Thanks for the offer. I will work on the arm for a while and let you know. I still have only 2 or 3 hours on it! Home life has been a bit buzy.
Tim
Tim
Eminent Technology ET-2 Tonearm Owners
Where are you? What mods have you done ?
I have been using these ET2's for over 9 years now.
I am still figuring them out and learning from them. They can be modified in so many ways. Bruce Thigpen laid down the GENIUS behind this tonearm over 20 years ago. Some of you have owned them for over 20 years !
Tell us your secrets.
New owners – what questions do you have ?
We may even be able to coax Bruce to post here. :^)
There are so many modifications that can be done.
Dressing of the wire with this arm is critical to get optimum sonics along with proper counterweight setup.
Let me start it off.
Please tell us what you have found to be the best wire for the ET-2 tonearm ? One that is pliable/doesn’t crink or curl. Whats the best way of dressing it so it doesn’t impact the arm. Through the spindle - Over the manifold - Below manifold ? What have you come up with ?
2,371 responses Add your response
Hi Tim - thanks for the impressions. I look forward to learning from your experiences. Are you familiar with our celebrity Acutex 420 str cartridge? http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1325551242&openflup&316&4#316 It has been waiting in the wings with me for some time now. I had thought the next recipient would on the other side of the world - downunder - but I have not heard back yet ? I am aware of four separate ET2, ET2.5 projects right now. All in North America. Three in the US and one in Canada. If I had to put money on it - it appears the cartridge will be crossing the border again. Once you are established in your setup let us know if you would like to listen to this cartridge and provide a short review for us here. The only requirement is you ship it back within 3 months so it can go to the next person. This offer is open to any ET2 user. Cheers |
Dover - in the winter the OTL's are enough to keep my room at the temp it started at - heating vents closed. The last couple summer months with the door/windows closed in my basement room the temp will go up 1 degree every hour. The OTL's are like two 50 inch plasma tv's as far as heat out put goes. With the door or window open this drops by half - 1 degree every two hours. |
Ct0517.. Increasing the room temperature by 5 degrees F ( 3 C ) is enough to soften the rubber suspension in the cartridge and drop the VTA by 1 degree. I would assume by the time you have finished a session you will have softened up the suspension and this may explain some of what you hear. Where you live it is quite easy to experiment - start with a cold room and warm it up, or put a lamp over the cartridge so the heat is localised. You will hear quite a difference - as the cartridge reaches optimum temperature the sound opens up and becomes more natural, as you overheat the cartridge the sound will literally go gluggy. What I have experienced is some cartridges mistrack on a seasonal basis (winter vs summer) here in NZ even though the temperature swings are not large, eg the Shelters. The Benz's generally spec out the optimum temperature and humidity ranges in their cartridge packaging. |
Dover The "included angle" has nothing to do with VTA Cutterhead angles are a minefield as they varied historically over the years and different cutting lathes were set up with different cutting angles. There was a standardisation of sorts in the 60's but bear in mind the US settled on 15 degrees +-5 degrees and the Europeans settled on 20 degrees +-5 degrees. first statement is true on its own. but in the data that you provided especially the last sentence - "engineers would alter the cutting angle to get a clean cut due to the changing properties of the lacquers at different temperatures" With the ET2 VTA system angle changes can be corrected without affecting VTF and alignment - see previous post. this is also documented in the manual. This is what I was referring to. Dover when you say Increasing the room temperature by 5 degrees F or approx 3 degrees C will lower the tracking angle by approx 1 degree. Lets say we have a situation where the room is left alone to go up in temperature. So the sound will become more warm and full bodied - less treble brightness - as you have lowered the tracking angle ? Is this because of warmer plastic (record) ? Can this explain why the music can sweeter (warmer) toward the end of a session? |
