SIMO Studio - Construction Phase

jup, second that :)

Hello ! I've got one last question about the speaker case. Sorry for pestering you with this…it's my last question - I promise :oops: - …well, at least about this subject :twisted: Ok - Would it be better to have the speaker case: a) firmly attached to the framing… screwed, glued, or anything to make it as firm as possible or b) totally disconnected from the surrounding soffit. I was going to go with option a), but then I started having this doubt after reading the very interesting method proposed by Barefoot (viewtopic.php?t=718). His approach is also very clever as it allows you to upgrade the monitor at a later stage, BUT the part that interests me the most is the principle that avoids building any structures that directly couple the speaker with the framing. This is to help isolate the speaker cabinet vibrations from the control room (I kind of like this idea!) …also, this pic I found on the genelec's website (different method - but similar approach of suspending the speaker on top of vibration isolators) got me thinking even more… Thus, I thought… why not try to do an hybrid approach, which is: Float the the speaker box by placing (say) 4 sorbothane hemispheres (I posted a picture before) underneath it. Then, still frame around the case to help keeping it firm, but sandwich the sorbothane hemispheres (in light blue here) between the stud and the box, to help stop the vibrations from transferring to the front baffle plate and so to the rest of the room, like this: It's worth mentioning that I already lined the box with a 5mm sorbothane layer. This hopefully will help minimize the transmission of vibrations to the surrounding case. BUT - if I place another "sorbothane barrier" between the box and the rest of the structure I'll end up with two "vibrations-reducing stages" (which sounds cool too :-))? What do you think? …. too much thinking? shall I just shut up and keep building quietly… or there is a small base for an exchange of thoughts here? Thanks as always ! ciao Simo

Hello Simo, I've been following your build thread since ... well, since I first saw it :lol: Very nice by the way ! Not sure I can help directly ... or confuse the issue more :roll: ... What I've read on isolating speakers from other surfaces seemed to make a point to MINIMIZE the number [or size] of the needed contact points. The less 'contact points', the less surface areas where vibrations can travel due to any possible flanking. My monitors are not soffit mounted, but they do sit atop of concrete pillars. Using a sorbethane material, I have 3 contact points [2 at the front, one in the rear] that separate the physical monitor from the stand. Back in the day, we used 'stand off' cones. The entire speaker bottom surface was reduced to 3 'pin point' tips. Since then, I've read criticism of using these metal cones, but never on minimizing the area size that was in contact. With sorbethane, it is very important to get the correct 'firmness' of the material based on the total weight of the monitor. just my 1/2 cent thrown in as I await GURU's reply in hopes to learn more. 8) BTW ... I think this is a very important question[s] you ask. Even if we think we know the answer, I think it wise to hear it explained from different viewpoints. Sometimes a broader understanding or interactive relationship sheds unexpected insights :mrgreen:

Hi RJ Great to hear from you! Thanks a lot for taking the time to answer me. Really good points...yes, I used to have my old speakers resting on three spike cones too in my previous small room ...just trying to make my life a bit more difficult this time around :-) Yes, let's hope someone would be able to shed some light on this subject :-) How 's your studio coming along? Have you finished it? Looking forward to see more of it. Ciao Simo

Hi guys (& gals) ...a little diversion... I just had a conversation with one of the forum member - Finck - via PM regarding the correct earthing for the electric circuit. After running a separated earth for each individual outlet, he was asking whether the earth within the Twin and Earth cable should be connected as well or just leave that disconnected. Following logic one would think that it should be left disconnected, to not recreate the loop that we were trying to avoid by star-grounding the outlets, right? With that occasion I asked the electrician that wired my studio, and I found out he connected the earth within the cable as well (I assumed that he didn't). I guess it won't take long to disconnect that if that's the case... What do you think?? Thank you ! Simo

Hi everyone a bit of time have passed since my last post… well, after a nice longish break in Italy I'm back with my (never ending - or at least it seems so) build… ...so to pick up from where I left in (more or less) chronological order: - I attached noggins (these little guys)all around where the rear lights will be and around the hooks to attach the clouds: in the CRin the LRI then filled in with insulation the front superchunk then I placed rockwool slabs between ceiling beams: Control Room same on Live room

