SIMO Studio - Construction Phase

I know I know John, don't worry :thu: it's just that removing the rubber underneath the box would have been impossible as it was sandwiched between two layers of ply screwed together so I had no choice really …actually, it turned out that even the sorbothane at the top and at the sides of the box was not easy to pull out…I kid you not, I even had to use the wrecking bar in two occasions as it got totally sticked to the box ! (that material IS quite sticky) …and I'm already at this stage anyway me impulsive… remember? :mrgreen:

just because I'm an idiot and act impulsively as per usual…my italianism kicking in I guess

Hey there Mr. Impulsive Italian! Slow down a bit, and wait for answers to your posts! :) I sort of understand the "Italian" thing, though: not because I'm Italian, but because I live in Latin America, and the Italian blood runs strong in many people here too... :) OK, so you don't run into the need for a wrecking bar again... How about if you put your front panels on temporarily at first, so that they can be removed easily a few times, just in case you need to make more changes, and only fix them in place permanently when you are satisfied that everything is working fine? For example, put just a few screws in each panel for the early tests, just enough to hold them tight, without any glue, finishing "plugs", decoration, or anything. Then you can take out the screws again if you need to get the panel off, without breaking it! Same with the speaker boxes: Don't glue or nail anything, just use screws, so you can disassemble the box again if you need to. You could even do some initial sine sweep tests without the baffles in place, just the speaker, to see if any vibrations is being transmitted to the frame.

I have to admit I could definitely feel the kick drum while touching the baffle!

That might not be the resonance I was talking about, but rather just the front panel of the soffit vibrating naturally at some resonant frequency. How thick are your baffles (soffit front panels)? Also, is all of that framing very firmly braced? (I mean the framing that the front panel screws to.) Like John said, the soffit itself has to be very rigid, so nothing can vibrate naturally, so maybe running a couple more cross pieces behind your front panel would help with that, and also perhaps using thicker wood, or more dense wood for the front panel. On the actual mounting of the speaker / box, there are two different approaches: I call them the "John Sayers" approach, and the "Barefoot" approach. There's a discussion on the forum somewhere that they had about this a while back, but I can't find it right now. John's approach is to hold the speaker and box extremely rigidly to the rest of the soffit, and keep everything very heavy, massive and rigid so it cannot vibrate. Barefoot's approach is to decouple the speaker and/or box from the front baffle, so it floats, allowing the speaker a little room to vibrate freely, but heavily damped with rubber, and not allowing it to contact the front baffle at all. But he still uses John's approach for the rest of the soffit: Rigid, solid, heavy. It looks like you were trying to do the Barefoot system, and that can work too, but only if the speaker/box really is floating. I've also see Barefoot do his system two different ways: one is to put the front baffle on one rigid frame with the speaker on a separate rigid frame, and the other is the way you are doing it, with a single rigid frame and rubber to decouple just the speaker. I haven't seen Barefoot on the forum in a long time, and I wish he were here to clarify his methods, as I might not be explaining it correctly, but that's what I've seen in his posts. So, with what you have there in your room, at this point you can either go 100% with John's method (all rigid), or 100% with Barefoot's second method (the way you were doing it) but getting the rubber deflection right so the speaker really does "float". So that's the decision you should make first. Now, as Ro mentioned, if you do use rubber in their to decouple the speaker, it has to be done correctly, to get the correct deflection so that the speaker really does "float", and that is generally in the range 10% to 20% deflection, depending on the type of rubber. I agree with Ro that your Sorbathane is probably not deflecting enough, since you have a very large surface area there but not all that much weight. So you might need to just use a few strips of Sorbathane cut to the correct width, rather than an entire large pad. Do the experiment that Ro outlined, to make sure you are getting at least 10% deflection in your rubber, and probably more like 15% to 20%. Check the specifications for the exact type of rubber you have (call the manufacturer for that), and keep within whatever range is correct. The specs should tell you what load you need to get optimum deflection (kg/m2), so if you weight your speaker assembly you can then figure out how many square cm of rubber you need, and cut it accordingly. I'd guess that your 6mm rubber should probably be compressing down to about 5mm, in order to float correctly.

it's just that removing the rubber underneath the box would have been impossible as it was sandwiched between two layers of ply screwed together

Ummmm.... if you screwed those together THROUGH THE SORBATHANE, then there is no decoupling at all! The screws are transmitting the vibration directly from plywood plate to the other, and the sorbathane is just sitting in the middle, as a spacer.... It wont float at all like that...