Frogman - I think the arm simply sounds better with moderate and similar torque at all the screws. I adjust the VTA adjustment screws so that the adjustment can still be made without loosening the screws; but with some effort Based on the years with mine I think this is really good advice Frogman. Frogman - VTA adjustment on the fly is, for me, THE most important feature of the ET2. I find it invaluable and use it all the time. I agree plus the fact it tracks in a straightline. In the early days I was trying to figure the arm out and did not even notice how Bruce designed the VTA system in the ET2. I was ignorant to it. How many ET2 owners are not aware (or take it for granted, not notice) that the VTA system is on a gearing system? The ET2 VTA cylinder mechanism (for lack of a better word) pulls the armtube in as you raise VTA and back out when you lower VTA. So it maintains the VTF and alignment. I just tried this again with my Dynavector tonearm the other day. Lowering VTA increases VTF. Raising VTA lowers VTF. Some are really anal about how they set VTF on their tonearms. Just be aware you are affecting your VTF. |
09-16-13: Ct0517 1. The "included angle" has nothing to do with VTA. The included angle of 90 degrees is the angle between the 2 45 degree walls of the groove. ( 45+45=90 ). In theory if the cutterhead is set up with an error of say 5 degree in the "included angle" then you would possibly need to adjust azimuth. 2. One of the fundamental problems is that the cutter moves in a fixed plane, whereas the stylus moves in an arc about the cantilever pivot, and therefore all cartridges with a conventional cantilever produce distortion. The notable exceptions are the Decca London Cartridges and the original Ikeda cartridges both of which do not have cantilevers and therefore these are the only cartridges that do not have this distortion built in. I own the Ikeda and have personally set up around 20 Decca's over the years. The speed, lower distortion and lack of phase and time smear with these cartridges is superior to anything else for the reasons outlined in the 1st sentence of this paragraph. 3. Cutterhead angles are a minefield as they varied historically over the years and different cutting lathes were set up with different cutting angles. There was a standardisation of sorts in the 60's but bear in mind the US settled on 15 degrees +-5 degrees and the Europeans settled on 20 degrees +-5 degrees. The actual cutting angle used would also depend on how the engineer sets the equipment up and that is unpredictable. Springback is a common problem when cutting and this will alter depending on the composition and quality of the lacquers used ( they are soft ). Temperature is a big factor and if the lacquers have been stored at room temperature, as opposed to the recommended cool room temperatures, then often engineers would alter the cutting angle to get a clean cut due to the changing properties of the lacquers at different temperatures. A few points to note : Increasing the room temperature by 5 degrees F or approx 3 degrees C will lower the tracking angle by approx 1 degree. Increasing the tracking weight by 0.1g will result in a lowering of the tracking angle by approx 1.5 degree A spherical stylus profile will help to reduce these distortions in points 2 & 3 above. If you add lead mass to the ET2 and remove the decoupled counterweight, as suggested earlier in this thread, then VTA doesn't matter as the increased distortion from a tracking angle error of +-5 degrees is almost certainly significantly less than the distortions introduced by the addition of lead mass and removal of the decoupled counterweight. For ET2 aficionados, with a conventional cartridge that uses a cantilever, the combination of tangential tracking and a spherical stylus would minimise distortions due to VTA issues. I have run the Denon 103 which although not the ultimate in transparency, produced very good timing and coherence. The EMT TSD15 with spherical tip option would be an interesting cartridge to try. |
Great topic! VTA adjustment on the fly is, for me, THE most important feature of the ET2. I find it invaluable and use it all the time. The benefits for me have to do with fine tuning tonality, timbre, and the integration of the uppermost frequencies with the lower highs (sibilance, among other things) and the transition-range between the midrange and upper bass. I have not found (maybe simply don't care as much) dramatic changes in soundstaging due to different VTA settings as some have reported. Azimuth adjustment (also relatively easy with the ET) does make significant changes to soundstaging in my set-up. Re the locking down of the screws that tighten the VTA feature: I feel that too much torque at ANY of the ET2's screws is a bad thing. I think the arm simply sounds better with moderate and similar torque at all the screws. I adjust the VTA adjustment screws so that the adjustment can still be made without loosening the screws; but with some effort. So, to make sure I am not stripping anything, I simply loosen the screws about a 1/4 (or less) turn, adjust, and re-tighten; just a couple of extra seconds for the procedure. |
