Raul,
Just to add that I am aware that I have drifted somewhat from your response in my reply but would note that my comment is based on my slight preoccupation with acoustic spaces and psychoacoustic factors.
I think the issues of distinct venues and quality of performances on distinct occasions still undermine my moments of certainty that I have captured "a" live event. This rears its head in my concern over distinction between listening rooms and performance venues in my reply. Of course, as your response points out, that is only one aspect to consider when addressing the authenticity of our hifi experience. |
Pryso,
Thanks for your valued reflections. I think they develop another dimension of Raul's reference to the distinction between the close mic'ed recording (as relayed to the home stationed audiophile) and the sitting position of the live spectator. I slightly drifted from the point in my initial reply to Raul. However, I find it fascinating.
I'm not sure who came first, HP or Martin Colloms, but the issue about soundstage as a criteria for judging ones hifi has been a fairly standard one since them. I do think your reflections on the importance of sitting position are critical for the general issue of perceptions of staging.
Beyond that, I think that your reflections on the impact of new recording techniques (some popular experiences of which I am still recovering from) provide much food for thought.
Might oak trees for small acorns (rants) grow.
Thanks |
Pryso,
Apologies, it should have read: "Mighty oak trees from small acorns (rants) grow".
I tend to be posting before 7am local time and I think this is affecting things. Apologies and thanks again. |
ArmPod Instructions - 1,2,3
This is for those that have been reading this thread, are interested in trying this out, but may need some help with it.
I have put together a short document to help with it. You are welcome to it - just send me an email and I will forward you a copy.
It covers.
1) How tall does the armpod need to be.
2) What shape do you want your Arm Pod to be ?
3) Acquiring materials
4) Tools for Holes
5) Drilling Holes on Metal
6) Assembling the ARMPOD
Thx for the pre-edits and feedback Banquo.
This project rates a 3 / 10 difficulty - about the same as assembling IKEA furniture, will cost you $100 and can get completed in a weekend. You can even get someone else to do the drilling of holes for you. I bet you will be so happy with it (sonically) that you may not even want a more expensive one unless you need some eye candy.
I was going to put some bullets into a post here but quickly realized that wasn't going to cut it.
Cheers Chris |
I tend to disagree regarding the space between the musicians on stage. My estimation is that with every added gain stage, the apparent body of every individual instrument, becomes bigger. I confirm that the perception of ambience becomes more impressive also and the music surrounds the listener.
But these bodies starting to touch each other closing the empty space between them. This fact alone is enough to put me in doubt about the validation of my (monoblock, batt. PSU, single stage, DHT, with Hytron OOA) active line stage and so, I've disconnected it permanently in favour of a buffered pot. These days I'm in search for a high output cartridge, in order to investigate if this apply also to the phonostage and is worth to retire my (dual-mono, batt. PSU, current mode, with Tele CCa) active pre-pre.
Some speakers don't like this approach, sounding dry & empty, as like they loosing harmonics. But at the same time, the depth, illumination, clarity and especially the definition of every instrument & every single note, becomes unveiled & exposed and maybe not so appealing in their nudity. In my search for an antidote, I've found the VDH "The Mountain" interconnect between pre/power (RIAA/power in my case) that recovers the presence by attaching importance to the substance of each note.
Regarding the armboard, I'm taking Lew's side & just watching your findings for the moment. I believe that we are not capable of integrate it to the bearing's chassis due to our limited knowlege about interactive materials & mechanics & thats the reason we accept the isolation as the only way (but is not the right one). |
Dear Geoch - regarding your comment on the armboard. This thread has really nothing to do with our knowledge on this or that - the thread is about people in this hobby trying something and letting their ears decide if it sounds good to them.
To them it has provided priceless passion and satisfaction.
Do you not trust your ears ? For amount of effort and time this takes to setup your response is well "just watching your findings " ?
All high end manufacturers use this concept. |
Dear Ct0517,
Of course it sounds great, the best we've heard till now, e.t.c. But still, it is just a way of giving a fight with what we have, and the results are quick and the success is great... And we are in danger to follow the wrong direction because of this.
Please let me apologise. It was not my intention to provoke or showing disrespect. I admire no less than you the experimentation. |
Geoch,
I see your reservations and hope you ultimately resolve them to your satisfaction. However, in line with Ct0517's comment, I would stress that your ssuggestion that "our limited knowlege about interactive materials & mechanics & thats the reason we accept the isolation as 'the only way' (but is not the right one)" is off the mark.
