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Offline Pete_w  
#1 Posted : 15 June 2020 21:07:12(UTC)
Pete_w


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Hi All

As per subject - Townshend Seismic Podiums; discuss BigGrin

My soon-to-be-finished new house has a floor (from a company called Cube 6) which is basically a 70mm fibre-reinforced concrete screed over (lots of) polystyrene. Walking about on it, away from the solid walls, it doesn't feel that solid, you can feel that there is a slight resonance/movement to it, even without jumping up and down. That's the price you pay in modern houses for low heat loss. And in that respect, this is a very good floor.

So my "new" second-hand speakers - Martin Logan Prodigy - are pretty much the definition of "full range speaker", and, given the 7m x 5m room dimensions, will be working quite hard. Each speaker has a pair of 10" bass drivers, and I have 300W available each side to wallop them with.

Given all that, I can't help thinking that spiking these speakers to the floor, as would be traditional for flat-earth audiofiles, might not be that clever a move. I suspect that I'll get the floor joining in with the bass rather more than I'd like.

Max Townshend's video (https://www.youtube.com/watch?v=dW9-r83IvhI&feature=emb_title is very persuasive. But the price for a set of his "size 4" platforms, which is what I'd need, is £2,600. Which, to be honest, is a little bit more than I paid for the speakers! Crying

Google finds me quite a few people saying how good the Podiums are, even some Martin Logan owners. I've seen no-one saying that they're rubbish. Anyone here got any opinions about whether I should add them to the budget....?

Thanks!
Pete
Offline Peter M  
#2 Posted : 16 June 2020 07:18:04(UTC)
Peter M


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Pete,

I used Townshend platforms to great effect in a previous house. This was in an upstairs bedroom with a lively floor, at least when driven by a pair of ATC active 50s. The floor was of conventional timber joist construction in a modern house. I note that you do not actually mention the nature of the floor structure in your new house, only the surface layer.
The bedroom was above the kitchen and the noise was unbearable for Janet if she happened to be to be working in there. It seemed that the ATCs were causing the floor to act like a large diaphragm.
The Townshend platforms tamed this unpleasant effect very well. The only downside, apart from the expense, was that the speakers were wobbly on the platforms, which could be slightly unnerving if the speakers were touched.
Peter
Offline Pete_w  
#3 Posted : 16 June 2020 19:15:40(UTC)
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Hi Peter

Thank you! Happy to get geeky about the floor. Actually, Cube 6 have a video on this page that helps, but basically it's a variant of beam'n'block. In trad beam'n'block, you build a perimeter wall, lay beams across it (thus creating a void of maybe 300mm), infill with concrete blocks between the beams, then lay some insulation down and then screed over that. This is sort of the same, except that instead of the concrete blocks infilling between the beams, they use polystyrene blocks!

So you have the beams go down over the void, and the beams are ever-so-slightly cambered (arched) up in the middle, so that when the weight of the screed goes on them then they flatten to give you a flat floor. Then polystyrene (some sort of high-density stuff) blocks lie between the beams, another thick sheet of polystyrene over the whole thing, then the UFH pipes get laid out and clipped to the polystyrene, then the fibre-reinforced concrete slurry arrives in a train of tankers and is poured over the lot to a depth of 75mm or so. And that's your finished floor surface.

So in music room terms I have this 5m x 7m concrete slab that's only 75mm thick, lying on top of a lot of polystyrene, spanning the room across sprung concrete beams. There's many tons of it, even so, but there's no doubt it does feel somewhat resonant under foot. I grew up in a house which had - in part - a solid earth floor, and this most certainly isn't that!

The builder and architect chose the floor construction between them, but even so it has freaked the builder out. Actually it's freaked both of them out. In Trad beam'n'block, you lay the blocks between the beams and then stop; you have a solid floor to work from to build the rest of the house, erect internal scaffolding and so on. Then when you're nearly finished you lay the insulation, the UFH pipes and the screed. In *this* construction, you have your *finished* (and easy to damage) floor and its encapsulated and frost-vulnerable UFH pipes before you've even started building the house walls. So we had nearlky a kilometre of pressurised pipes full of glycol all through last winter....

Joint conclusion seems to be that it's a very good floor system but not one that either of them would choose to use again for bespoke housing....

