SIMO Studio - Construction Phase

By the way, while we're on the topic of grounding, something else you might consider ... Many of todays effects and audio gear are powered via adapters - wallwarts. As such these devices have no grounding and are simply floating. Under some configurations these too can cause ground loops and sometimes need to be grounded. So you might want to provide near (some of) your receptacles, a binding post or banana jack tied directly to ground (because of proximity these can be tied to the local receptacle ground). Case in point: Sometimes I digitize vinyl records - recording, cleaning, and burning onto CD. I plug my turntable into a small soundcraft mixer (because this has a built-in RIAA filter). The turntable (as many do) has and requires an additional ground wire (otherwise it hums). The mixer which has a grounding binding post on the side just for this eventuality, is powered by a wallwart so there is no real grounding at the mixer. If I go directly to an amp, usually the grounding over this path is sufficient, but if I route through my main mixer and into my PC the hum is evident. So I've included a green banana socket mounted on the panel where I usually power the Turntable and I simply plug a wire between the small mixer's ground lug (which also accepts a banana jack) and this socket - problem solved. FWIW

Thanks for your input Brian, very helpful indeed! I've just emailed my electrician, so hopefully I should be able to make it a bit clearer very soon. Great tip the banana jack tied directly to ground…I do use turntables too so that option could be handy. ciao simo

...Ok this is what my electrician told me:

BriHar wrote:

It looks like your Electrician is branching 3 phases to the out-building (or is it 2 phases and neutral?)

It's Single Phase (1 Live, 1 Neutral, 1 Earth)

BriHar wrote:

I had assumed a sub panel off the main panel but in this case it is being treated as a separate service i.e. parallel (split after the meter), in which case the original grounding scheme may indeed be correct particularly if the neutral has to be spearately established.

It's split off Hanley block from Main Supply (small garage board in house and Main board in studio).

BriHar wrote:

2.5mm² being specified for your circuits then I assume your branches are 25 or 30A

Lighting (6 Amp), 2 x Ring circuit (32 A) Hope it makes sense :?: :) ciao simo

Single phase, two would be preferable (isolation of audio circuits a described earlier) but perhaps you only have the 1 phase available. Still, I wonder the 16mm² wiring - do you mean 16mm² cable (i.e. containing all 3 conductors)? OK I checked, in the UK this is apparently the diameter of the whole cable - OK.

It's split off Hanley block from Main Supply (small garage board in house and Main board in studio).

Terminology problem here, never heard of a Hanley Block, you refer to 'main supply' and 'main board' then 'garage board',and that being in house while 'main board' is in studio ... now I'm really getting disoriented. Regardless, as I now understand it Somewhere the power is delivered to your property, and this then goes to a meter from whence it is fed to the buss bars (Hanley block?) of your distribution panel. Here too, the Neutral and ground buss are bonded to a rod driven into the ground in the near vicinity. From this Panel your (16mm²) 3 conductor cable is attached directly to the hot, neutral and ground busses, and this cable goes to your distribution panel in the studio. The main point of this was simply to determine the necessity of a separate ground rod. Regardless where what panel is, the description of your service shows that a separate ground rod is not required. Again, star-grounding is all about potential - a common grounding, potential reference for all devices and gear in the studio. Exactly where it physically bonds to the grounding rod is not so important - but also why I recommend the heaviest gauge wire for this connection as is feasible.

Hi there, Here is the updated drawing of the electrics for my studio: Brian, I hope I can answer your questions with that :-) …but, quickly:

BriHar wrote:

I wonder the 16mm² wiring - do you mean 16mm² cable (i.e. containing all 3 conductors)?

Yes, it's a 16mm² SWA (Steel Wired Armoured) cable containing all three conductors.

BriHar wrote:

Terminology problem here, never heard of a Hanley Block, you refer to 'main supply' and 'main board' then 'garage board',and that being in house while 'main board' is in studio ... now I'm really getting disoriented.

What they call Henley Block here is a junction box (essentially a splitter). The small consumer unit in the house, what he call "garage board" (after the henley block), which has it's own main switch and a 50A circuit breaker, is there to avoid that if something trips in the house (washing machine, fridge, etc..) it won't affect the studio.

simo wrote:

The main point of this was simply to determine the necessity of a separate ground rod. Regardless where what panel is, the description of your service shows that a separate ground rod is not required.

For what he told me, actually there isn't a rod into the ground in the house. He said that here in UK the rod is outside (before entering the property) and so it comes in already 'earthed' (this is different for houses in the countryside and/or for out buildings). And that's why he was suggesting to have a separated rod for the studio. Hope that makes a bit more sense…(?!) Please let me know if I'm missing something? Many Thanks ciao Simo