No one is suggesting that this is the "only" way. Those of us who have tried it do, however, suggest that it is "THE BEST WAY WE HAVE EVER TRIED AND/OR HEARD." |
Dear Geoch
No offence taken.
Life is short and this hobby is one of the avenues that has allowed me get into the right frame of mind to help deal with my real family and work challenges. We have all probably done what others would call "extreme things" in our hobby. I have a problem with speakers. 7 pairs in 3 systems and I just brought home Wayne PK Quad 57's to try out.
Those of us using this approach will not be offended if you try it and do not like it in your set up. We are content. Unless you can suggest a better way and we will be all over it. I know I would be.
When you go to some of these web sites and see what just a couple of manufacturers charge for these isolated armpods. They are thousands of dollars with no cartridge. |
Dear Ct0517, I agree in general about the 'extravagant prices' in analog domain but disagree that manufacturers are the primary cause. Those from abroad hardly get 30% of
the selling price. First there is the import duty +VAT,then
the importeur and then the dealer. Above this also the value of the national currency. I got my Reed arm pod for
less then $500 thanks to the EU and absence of dealers.
Regards, |
Dear Nandric - I agree with you - my statement should have been clearer and implied "the end cost to us" when we finally get the product. I realize in a small market like this it must be very difficult for the manufacturers. |
An alternative to DIY or a mass manufacturer is locating a local machinist who can do the work. That's what I did. The machinist marks the middle ground between the other two options. My guy didn't charge me much more than the DIY option and mine required much more elaborate machining--it's all in one piece with no separate arm board. Having said that, if I had thought of Ct0517's 'simple' method, I would have probably opted for it. Of course, the simple method requires one to have an arm board, which I didn't have. |
Dear Banquo, A local machinist with an CNC lathe would be ideal. In particular for the tonearms with a collar because
such an armpod need to be milled from,say, solid brass. Ie
a 'sandwich' arm pod with different layers is more difficult to make. For such a machinist our 'DIY' person needs only a good drawing with exact dimensions because the
machinist can order any kind of material for the purpose.
This kind of 'construction' will need a plate with the hole
for the arm with the obvious advantage : different plates=
different tonearms. For the plate one can use acryl, aluminium, steel, etc. but I personaly would use solid brass for the 'base' because of the weight (demping).
Regards, |
During my project keeping it simple was the objective and not having to get machinists or other people involved. It was a DIY project to see if I liked the sound. My next step would have been to make a nicer arm pod with the help of a machinist and other folks. It sounds so good to me however that this will not be necessary. This approach allowed me to get intimately involved with the materials and setup.
As the guide says - the key is getting your tonearm base on the plate. What do your tonearms arms sit on now? Are they attached directly to the plinth or on a separate plate that attaches to the plinth. For me I had hardwoods that I had already experimented with when I used a plinth. Common options are maple, oak, birch, acrylic, but even panzerholtz or metal can be considered. I went to home depot and picked up 3 and 4 inch wide solid pieces of wood in varying thicknesses and cut the length from it required for my tonearm. The entire lenghths of the wood themselves were about $8.00.
Both the tonearm bases for my ET and VPI JMW 12" arm are shaped like a closed letter U so a rectangular piece of wood worked well.
As per the instructions in the guide I left extra wood on each side for two machine bolts - this is how the tonearm plate attaches to the actual armpod. Then the shape of the armpod becomes your choice as long at the plate fits within it.
The tonearm gets attached to the plate first - then the plate is simply attached to the armpod with the two bolts. The guide stresses making sure your plate is thick enough to accept the tonearm bolt/s without protruding thus allowing a flush fit with the armpod.