Cheers
Pete


Offline Peter M  
#4 Posted : 17 June 2020 07:17:58(UTC)
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It seems to me that not even ATC active 50s would energise a heavy-weight floor such as this!
Peter
Offline Martin Colloms  
#5 Posted : 17 June 2020 16:08:31(UTC)
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There is a question here which I have not yet fathomed an answer

1. Should a loudspeaker system be coupled to a building ?
Perhaps to stabilise its position in space ( e.g. for sharp image focus)
to avoid fore and aft reaction rocking from bass driver kicking,
and allow some vibration energy to leak into a larger better damped
structural mass? ( dynamics , focus, timing and transient power?)

2. Or float the loudspeaker at a few Hz on a pneumatically supported
steel plate when the resulting rocking is only weakly energised and is
subject to damping. Now, the inherent higher frequency vibration from
loudspeaker operation is retained in the floating assembly, not
coupled to the floor. It must be dissipated locally.
( result : greater definition from the removal of room coupled structural
vibration and floor drumming noise)

3. And what about concrete, and/or semi concrete floors?

4. Magico Mpods did not work on my concrete floor until I put thin fibrous
dampers under the steel discs which engage with the floor spikes.


Martin Colloms
Offline Peter M  
#6 Posted : 19 June 2020 16:02:41(UTC)
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Martin,
In my position as an interested and inquisitive layman, I see that the the floor structures that you, me and Pete_w have are somewhat similar but with some differences. Those of you and Pete are suspended whereas mine is not. They all have solid concrete bases and probably both yours and Pete's are of concrete beam construction. The important similarity between Pete's and mine is that they both have a thick layer of polystyrene foam between the concrete and the surface layer. I would therefore hazard a guess that Pete's floor might respond much the same as mine.
The problem that you encountered when testing the Magico M2 speakers is clearly unique and since you have reviewed other speakers on that same floor without this difficulty, the issue must lie with the speaker when placed in this rarely encountered coupled system. I am in no position to say definitively that the problem is in any particular feature of the speaker, but I note that it is unusually stiff. So far, this much must be obvious. As a wild guess, could it be that the M2 speakers were too efficiently coupling and draining energy into your floor? I say this only because you solved the problem by interposing fibre pads between the speakers and their floor supports. My guess is that these pads reduced the energy transfer.
But the answer for Pete is surely to suck it and see. If his floor reacts as mine does, I doubt whether isolation platforms will be required.
Peter
Offline Pete_w  
#7 Posted : 21 June 2020 13:20:22(UTC)
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Yes, I was very intrigued, Martin, that your "solution" to the Magico "problem" in these supposedly so-scientific speakers was in fact to add a relatively uncontrolled damping layer. That does rather imply that there's too much energy flying around somewhere.

I found Max's video quite persuasive, though I have no idea how representative tapping the box is (to demonstrate speaker-to-speaker transfer through the floor) of real energy in a real working speaker. I don't think that modern screed concrete floors are as solid as people think. Somewhat tangentially, I have a memory of a school physics lesson from 40+ years ago - physics teacher (big bloke, rugby player) puts both fists together and slams them down as hard as he can onto his (good old-fashioned hardwood school science) bench. Bang! Strategically-placed items that he's positioned without us noticing at the edge of the bench promptly fall on the floor with a big crash. Everything, he announces with some pride, has a resonant frequency!

Yes, the answer to my original question is clearly suck it and see, on sale or return. The important point for me is that no-one's come back and said "no, they're rubbish, they kill the sound". I'll report back, but it'll be at least October, possibly later. Have you ever tried them in that room of yours, Martin? As far as I understand it, your room is on the first floor on concrete beams....?

Pete
Offline Peter M  
#8 Posted : 21 June 2020 15:14:43(UTC)
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I have an unexpected update for you Pete.
I too was intrigued by Martin's Magico solution. and I decided to try it out with my speakers which, as you may recall, are Wilson Sophias. Luckily I found a packet of self-adhesive felt discs intended to be placed under the feet of furniture to provide some floor protection. I stuck them to the undersides of my existing metal spike cups under my speakers. The first thing that I noticed was that the music volume seems reduced and accordingly I had to turn up the volume by two or three notches to get it to my regular level. This itself was intriguing! I began by playing a piece of choral music of which I am particularly fond (Brahms German Requiem since you ask) but which has always had wince-inducing rough edges in its many Fortissmo passages. For the first time the music played cleanly and clearly, which is a huge bonus. I then played some solo piano music and immediately noticed an increased level of detail and involvement. It was difficult simply to tear myself away, and as you know, my system was already fairly decent.
All in all, this upgrade was not only worthwhile but was the most inexpensive one that I have ever made. The only cost is that I have to replace the felt floor protectors before Janet notices that they are missing and perhaps the odd twinge in my knees from grovelling on the floor.
Of course, the question for me is what is happening? I still think that the concrete sub-structure of the floor is stiff for all practical purposes. I do not think that there is enough stray energy from the speakers to energise a massy structure such as my concrete floor. I have come to think that the timber surface layer of the floor, which I believe is simply floating on the polystyrene insulation layer, is sufficiently resilient to be energised by the speakers to the extent that it is making an unwanted acoustic contribution. I seems that that the felt pads are simply reducing vibration into the surface of the floor to an extent sufficient to prevent energising this surface layer. This is not the same problem as in my last house where the whole floor structure was being driven as a drum by my speakers, but is probably confined to small areas immediately around the speakers.
Peter
Offline KevinF  
#9 Posted : 28 June 2020 14:10:16(UTC)
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I have some Gaia footers from Canadian company Isoacoustics here to try under PMC MB2se speakers.