...update part-2 Door time (finally!): all door frames are 35mm hardwood (sapele). Same wood was used for the window frames (a bit thinner though). The two doors in the control room have two sets of stops The doors were made with two layers of 22mm MDF and an additional layer of 18mm MDF (smaller all around apart the bottom to create the bank-vault type of closure), hardwood on both edges of the doors, both faces oak veneered. The door of the live room and toilet have been made with the same construction but without the 18mm MDF layer in front of it and so their frames have one set of stops Now, on the seals: All the doors have (drop-down) Bottom seal mortised in the door. The rubber drop down to close the gap between the lower edge of the door and the door frame, as soon as the plunger on the side hit the jamb (you can regulate how much the rubber seal drops by changing how much the plugger is sticking out with a screwdriver) This is the seal I used for the head and jamb on every door You can still regulate how much the rubber is sticking out, or how much it gets compressed when the door closes by adjusting the little screws on its back (I like this feature as it easy to install as you regulate the seal after the installation and also you can tight them up if they get loose in a few years time by just turning a few screws) Obviously for such heavy doors, heavy duty door closers are needed

...update part-3 I cut three 9mm MDF sheets into 50mm strips, then built the frames for the cloth to cover the inside-out ceiling. The process has been: - place the mdf strips over the ceiling beams, temporarily pin them so they didn't move and staple them together - give it a quick coat of black paint on the small areas that won't be covered with cloth (i.e. the frames around the hooks to hold the ceiling clouds and the spot lights at the rear of the room) - take the mdf frames down - staple the cloth on their back - and then put them back up for good. To hide the nail's head, I first hammered it half way in, then chopped its head with cutting pliers, hammered it fully in, then used a sawing needle to pull the cloth back out for a smoother finish I placed an insect mesh over the fresh air and stale air out nozzles, to avoid insects travelling in and out (or at least to make their lives a bit harder!). I put a thin plastic sheet over the rockwool (before placing the cloth frames over it), in order to avoid having too much high-frequency absorption making the room sound too dull. …well, that's all for now… Ciao! Simo

Looking good, Simo! Very good. I liked the way you hid the finish nails, too. Very neat idea. - Stuart -

Speaker case & Soffit construction Part-1 This was the old speaker case I built when I was still planning to go with the duct+vent design. I already posted the plan before, but here it is again just to make it easier to understand: I then decided to go down another route and to pull out the amp behind the speaker (Genelec 1031A) instead, and extend their connection in order to have the amp in the room (to have the option of changing settings and/or service it at any time), instead of it being "trapped" inside the soffit. Thus, I had to build another box (smaller, as in that case it doesn't need the space behind the speaker with the top and bottom openings): lined with a 6mm sorbothane sheet all around Then I attached a plywood plate below the speaker case that you see here upside down (with another layer of 6mm sorbothane sandwiched between them) which is wider than the box itself, in order to be able to screw it to the plane it is resting to Then it was time to connect the speaker cabinet with the amp, before adding the front baffle plate. New connections @ the speaker's end and this is the cable for the connection. Following Genelecs' advice, I used a cable with a greater section to compensate for the longer run and to maintain the speaker's frequency response Connection made (these connectors are very sturdy and almost impossible to pull out by accident…. in fact to disconnect one it took me around 15 sec of twisting it :-) ). I gave it a good squeeze with pliers and then applied heat shrinks to cover the connection further

Speaker case & Soffit construction Part-2: I did a quick test to check that everything was connected properly before adding the plywood baffle plate All ok ! … I passed the cable through the frame to have it coming out at the bottom, and cover it back with the 100mm rockwool I framed all around the speaker box to keep it firm…It's quite tight and that thing will have some problems to vibrate ! I cut the left over sorbothane sheet in strips 50mm wide (same as the frame surrounding the speaker box) and sandwiched them between the box and the frame. These strips in addition to the sorbothane layer below the case should help to damp some more vibrations. My attempt was to have 2 sets of decoupling: - speaker with the case - case with the surrounding frame I mean, I'm not 100% sure this will actually work but I had some leftovers of this NOT cheap material, so I thought I'd give it a try and use it… it shouldn't do any harm I guess :-) I filled in the cavity with fluffy insulation Added rockwool between the studs Front plywood baffle plate attached the baffle doesn't touch the speaker case as well, but it stops 5mm off it (you can see the sorbothane underneath)