|
As the guide says - the key is getting your tonearm base on the plate. What do your tonearms arms sit on now? Are they attached directly to the plinth or on a separate plate that attaches to the plinth. Assuming that this is directed at me, the actual answer is that I don't have my turntable right now. I've never had a plinth for my sp10 though. The first go around I just bought some 10" rectangular oak boards at HD, drilled some holes and mounted the tonearm that way. It sat next to the TT. Sounded great but looked like crap. After seeing Halcro's design, I decided to have similar pods fabricated. One pod has been made and another ordered, and neither has a separate tonearm plate in the design. The arms will sit directly on the pod with holes appropriately drilled on top and bottom. Note: cutting a slot on the bottom so that one can connect the tonearm cable was evidently a huge pain--and probably not recommended. My second pod will have the tonearm sit directly on the pod as well, but the top hole will be cut wide enough to accommodate various tonearms (didn't think of that the first go around, Nandric). For each tonearm, he will fabricate a new 'collar' so that the base of the tonearm will fit snugly into the pod's hole. So, I guess that collar will act like your plate. For the second pod, I proposed that he fabricate separate plates that would be mounted on an adjustable rod connected to the pod, but he said that that would be more difficult. I didn't argue. Dear Nandric: do you believe making the pod out of brass makes a significant difference? If so, perhaps I'll tell him to do that if he hasn't already made it. I see though that brass is pretty expensive compared to SS. |
Dear Ct0517, The problem by an description is the fact that
we are not able to 'visualize' the construction. What is: 'the key is getting your tonearm base on the plate?' Assuming an arm pod next to the TT what kind of plate you
are talking about? If you presuppose the usual arm base which is on any TT we all are able to think of some other
kind of material for the purpose. My point is this. For the tonearms like Triplanar ,without a collar , one can use
a cylinder of, say, brass and drill 3 holes with thread on
each side. But for the tonearms with an collar this will not do. BTW the most tonearms are with a collar so one need to get them trough the arm pod and connect them with
the phonocable 'inside' the arm pod. There is alas no way an DIY can mill such a 'hole' in a solid brass cylinder. The plate on such an'drilled out' cylinder is of course very easy. One can use an acryl plate and drill a hole for any tonearm with an collar.
Regards, |
Dear Banquo, In the first place I got the meaning of 'the
plate' that Ct0517 is talking about. He means 'the rack' on
which the TT sits. Well on my rack there is a sand filled
SHELF on which my Kuzma Stabi reference and my arm pod sit.
The sand in the shelf has a demping function and solid brass as a alloy or amalgam has also a good demping function. My Reed arm pod has different layers of different
materials with the intention to get the arm pod acousticaly
dead. I don't believe that a solid piece of metal is acousticaly dead but the weight of such a piece of metal
may function as such. Ie that is what those heavy TT's are
about: you always need more weight. To put it the other way
'the heavier the better'. Otherwise one need to use springs as is the case by many TT's.
Regards, |
Hi all,
One suggestion for an arm pod that I am about to fabricate from a proto-type that I designed. I purchased a solid brass pivoting arm board manufactured from tw acustics of raven tables.
Using a pivoting arm board will allow you ease of flexibility during set up especially with 9 inch arms and any tables with a chassis top deck like the Technics SP 10 MKII.
Also if desired the added use of a tone arm heavy nut as used with some models of Micro Seiki, Fedility Research just to name a couple.
i plan on using laminated layers of B-25 panzerholz and a 30 mm thick length of brass tapped and threaded for the arm board.
The feet I have not settled on as of yet.
As for the platform which all this will rest on will have to be inert. I can forsee problems with out door variable climate change/ house hold humidity, the platform will expand and contract enough in some cases to throw out the tone arm and cartridge set up.
This is just my 2 cent contribution.
Cheers
|
Dear Nicola, The British TT manufactures says "there is no such thing like mass damping". But the high mass of Brass is indeed very good for this purpose (arm pod) because of it's stability. The "damping" properties of Brass realised by Goldmund on their Steel/Al/Brass chassis construction because of the synergistic differential inherent molecular structure between them, that resulting to the decreased speed of resonances when collected from Steel and directed through Al to the final lower lever platform of Brass and from there to the ground. The Goldmund's material sequence is a way different approach than Vidmantas'. He is looking to provide a clean upper level for the armboard by progressively decreasing the incoming resonances from floor & air. The cork decoupling level is used as an isolation point between the materials. Critically examination of these 2 different solutions opens up many queries concerning the natural predisposition of metals, transmitting energy with different speed and also ringing on a different frequency to each other in order to weak the intruder resonance. I used to have many top range Goldmund products and I could not verify the validity of the Steel/Al/Brass for a general purpose, not even for component chassis construction that Goldmund claims successful results. If this approach works, depends by other things of major significance like the matched coupling to the matched shelf of the matched foundation rack. And because life is too short (Thank you Chris for this I always tend to forget it) I think I'm gonna take a second thought to Vidmantas' outlook as I'm starting to feel more close to the "isolation" idea as the most capable & effective if one wants to arrive in time (and catch up the limited time that left), and listen some music instead of argue endlessly for the imaginable ideal. After all the result is what counts. But I have to get over the cork thing first. Perhaps it can provide a torsion breakdown moment. (although I know first hand it is effective) |
Dear Banquo - my comment was a general one to anyone reading our thread and to those that have emailed me for a copy of my guide. Thank you again for reviewing it.
