Hey Chris,
It's ok to throw money at things as long as you don't spend your capital. Mom told me that a while ago, and it has worked for me. After all, it's only money. -Enjoy it if you've got it.
Hey Harry,
Do you have the Calypso or Callisto. -Just wondering.
-John |
Re "straight shot to preamp" wiring:
As just a gentle and friendly nudge to anyone the least bit curious about trying this. In my experience this "tweak" yielded the single biggest improvement in sound quality of any other tweak or adjustment to the ET2. All the other tweaks like using the correct spring compliance for mm or mc, magnesium arm wand and others which deal with resonance and which, to at least some degree, simply shift tonal balance around a bit which, in turn, may add to the impression of "improvement" in the context of a given system are not nearly as large in overall scope. The "sstp" wiring is a very significant improvement of a very fundamental nature with no downside that I ever experienced. Think about it: you are removing at least four solder joints and three connectors of different metals from the path of the tiny and fragile phono cartridge signal’s path. The increase in purity of sound, soundstaging detail and rhythmic coherence is huge in my experience. Of course the choice of wire is important, but secondary to the benefits of getting rid of all the "bumps in the road". The really committed (in more ways than one 😱) can always eliminate the connectors altogether and hardwire the wire directly to the circuit board of the preamp as I did.
Cheers. |
I’m with you frogman. The first wiring in an analog system is that in the arm, and the most important to improve if need be. A whole industry popped up to cure the sub-standard Rega arm wiring, but a lot of other arms need it just as badly. A single, unbroken run from cartridge tags to RCA plugs is great, but some systems incur hum problems from the unshielded internal wiring being outside the arm. Some rewiring kits include shielding sleeves for the exposed wire, which often prevents any hum problem. The delicate internal wire is very fragile, and it doesn’t take much to break it off RCA jacks, or even the Cardas RCA block, so take care. I speak from experience! |
Frogman, I can only second what you wrote! To hear the elimination of contacts or to compare different connectors under controlled listening tests has been my most educating experience in audio. I think the effect of contacts on sound quality are highly underrated. I guess that from the omnipresence of brass based "professional gold" contacts in a wide field of the audiophile market. Listen once, never return back.I was an anti-WBT low-budget "snob" :-) but the copper based WBT RCA connectors and the Clearaudio MPC were hugely better than any silver- or gold-plated brass connector back when I compared these (with ca. 7 identically constructed & oriented silver interconnects). Yo don't get what you haven't paid for - except for soldering directly!
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I made the same change after seeing the nice "loom" made by Take-5 that one of you posted years ago, ordered the Cardas wire, clips and plugs and did my own, my tips on the RCA were not as nice looking, but still functional. Later, bought a second wand from Bruce and made my own new loom with Litz wire I acquired from Trans-fi (the Terminator guy, Vic), he has a smoking deal on kits with clips and reasonably priced wire. Now I can swap cartridges and/or wire much easier, currently very happy with the Litz / Ortrofon Quintet Black combo. |
Audio setup can be like a jungle.
Running your setup with a Straight Shot To Preamp "Unshielded Loom", is akin to ....running through the woods naked.
Free Willy. Well.... maybe some running shoes.
In both cases try to keep the run / loom short for best results, and with running - best not to Free Willy in May when the blackflies are hovering.
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Cardas still makes his RCA jacks and plugs of brass! The WBT Nextgen and Klei use copper and/or silver, and with anti-eddy current RCA "barrels". |
Hello all,
Been away for a while. Spring has arrived in Western Carolina and my mini farm has been demanding attention.
John,
I don't know what Calypsos and Callistos are so I guess I don't have either. Enlighten me. I agree, with my Delos level and all other parameters set I find myself playing with VTA less and less.
Chirs,
My complaints were just poking fun at myself. All of these choices/tweaks, aside from being a great learning experience, have brought me a whole lot of great listening. I agree, don't start playing with the sub until everything else is set up to your liking. I don't run my sub from the preamp and only use the crossover in the sub for setting the upper limit for sub. Main speakers are driven directly from power amp and sub driven from power amp to high level inputs on sub.
You straight in loom guys are ganging up on me. It's not that I don't believe you. I'm just intimidated by the thought of all that loose wire hanging all over my ET II.
