Hi All

As per subject - Townshend Seismic Podiums; discuss

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!

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

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

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

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

I have some Gaia footers from Canadian company Isoacoustics here to try under PMC MB2se speakers.

Some reading matter for those interested.

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

KevinF.

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