with, or at the very least, have never discussed with another designer who has had hands-on experiences with the topic in question. This thread is no exception to my policies. I have tried and listened to independent arm-pods on multiple occasions, spanning from the early 1980s to earlier this year. Any dissent that I may have voiced for independent armpods or other design particulars espoused in this thread, is based on a combination of personal experience (including listening), engineering training, and study and analyses of other turntable manufacturer's design efforts. Everything that I have learned and experienced about turntable design (particularly regarding DD) suggests that the plinth should have very high moment of inertia but with as few structural or cavity resonances as possible, and as small diaphragmatic area as possible, while the tonearm mount should be non-resonant and completely rigid in relation to the platter so that there is no possibility for relative movement between the LP and tonearm pivot. The reason is that if any relative movement occurs between the LP and tonearm pivot, the cartridge has no way of distinguishing whether the relative motion comes from noise or vibration in the environment, or is part of the LP groove. This should be accompanied by full isolation from structure-borne noise and vibrations from the environment, and preferably full isolation from air-borne noise and disturbances from the environment. Some of the posts in this thread very clearly suggest that the poster isn't hearing distortions that should be quite measurable and audible, or that the sound of their system is deemed to be preferable with those distortions present. cheers, jonathan carr (hugging a pneumatic isolation platform - grin) BTW, if you place equipment between the speakers, you create an acoustic problem for the speakers, not only a vibration problem for the turntable, CD transport or electronics. IME, if you must place equipment between your speakers, it should present as small of an acoustic profile to the speakers as possible, and should be placed as far away from the speaker's radiating pattern as possible. |
Dear T_bone, For someone who is refering to the 'original marketing material' as a 'argument' for his church you should understand how important the right words are. To me the pedestal also sounds much nicer than a'pod'.I am alas not familiar with the church furnishing but for our church we (should) prefer 'pedestal' above a 'pod'. Ie you and other members of your church are free to pray before a plinth we have, I think, a much more sacral object in our church: the pedestal. Besides our religion is the true and the right one. Regards, |
Dear Raul: I feel that your posted of 9-11-11 was a direct response to my posts. I would like to make two points in this regard. First: Being critical of a given approach or "road" as you put it, does not mean that one is against it. I doubt that the purpose of this thread or Audiogon in general is to host forums where people spend there time complementing each other's system. (BTW you have a very impressive system). Being critical challenges these approaches and helps them evolve. While receiving complements is pleasent (I enjoy receiving them as much as anyone) they will only lead to status quo or possibly shinnier and more expensive systems. Second: you suggest that unless we try a given approach we cannot comment on it. Once again, then why participate on A'gon. I thought the point was to gain from the other participants' experiences and mutually advance. Moreover, I do not have the means to try all that I would like to. With this said, Raul and the others, please explain the following. With the TT mounted on a suspension system above a mounting surface and the armpod rigidly seated on this same surface how is the distance that must remain fixed between the pivot point of the TT and the tonearm fixed? The trade off, is between the variations in this distance, most likely in scale of 1/10 to 1 mm vs the variations caused by the micro vibrations from a bearing of a shaft turning at 33 or 45 rpm with a scale in likely 1/1000 to 1/100 of mm. My instinct would lead me to believe that the first problem is far more problematic then the second. |
T_bone - I think you are wasting your time on this. This thread goes round in circles. If I look at Halcro's system it astonishes me that for all the discussion on turntable set up I see the following issues in his system - Turntables located on a large resonant shelf behind the speakers where there is massive feedback. There is effectively a bass trap where his turntables sit. Gear stacked on top of each other rattling away ( yes electrical components resonate when on ). He has a TV spewing out RF inches away from turntables and sensitive phono stages. He has a massive glass coffee table bouncing off hi frequencies in front of the listening seat. I also note that the speakers have huge lips around the edges which will cause a tunneling effect and restrict soundstage. He may like a horribly discoloured sound who knows, but for me strapping a cartridge on with a rubber band might well sound better in this suboptimal set up. |