Bill Evans is calling,
Harry
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Hey Harry,
I was mixed up about which preamp you were using. Sorry.
I'm with you on the loom thing. My AQ interconnects with the DBS system are working just fine (it apparently keeps the dielectric in the cables constant), and the original litz wire from Bruce effects the arm balance not at all. There are trade offs in everything. I'm sure that a straight shot from cartridge to preamp with a loom would sound great, but I simply don't want to take everything apart and start over again.
-John |
You straight in loom guys are ganging up on me. Damn straight shooters .....8^0 Choices are clear to me. One can walk around the forest, or go through it. Harry - re: your mini farm comment. Farms, gardens, even "lawns" are a lot of work. Lawns around here are going to hell with the Pesticide ban. Controlling ones lawn has become a very difficult thing. Friends cross the border into the US at Niagara Falls to purchase (Killex) at big box stores; then smuggle it back. My neighbor’s "hobby" is his lawn. He goes out there and picks the weeds out one by one. and the original litz wire from Bruce effects the arm balance not at all. IMO, The best way to determine this John is with Gravity and physics. Forget the bubble levels. Move your arm to different spots on the platter. With air on - place the cartridge weight blue tac blob on the weights. Make it free float. If the spindle does not move it is balanced. Try it at the lead in, middle and run out grooves. I should put this much detail into my lawn. :^( |
Hey Chris,
I've always balanced my arm that way. Doesn't everyone? I don't use the damping trough, however. I'm also only using 7.5 psi on the arm, as that's the best two wisa pumps in parallel can do. Am I missing something here?
-John |
John
The owners I have talked with before this thread started used to use bubble levels. If one really wants to find out the wiring effect (push and / or pull)... set the arm up without the wiring. Then add the wiring in and find out the truth. This is how I do regular setup. If one were a wire loom swapper kind of audiophile - which I am not. It would take all of 10 minutes to swap out entire wire looms using the wiring layout I am using.
As far as PSI - people should be using the PSI designed for the manifold by Bruce. If someone picks up a used ET2 and this is unknown - we have discussed the process on how to determine the PSI. If anyone wants to rehash, then lets rehash. Higher PSI won’t harm things unless you go over 19 psi. We can discuss why this is too if someone wants. There is a reason Bruce designed my ET 2.5 for 19 PSI.
With that it bears repeating that if someone is using higher PSI and it sounds better, it is likely because;
1) air flow quality is better over the previous pump - not because of the higher PSI.
2) your manifold capillaries are partially clogged.
If using the original pump on a stock ET2 - the pump may be producing PSI but it is unlikely the diaphragm is in spec. Air flow quality suffers.
The ET2 is like an Olympic runner when it comes to good air flow. The better the flow, the better the operation, and therefore the sound. If we analyze how other air bearing tonearms work, it is really quite fascinating (to me), how different each design is.
Cheers Chris
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Regarding pumps and pressure:
a) Back in the 80's I found that the WISA 300 "high pressure" model (of which I bought several, directly from the company) was a single membrane pump, not a double one like the original HiBlow. My high pressure WISA model dropped in actual measured pressure level at the arm below the HiBlow, and had a high variation of pressure (mains frequency) - and the needle vibrated. This resulted in a "homeopathic 50Hz drone" that subjectively gave more, but a slihtly tubbier bass - this was *with* a ca. 7.5l tank.
b) I then chained two HiBlow pumps, ie. I hot-glued a piece of silicon tube to the inlet of one pump and to the outlet of the other pump. This resulted in (if I remember correctly) ca. 0.45 Bar (6.5 psi?). Three pumps were around 0.6 Bar, all this sounded very good, and was more silent than a WISA pump. The HiBlow has a surprisingly steady flow and it's limitation can be surmounted by chaining two or three. On the ET 2's "normal" low pressure bearing the two HiBlows were a remarkable improvement.