Since your feedback - I also sent a copy to Raul, Halcro, Nandric, and Lewn for their comments late yesterday. Again if anyone else wants to see it just email me.
I have had a number of people request copies of the guide already. Some in Malaysia and the UK. I do say in it to use aluminum and not steel as it is magnetic. My first one was steel nice and heavy but it is now a bookend. I will be adding more pictures to the guide.
Dear Nandric - I have already posted a link to my set up in an earlier post. The armboard can be seen closer here.
http://www.canuckaudiomart.com/view_userimages.php?user_id=5181&image_id=41886
Note: This guide is strictly to help those that may want to try this out and not a professional document. It is just the way I chose to do it and it worked for me. I am one of those people that like getting to the point and not making things more complicated than they need to be. This was the intent in my approach. |
Dear Geoch - it was my intent for the next project to replace my solid aluminum armboard with a brass one and maybe add a panzerholtz tonearm plate on top. From your last post - do you feel this would be worth the expense and effort?
Pictures of my setup were in my link in my last post.
Appreciate any thoughts on this ?
Cheers Chris |
Whilst Chris' Guide to making your own armpod is admirable, he appears to have concentrated on his ET parallel-tracking arm which I feel is different to the majority of pivoted arms? When I designed my armpod, I attempted to make it 'universal' in that it could accommodate all the vintage pivoted arms I could find and all the modern ones as well. The major differences between the vintage arms and the modern ones are most likely to be the fact that vintage arms have a bottom plug-in din phono cable which needs to enter the armpod. There is also the 'barrel' of the arm-base to accommodate the rising VTA mechanism and this varies in diameter for all arms. Some modern arms have this 'barrel' as well although their wiring usually exits the arm on top of the arm-base rather than under it. The largest diameter 'barrel' I could find was that of the Copperhead arm and a hole of 55mm diameter could accommodate that. I later found that the VTA barrel of the FR-66s arm was exactly 55mm diam so I'm not sure if this would easily fit? To accommodate all the different diameters of the arm bases available, an independent top-plate is used to 'attach' the arm to the pod. HERE |
Hi Chris, I think the decoupling offered by the wood plate is a very drastic solution, applied in desperate situations. My concern is about the strength & tightness of the surface that couples the arm pillar with the arm pod.
I'm sure it works OK, but from the theoritical point of view, I would be more comfortable if you choose a more solid upper fixed point, in order to modify the ET arm pillar, as if it is one piece with the first block of the arm pod. Even if it is applied at the bottom* (the decoupling by wood), may not be necessary -in your case- considering there is a film of air in between the arm tube & the arm pillar.
* Steel at the top plate, your own Al main block, Brass as a foundation or intermediate level. Especially the discs that rests the spikes must have great hardness. You can close the microscopic open moleculars between the metal surfaces simply by applying some silicone oil without bonding or bolts. Easy if you uplevel your main wood shelf with a second & preferably denser platform only for the TT and so, you will have the apparent hight for steel, brass & discs. Just a thought. |
Dear Geoch, 'life is to short' but it is never to late to learn. So as soon as I get my engeneering degree I will
respond to the 'demping question'. Meanwhile you can direct
your inquisitive mind to Vidmantas and ask any question about cork you like (Ruta@reed.lt or Vidmantas@reed.lt).
I am very reluctant to ask Halcro to bring some 'light'
in this 'mass matter' because I think that he is angry at
me.
Regards, |
As I understood the manual, any armboard will do. Part of it will be drilled onto the pod and the part with the larger hole where the tonearm mounts into would protrude beyond the dimensions of the pod itself. So, this would be different than Ct0517's set up but would still work for pivoted arms. In fact, that's what I did the first go around, but instead of using a metal foundation, I used red oak.
My current pods are similar to Halcro's; but, sadly, far less cool looking. |
Hi Chris, I think the decoupling offered by the wood plate is a very drastic solution, applied in desperate situations. My concern is about the strength & tightness of the surface that couples the arm pillar with the arm pod.