Oops. Writing on an iphone is a sure-fire way to make lots of typos. So please ignore those. One can add to the last point that it is not necessarily a BAD thing to exchange one set of undesirable resonances for another set of undesirable resonances. It could be that one likes the flavor of the second better. But for people who are trying to get rid of ALL distortion, introducing an isolation layer (distortion transformer) between two points which are supposed to be absolutely fixed together with zero distortion between them is in some way 'giving up.' And while it may be better than it was 'before', it makes one wonder about the state of the 'before' and almost certainly can be improved upon. That said, it is not a difficult thing to do, and I will try at some point. I can think that it might even be an improvement on some of my stock plinths (because some of them were not top-notch). I can probably figure out an armpod of some sort relatively easily (it could be an arm attached to an current plinth and the motor outside it, either spiked (rigidly coupled) or isolated (on magnetic levitation footers) with regard to the surface below. |
Ct0517, A pedestal is nothing more than a 'plinth' :^) The issue of having isolation between the arm bearing and table bearing can be illustrated, in extremis, by imagining a jack-in-the-box with an immovable armpod next to it. After jack has popped out of the box and does not bounce anymore, he is perfectly stable and unmoving at the end of spring. As long as he is perfectly still with absolutely zero resonance, the relationship between your tonearm pivot and jack's nose is always the same, whether Jack is encased in concrete (a plinth) or perched on the end of his spring (on top of a 'platform' which moves in relationship to the world around it. As soon as there is any resonance in the system however, jack will move with regard to the tonearm pivot (and therefore the stylus), and may do so in slightly unpredictable ways. In any case, the slightest movement will cause a kind of intermodulation. If you fix Jack to the platform your armpod is resting on in order to keep the relationship between his nose and the armpod-mounted arm pivot perfectly constant, you have effectively plinthed him. If Jack has some kind of internal resonance, the method of fixing him to the board may have more or less resonance. This is the difference between a bad plinth and a good one, but the inherent goal of a plinth is to keep the relationship between the arm's pivot/bearing and the motor bearing as stable as possible. If one removes the plinth which surrounds the motor, and mounts it naked on the same table as the armpod, one has removed an intermediate coupling material (the one which connected the frame of the motor to the bottom of the footers, but one has not changed the concept/goal, one has simply changed the method of execution. If, however, you stick your TT motor on an isolation base which is not the same base that your arm bearing is resting on, you are effectively changing the distortion relationship. You may find that a substandard plinth will resonate unpleasantly because of a resonant frequency of the material which is in the audible range. If you change this frequency to a 3-5Hz frequency (the goal of most isolation systems), you have exchanged the plinth resonance-induced distortion for one which is like an off-center 45 record. |
From Nikola's last post I have to admit that having a lawyer with an armpo... sorry I meant to say pedestal :^) -has advantages. T-Bone - you said. "The philosophical issue some of us have is that of putting an isolation layer between the motor bearing and the arm bearing." Why is this ? Can you provide more info on this. I thought about it. I have limited knowledge of bearings other than actually changing the one in a turntable, as well as the wheel bearings on my trailer and my automobile wheels. I would have assumed that a TT motor bearing is different than an arm bearing both in the way it is designed and works. In fact who here actually uses a table and arm from the same manufacturer even ? Fleib gave a really good description of how bearings are selected at REGA on the MM thread. So I am thinking with these two disjointed designs being joined somewhere on a plinth or by appendage - attached somewhere. That this would lend itself to more rumble/chatter, etc... Remember I have heard an armpod so I have a comparison to make here. I would tell the design team to separate the two or prove me wrong with test results. Now lets make it more complicated a Unipivot arm does not have any bearings but point/s ? Lets go another level still - an air bearing arm ? Wonder how those things sound on an armpod ? At least you are coming up with reasons T Bone. I agree with Henry with your gear you are the perfect candidate. I am actually selfishly hoping you could provide me with tips to improve my setup based on your experience. Cheers |
There is no question in my mind that our hobby has some religious aspects ( aka it is about what one believes). But we are used to use 'scientific' arguments in our discussion. Who would expect that, say, the Catholic churh will ever reach any agreement with, say, Greek ortodox church despite the fact that both were once 'the same' church? To admit that the 'other' may be right is like loosing a game. So Lew refers to Newton and T_bon to some 'original marketing material' to prove their case. But we all can enjoy leterature while we know that this 'art' has nothing to do with the (real) truth. I myself always enjoy the post of , for example, Lew and Herr Professor in this sense. I wish btw that I could afford the 'big one' from Kuzma with 3 of those 'golden' arm pods. One should I think refer to those as 'pedestals' because a 'pod' looks so miserable in literary sense. Regards, |