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^^ "This resulted in a homeopathic 50Hz drone"’8^0 If one wants to hear if their pump is introducing noise. Ensure your setup is good before attempting this. With the air pump ON and system on mute, lower the ET2 onto a "STILL" record. Now turn OFF the air pump, and unmute the system. Have your friend now turn ON the air pump, while you listen close to the speaker. Ensure your setup is good before attempting. |
This is indeed the way I tested this. Stylus in groove, platter stationary, pump running, phono gain turned up. In this test the HiBlow was audibly quieter than *my* WISA 300 high pressure. |
I use two wisa pumps working out of phase with each other in parallel, two large surge tanks in series with a small surge tank made from a plastic radio control gas tank, sitting a few feet from the ET-2. When I did the above test, it was complete silence with and without the pumps on. -Guess my pumps are different?
-John |
Hi John, no, your WISA pumps work the same. But connecting them parallel and out of phase makes them work the same way as a double diaphragm pump, like the original HiBlow: Single ended vs. push-pull... The air pressure is much more constant, "stabilized" pressure being about the same as the pressure peaks of a single WISA.
How high is the pressure? I assume it’s still not much higher than the original pump, and the worse noise/vibration is remaining. Besides I was not able to connect WISAs in series (nor will such a parallel combo), contrary to the HiBlow pumps with their air-sealed housing, which allows operating them above normal atmospheric pressure. |
I get about 7.5 psi out of that setup which is what Bruce told me to expect. The noise isn't a problem as the pumps are in the next room in a closet. If I deadhead the pumps' output, I get around 12 psi. -And my manifold is the high pressure version. It's a lot of hot air in my opinion.
-John |
It's a lot of hot air in my opinion. John - this reminds me of the ET2 guy in Texas on this thread a couple of years ago. He kept his pump in his unconditioned garage - temps would reach 120+ F. Guess what happened to that hot air when it finally reached his ET2 manifold in his listening space at an air conditioned 70 F. Wish he was still around. I would ask him to talk to those Oil Guys and tell them to turn the taps down. Just for a bit (pun intended), so I could get a little pop. "8^0 |
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Been in meetings with the Bears. No.... not the ones on Wall Street. The real ones. The ones that speak the truth. heh heh gyneguy225
PV=nRT as I remember. John I would never have taken you for a formula kind of guy ? Formulae (Formulas?) make my eyes do this * ^ ( So, If it was all about formulas; shouldn't the Perfect Sound have replaced vinyl long ago ? . . . . Blackfly....... Blackfly......please go away. |
-Just a remnant of my undergrad and HS years. -Not much else is left in this old cerebrum. |
Hello all,
Bruce's long I-beam with double spring arrived today. 6 inches long not including spring(s). Very nice improvement. I'm down to the single weight about 5" out. I noticed deeper and tighter bass which extends to lower mids giving a richer sound along with increased inner detail. Has anyone else tried this new beam?
Harry
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Chris,
Be happy with your black flies. Yellow jackets got me twice in the last two weeks. Hope you are having a great summer.
Harry
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Not to be disrespectful to ET owners (and I consider Bruce Thigpen the most interesting living h-fi designer), what are ya'lls opinion of the Trans-Fi Audio Terminator in comparison? Just curious. |
Hey Harry,
I'm glad you appreciate the tweak, and glad I could contribute something to this thread.
John |
Hi Harry got an email from Bruce that my I Beam is in the mail with some leaf springs. This is coming a little too early for me and is making me a little anxious as I am not home except for maybe 5 or so days, over the next 8 weeks. :^( Have always been amazed when pulling off the I Beam/weights; by the amount of HEFT, there is in the armtube/cart without the I Beam/weights attached . Very heavy. Pulling off the balancing act with just one single weight and an MC cart. Very impressive. Significant vertical inertia happening here. The best bass. For readers not aware the ET2 was built to go on many different types of turntables. The I Beam was made shorter to accommodate the different tables some of which came with dust covers. Bruce' new I Beam represents the Ideal length based on his testing. Look forward to trying it. Harry - last year I got multiple yellow jacket bites - won't say where - it hurts just thinking about it - when I tried to put some bolts into exposed holes in a steel roof only to disturb a nest. Felt like jumping at one point. *********************************** Hi Eric (Bdp24) what are ya'lls opinion of the Trans-Fi Audio Terminator in comparison? Just curious. IMO. There are more design and build differences between air bearing tonearms, than between pivot tonearms. This is because each air bearing tonearm is very unique in how the air bearing is executed, and its air requirements. Re; Transfi Bruce' tonearm uses a captured air bearing. The film of air inside the manifold fully surrounds, encloses the air bearing spindle. 360. My understanding is Transfi is designed more like a sled on snow, a boat on water, as it rides on a film of air and is not enclosed. A very different design. Someone correct me if I am wrong. |
John - yes, yes I was remiss in not giving you a nod for this wonderful tweak.