Offline Pete_w  
#10 Posted : 28 June 2020 18:42:17(UTC)
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Please report back, Kevin!

The way this thread is going, we'll all be reverting to castors on carpet soon! Confused
Offline KevinF  
#11 Posted : 01 July 2020 10:18:01(UTC)
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Some reading matter for those interested.

https://isoacoustics.com...er-isolation-technology/

KevinF.
Offline phil page  
#12 Posted : 01 July 2020 15:00:23(UTC)
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I'm about to try some of these too, having heard good reports from two people I trust, both allergic to snake oil
Phil
Offline Pete_w  
#13 Posted : 02 July 2020 14:26:26(UTC)
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Hmmm, interested to hear how you get on. Roughly how much is a set of 4? (As I said, Max T's solution cost more than my (second hand) speakers!)

These are deffo better looking than Max's podiums, but they do add another 2" to the speaker height, and ML Prodigies aren't exactly inconspicuous when it comes to height already....

Cheers
Pete
Offline KevinF  
#14 Posted : 02 July 2020 14:47:02(UTC)
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Circa £600 for four size 1s which together will support up to 100 kg.

There are some technical differences between the two offerings that can be easily identified by reading the Isoacoustics .pdf and Townsend's Web pages and which might or might not be significant in terms of performance.

KevinF.

Edited by user 02 July 2020 14:47:52(UTC)  | Reason: Not specified

Offline hussain  
#15 Posted : 06 July 2020 13:48:19(UTC)
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Dear all,

I use the Gaia feet (size 2 - so much cheaper) under ATC50ASls, so right at the threshold of the weight limit. This is, as someone has said, much more visually elegant a solution than Townshend podiums especially under large standmounts. Their installation made a marked positive impact - more so than (say) Kimber mains cables, or indeed expensive Clearaudio Magix2 under PS Audio transport/DAC. Really worth looking into in my view.

All the best,
Salman

Edited by user 06 July 2020 15:16:10(UTC)  | Reason: Not specified

thanks 1 user thanked hussain for this useful post.
Pete_w on 06/07/2020(UTC)
Offline Pete_w  
#16 Posted : 06 July 2020 18:47:15(UTC)
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Thanks, Salman, much obliged. If I ever finally finish this house - October!?!? - I'll try and get hold of a set on sale or return. I see what you mean about the price differential between I & II; II is stated to be for speakers of up to 54kg, my MLs are 60kg... Crying
Offline KevinF  
#17 Posted : 07 July 2020 21:00:12(UTC)
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I have received the go-ahead from our Contributing Editor to write about my experience with the Gaias for a coming issue. For now, I can say that the results with the PMC MB2se monitors, in my room, are both very obvious, and thoroughly intriguing.

Offline Pete_w  
#18 Posted : 14 July 2020 10:26:35(UTC)
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Oh you tease! BigGrin
Offline KevinF  
#19 Posted : 15 July 2020 18:39:17(UTC)
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Guilty as charged.

As MC found with his trials of the Magico footers, this particular interaction with the room is not always simple. What works very well in one setting may be quite inappropriate in another. Like me, you will no doubt have looked at the IsoAcoustics written material and formed a view about whether the products appear to be well-founded on physics.

Perhaps the most pragmatic advice I have seen about these and other isolation devices (and it surely holds good for most stuff) is, if you can, try before you buy.

KevinF.
Offline Simon Briggs  
#20 Posted : 19 July 2020 13:24:32(UTC)
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Originally Posted by: phil page Go to Quoted Post
I'm about to try some of these too, having heard good reports from two people I trust, both allergic to snake oil


How did you get on Phil?, I may need to use ideas like this between my big new Loudspeaker design and my floor / room
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