Random Included Record Angles When they Make Records You play a couple of records from your collection that are the same thickness. They sound different for some reason ? One might be brighter, the other a little warmer and full ? This was not something I took much notice of many years ago with a very basic TT and tonearm. But as the TT and tonearm got better it became more noticeable. We hear about how engineers in creating the master disc put their spin on how the records will sound. But how about the physics part of it. In addition to the final engineering differences record masters are cut with random included angles by the cutter. The angle of the cut when the record master is made. http://www.aardvarkmastering.com/riaa.htm from the site Recording Groove Contour Notice the record included cut angle standard that was set can be 90 degrees give or take 5 degrees....:^( So there is no standard. This is also captured in the ET2 manual and has been mentioned before. Bruce realized the importance of this and the reason he built into his arm VTA on the Fly that does not change parameters when used. Vertical Tracking Angle Adjustment (VTA) - Page 51 ET2 Pt. 2 manual "Several articles have appeared which address the area of cartridge performance. Vertical Tracking Angle (VTA) and Stylus Rake Angle (SRA). We have designed the Model 2 tonearm to optimize the vertical tracking angle of the cartridge. Maybe those that use scopes should be pointing the camera - down - to the groove to try to figure out what angle has been used ? Some ET2 owners I have talked to have locked down (tightened the screws controlling the VTA feature) to make it more rigid? fwiw - I have sent an email to a couple record pressing plants as I am curious what determines what angle they cut at. Is it based on temperature, record thickness, condition of stylus cutter ? Will post back what they say ...if they respond. How important is the VTA adjustment to you ? |
Hi Tim Congrats on the ET2. Please let us know how you make out. A number of folks here with many years experience with the ET2 & ET2.5 to help out if any questions. There are also measurements on page 63 of the online manual on Bruce' website. from looking at the online diagram for the mounting hole. 1) From the middle of the spindle go out 8.258 inches (209.753) millimeters anywhere on the plinth that works for you and mark the spot. 2) Draw a straight line from the middle of spindle to this marked spot. 3) Go up 90 degrees from this line .885 inches (22.479 millimeters) Mark the spot - that's where the mounting hole goes. Welcome to the thread. Cheers Chris |
RK - but it is very noisy and does not pass your stylus on a stationary record test. ...the old dreaded stylus on a stationary record test with the system volume knob cranked to hear turbulence and hum test..... Air Bearing linear trackers everywhere that depend on clean consistent air delivery cringe at the thought of owners subjecting them to this test. Its bad enough if they have not been set up to operate in a straight line evenly. But being subjected to a partner pump that is not so great is un-imaginable. Some of the worst arm/pump relationships I have heard of don't even relate to the quality of the pump itself but its placement. There are some owners in the southern US where winter does not exist. These owners place compressors in their garage (not climate controlled) with a long line going to where their stereo is in a nice climate controlled room kept at 72 degrees F. The garage where the compressors starts air delivery can be anywhere from 30-40 F in the winter at night to well over 150 degrees inside the closed barn on a hot summer day with wildly differing humidity. Imagine the changes to the air as it travels down 100 feet of tubing. RK - I will do the compliant CW arm and spring test once the proper compressor arrives. I look forward to your impressions Richard. |
Dgarretson - If not carefully dressed between the gantry and the wand, the tonearm wires have the greater potential to do harm by fouling the wand's free movement. DG - I will make sure the petition of names to the cartridge makers for a wireless cartridge makes it to your house too :^) Thanks for the info |
Chris Am I up and running? Yes and no. I have a loaner compressor, so I have music but it is very noisy and does not pass your stylus on a stationary record test. I will do the compliant CW arm and spring test once the proper compressor arrives. I have been thinking about making a longer fixed counterweight rod. The current one is around the same length as original. The issue is making it stiff enough, not easy with conventional materials. |