I'm sure it works OK, but from the theoritical point of view, I would be more comfortable if you choose a more solid upper fixed point, in order to modify the ET arm pillar, as if it is one piece with the first block of the arm pod. Even if it is applied at the bottom* (the decoupling by wood), may not be necessary -in your case- considering there is a film of air in between the arm tube & the arm pillar.
* Steel at the top plate, your own Al main block, Brass as a foundation or intermediate level. Especially the discs that rests the spikes must have great hardness. You can close the microscopic open moleculars between the metal surfaces simply by applying some silicone oil without bonding or bolts. Easy if you uplevel your main wood shelf with a second & preferably denser platform only for the TT and so, you will have the apparent hight for steel, brass & discs. Just a thought. |
High Density & CLARITY are BFF |
Dear Nandric,
I'm certainly not angry with you :-)
A little disappointed that you didn't understand my sense of humour about your 'Australia' remark which I found very funny :-)........so I thought you took offence?
I hope we're 'cool'?
Regards
Henry |
Dear Geoch - thank you so much for your thoughts. You are absolutely correct - I can eliminate that wood layer totally and mount the ET directly to the armpod with the one bolt. The mounting post rides on air with 3 of its own couplers. The plate I am using is dried oak and it is firmly held on with 2 - 1" inch machine screws. I used the plate to allow for ease of changing arms but I will be making other pods for those arms so it is not required. Now the important part - how much will it change the sound by removing it.
I will think more about the second part. The adjustable AT616 footers are at their lowest point right now and they adjust much higher to accommodate a higher pod. My problem is at the pod side I will need a taller one.
So for the interim I think I will replace the AT616s with the lower mapleshade spikes I was using previously this will give me the room to experiment with the pod and that layer.
Henry My VPI 12 arm mounts directly on top with phono cables out the side. It is very easy to drill a hole into the armpod to accommodate the bottom cables especially if aluminum. But it still wont look as good as yours. Our imagination is the only limit here. Many ways to skin. |
Dear Halcro, I am truly glad to hear this;we are cool now.
But your arm pod remind me somehow about Picasso. 'Look',
he said to a friend, 'how easy drawing is'. He then draw with a single stroke a pigeon. 'Anyone should be able to do this'. He added. Now an arm pod is of course a'different
animal' but do you really think that we can make the same as yours? If so I don't believe that I am able to understand anything about Australians. Except of course that they must be onbelievable optimistic kind of the human kind.
Regards,
Regards, |
Dear Chris, It will change for sure, but you need an intermediate level of different material in order to break up the resonances. If I was in your position, I would start with a 7mm Brass top plate for armboard, and Steel for the discs under the spikes. By this way you have the Goldmund's list & sequence of metals. I'm not supporting their option, but you may want to try something that is so much praised by them.
Kind Regards |
Dear Nandric,
Thank you, that's very flattering but I can only 'design' the armpod.....I can't make it.
For that I need a good foundry to make the mould and cast the bronze after which I need a good machine shop to make the aluminium top plates and to drill and tap all the holes so that a good automotive paint shop can finish the job with 2 pack polyurethane.
Here in Australia we are lucky that there are many places which will readily do small quantities or 'one-off' jobs like this.
I'm sure in Holland you could also find places?.......look how Thuchan was able to have his new speakers made so professionally?
Of course.......price may be a factor and that's why Chris and Lew are looking at commercially available billets of brass and stainless steel which may be available in the States.
Solid billets of the sizes I designed are simply not readily available in Australia.
There are many people who can 'draw' like Picasso...........there are very few who have the IDEA of what to draw?
That's the difference between a 'craftsman' and an 'artist' :-)
Regards my friend |
Dear Geoch - thank u for your recommendations. I use the discs under the spikes. I have however been experimenting with different materials under them. The most recent pics in the site link show the discs along with the removal of the armboard top plate.
Will consider the 7 mm brass top plate but have a question.
I like the design of the ET post mount which has one bolt holding it with 3 leveling threaded spikes surrounding it. It can be seen in the link here.
http://www.canuckaudiomart.com/view_userimages.php?user_id=5181&image_id=41907
How do you or others here that have looked into isolation between metallic materials feel, on whether the top brass plate you recommend is attached firmly against the armboard below (easy to do) or if it should ride on air like the ET post mount. More difficult but still easily doable. I would just need to find a place that sells the threaded spike couplers to use with it.
Then the top two levels of the armboard would be riding on air.