Dear T_bone, Go on........try it. You know you want to :^) You have the TTs ( a plethora)...I provided a recipe for a cheap armpod.....you have the arms.....and you really want to prove it doesn't work. You're the perfect candidate.......well, you AND Lewm....to be converted? Imagine the mental exercise to be enjoyed IF.........your ears tell you something your brain cannot yet compute? :^) |
Raul, If you look at the original marketing materials for the Kenwood L-07D from almost 30 years ago, you will find a clear 'explanation' against having the arm base be dis-connected from the bearing mount of the turntable. A similar explanation is in some of the original marketing materials in Japanese for the Exclusive P3. In fact, the P3's construction is not terribly different than some of the 'armpod' implementations. What some of the philosophical 'naysayers' bring up as an objection is not necessarily the lack of bulk-cladding (plinth) around the motor OR a heavy armpod. The philosophical issue some of us have is that of putting an isolation layer between the motor bearing and the arm bearing. In the design of your arm, I imagine you are not going to put an isolation buffer between the armwand and the bearing - that would strike you as less than optimal, and not even worth testing. Some of us feel, perhaps to our detriment, that an isolation layer between motor bearing and arm bearing is not much different. |
Dear Halcro: Way before we go into the tonearm isolated/stand alone arm boards some TT manufacturers already had in their designs like: Red Point, Kuzma, Galibier, etc, etc. My point here is that I can't remember any single post against/questioning these commercial turntables with stand alone/isolated arm boards. It was till we " amateurs " bring the subject at this forum when all the " enemies " arrive: well the audio world is something " weird " for say the least. Regards and enjoy the music, Raul. |
Raul makes a reasonable point. Whilst it is in our 'audiophile' nature to be skeptical and delve into philosophical discussions regarding our understanding of the playback system, there has not been one report from those who have actually tried the isolated armpod, which casts doubt on it's benefits? In the interests of proper discussion it would be worthwhile if anyone has had contrary experience, for them to hopefully contribute their findings in this Forum? In the absence of any dissenting personal experience, it is hard to accept seriously, the views of the naysayers? And I know Lew.........too many question marks? :^) |
Dear friends: Several yeras ago when I bring to Agon my first naked TT fashion subject and latter the isolated armpod for that naked TT I remember that almost all the people that argue against were persons that argue against it with out having any single experience on that naket/TT-tonearm isolated fashion. Almost all the more fierce persons were the ones that not only never had any experiences but that never will try that " experience " even that they can did/do it. I almost don't like to post or give my opinion only based on speculations and theory. In this thread is happening the same that happened when I start on the whole subject, more than half of the posts were posted for people questioning the subject that have no single idea on what is its real quality performance and even that people like Chris posted that through the time his armpod stay in place other people continue argueing about. The TT naked/tonearm isolated overall " fashion " certainly is not perfect as the plinthed one is not either. The main sunbject here IMHO is where the trade-offs of either/each " solution " arrive in favor of better music sound reproduction at home. Almost all the persons that like the naked/isolated " road " likes because our ears and audio/music experiences over a lot of years tell us that this " fashionable " version in our systems gives us a better quality performance level than the stock plinthable version and this is the main subject: we already made comparisons with and with out and there is no single opinion where to a person prefered the plinth version: means all these something to you people that are questioning our version with out have/live any experience in your own system about? Regards and enjoy the music, Raul. |
Hi Nick_sr, The Copernican view of the armpod and tonearm as the centre of the turntable system, is predicated on the fact that the armpod is an 'immovable' object. How that is achieved is open to debate. I prefer to see mass (and plenty of it) concentrated on 3 spikes which would be equivalent to tons per sq in 'digging' into the supporting shelf. You would be surprised how difficult this is to move without lifting the pod off one or more spikes. And that is how the correct Spindle to Pivot distance is accomplished......by tiny lifts and nudges of the armpod. Until you try it you won't believe how easy it is and how accurately it can be achieved. As you correctly say........isolating the tonearm from any motor noise or platter vibration is a huge benefit and can only be achieved in this way for Direct Drive and Idler design TT. Belt-drives can have (and often do) their motors isolated from the platter and plinth via a separate module. The degree of stability and ease of set-up is something that differs with each solution and is something you quite rightly point out. |