Chris - Wish I could come off as a pro and tell you balancing was a snap. Alas it was not. It took a good deal of time and patience to acquire a neutral balance for leveling before adding the weight.
Interesting you used the word "heft" in describing balancing. Heft is a good deal of what this upgrade added to my listening. The sound is fuller without any bloat or loss of detail. Indeed, detail was improved. Not the kind of detail that is clinical but the kind that lets you hear fingers on strings and spit in the reed. All in all very nice.
Let me know what you hear with the long plank when you get back home.
Re yellow jackets, I've been stung 3 or 4 times since retiring here to "deep rural" and had no problem except the pain. This time I had an anafalactic reaction and ended up at the emergency room. I am now carrying an epi pen. Ahh, the price we pay for shunning civilization.
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A few thoughts regarding longer i-beam and leverage:
- While the captive air-bearing has advantages in stiffness, the ET design with stationary bearing has only one point with centered forces within the bearing along the arm travel. This "allows" some maximal leverage at the beginning and end of the travel.
- Having a short i-beam compensated with more weight on the i-beam side increases (lateral) leverage.
Eliminating the leverage on the air bearing by using a moving air bearing has some advantages, but a drawback too:
Either one needs an additional flexible air-tube, which increases vibration coupling between arm and tt chassis, and also vibrations within the air feed.
Or one needs an open bearing with less bearing stiffness, like the (very good) Adanalog MG 1 arm, or the many Ladegaard variations incl. the Trans-fi arm. (see below)
- It is desirable to keep varying leverage at a minimum, a) on the air bearing as well as b) on a sprung subchassis. The latter will lead to varying lateral desiquilibrium, visible as increased "slipping" from a balanced middle position to outwards gliding at the start and end positions of arm travel.
- So a longer i-beam reduces the leverage on the bearing, and on sprung subchassis. It improves balance of the center of gravity along the bearing travel. And it increases vertical mass, which often improves the sound too.
- Regarding "optimal" vertical resonance I did put up the idea, that (maybe) there is not much useful out of phase bass information below 100Hz - this might not be the case... as increasing the (out of phase) bass bandwith below eg. 15Hz, by lowering vertical resonance seemingly still is audible.
- However, there is an end to that, probably below 10Hz because of subsonic vertical garbage information with a maxiumum around 5Hz. This contrary to lateral resonance where the main problem frequency (correctable) is not higher than 0.75Hz.
- Trans-fi arm:
I trust several keen and independent ears, that this is a superb design, technically by design and subjectively by constant tweaking and improvimg.
- the stability/stiffness of it's "open" bearing is still very good by it's v-shape which forces centering of the air bearing by help of gravity.
- the vertical knife edge bearing is a very good and elegant design with no bearing chatter, and with selfcentering by gravity too.
- "optimal geometric design practice" followed by ET keeps the vertical bearing axis on the same height as the tracing / platter level, This reduces FM wow induced by vinyl warp,
- However, this is not without a price: Lifting this tracing level has it's advantages too, leading to improved bass: Trans-fi and RS labs ar examples. This is, because putting the vertical axis in line with the cartridge cantilever ((ca. 20-30 vertical degrees)) eliminates vertical pull on the cantilever bearing, reducing vertical resonance of the arm activated by dynamic friction changes by tracking vinyl, and by variable friction...
No free lunch therefore for ET... and the above mechanism is rarely looked at.
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@pegasus
As always your posts are insightful.
re the vertical bearing axis, as set up on the ET. Do you see any reason why this could not be lifted to 20-30 degrees? (Warp issues aside.)
This assuming there is enough travel in the vertical slide. I guess that the platter would need to be very low relative to the armboard.
Have you tried this?
Results?
cheers
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@pegasus
What I didn't say, racing to catch a plane.
Would need to mount the goose neck upside down and likely drill and tap a new wand clamp thread in the adapter on the other side.