!! right, back to square one - wish me luck… and patience

Patience more than luck! And put down that wrecking bar.... :) - Stuart -

Hi Simo-- Sorry to hear about your frustration; I have definitely had too many of those moments myself! Just to add my two cents' worth (or maybe less), here's a link that might illustrate what Stuart is talking about, where Nativeluv17 used only small squares of sorbothane, which presumably gave him the proper deflection. viewtopic.php?f=2&t=11508&p=109443&hilit=durometer#p109443 In a conversation with tech support at sorbothane, this approach is what they suggested for my build, as well. They're quite helpful, and if you give them the weight and dimensions of your monitors, along with the thickness and durometer of the sorbothane you're using, they might give you a suggestion for the number of and dimensions of some smaller sorbothane pieces that might work better for you. You could then use REW to compare. Here's their web page: http://www.sorbothane.com/blog/contact-sorbothane/ It might be worth a phone call across the pond....I hope today is a better day! :D

Hi Stuart, I used screws throughout, no nails or glue…. the plywood came off with no problems, but the MDF, as it has a different consistency did not…also, I used quite big screws and perhaps that didn't help too…. lesson learnt :-) I'm using a 18mm plywood and an 19mm veneered MDF (which is quite dense, definitely denser than the ply) on top of it, both screwed to the framing underneath. The soffit was very rigid indeed, but this time around I'm making it even more rigid. I guess in my confusion I was going with an hybrid approach…. (yes, I realised too that screwing the bottom of the speaker box with the plate below through the sorbothane was cancelling the decoupling I was trying to achieve! silly mistake !) Your explanation looking at it in terms of Mass-Spring-Mass opened my eyes! So this time, I excluded the extra layer of sorbothane outside the box but I am keeping the layer inside it, and I'm making the structure as solid as I can. Hi Mark, thank you very much for your support and info ! I did ask for advice to the company I got the sorbothane from (www.lrcltd.co.uk), and after explaining what I needed it for, giving the measurements and weight and saying that I needed it to damp vibrations (I remember now that I did asked about the need of being compressed by 15-30%, following Brian (BriHar)'s kind advice (pag.8 on this thread), they got back to me saying that 5-6mm thickness should suffice for that purpose. Thanks guys !!

they got back to me saying that 5-6mm thickness should suffice for that purpose.

OK, yes, but that is THICKNESS they are talking about: You also need to know how much AREA is right for the load you are putting on it. Think of it like this: If it needs 1000 kg/m2 to get that 15% deflection with 6cm thickness, and your speaker weighs 1000 kg, then obviously you need one square meter of rubber, measuring 100cm by 100cm. But if you speaker weighs 100 kg, then you only need one tenth the size, which would be a piece measuring 10cm by 100 cm. And if your speaker weighs 10 kg, then you'd need a piece measuring one hundredth of a square meter, which is 10c, by 10cm. If you put your 10 kg speaker on one square meter of rubber, then it won't deflect 15%! It will only deflect one hundred times less, which is 0.15%!!! Nothing at all. So it won't float. OK, I just invented all those numbers to make it easy to calculate: they are not real number at all! I just wanted to illustrate the math that you need to do. If you look at the thread that Bigsby linked you to, you'll see that Nativeluv used very tiny squares of rubber to decouple his speaker, not an entire sheet. So its a function of thickness and area that you need to calculate. When you called the Sorbothane dealer, they told you what type to get (thickness), but they didn't tell you how much area of that you need. I would call them again, tell them how heavy your speaker is, and ask them to tell you how much surface area you need to float that much weight, using the 6mm rubber they sold you. Then spread that amount of surface area around underneath your speaker. Then use the SAME area of rubber on each side of the speaker and make the surrounding box 10mm wider that the speaker, instead of 12mm wider (so you get the same deflection horizontally), then use the SAME area on top of the speaker as underneath and make the box 10mm higher than the speaker instead of 12mm higher, to ensure that you get the correct deflection in that direction too. I would arrange the rubber as one thin strip under the full front edge of the speaker, then small pads arranged under the sides and back, until you get the right total area. Do the same up the sides and across the top. The reason for the thin trips around the front edge, is to get a good air-tight seal between the speaker and the box, to reduce low frequency "pumping" effects from forcing air in and out around the edge of the speaker. Not sure if that makes any sense! It's not easy to describe it in words... - Stuart -