Nick_sr, Btw, I don't think what I have tried to say necessarily disagrees with your points, particularly about residue vibrations and the like. As I said, I have simply sought to understand what I am hearing in a (possibly) completely 'unscientific' way. Uncertainty therefore remains about the why's. What is not in doubt is the what's: i.e, very, very high quality and believable play back. |
Nick sr, I imagined that the turntable produces vibrations when it rotates. These mechanical rotations are not the same as the indentations on the record and would be transmitted to a coupled tonearm (no matter how small the transmission). To isolate the tt is to isolate it from external vibrations but not its own self produced ones: here you can consider the difference that we get from isolating CDp's say with rollerblocks or the like! To decouple the tonearm from the tt would therefore be to remove these additional vibrations. The issue about mating with the vibrations on the record would then (once the decoupled tonearm and armpod are equally isolated) become a question of the quality of bearings and trackng force accuracy and of the ability of that tonearm to match the movement of the indentations that are on the record's surface. This is just me trying to understand what I hear in a (possibly) completely 'unscientific' way. |
Halcro, I am not opposed to your approach, in fact I find it attractive. Your idea of the concrete arm-pod seems like a fun DYI project that I have considered for use on SL-1200 table. But that got me to analysing this approach and the big hurdle I see is locating the arm-pod. Really my question is how can you guarantee this geometric relationship when considering using a Baerwald type set-up. With this type of setup we are taking about degrees of precision in fractions of milimeters. I have trouble seeing how simply placing, with out any means of mechanical fine adjustment, an arm-pod on flat surface(albeit very diligently and carefully)can provide such a degree of precision. Can you explain the approach you use? One Idea I came up with would be to have mounting locations machined into the base used. But in doing so you then be coupling the arm-pod and turn-table to the mounting surface, and you would essentially be back at square one. |
Nick_sr, The approach you describe is a common one and has been in use by different manufacturers for decades. This thread is simply proposing a differing approach albeit one which still maintains the geometrical relationship between tonearm and turntable. No-one here believes movement in that relationship, should be tolerated? |
Dgob, that'd be my view (and hence my reference to the seismic stand from Townshend). All of this (legitimate) concern with resonance has to deal with an originating source for the same(either airborne or transmitted via stands or gear, or as a function of playback itself--say in the case of a warped lp, or one that is not damped/clamped). Dealing with the resonances always comes down to the necessity of keeping the cartridge (the stylus, actually) "absolutely" stable. Read the accompanying text for the Rock 7 TT in the Townshend link previously given. That said, the assumption is that the arm, pivot assembly, etc, are capable of minimizing the effect of any resonance that had been decoupled by the stability of good plinth design, that is, whatever resonances are "left over". Those "left over" resonances are either airborne (and some here suggest that those are minimal to non-existent in their effect, but I suspect that depends on the gear involved) or are generated by the physical effects of playback (again, warps, off-centers, and unclamped/damped lps). One of the observations made by Townshend is that (at least) to date, the bulk, if you'll pardon the pun, of high-end TT design has dealt with resonances by increasing the mass of the plinth, and in some cases of the integrated plinth stand (say as in the case of the Caliburne/Continuum). You look at most of the really expensive TT gear and the one thing that is inescapable is that it is massive. Another way to deal with the issue of defeating vibration is to shorten the chain of resonant materials/connections (equivalent to fretting the string on a guitar)--a shorter tonearm for example (which involves other problems, one of which is the fact that it requires a different level of energy to set it vibrating). But Townshend has been dealing with the issue in an entirely different way and that is by damping the headshell. In terms of resonance control, I think a simple illustration should suffice. Imagine a piece of 3/8" or 1/2" steel tubing that is four feet long and has one end clamped into a vise. With your finger you can take the free end of that tubing and push or pull it down a fraction of an inch and let it go and it will resonate. That free end of the tubing is behaving like a tonearm hanging out there over the record supported only by the most sensitive of supports, the stylus. But if you clamp down the free end of that tubing and apply the same force with your finger on the center of that tubing, the tubing will not move. It will take a substantially greater amount of force to move the tubing and the vibration and an order of magnitude greater amount of force to keep it vibrating. Methinks Townshend is on to something, and he's been doing it for awhile. |