Speaker case & Soffit construction Part-3: Before cutting the holes for the speakers on the veneered MDF finish, I made a template (using the same 10mm MDF strips I used for the cloth frames on the ceiling) to give me a precise guide of the cuts…I will recycle them for some more cloth frames after I finish this job Even the MDF finish does not touch the speaker box (hopefully still keeping it decoupled) The oak trims finally close the gap between the case and the soffit. These are touching just the plywood speaker case behind them (nailed to) and they are literally 1-2mm from the MDF plate I'm planning to cover the screw heads for a smoother finish by cutting plugs from the veneered MDF off cuts using a plug cutter…this is a quick test I made just to see how the result could be…from a fair distance the plug is not too obvious. Also I noticed that if you pay attention in matching the colour of the plug with the area it is going to, the result can be acceptable :-) So that with a bit of more practice, sanding and another quick coat of clear varnish should do it I hope :-) But I'm going to leave these cosmetic touches to the end of the build as it's a bit time consuming and to be honest I rather crack on with more important stuff at the moment... QUESTION (I already asked this before, but didn't get an answer…so here it is again :-) ) : I'm planning to extend the superchunk at the front of the CR.... this is how I was thinking: ...basically using all that space that seems a shame not to cover with nice itchy insulation :twisted: My only concern is: Would that compromise somehow the speaker soffit at all? as I would have to attach some sort of small frame to the front MD baffle in order to have something to attached the cloth frame to? Any advice you can give would be greatly appreciated ! Many Thanks Ciao Simo

Hi Simone-- I wouldn't presume to know the proper answer to your question (sounds like a good idea to me, though), but I just wanted to take a minute to complement you on your build. I've been following it from the beginning, and your attention to detail is something I can only aspire to. Every time I see a that you've made a new entry on your thread, I eagerly open it to see what you've done. So anyway, kudos to you! Mark

Thanks a lot for your nice comment Mark, very kind of you and much appreciated ! As a matter of fact I am following your build too… you are doing a fantastic job!…and being stickied :D by John himself is definitely a proof of that ! love this place where we can all learn from each other. Keep up the good work :thu: !!

I wish I could work half as neatly as you do, Simo! Your work is actually disgustingly good! :) It makes me jealous... It just looks so darn GOOD!

Then I attached a plywood plate below the speaker case that you see here upside down (with another layer of 6mm sorbothane sandwiched between them) ... These strips in addition to the sorbothane layer below the case should help to damp some more vibrations. My attempt was to have 2 sets of decoupling: - speaker with the case - case with the surrounding frame

There might be an issue with that, but hopefully not. That's basically the same as a 3-leaf wall: You have mass (the speaker) a spring (the sorbothane around the speaker) mass (the box) another spring (the sorbothane under the speaker), and mass (the soffit structure). So there might be a resonance issue there, but with seeing that you used sorbothane, I think you might be OK there. One way to tell is to play very slow sine sweeps over the speaker while touching the speaker cabinet gently with one finger, touching the box around the speaker with another finger, and touching the structure with one more finger: as the sine sweeps up through the spectrum, you might notice some frequencies where only the speaker is vibrating, and others where the box is also vibrating at the same time, but there should be none at all where you can also feel the structure itself vibrating. Another way is to use a stethoscope on the structure while playing sine sweeps: if there are some frequencies that you hear much louder on the stethoscope, then you have a resonance issue. Hopefully that isn't the case.

I gave it a good squeeze with pliers and then applied heat shrinks to cover the connection further

Your attention to detail is amazing!

I'm planning to extend the superchunk at the front of the CR.... this is how I was thinking:

Yup! That's how I would do it.