My guess is that this would sort the VTA adjustment.
cheers
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Richard did you not like my sled and boat analogies ? Pegasus
Or one needs an open bearing with less bearing stiffness, like the (very good) Adanalog MG 1 arm, or the many Ladegaard variations incl. the Trans-fi arm. I tell you snowmobile and boat racing on a slalom type course can be alot of fun .... the sliding and drifting around on turns is very addictive. 8^0 |
@Chris
In my younger days, I did a lot of slalom waterskiing. The sensation is indeed addictive!
And your analogy fits the Trans Fi well.
I have a revised ET tower on the drawing board. It will probably be made out of Zinc and correct some of the minor issues I found with my last version.
Will keep you posted.
Itchy design fingers.
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Hi Harry
Still has not arrived. a border customs thing ?
I have used a combination of different length I Beam bolt, the one the threaded hollow piece screws into that holds the weights, and different size cart bolts, to help get to the end of the I beam in the past.
Richard
I won't water ski for fear of throwing out, or twinging one of my knees. I consider my daily run as far as my health (physical and mind) goes - No. 1. Listening to music is a solid second.
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Hi Chris,
Did customs figure out your $15.00 piece of plastic is not a danger to society yet?
Been reviewing prior posts and ran across those dealing with magnetic damping for the ET. I'd like to try it but, dunce that I am, I can't figure out where the platform to the left of the manifold where you put your magnet is located.
Harry
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Harry,
You place the magnet under the bearing spindle, right next to the manifold. You want the magnet close to and parallel to the arm tube ( if you are using say a cupboard door magnet ). If you place it on the side opposite to the cartridge end then it won't affect the cartridge signal at the end of play.
Cheers
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Chris,
Got it. I'll be off to Lowe's for a cabinet magnet. I'm really enjoying Bruce's long plank.
Harry
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Harry the previous post was from Dover. I do not use magnets on my 2.5. FYI and FWIW Some years ago, Bruce was intrigued about our experiments when I asked him about this. So much so that he did try it himself. Feb 2013
Chris,
I tried this with neodymium magnets and the resistive force is extremely low, almost nothing, the velocity of the spindle would need to be much higher to induce back emf. It is a neat concept and I would like for this to work because it is very simple and easy to implement, but the measured force applied to the spindle is so low that nothing happens to the frequency response of the cartridge at resonance. I hope this helps.
brucet
When I asked him about how it was possible that people were hearing differences ......audiophiles believe quite a bit that is unexplainable from a science point of view, so yes it can be so.
brucet
IMO - This topic goes "Into the Dark" category as far as Audiophilia is concerned. You will find supporters on each side. Now the magnetic damping happening with my turntable is indeed real. Two large magnets bottom one stationary, top one moving fast enough to produce by design - a braking effect - to deal with the records behavior. See the gold rings in picture number 5 of my virtual system. Should be back home mid week will check the mail. |
Chris/Harry Interesting Bruces comments. What was not imagined from using magnets for eddy current damping in my system was increased volume, I had to turn the volume down. I used cupboard door magnets - 2 in parallel underneath. Bear in mind the eddy currents are only induced when the arm moves - i.e. it only comes into effect with eccentric records. If the record is not eccentric then there would be no difference. Dynavector uses the same principle with their biaxial arms http://www.dynavector.com/products/tonearm/e_507mk2.html |
Bruce's long I Beam update (yes, Chris, the plank :)
Went by my mechanic this morning and picked up a couple of wheel weights. I was able to fashion one to fit in the slot where the first weight goes. I am now out to about 1/8 - 1/4 inch from the end of the plank and the music keeps getting better and better. My Delos now has a mid range bloom and richness I did not previously think was possible from a Lyra.
Lyras have that wonderful upper extension that we detail nuts crave. However, I have often thought that my Delos (and previously my Clavis) had a slight gap between the midrange and the upper frequencies. This seemed to contribute to a lack of bloom in the midrange. Just not so rich in the middle like, say, a Koetsu.. This has all changed with less weight further out. Still not a Koetsu in the mids but a Koetsu can't retrieve the detail my Delos does. (Oops, I don't want to start a cartridge war).