Hi Nick sr, I have little interest/knowledge of scientific possibility (trying Hif Tuning fuses gives one example of why this is more fraught with options than seems scientifically likely!). However, wouldn't the answer to your ultimate question be: 'that depends on the stability and inertness of the plynth - on which the armpod rests and from which the tt is decoupled?' |
The base as an island, I am not sure? The fundamental objective of turn-table design is to maintain an optimal geometrical relationship between the stylus and the groove in such a matter to allow, as Halcro so eloquently said it (paraphrasing), the cartridge to transmit perfect information by moving up and down frictionlessly to allow for correct VTA as the groove modulates. This in turn consist of two factors the geometry and the maintenance thereof. Geometry is the initial location (for the lack of a better term) of the tone-arm pivot point, stylus contact point and center of rotation of the disk, such to achieve Baerwald or Stevenson setup (or whichever one you believe to be best) and including optimal azimuth and VTA. Maintenance is the ability to prevent outside factors such as vibration and noise to change the optimal geometry. Now to separate and isolate the arm pod from the platter, in perfect world, seems to address the maintenance issue. If the arm pod is isolated, any vibration from the motor or bearings will not be transmitted to the tone-arm or stylus. This raises the question how is the arm pod accurately located in relation to the platter? Many of the systems in this thread show the arm pods simply placed alongside the platters with no means of accurately locating relative to each other (this is an appearance based on the photos) clearly these tone-arms are properly setup, but how accurately (initial geometry) and what prevents them from moving over time? Ultimately, the arm pods must sit on a surface that is shared with the platter. The platter is isolated from this surface by pneumatic footer or other method, which no doubt prevents the platter vibrations from transmitting through the surface back to the tone-arm. But now since the platter location is no longer rigidly held relative to the tone-arm pivot, other environmental factors, such heavy footsteps on the floor or ambient noise, can cause these distances to change momentarily (vibration) or permanently (until readjustment). Is the arm pod as an island truly ideal? A rigid location of the platter vs. the tone-arm pivot ensures optimal geometry, and high mass plinth minimizes the impact of vibrations and noise from the platter. Then isolate this assembly from the room. Is this approach not superior? |
Interesting thread. Reading comments about resonant energy in stands/shelving etc. I was reminded of this "seismic" stand product from Townshend I just read about and which looks very intriguing to me (I love the TT too but that's another topic). Check it out (below the Rock 7 TT) http://ear-usa.com/townshendsinks.htm |
Hi Pryso I agree with what Jim Smith and yourself say. I also keep my TTs on racks 6 from the side long wall wall in the 12 x 24 ft room. Speaker Angle This picture is the regular placement. The only positioning change I needed to do for this experiment was to rotate the midrange/tweeter module and angle the woofer box a few inches inches to point at the TTs directly. The front of the woofer is 9 feet from the front wall. The SP10 TT at the rear is actually 7 feet from the back wall looks deceiving. The Lenco is only 5 feet from the speaker woofer not 6. Armpod Recommendation For those of you that use a metal (brass, SS, bronze, other ) armpod have you tried a few drops of oil in the tonearm mount screw holes before you mount your tonearm ? Id really like to get your impressions on what this does to the sound for you. I am using some oil in the armpod and the SP10 SS legs. Cheers |
Pryso, Jim Smith went around my listening room with a mic measuring bass energy and concluded that my rack was in a good location on a side wall behind the first reflection point and not near a corner. I believe his recommendation that the rack not be placed between the speakers has more to do with the mass of the equipment and rack effecting the imaging and soundstaging of the system. Soundstage depth and center-image density and clarity are improved when there is open space between and behind the speakers. At least this is the case in my system and I would think in most others. |
Chris, maybe it is just me but this seems to be a bit confusing. You said you tried two tts on the side wall, "directly opposite the firing of one of my speakers". Does this mean one speaker is toed-in to such a degree that it is aimed at one of your tts? Now perhaps a few points were suggested in my earlier comments that were not made clearly. First, it is not always easy to differentiate between airborne and structure borne vibrations. After I moved my tt, it was then located in a position with less structural bracing (likely bad), yet it sounded cleaner. So in my case I must infer the minimizing of airborne interference was a net gain over the increase in structure vibrations. Second, I think a lot can be understood about equipment location from the study of speaker interface with the room. It seems to