Would that compromise somehow the speaker soffit at all? as I would have to attach some sort of small frame to the front MD baffle in order to have something to attached the cloth frame to?

Not a problem. That is so far away from the speaker that it wont cause any harm. - Stuart -

Just cuzin' through the forum ... Simo ... your workmanship and attention to detail shows in the beauty of what you are creating. Your build thread has been a pleasure to follow and learn from. Just wanted to let you know, I join others here in admiring your build ! Sincerely.

Thanks so much Stuart and RJ… really kind of you both!!! Stuart - Thanks a lot for pointing that out. To be honest I started panicking when I read your post :-), but it was too late to start the test…so after a veeery long night :oops: first thing this morning I did the test you suggestedwith the sine sweep + touching the speaker, the box (I removed the trims to do that) and the front baffle. OK, there were a few frequencies where I could feel vibrations, more precisely around: 50Hz - just the speaker 55Hz - speaker and perhaps the box too, not the baffle 158Hz - perhaps all three 260Hz - perhaps all three no other vibrations above that Now, I'm saying "perhaps all three" because I was playing back the sine waves quite loud and all these vibrations were barely noticeable in the area around the speaker. They weren't by any means making the whole baffle vibrate (hopefully, as you hypothesised, using the sorbothane is contributing to reduce the problem?) Still in a state of panic, I started playing some music at even louder volume, hip hop with lots of low end…. well, I have to admit I could definitely feel the kick drum while touching the baffle! :cen: But then I started moving around the room and touching any hard surface I could find… again I could feel some faint vibrations here and there, surprisingly even on the studs forming the rear hanger traps ( :ahh: ???). So, now I'm confused and worried at the same time as there is no way I could dismantle the whole studio (both for the time I've got left available and more importantly for my mental sanity :asth: !), and I'm not even sure I could do it any better than what I did so far… What about if I dismantle the whole thing, remove the extra sorbothane, re-assemble it and the problem is still there, perhaps even worse as these slight vibrations are not down to it?…I would have to re-dismantle and re-assemble it once more to take it back to the where I started… and then finally go and kill myself, if of course, by that time I'm not already dead having had gone through that whole painful process :evil: On this matter, several times I happened to notice structure vibrations when doing loud sessions at the studio I work, where even the ssl and the rack bay were vibrating slightly....so I'm puzzled if is it even possible to keep a 1.2m x 1.8m panel (forming the baffle) right next to the sound source from not vibrating even slightly while playing back loud low frequencies, when even smaller surfaces meters away from it do vibrate as well? (it's not a critical comment…I'm truly curious!) …perhaps with a much bigger budget that would be achievable, who knows… And at the end of the day - in the hard attempt to console myself - the music I was playing during the test was honestly sounding very good indeed…much better than I ever hear those tunes. So what I'm saying is that what I got so far (even at this unfinished stage) is already a big improvement from my previous listening environment (my bedroom), so I'm gonna stick with it, keep trying all in my power to make it even better and ultimately hope for the best :-) Thanks a lot for watching my back - don't know what I'd do without it ! Simo

Simo - I have found that the idea of the box around the speaker is to nail it down tight, to make the speaker box become part of the much bigger and more rigid structure that you've built around it so I slide the speaker in with 1mm tolerance all round. cheers john

Thanks for the reply John !! I did screw the box down to the plane it's resting, see here: for the very same reason you are describing, that is to make the speaker become integral part of the surrounding structure (a bit like creating a much bigger speaker cabinet, by extending the real one). and the speaker protrudes from the front baffle just about 1mm. …hope I haven't misunderstood your comment ( :oops: ), and that it puts me back on the right path :-)… thanks for the help !!!

I'd replace the 6mm sorbothane around the speaker box with 6mm MDF glued in it's place - then slide the speaker into a tight fit.