Henry - it appears your arm pod top plates are screwed directly to the armpod ? Did you consider this ? What if that top plate was riding on air like the pic in my link ? Would it increase resonances or provide more isolation?
Any thoughts on this ?
Cheers Chris |
Dear Inshore - look forward to seeing a picture of the armpod. Just curious as you mention humidity - Is panzerholz affected by humidity as other woods - maple, oak and birch?
Cheers Chris |
Dear Halcro, I know that you are a very 'smart cookie' but
clairvoyant? Well as you presupposed I was able to find a
craftsman with an CNC lathe in Holland and I really enjoy
to look how he works with this 'monster'. However Thuchan
is a different 'cookie'. He is an entrepeneur with a clear
thought of what he wants and has the capability to organize all the needed work. Dertonarm is btw a close friend and they are at the moment adjusting the Bavarian voice (aka speakers). So obviously he was also in the position to find all the needed professionals in Germany for the job. So you made a good quess. I am in particular interested in this 'trumpet' in front of the TAD 2002 driver but even Daniel was not able to explain to me what
the 'clue' is . My shortcoming of course.
Regards, |
|
Hi Chris, Is Panzerholz effcted by humidity or dry conditions? Im assuming it would. Directions point out helpful guide lines , one being after cutting seal cut edges.
This being a product designed for multipal applications in heavy industry it being in your home used for delicate duties I so far found no issues over a year in use.
It is extremally dense stuff dulling high grade carbide cutting edges very quickly.
For use as arm pod or plinth material for sure. Is it like other material commonly used in audio, No.
Is a plinthless table a good sonic step forward, Yes
Is a table set into a panzerholz plinth a sonic step forward , Yes
Cheers |
Dear Chris, IF... (and this is very important)... you keep the 2 big bolts also, to maintain the contact firm, then...
the spike couplers under the 7mm Brass armboard are using the same logic of Orsonic headshells & Midas Touch indermediate headshell weight : They provide a clean (rigid coupling without soft materials that have any compliance) but short path and thus allowing only a fraction of the resonances to pass through the next level.
This is not counting as an isolation (rigid coupling of metals) and it seems that it works for cartridges !!!
Now I'm thinking an alternative : As the 2 bolts are allready provide a path from Brass armboard to Aluminium armpod, you can cover the entire underside surface (except the 2 holes) with a very fine velvet textile (extra thin without compliance) in order to damp the 2 metals that are coming in contact. This is a very different option from just applying the silicone oil to the same surface. You have to choose by trial & error these 3 options unfortunatelly we cannot predict the results. Depending by the mass of the armboard, (and especially the tolerances in execution) the 2 bolts may not be enough for the 3 coupling spikes option and can provide space for ringing or even worst a possible diformation of the Brass platform. I would prefer : ability adjustment only at the bottom spikes, the steel discs about 6cm diameter and replacement of the upper coupling spikes under the Brass armboard by very tiny bearing balls (if you decide to try this option, by this way becomes easier. Although the marking points of the Brass armboard & the Al armpod by the bearing balls is of no concern 'cause they can only form a round scuff, I'm anxious about the proper amount of tightness by the big bolts).
Of course anything soft under the discs makes the whole armpod isolated from the shelf, interrupting the passing of resonances from armpod to the ground and it needs experimental verification also, since it is only depended by the shelf prorerties. |
Dear Geoch excellent post. You have provided me with three clear options that I understand and am thinking about.
you can cover the entire underside surface (except the 2 holes) with a very fine velvet textile (extra thin without compliance) in order to damp the 2 metals that are coming in contact.
This would be an easy solution and I can experiment with different velvet textiles.
2 bolts may not be enough for the 3 coupling spikes option and can provide space for ringing or even worst a possible diformation of the Brass platform.
Excellent observation.
I could add 2 more bolts to form a square around the 3 spikes? I can make the Brass plate smaller as well ? The ET tonearm post covers a very small area on the armboard.
replacement of the upper coupling spikes under the Brass armboard by very tiny bearing balls (if you decide to try this option, by this way becomes easier. I'm anxious about the proper amount of tightness by the big bolts
I really like this option - picking up some ball bearings is easy but just like torquing special wheels on cars - how do you know how much torque to use on the bearing. I guess I would start with a low torque and listen to familiar recordings tightening a little at a time. When I used my TNT belt drive I would adjust the SDS by tone so I trust my ears for this.