The second thing I noticed was a slight taming of horns and certain voices. No detail lost but just a little smoother. For example, I love the three standard albums Linda Ronstadt did with Nelson Riddle. Linda's voice has a slight edge on it that I some times found a little fatiguing. With the long plank that edge is tamed. Once again, no loss of extension just a little smoother.
This is arm is truly amazing. It seems there is no limit to the improvements one can accomplish with a little effort and great input from the audiophiles on this forum.
Cheers,
Harry
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Another long I-Beam update:
If you missed my earlier post Bruce's new long plank is a little too thin for the weight clamp. It won't clamp down tightly. Bruce just updated me to say he is working on a second run that will correct this problem. Should be available in a couple weeks.
In the interim, if you already received the long plank there is an easy work around. Just reverse the clamping screw so it can be applied directly to the plank like a set screw.
Harry
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Give me a place to stand and with a lever I will move the whole world.
Archimedes
These are the thoughts that come to me with this sample I Beam that arrived by Australian Camel. The physics involved with playing vinyl and having it outdo the Studer (on some tapes) and my Digital just fascinates me. Significant leverage happening here. I am balanced with only the one molded weight on there. An inch from the end. I had to remove my larger horizontal bolt and go back to the original smaller one, along with the threaded weight holder. They are no longer needed with just the one molded weight on there. Just too much weight. The package of weights Bruce provides with the tonearm is now serious over kill. This is with my freedom fighter cartridge. I suspect my lone weight will go all the way out with the XV1 and maybe one skinny weight - maybe not. Initial impressions from a quick session. Nothing negative and all perceived positives. I am being punched in the stomach with the bass; like sitting 12 feet from the stage and Bdp24 (Eric) is playing his drums like he just got some really great news. 8^) The I beam is now the same length as the armtube; to me, it just looks right, balanced, the way it was meant to be. As Harry mentioned these first samples will be improved. I got word from Bruce that he was making updates to the printer. |
It's funny how that little styrene I-beam I bought at the hobby shop 10 years ago works pretty well. I tried using less weight on the I-beam further out, but when I moved the arm in or out, the I-beam waved back and forth like a dog wagging its tail! I can't place the weight out the same length as the arm wand for sure.
Am I missing something?
-John |
John,
While my longer beam with weight almost at end does seem to flex a little more than the shorter one, it is not excessive on my rig. Two thoughts. Are you using a double or triple spring on your beam? If not, that may solve the problem. Secondly, perhaps your hobby shop beam is just more flexible than Bruce's.
Chris,
Interesting observations. My first setup with new plank was the same as yours. With only the molded weight I could only get out to an inch from the end. With only my diy smaller weight I got out to within 1/4 inch from the end with further improvement.
Harry
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Am I missing something?
What Harry said. +1 You are not using Bruce’ Long I Beam designed for the tonearm. Getting one would allow us to do an apples to apples comparison. Remember, I did try to get a hobby shop I Beam. The ones I found were not fit - too flexible, cheap, mass produced. Bruce’ long I Beam is 3d printed. V2 should be ready in a few weeks. Also If your end cap is the original one, take it apart, and make sure it is still fit to take the extra stress the longer beam brings. imo - This is a cheap upgrade that affects the heart of the arms performance. The I Beam/weights. The most misunderstood aspect of this tonearm’s setup. Bruce has built the Long I Beam for the ideal length based on his testing. All ET2 owners should be contacting Bruce and getting one. |
thoughts on two or three open questions & i-beam
@richardkrebs:
- I'm looking forward seeing pictures of your bearing tower!
- I did not yet try the elevated bearing position with the original ET bearing tower, as there will be drawbacks stiffness-wise because of the (practical but) rel. narrow tripod feet of the design.
- I think a 20 degree angled piece of good wood (with a slit / hole for the cartridge nuts) would do the major part of adaptation.
- arm lift adaptation could be tricky.
- magnetic damping: "My" magnets are kitchen magnets. They are round and have a simple collar-shaped pole piece which focusses and intensifies the flux around it. This will make a considerable difference in efficiency regarding damping compared to a normal "open" magnetic structure.
The magnets need to be placed really close, not more than 1mm on the closest place. The flat magnet shape vs round bearing tube is obviously not ideal. My feeling is that it kind of cuts the peak of the resonance. It sounds and feels a step more stable - i don't like the sound of too much damping anyway.