be understood that where three planes intersect (any corner) you will find the greatest build up of bass nodes. (Insert assumption that bass frequencies have more energy, thus are more detrimental than higher frequencies.) While the corner of my alcove may not have been as severe as a room corner with longer walls, my experience (two shorter walls and a large shelf = three planes) still supports this point. Less of a problem with bass node build up may be realized where two planes meet -- two walls, a wall and floor or ceiling. Further reduction occurs with only one plane (along a wall and up from the floor) while the least airborne interference may be away from all walls and the floor, while admitting this may be the least practical. I believe this also relates to Jim Smith's recommendations in "Get Better Sound" when he promotes side wall equipment locations over front wall between the speakers. Conclusion: try locating your tt/arm/cartridge where there will be the least bass node build up. |
Addendum. Dear Chris, you made an important discovery without knowing what you discovered. Otherwise you would at least pronunce: Heureka. There is no way to value anything without comparison. Even 'better' assumes some, not to mention 'the best'. Alas your method is to expensive: two or more 'locations' are not attainable for the most of us. So I have a proposition which is even cheaper than Halcro's concrete arm pod. Buy the cheapest MM cart you can find ( I have some from East Germany) and use it by every listing session for one hour and then switch to whatever other cart you own. You will be suprised with the result. BTW such results seems to be the 'basics' in psychology. Regards, |
Hi Nikola As long as I stayed in my chair it was very nice but loud - the vibrating chair added to the effect :^) . But sustained levels would not let me enjoy this hobby for very long. It did however start feeling like a shoebox at those levels when I got up to check the gear, walls, etc... Yes the other building has many problems. Adding vinyl there exposed many of them. It will be a challenge. Cheers |
Dear Chris, This remind me about this Jew who was complaining about his shoes:'they are killing me'. His answer about the cause was that they are too small. But when asked why he buys too small shoes his answer was: 'it feels so good when I put them off'. BTW I think that you have some other 'structural problems'. 'the other location' imply that you can use the 'other one' without 'structure feedback issue'. Regards, |
Observations of Direct Sound Pressure on a Tonearm The recent posts have been great, informative and enlightening for me. Thanks guys. TBone - looking forward to your results as well Sorry for the long post. I was curious, so I tried to create a direct air borne problem before it became a structure feedback problem just to see if possible. Two TTs together on the side wall directly opposite the firing of one of my speakers. Everything u wouldnt want to do to get direct airborne feedback with a TT I did. The first TT is no more than 6 feet away from the drivers of my speaker. Before I tell u what happened let me say I have played around quite a bit already with this air pressure phenomenon but from the other end. I have experimented with my air bearing arms to see how the air pressure affects them as it comes out of the air bearing. I learned what their maximum PSI threshold is. Go past this point and they start to resonate from not being able to handle the PSI. Keep just under it and you have magic happening. Anyway above this threshold they resonate and cant hold the cartridge/stylus in the groove properly anymore. A loss of detail happens. Your $$$$$ TT rig starts sounding like a $$ rig. No surprise right ? So I thought what the hell, this is going to be more fun than yelling at the cartridge so I let loose on them hoping to make the tonearms/cartridges show some signs of sonic deterioration. I played big music at well over 100 db. What happened? Well first thing is not what I could hear but feel because my listening chair was vibrating. I then went over to one of the speakers and felt the sound anchor stand holding up the 110 lb speaker. The heavy metal SA stand was resonating. They are spiked to the basement concrete slab. My room is closed 12 X 24 FT. with speakers in nearfield firing down the length. The side walls were also resonating. But what about the music ? Nothing NADA the music and tonearms were fine as far as I could hear. So in my case with this little experiment I heard no direct sound pressure effect on the tonearms. If you dont believe me. Ask this Audiogon member if he is worried about Direct Sound Pressure from the Speakers ? So based on this I agree with what Henry said. The airborne feedback is changing (mutating) into structure feedback. Its going into the walls, the floor, the racks the gear. Everywhere. Structure Feedback is the audiophiles version of VIRUS movies. Go ahead put up a shield - its going there too - now u will have something resonating next to your precious $$$$$ tonearm - does this make sense ? I dont know I didnt try it but I'm also not going to Home Depot to buy plexiglass or something else to surround the TT either. I've heard enough. Structure feedback is there but until you discover it no matter how small a problem it may be and correct it as Pryso's experience tells, you may not even realize its there. This has to be one of the leading causes of why gear may sound good at the dealer, but then people bring it home and it sounds different ? This experiment was good for me because it gave me a better idea on the limits of what my room are. My racks isolate ok to well above 100 db so below that where I actually listen I am fine for now. Could they be better - definitely - maybe I will ask Don to build me a nicer rack ? But I think I need a new listening chair first? Thoughts ? |