ct0517 wrote: " Does the wiring on the Terminator play a role in damping (stabilizing) the stylus?" It may do so, but not by design. If not carefully dressed between the gantry and the wand, the tonearm wires have the greater potential to do harm by fouling the wand's free movement. The torque effect is exacerbated with a five-wire balanced harness. To minimize torqueing, one of these days soon I'm going to try making a harness with very light-gauge AN silver wire. |
Thigpens' recommendations are that with records with an eccentricity of 1/8" a low mass pivoted arm will be superior. Dover this has been mentioned many times here and is documented in the ET2 manual. What I am curious about however is that at the time of printing of the original ET2 manual MM’s were in their heyday. MC’s became more popular later and BT adjusted with the 2.5. I am wondering if he was printing an update to his manual, if a heavier mass pivot over a lower mass one would be recommended for MC specifically. Any opinion ? Fwiw From my record collection there are idk maybe 150 -200 put aside – they can be seen on the ground in the pic of my listening room. These I listen to on a regular basis. From this group there is only one record I am aware of that falls in that range of 1/8 inch. This record happens to be one of my wife’s favorites and I use it to ....entice her into the room :^) My solution to this oddball record was to drill out the hole and spend 30 seconds centering it with my DIY center weight seen here. http://cgim.audiogon.com/i/vs/i/f/1366423048.jpg The pressure points are on the outside and there is a washer underneath. Actually various size washers can be used as needed. Mostly however my records are in good shape warp and off center hole wise (meaning not visually noticeable). Cheers |
RichardkrebsActually it is the tracking angle that propels the arm inwards, which is different from offset angle. The skating forces are proportional to the tracking angle and tracking force. With higher tracking forces the skating force reduces. It also reduces with longer arms due to the reduced tracking angle. If you are tracking from about 2.5g with a 12" arm the skating force becomes very small, and if the tonearm is designed with breakdown torque taken into account at this point it is possible to run a pivoted arm without anti skate. Stylus profile also impacts the skating force. Ladegaards theory ignores these causal factors and assumes no anti skate is applied, therefore it is a worst case scenario and improbable in reality.. Conversely on eccentric records the high horizontal mass of a linear tracking arm will create tracking distortion. Very few records are truly round, and increasing the mass with lead on a linear tracker will increase the inertia of the arm in the horizontal plane and increase distortion on eccentric records due to cantilever flex. Thigpens' recommendations are that with records with an eccentricity of 1/8" a low mass pivoted arm will be superior. Dgarretson - your listening experience that lower mass is giving superior results with the Terminator mirrors most ( actually all except for one ) of the users of the ET2 on this thread that have attained optimum sound quality from the correct application and tuning of the low mass/decoupled counterweight design parameters that the ET2 is based upon. |
Dgarretson. I look forward to your tests on stiffer carts. Also re pivoted arms, I argued inelegantly a way back that the offset angle on a pivoted arm has a multiplying effect on the effective mass as seen by the cartridge. That is, the cartridge is not expending all its effort in trying to rotate are arm but a vector of this force due to the offset angle. Then of course we have to take into account the asymmetrical nature of anti skate. This could be what Mark or Poul are referring to? With these parameters at least, chalk up a big advantage to a linear arm. |
Hello Ct0517 & Dover, of course no offense taken. The discussions about the significance of variations in horizontal mass have been of interest here and in several AA and DIY forum threads. I have yet to try a really low-compliance cartridge on Trans-Fi-- which may change my current opinion that "less is more" w/r to horizontal mass. I've experienced this with a large number-high compliance MM/MI cartridges and a small samples of medium-compliance MCs. I'd have to dig for the URL, but I recall that either Mark Kelly or Poul Ladergaard calculated the lateral stylus force applied by a linear tonearm as compared to force attributable to overhang and off-set in a conventional pivot arm. If as modeled, the lateral forces of a pivot arm(to which we must also add the tonearm's effective mass) are significantly greater than that of a 100gm linear arm, then this may suggest that a linear arm(whether 35gm or 100gm) cannot be faulted for its large lateral mass. Perhaps this is what F. Kuzma meant when he said that 100gm is "no big deal." In any case, I was not suggesting the relative superiority of any of the three very different linear arms under consideration. |