Ok, I will follow your and Stuart's advice to remove the extra sorbothane around the box (NOT the one that is lying on the inside, between the box and the speaker !?). Actually I already started and it was not a good start… both the MDF panels cracked !! :cen: :horse: :cen: !!! I'm gonna take the rest of the day away from "that" place :evil: and come back with more calm tomorrow. Just one last question if I may: if the box needs to be essentially part of the whole structure (screwed, glued, kept as firm as possible…), then there is NO point in stopping both the first plywood layer and the finishing MDF layer a few mm away from the box either, right? I might as well have them both touching the speaker box, as that too should contribute to the overall rigidity and it's nonetheless way easier to build… (I don't recall where I saw the advice around the forum about leaving that small gap there - I did followed it as it seemed a good idea at the time, but at this point I'm not sure anymore) Right, I'm gonna have a few drinks :snack: :snack: , spend my time with my wife and two lovely daughters :love: , and let's hope for a better day tomorrow. As I will start from scratch again I will make that mother even more rigid… actually if you have any other tip to improve resonance problems @ low frequencies…I'm all ears !!!!! Grazie ! Simo

One thing you could do first, Simo, is to do a REW test of the room, and see if there are any signs of resonance in unexpected places on the graphs. If REW can't see them, then you certainly won't be able to hear them! :) The more I use REW, the more amazed I am by two aspects: 1) It's ability to drag out tiny details and show them clearly, and 2) It is free! I never have figured out how the best darn acoustic tool out there is zero cost, while it does so much more than other tools that I paid good money for! I'm relying on it more and more... So do a quick test with REW, and post the MDAT file so we can take a look at it. - Stuart -

Hai Simo, I just browsed through your latest updates and I too am impressed with your craftsmanship. Cheers on that, mate! Now, about your resonance problem. Dealing with low-end pulse frequencies, like a heavy kick, is a burden. Making anything "floating" is not that easy. Just putting rubber, foam or whatever "soft" material under an object doesn't make it float. You need to create a spring that is about 10% loaded to make it active. If the material is to hard it won't compress and just flanks. If it's to soft it'll compress too much and flank just the same. To test your set-up. Take that piece of rubber you've put UNDER you speaker and place it on a flat surface. Measure the height of the rubber (6mm right?) Now, place your speaker on top of the rubber. Again measure the height of the rubber, see if it compressed. Optimal is 10% so the height should now be about 6mm-10%=5,4mm. That way you know it is compress about 10% and therefore "loaded". I'll bet the rubber isn't compressed at all, it's to rigid and your speaker-mass is just too low. There's your problem. Now, finish that lemon and start crackin' !

Hi Stuart, unfortunately the damage is done already, just because I'm an idiot and act impulsively as per usual…my italianism kicking in I guess :-)…dismantling the front MDF panels I broke them…both!! would you believe that??!! :evil: I was soooo cross ( to use polite term)! Thus, since I'm at this stage I'll go ahead and take off the plywood layer too (which should be much easier to remove) and the insulation in order to expose the box. Then I'll remove the sorbothane around the case, throw it as far as I can :mrgreen: and re-frame tight around it. It does make sense to me what you're saying about building a three leafs structure the way I was doing it, so I'm gonna correct that before it's too late. Then after I'll put back the new MDF panels I'll make an acoustic test to see where I'm at. (p.s.) Thinking back to what I was asking above and answering my question by myself, I don't think it should a problem if the plywood layer is touching the box, as this is already screwed to the structure below (which the plywood is part of anyway), so there is no point at all to keep those separated….the only thing de-coupled from the overall soffit structure should just be the speaker, which has the sorbothane layer around it doing just that ---> Mass (speaker) + Spring (sorbothane) + Mass (rest of the soffit) - full stop! …. so in theory, as long as nothing else is in contact with the speaker (bridging the two Masses) the de-coupling should be maintained Ro - thanks a lot for your post ! "10% compression load" in order to work effectively… I've heard about this already…probably from you too before…it's just managed to find its way out from my little brain…argghhh :evil: !!! Having gone so far with the build, there is no sense in ignoring this resonance problem pretending it doesn't exist just because it's frustrating having to re-do it…otherwise I know I'll regret later down the line, when to intervene would compromise the rest even more. !! right, back to square one - wish me luck… and patience :-)

Oh Simo - All I suggested is you remove the sorbothane around the speaker and replace it with MDF - that wouldn't involve altering anything else.