You have to choose by trial & error these 3 options unfortunately we cannot predict the results
Everything we are doing in this thread is uncharted watersfor me that is the allure of it the discovery the learning first hand how resonances work in my vinyl setup. We only need to please ourselves. This makes the improvements very satisfying.
I have learned alot by your post.
thank u Chris |
The SME type base of my Pluto 9A tonearm is covered with a very fine velvet textile, but has greater mass & height for it's small dimentions, is made of titanium that is bonded to a brass lower level & furthermore has 4 bolts that compressing the thin textile underneath and eliminate the possibility of compliance. To use only 2 big bolts its risky for this option as is also dangerous for the 3 bearing balls solution. There, you change the resonance freq by tightening the 2 big bolts, but they leave a free & lengthy surface that remains open & undamped to the mercy of any remaining vibration. |
I'm sceptical about all this 'isolation' of the armpod that is being discussed?
Sound is transferred in only two ways:-
Structure-borne transmission
Air-borne transmission
In both these cases, we are interested in transmission in two directions......from armpod to tonearm and from tonearm to armpod.
With the tonearm mounting to the arm pod in the first instance, if there is any 'transmission' from the tonearm base, this indicates 'movement' in the tonearm base which is 'information lost' from the cartridge.
The aim of the tonearm is to have zero friction at the pivot point which means no transfer of any movement to the arm base. The arm itself must
be rigid enough to allow the cartridge to transfer all the stylus movement
to the tonearm wiring only.
In the other direction, the base upon which the armpod sits needs to be stable and immovable. The armpod needs to be 'decoupled' from this base (unless the base itself is acoustically decoupled and levelled) via spikes and the armpod must be absolutely level. With the mass of the armpod (at least in my situation) so large, any structure-borne transmission which somehow transmits across the spikes, is so small and high in frequency, that it is easily absorbed as 'heat' by the armpod.
With the air-borne transmission, please remember that the tonearm and the cartridge assembly themselves, are both directly affected by these same sound waves and are far more susceptible to vibrations (because of their more delicate masses) than the tonearm bases and armpods.
Again if one employs mass-loaded armpods, the amount of sound at varying frequencies which can be reflected and/or absorbed as heat is far more than that of any tonearm or cartridge.
If one wishes to employ a combination of dissimilar materials to counter the transmission of certain frequencies, I see no harm in that as long as visco-elastic ones which allow movement to occur, are avoided?
The above is simply my opinions based on the physics, acoustics and materials science with which I am familiar as well the 'in-field' experience of my Project. As usual YMMV? :-) |
Dear Halcro, I can't see even one point in our texts that indicates any dispute. The armpod is by nature isolated once it is free standing & not attached to the TT chassis. Other than this isolation, not me, neither you we were willing to recommend any farther (ie: under the spikes' discs, or even in between the metal layers) as long as we can verify the ability of the shelf to drain the vibrations that intruding from air & floor, and also the effectiveness of the 6x1cm steel discs to drain the resonances coming from up through the spikes. But I feel that we must perceive the spikes as couplers. Theoriticaly we use to refering as decouplers all those viscoelastic materials that we want to avoid. I think as its going till now, this project is promising. Have you noticed any contradiction in the process so far ? |
Dear Halcro, Thanks for the lecture reg. 'structure-and air born(sound) transmission'. This is done in the context of the arm pod formulation but, cause of the generality, must also apply to the TT's. We can see, so to speak, two
opposite approches: Raven, Brinkamann, Kuzma XL ,etc. on
one side and ,say, Thorens and Linn-LP12 on the other.
But the last mentioned use springs while the other don't.
Does and how 'mass matter' in this context? BTW this is a
kind of reformulation of my earlier question.
Regards, |
Dear Nandric,
the "trumpet" attached to Thuchan's TAD-2002 driver was designed by me and I prepared the technical drawings to have it fine milled from one solid piece in a 3D-CNC-precision milling facility here in Bavaria.
It was not easy.
It is however kind of Thuchan's property now.
Furthermore it only works with the bandpass of his X-over, the TAD-2002 and within and in conjunction with the whole Bavarian Voice-system.
Nothing that can really be copy-paced and transferred to another speaker.