Dover Point taken - for some reason these comments from DG 08-18-13: Represented results and reference points to me and assumptions got made. This triggered a need in me to summarize some of the discussions that have been held here on this thread between the two tonearms. This is an unfortunate habit (summarizing) from my work career and the comments were not related to DG’s comments. imo - it is not valid comparing the ET2, 2.5 and Kuzma Airline in this manner bad wording on my part. I certainly hope DG took no offence. I blame the summer heat. Thanks for letting me ramble on and get off with only a warning – this time. |
08-21-13: Ct0517Dgarretson is not comparing the ET2 & Kuzma. His post is quite clear - it is a report on the effect of running the Terminator with different horizontal effective masses. At no point in his post is he comparing the ET2 and Kuzma tonearms. |
08-19-13: Dover Interesting comments from DG as they relate to the Terminator arm. I have only seen pictures of it. imo - it is not valid comparing the ET2, 2.5 and Kuzma Airline in this manner because although the later Kuzma resembles the ET2 in appearance their design objectives are as different as apples and oranges. This has been discussed here. Some facts The Kuzma Airline requires the wires and air tube for damping of the cantilever. Through private Kuzma owner emails I have learned the Kuzma has difficulty with lower VTF and higher compliant cartridges. Requires a heavier cartridge with a stiff cantilever. Any Airline owners disagree with this comment? I don't own it and the reason I ask. The ET2 (2.5) in contrast can play a light high compliant (how about a sonus blue gold at .2gm) or an Acutex 4 series then turn around and play a stiff cantilever on a heavy MC. The ET2, 2.5 requires neither the tubing or wiring for damping and tracks best with no wiring. I know this because I use it this way (no wiring) now to level it and have had it track the record this way - once. I say once because I haven't figured out how to get any sound when I run it this way. again I ask - how do we make it wireless ? Johnathan Carr, Peter Ledermann or another cartridge designer if you see this - this thread is at over 150,000 views. Does anyone have any plans for a wireless cartridge ? I will buy your beta cartridge even if it means putting in some kind of computer chip in my preamp. C'mon Nobody likes wires anyway. They just get in the way. Unless you can set the wires up like Frogman. http://cgim.audiogon.com/i/vs/i/f/1366422461.jpg Then we can call it Art. I have no problem with that. Remember when phones needed wires. My kids don't - they laugh when I tell them. The ET2 also has VTA on the fly that doesn't change parameters like VTF. Set your Airline at the highest and lowest setting and you'll notice your VTF has been altered. This is an owner confirmed comment. Does "any" other arm exist that does vta on the fly? Same thickness records have included cut angles that are random from the different record plants. How do you guys deal with this? The ET2 can also be tuned for different compliance cartridges MC and MM. Cheers |
Interesting comments on the Terminator linear tracking arm from Dgarretson on the MM thread who has fabricated a lightweight carriage from carbon finer instead of aluminium.... 08-16-13Just another reminder that the best place for adding lead mass is on the end of a fishing line. It has no place on the ET. |
Frogman - I may just do that; would be the only fair comparison of the two arms That is a review of impressions I would be willing to cough up some coin to read. something a little different - I came across this. The man behind this thread. Scroll down to the bottom for a picture of Bruce. His rotary woofer is the only loudspeaker in the world that can reproduce the sound of Niagara Falls accurately. Falls Fury Rotary woofer |
I may just do that; would be the only fair comparison of the two arms. Interesting comments re thrust bearings; makes complete sense. Re thread drive: I have no doubt its the way to go; just one of the many unfinished projects and will definitely try it. BTW, spending most of the summer at our upstate place while I play at a couple of summer music festivals and finally had a chance to get the system up here up and running. Vintage Luxman DD has been showing the advantages of DD's pitch stability. But, boy do I miss the tonal qualities of my TNT/ET setup. Also, speed stability yes, but also a strange lack of rhythmic impetus; almost as if the music doesn't move forward the way it should. More tweaking is in order. Regards. |