It's difficult to extrapolate Bruces experiences & comment to different implementations without exact descriptions.
- i-beam: I checked the rotation pendulum formulas to be correct about this: If one doubles the length of the i-beam one halfs the needed weight, because of double the leverage. But the inertia grows with a square factor: 0.5 of the mass x 2^2.This results in double the inertia and 0.7 of the resonance frequency.
The whole double mass double spring system of the ET is very ingenious but also quite complex. It is a 4th order resonant system instead of the usual 2nd order one. With one short attempt :-) i did not yet successfully find the correct CLCL model for simulation.In the most simple view there is an i-beam resonance and a bearing tube/cartridge resonance, with a zone where the i-beams spring and the cartridges compliance work in series (the i-beam springs damping can control the cartridge/bearing resonance, if the i-beam resonance is well chosen... ;-).Problem is seeing / knowing what each one does. Simulation? Empirism?... :-)
My techno-intuitive thought on this is:
- The lower the resonance of the i-beam, the wider the frequency range over which the bearing/cartridge resonance can be controlled by it.
- the higher the resonance, the closer together both resonances and the more resonant interaction instead of control.
Does Bruce have the model? Or should I ask my more MATLAB-experienced son?
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Chris,
When you get a chance, I sent an off topic question to you by pm a few days ago.
Harry
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@pegasus.
The bearing tower/manifold is in the concept phase at present.
Some features are almost locked in.....
> The air feed into the manifold will be like a flattened funnel to slow the airs velocity before it gets to the bearing sleeve. The original jet of air has to cause turbulence where it first contacts the sleeve. This funnel will probably be lightly packed with wool. The manifold will be undercut to allow for a multi wrap of filter paper around the sleeve to further smooth/ equalise air delivery to the capillaries. The manifold will also have, as per my current version, the cap screw and shim metal locking arrangement between the manifold and sleeve to lock the two o'rings.
> The manifold and tower will be a male/female VEE slider arrangement with a single capscrew locking them in place. This will ensure that the manifold stays exactly horizontal at all VTA positions. It also gives a very solid join between the two parts. A vertical capscrew between the two providing for VTA adjustment. The slider will be straight.
> The tower will have one fixed, parent material, foot and two PVC adjustable feet. The PVC feet provide for alignment of the tower to the platter surface. The single, parent material, foot provides a "virtual" single point of contact with the arm board.
> Parent material will be either zinc or aluminium and will have machined galleries containing damping material.
This is a long term project. I will keep you posted.
Re radically raising the arm to 20 degrees. I get the stiffness issue. Would the wedge idea work as desired? Do we not want the vertical pivot point to be in line with the cantilever. Maybe I missed something in your initial or your latest discussion on the topic.
cheers.
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Thanks for the captivating infos!
- Although I agree on the idea of eliminating turbulence - isn't damping it not also introducing an additional flow resistance which will upset the "balance" of implicite air flow resistances from air feed via calibrated air beaing openings to bearings air film? Personally I'd be very (self-) critical when changing this, I like to be double on the safe side about changing such crucial areas (at least with my limited understanding of air bearings).
In fact I'd contact Bruce about his thoughts regarding keeping the correct pressure on the distributed points/air openings when introducing additional flow resistance.
- raising the arm bearing: I meant lifting the back of the arm, and correcting with a 20 degree wood wedge between arm and cartridge (the wedge pointing to the front of the arm),
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Pegasus
My techno-intuitive thought on this is:
- The lower the resonance of the i-beam, the wider the frequency range over which the bearing/cartridge resonance can be controlled by it.
- the higher the resonance, the closer together both resonances and the more resonant interaction instead of control.
Does Bruce have the model? Or should I ask my more MATLAB-experienced son? Pegasus The model for the original I Beam was in part influenced by business priorities. We know this. This limitation is no longer there. Why don't you send your theory and questions to Bruce direct and let us know what he says ? brucet (at) eminent-tech (dot) com I am interested in your, John and others impressions of Bruce' Long I Beam. Harry and I seem to be in sync. Also, still am interested in seeing pictures of your dual path wiring setup. Cheers Chris |