Hi Halcro/Pryso/In_shore, I have for a long time thought that new equipment needs time for the room to settle into it. This is most obvious with changes in speaker systems but seems applicable to equipment more generally. However, this is all dependent on my challengable tools of assessment: my untrained/self-trained ears! What you've all said does provide food for thought. |
I believe that Pryso and In_shore are correct in the fact that the air-borne sound pressure levels, affect the room's fabric to different degrees depending on their materials and structural means of support. This transforms into 'structure-borne' feedback affecting the turntable depending on it's construction and isolation. 'Sprung' decks, because of this, are more susceptible to this feedback than 'mass-loaded' ones. |
In my current home, room and speaker interactions are a source of some real problems. When the gain is turned up i believe this excites the built material of the walls ,ceiling ,suspended floor causing many problems. With my sources 13 feet away from the closes speaker i decouple my stand from the floor the best i can for now and then decouple the turntable from the stand, it's a job still under construction. Our previous home listening room was so much friendlier and a real joy to listen music in, concrete slab on grade timber framed home with open vault ceilings. The living / listening room simply had excellent acoustics. One experiment listening for feedback problems in our previous home by placing an lp on the platter then resting the stylus on a stationary lp ,turning the gain up full i would be hesitant to try in our new home yet. This may sound all bad however using a Placette active preamp with a Hell of a nice headphone section and Sony R-10 headphones immediately solved all my room related problems, I think. |
Chris, I can offer an experience to help answer your question. My turntable is placed on a 60" shelf, fitted within an alcove on a side wall of the listening room. The shelf is 18" deep and the walls forming the sides of the alcove extend a few inches beyond the shelf. For some time I had the tt at the far right end of the shelf. This placed the arm/cartridge close to the corner of the alcove. One day I was dusting the table/arm (using a camel hair brush) while I had a CD playing. I happened to lean over the platter while some fairly strong bass was being played. I was amazed with the amount of bass energy heard with my head close to that corner. Realizing the probable harm from my cartridge working in that environment, I relocated the tt to the left end of the shelf. This resulted in the arm/cartridge being slightly left of center along the shelf and away from the corners. When I then played an LP with only average bass content (probably a jazz quartet) I heard improved overall clarity. This shelf is 3/4" ply and attached to the walls on three sides and has an added brace along the fourth side. It appears to be rigid but if I place my fingers lightly on the surface while playing music with much bass energy I can feel some structure-borne vibrations. For this reason, I use a 2" deep sand box between my tt and the shelf. So, for whatever degree of structure-borne vibrations that reach my arm/cartridge, and they would logically be greater at the mid-point of the shelf than the corner (less bracing), the change to reduce air-borne vibrations resulted in an overall sonic improvement. |
my thoughts on airborne feedback. i believe it to be real, but difficult to identify. what i did to minimize it was to minimize the surface areas that could absorb airborne vibrations/waves. i did this by building a "nude" rack. i eliminated side panels and shelves and rest my equipment on the frame itself. i also incorporate alto extremo feet to absorb and isolate. for the equipment, such as tables, that would not fit onto a nude rack, i made isolation platforms for them, filled with dense steel shot. that way, any airborne waves would have a hard time moving the heavy weight. i have to update the pics in my gallery (actually, i thought that i had done that!!). don |
Halcro, What does it mean if the feedback increases as volume increases. If airborne feedback is the ONLY problem, one would figure the effects to increase. Personally, I am not convinced that airborne feedback affecting my rack, and then feeding 'structural feedback' through an isolation system (designed to combat structural feedback) to my turntable is a more insidious problem than the same airborne feedback affecting the record, tonearm, or dustcover itself. In testing now... |
On a serious level.......it is often difficult to isolate 'structure-borne' feedback form 'air-borne' as the 'air-borne' feedback can be absorbed into the equipment rack or floorboards and thus mutate into 'structure-borne' feedback affecting your system. If the feedback increases as your volume increases.....this can identify the problem. |