Hi Simo, thanks for posting, really nice work!!! I'm currently building my room and now i'm scared about my soffits (they are also angled) as i'm not a carpenter :ahh: i should rethink my design without soffits, maybe same as northavenue studio (designed by John) before i make mistakes!!! To do or not to do... :roll: Anyway, any measurement yet??? How does it sound??? As always sorry for my english, i should include it in my signature! :mrgreen: Greetings from Italy!

Ciao Finck! tutto bene? No, no measurement yet…I'm currently re-building them…hopefully - all going well - they should be finished by the end of the week. In terms of how they sound…. well, just by trusting my hears I was already extremely pleased with them even with my previous construction, which was a bit of a three leaf-structure (thus, for what I understand, it should no behave well at low frequencies)… I mean, I was literally laughing when playing back music that I know well through them... I noticed small details I never focused on before, plus I great stereo image and very well balanced low end. Hopefully that would improve with the new construction which is way more solid than the previous one and without the extra sorbothane… we shall see :-) Basically, all of this to say that I would give it a try building the soffit... It's almost fun….If you don't have to do it twice !!! :twisted: :mrgreen: I am Not a carpenter myself…actually I never build anything in my life before, but necessity got me here…just take your time!!… and I'd recommend to do a very detailed model with SketchUp… that FREE program will surely help to figure out any "strange" cut and to see in advance how it will look like In bocca al lupo Fink !! Simo

Ciao Finck! tutto bene?

Tutto bene, tu?

I am Not a carpenter myself

Me too, but i'm not as good at it as you! :mrgreen: I'm waiting for your next update! Bye! :thu:

Hello all ! I'm moving at a snail rate especially comparing to some of you guys (sometimes you make me feel even slower :-)), but I'm nevertheless moving forward, so update time I guess… … Update Part-1 first of all this is the updated speaker soffit, the MKII :-) As planned I extended the superchunk above the speaker: filled in the cavity with insulation rockwool between the framing plastic sheet layer and final black cloth cover end of part-1...

… Update Part-2 Time to finish off and hang up the clouds. First I placed a layer of a material called "batten' (following RJHollins' advice) which - along with the small wood strips - should help to avoid the insulation from sagging over time… On the part of the cloud that will be closer to the ceiling, I made the plywood backing flush with the framing, in order to be able to lift the cloud closer to the ceiling….my room isn't very high so I figured that every inch will help (I tried with and without it and the difference was very noticeable). rockwool and plywood back cover front view For the finishing layer I added a thinner (9mm) planned softwood all around to hide the screws, and stained it Exact same process for all the other clouds: end of part-2...

… Update Part-3 Time for the cloth…I went Blue for the Live room and Red for the Control room. cloth stapled to the wood strips and cut off the excess And finally I added the wood trims all around the cloth to cover the staples: end of part-3...

… Update Part-4 (Final :oops: ) Time to hang them up (can't find any more excuses to postpone it!) :-) Control room: Live room: That's all for now. Next slot resonators and cloth cover frames for the rest of the walls…. hope I will speed up a bit. Ciao Simo

Hi Simo, really nice clouds!!

As always, Simo, just BEAUTIFUL! You claim to be slow, but the work you're doing warrants it. Really looks spectacular!

oooooh, yeah. It is slowly coming together. And, as usual, rich details and perfect planning. It pays of, clearly. Hope it "sounds" as good as is looks. ro

wow, that is beautiful!