Cheers,
D.
post scriptum: Halcro is right - it shouldn't be all that problem to find tooling-facilities around any major city in europe or the US who can handle milling work on solid metal (or wooden ) pieces to create nice armpods. |
Dear Geoch and Henry thank you for providing very valid points for consideration. My current armpod has served its purpose - it was built to determine if this approach was valid. It was not expensive to make as materials are available and cheap where I live. I am ready to setup up the next one.
It can be done in stages and allow me to use at each stage. I enjoy the DIY approach so would like to continue this way - Thinking of a 4 diameter brass cylinder pod and to mount my Tonearm directly to the top of it with three steel spike couplers on the bottom. This would be the first stage.
I then would make a decision on whether to add a top plate of aluminum to the brass. I need to think more about what has been said here about this.
I was speaking to Bruce of Eminent Technology who informed me that my tonearm uses Cone Point Set screws to level itself to the base. These come in many lengths and diameters.
http://www.radax.com/store.asp?pid=15198
I could mount the top aluminum plate on the brass using the same approach. 3 of these screws close to the perimeter to level it. 2 or 3 bolts would then be placed just outside of the footprint of the tonearm base that it will sit on it to secure it to the plate. The plate would ride on air as well as the tonearm. Do you feel this air is an advantage or does it not matter ? Can I get your thoughts on this.
From a DIY point of view - It seems to make more sense if adding this plate to just have it touching the brass at specific touch points with the set screws and bolts and making sure no movement and it is rigid.
I did some research today on materials and pricing.
Metal Supermarkets is located in Canada, the US and the UK.
http://www.metalsupermarkets.com/MetalGuide.aspx?CategoryID=BRASS&ProductID=TUBE_ROUND&ProductSubCategory=360
Prices are for solid brass and SS armpod cylinders. Prices are in Canadian dollars.
4" diameter brass (360 grade) 4 inches high - $152.55 (16 lbs)
3 diameter brass (360 grade) 4 inches high - $79.91 (9 lbs)
4 diameter Stainless Steel 4 inches high - $94.81 (15 lbs)
3 diameter Stainless Steel 4 inches high - $59.71 (8.5 lbs)
3 or 4 (7 mm - approximately ¼ inch) brass top plate is about $10. |
Dear Chris,
The stainless steel pricing looks better than the brass. The only down side is it is harder to mill yourself so you might need a professional machine shop?
I'd go for 316 grade rather 304 as it does not tarnish and is definitely non-magnetic.
I can't quite follow the 'air' reference to the top-plate? I personally would want the top-plate connected to the mass of the armpod as securely as possible. In fact the only reason for a top-plate IMO is to allow clamping of the tonearm and connection of the Din cable, otherwise I'd happily screw or clamp the tonearm directly to the armpod.
Cheers
Henry |
Dear Chris, I present to you my reservations about the possibility of ringing. The 7mm Brass is a lengthy piece and the porpotions are not quite ideal for doing this "air" mounting. Furthermore I believe that the 3 tiny bolts are not so absolute idea in terms of controlling the resonances, even if they can provide the convenience of alignment, the threaded holes together with the asymetrical body of the tiny bolts , are not comparable with some pretty harder & perfectly round bearing balls in order to detune the armboard resonance & above that, in terms of rigidity are more secure.
I'm with Halcro at this. You better try the massive & solid approach -as the more secure way- that is also more tolerant to some crafting inaccuracies. Also keeping the project simple is always the better way. I agree with your choise of Al plate / Brass pod / Steel spikes for your next project. (Although I prefer the Symposium Rollerblock JR instead of spikes) |
Geoch/Chris,
I'd be careful about using Rollerblocks beneath an arm tower. The ball bearings are not secure enough and movement when lifting and placing the arm would almost certainly create ongoing alignment problems. In fact, the only place that I find the rollerblocks ideal is beneath my CDP, where mechanical movement is minute enough to never create a problem and yet the benefits can be easily heard. |
Here in Greece it is common place the Rollerblock JR under really heavy mass loaded free standing arm pillars when we are using parrallel tracking arms. |
Dear Geoch I am trying to understand the benefit or reason for using the Rollerblock Jr.
Based on what Dgob is saying and the fact the Rollerblock use bearings how much weight are we really talking about when you say really heavy loaded.
I ask because I have two 2 ET tonearms. If there is one thing I have learned about that air bearing - is that it is very sensitive. It is set at 19 psi and it needs to be totally rigid and parallel once set and not move or it will introduce coloration, and distortion that is audible.
But I also think that this would apply to other "pivot" arms as well - any movement at all is not good ? |