Hi Frogman the Forsell is still packed in it's boxes. I hope to be able do a shootout between it and my TNT6/ET2 before too long; will keep you posted. Exciting shootout ahead. Brings back memories for me. Please let us know how it goes. Actually Frogman with your knowledge of the ET2; I selfishly would like for you (if you don’t mind :^) - to drill a very small hole (no big deal) in the Forsell and mount your ET2 on it if possible. Compare your ET2 to the Forsell tonearm - on its own home turf. Sort of like vinyls version of “mano a mano” ? My ET2.5 reached new sonic levels with me once it went onto a table that does not require the thrust bearing. Bearing resonance is real and they (bearings) impart their sound on tables I have owned. Anyone that has tried different bearings and lubricants with their tables know this. Thicker lubricants slow and dull the the music; thinner oil makes it leaner but it loses texture. My JN Lenco bearing is self lubricating. So I was aware of the bearings impact on the sound; but it did not hit home to me until I used a table that had no bearing. I am willing to bet 100 Canadian Loonies that the Forsell will forse (sic) you to convert the TNT to thread. :^) Cheers |
Been away for a while, hope everyone is well. Chris, the Forsell is still packed in it's boxes. I hope to be able do a shootout between it and my TNT6/ET2 before too long; will keep you posted. Re your most recent post: just wanted to remind all about the importance of not overtightening the bolt that secures the elbow to the bearing tube (any and all bolts, for that matter). Doing so will certainly misshape the bearing tube and affect tracking the inside of a record. |
I hope no ones counterweight cap looks like the one in this link? This is a easy replacement for a new one - $50 or so. http://www.ebay.ca/itm/Air-Bearing-Tonearm-Eminent-Technology-Model-two-/330963316997?ssPageName=ADME:B:SS:CA:1123 Not affiliated with this ad. |
what you heard was meaningless, unless the system was described at the time of testing John - I list out my gear as well as pictures of the room. I am very interested in seeing what some of the rooms look like downunder. I don’t even need to see the gear. Rooms and speaker (type) placement tell a good story that I find fascinating. re: science and concrete evidence. fact - there is no perfect room. fact - no one has perfect ears. fact - this means if all our gear was the same our speaker placement would all differ - the room rules. its the elephant in the room. cheers |
Chris: further to your comments on changing to the magnesium wand. According to Dover, what you heard was meaningless, unless the system was described at the time of testing - it could have been due to colorations elsewhere in the system. Additionally, without science and concrete evidence, its useless 'just' describing what you heard. |
Imo – the only thing an amateur (hobbyist / audiophile / music lover) can do is to keep to the golden rule. Change only one variable at a time. As an amateur I only need to please myself. I am selfishly in this hobby for me only. I am also my own worst enemy. I know this. I have known amateur audio friends in the past - who seemed to want to please their friends more. Now - if I wanted to analyze what I did and tried to put some science at it. Going back to the post about materials ability to pass sound/resonances. Higher number being easier to pass – lower meaning it hinders. I went from a Carbon Fibre wrap aluminum armwand with a Teflon insert. carbon fibre......30, all plastics......1-4, aluminium.........17 to a heavier Magnesium armwand. magnesium.........10 everything else stayed the same. |
Chris. Yes the glass arm was special. I used magnesium from a broken aeroplane wheel hub to mill the headshell. Slotted mounting holes to facilitate correct cartridge alignment. I have one of the slate TT's somewhere in storage in the attic. Will see if I can find it amongst the detritus of time, maybe post some pics. |
Dover, you wrote regarding Richardkrebs (and Chris/Ct0517 when he changed to his magnesium arm wand, as they used the same methodology) .... "I see very little science and no concrete evidence to support your observations." With all due respect, would you please articulate what 'science and concrete evidence' you apply in similar situations. |
Richardkrebs, With all due respect the sonic signature of the different materials you outline are meaningless unless the rest of the system is described at the time of testing. For example it might well have been that the system was slow and the concrete, whilst sounding hard, may have been showing up coloration elsewhere. I see very little science and no concrete evidence to support your observations. Furthermore, it is well known that the geometry of the original Hadcock 228 was in fact incorrect and if you had built an arm to that geometry then I'm surprised you could not hear the high tracking error and distortion. Specifically the offset angle was incorrect and this was remedied with the release of the 242 in recent years. |