Thanks a lot for the encouragement guys. It does mean a lot !!

Floor time 8) Firstly I used the self levelling compound to compensate for some unevenness in the concrete floor (no pics….don't know how but it did managed to escape my photographic rampage :twisted: ) I then applied this liquid damp proof membrane (3 coats)… It's cool as when it dries out it becomes a thin waterproofed rubber layer - really cool ! On top of that I put down the fibreboard underlay plus a thinner (3mm) foam underlay. …and this is the result: Live roomand Control room My question is: I've been advised to use these cork stripsto fill in the (15mm) expansion gap between the floor and the walls…. A) Would this be ok (as the cork is quite flexible) ? - or - B) perhaps use the foam strips often used in the walls expansions gap ?- or - C) am I better to leave the gap totally empty ? Many Thanks in anticipation Ciao Simo

Flooring always makes a room more pretty, donnit! I wonder why you didn't just glue the floor to the existing concrete/rubberlayer. Making it "one" with the existing floor will make your floor more quiet (less resonance). anyhow, since your floor isn't decoupled from the wall (or vice versa) it doesn't matter what you use to fill the gaps. I did it with transparent sealant (kit).

Simo - when I started out in studios at Armstrongs in Melbourne in the 60s cork panels were our 703. :)

Thanks for info Ro ! John, good to hear that :thu: I actually used those cork strips today for the expansion gap… they are quite soft, so should allow for any slight stretch the wood floor might do with changes in temperature, whilst keeping it more compact as well.

Hello all, hope you had a great end and even better start of the year ! I just finished the slat resonators on both CR and LR, and am now finishing off the cloth frames for the remaining walls …I'm sorting out the pics and I'll post them asap. As, in the meantime, I'm shopping around for the glasses for the windows, I've got a quick question for you: How many mm smaller should the glass be compared to the actual window's frame, so it is not too tight? what would you advise? (obviously I will seal those few mm gap) Would 5mm (I mean 2.5mm all around it) be ok ? Also, I read it's good procedure to place EPDM setting blocks under the glass to help settling it centred in the frame…but what thickness should the setting blocks be in your opinion? Many Thanks in anticipation as usual !! Simo

How many mm smaller should the glass be compared to the actual window's frame, so it is not too tight? what would you advise? (obviously I will seal those few mm gap) Would 5mm (I mean 2.5mm all around it) be ok ?

That's probably fine, but do check that you have enough space to be able to tilt the glass into position! You normally set the bottom edge in place while holding the glass at an angle, then tilt it up to vertical. Make sure that there's enough clearance between the glass and the frame so you can do that.

Also, I read it's good procedure to place EPDM setting blocks under the glass to help settling it centred in the frame…but what thickness should the setting blocks be in your opinion?

Thick enough to do the job! :) :shot: Seriously, get whatever your glazier recommends for the size (weight) of glass you are using, and use enough of them to support the glass without over-compressing the rubber. - Stuart -

Thanks for your answer Stuart. I think I settled for a 50' roll of 1/8" x 3/4" (3.2mm x 19mm) neoprene setting block. The other option I found is 3/16" (5mm) setting blocks, so the gap under the glass will end up being bigger than needed in my opinion, even if I will completely fill that in obviously… also, the other down side it's that It comes in 7/8" width, thus it's not ideal as it will require trimming it as well… I'll be put up 15mm laminated glasses, so that plus the thickness of the glazing tape (which, as far as I can see it is commonly 1/16" or 1.5mm) between glass and both inner and outer stops should give me approx the 19mm width of the setting blocks I'm going for (mentioned above). …playing with millimetres here y'know :-) anyway, Update time (Part-1): Frames for the cloth made with the usual 9mm MDF: Control Room Rear: removed the frames and stapled the thin plastic sheet: all coming together Control Room Front: under the speaker soffit and overall view ... more to come ...

Update (Part-2): Slot Resonators… Live Room: looking from CR and Control Room: Right-hand side Left-hand side Looking from the front of the room, between the speakers here artistically from the floor :-) and from the Live room …getting there… :yahoo: next installing glasses and door/windows architraves Ciao ! Simo