Chris. My trash bin.... Too many years ago to count, I went about building 5 off BD TTs in quick succession. The platter was aluminium, bearing had a tungsten carbide thrust plate with replacable steel ball on the shaft. All five were of the same design, the difference being the plinth material. I simply changed the bearing, platter, motor and arm from one to the other. #1 Laminated MDF. Slooow and colored #2 Laminated hardboard( like compressed MDF.) Better but still slow and colored. #3 Concrete. Hard and bright #4,5 Slate. Quite good, slightly bright, which was mitigated with a lamination of MDF on its base. I sold #5 to a then Linn owner. After this I went on to build 4 off unipivot arms. Based on the geometry of the Hadcock CH228. They all had saphire bearing cups with ss pins. Brass pillars and magnesium headshells.The only change was the wand material. #1 epoxy resin infused balsa wood. This was not as stiff as expected and this was reflected in its sound, smeered and soft. #2 hard wood dowel. Lovely, glorous, romantic but colored. #3 undamped aluminium tube. Nice and clear with a slight rising top end. #4 damped thin wall glass tube. Easily the best. Clear and articulate. This was broken awhile later during transportation and I was too devistated to rebuild it. Does any one else have similar war stories? I am interested in your findings. |
I imagine TT designers trash many prototype materials before arriving at what they choose for their product. It should be a requirement imo, especially for some of the higher priced tables to understand the room/gear used to arrived at a turntable design. This should be published information. Regarding building turntables and materials used. Here is a list of materials along with a number beside them. The number indicates the materials ability to pass thru sound (a high number) or hinder sound (a lower number). The higher the number allows a better pass thru of sound. the lower number deadens, inhibits, absorbs. Material Z0 [MRayls] aluminium.........17 brass.............37 copper............42 cast iron.........37 lead..............25 magnesium.........10 steel.............45 tin...............24 tungsten..........101 araldite..........4-13 brick.............15 concrete..........7-10 glass.............10-15 granite...........27 marble............10 slate.............12 all plastics......1-4 all wood..........1-4 except cork.......0.1 carbon fibre......30 This data is informational only and was taken from this site. http://qualia.webs.com/plinthbuilding.htm "Another property of materials is the acoustic impedance, that is, how easily sound passes from one material to another. Nearly all the data available is concerned with supersonic frequencies of sound, typically 5 MHz, so not really useful in the audio range. However, it does suggest that getting sound from one material to another seems to be dependent on their respective acoustic impedances, easily calculated as: Z0 = p x c where Z0 is the acoustic impedance, p is rho, for density, c is the speed of sound through the material [longitudinal wave velocity] Some acoustic impedances of common materials: Z0 in N•s/m³ /106" So to transfer sound from one material to another effectively may mean using materials with similar acoustic impedances, or, to hinder transfer, (as in isolation), choosing materials with very different acoustic impedances. What about rounded edges for the plinth/armpod materials themselves over straight edge; to better deal with resonances? This is done with speakers. |
John I have owned 3 regas........all digital Planet, planet2000, my current Saturn of 8 or so years ?, is one of my current digital players. It sits on 3 symposium rollerblocks Rega was one of the last companies to enter the digital world. So I guess I like the company but I have no experience or knowledge of their analog items. The RP8? how do you put an ET2 on that ? :^) |
Slaw "I have to say that as regards to using acrylic as a platform for the vinyl record ......" Further reading, TAS 40th issue. Wayne Garcia on the new Rega RP8: "Most notable is a two-piece, 16mm thick flywheel platter made of float glass, a technique wherein molten glass is Floated over molten tin in order to create the flattest possible surface and overall uniformity of thickness. To form the flywheel platter, Rega joins two separate pieces of float glass to the underside .... adding mass to the circumference. Damn marvellous I say! |