Hi there all, I'm presently enquiring about HVAC systems as I can't postpone it any longer and so should be the next step in my build. So far I've received three quotes from companies that have experience in HVAC system for studios. The result is that they all are WAY too expensive for my pocket, so I need to think of alternatives. Comparing these quotes, one common point is that all of them opted to install one SPLIT ducted heat-pump A/C system per room (1 x 5kw for the control room and 1 x 3.5kw for the live room), with ducting and in-ceiling attenuators plus a fresh air system. In my studio, the option of installing a SPLIT HVAC system becomes unsuitable as the void between the outer and inner ceiling is minimal (only 35 cm). This makes it very difficult to fit the fan coil unit in such a small space. For this reason I was considering to install a MINI-SPLIT AC system instead (one per room), and provide Fresh air through a separated ducting system. That should be sufficient, right? Since my understanding of  HVAC is very limited (just about the same as my knowledge of electrical systems :oops: ) I was wondering whether you could check if the following is correct: From what I understand a MINI-split system does not have any ducting at all, as the only connections between the outdoor unit (Compressor) and the indoor wall mount unit is a Refrigerant and an Electricity piping connection. So the question is :shot: : Using this approach, do I need to use the ducting (with silencers) JUST on the system providing fresh air in and exhausting stale air out (as it's the only connection with the outside world)? or I'm missing something? Also, being that the fresh air supply is not connected to the AC system (or at least I don't see how it could be done?!), does this mean that it won't be possible to condition the fresh air (heat it or cool it down)? Any help to clarify this issue is much appreciated !! Many Thanks ciao Simo

For this reason I was considering to install a MINI-SPLIT AC system instead (one per room), and provide Fresh air through a separated ducting system. That should be sufficient, right?

Yup! That will work just fine.

From what I understand a MINI-split system does not have any ducting at all, as the only connections between the outdoor unit (Compressor) and the indoor wall mount unit is a Refrigerant and an Electricity piping connection.

Exactly. Normally there are two pipes and one electrical cable.

So the question is: Using this approach, do I need to use the ducting (with silencers) JUST on the system providing fresh air in and exhausting stale air out (as it's the only connection with the outside world)? or I'm missing something?

Exactly. You'll need two silencers per room, one on the incoming fresh air duct, and one on the outgoing stale air duct.

Also, being that the fresh air supply is not connected to the AC system (or at least I don't see how it could be done?!), does this mean that it won't be possible to condition the fresh air (heat it or cool it down)?

That depends on how you route your incoming fresh air! If you arrange things so that the register on the end of the fresh air duct is right next to the intake grill on the mini-split, aimed right at it, then most of the fresh air will get sucked straight in to the unit, and be conditioned before it goes into the room. :) In that case, you should have the intake register for the stale air duct on the other side of the room, hopefully high up, where the hottest and "stalest" air will be in the room, near the ceiling (or in the ceiling), and as far as possible from the inlet/mini-split, in order to not suck out and throw away air that has just been brought in, cooled and de-humidifed. So try to put those exhaust ducts where the hottest, dirtiest air will be in the room. You will still need fans in all of the inlet/exhaust ducts, to move the fresh/stale air into and out of the rooms. Those fans need to be sized correctly to move the right amount of air for each room (CFM / room changes per hour, or whatever else you calculated). - Stuart -

Stuart - Thanks so much for your advice man, Very kind and very informative as usual !! I'll make a sketch as soon as I can and will post it to see if I'm on the right track. Grazie ! Simo

Hiya ! Here is a sketch of how I was thinking of doing the fresh air in / stale air out system - hope you can follow it. I made it just for the control room, but obviously the idea applies to the live room as well. I've got a few questions BUT let me check first if I'm on the right track, just to avoid wasting mine and your time :-) Any advice or suggestions always very welcome! ciao Simo

The air plan looks fine to me, but I'm wondering why your "main studio ceiling frame" does not go all the way to the rear wall and the front corners! :shock: :?: The frame only goes as far as the front of the soffits and the edge of the rear bass traps. ??? - Stuart -

Soundman2020 wrote:

The air plan looks fine to me

Great, Thanks Stuart!

Soundman2020 wrote:

I'm wondering why your "main studio ceiling frame" does not go all the way to the rear wall and the front corners! :shock: :?: The frame only goes as far as the front of the soffits and the edge of the rear bass traps. ???

Fair question :-) The front soffit, the slot resonator on the right and the rear bass traps are all closed at the top with two layers of 15mm plasterboard (given the small void between outer and inner ceilings, it was much easier to build the frame that way). On my previous post I exported the 2D graphic from SketchUp with their level hidden, just to be able to show better the fresh air plan :-) ciao Simo

OK, that makes sense. Smart idea! - Stuart -

Right..bad news…the budget is drained ! :( As it stands now I won't be able to do the air con at this moment . If i did, I'd be left with just stud walls and a beautiful HVAC system BUT nothing else :horse: … so now the plan is: I AM going to do the fresh/stale air in/out system as I understand that step can't be skipped ! Then, after the studio is finished and hopefully bringing some money in, install the two mini-split systems at a later stage. Also, as the fresh air system is the only part of the HVAC that needs to be in the void between the two ceilings (as the two mini-splits will be mounted on the walls), I will finally be able to close the ceiling frame with the plasterboard layers and crack on with the rest of the build ! When the time comes (I hope very soon), I will position the wall-mounted part of one system on the back of the control room. Then another one will be mounted on the live room (on the wall opposite side of the window). Luckily both these walls are built inside out (i.e. two plasterboard layers attached to the stud frame, insulation between studs and a cloth stretched over it)…. so it should be fairly easy to remove the cloth and insulation, and drill the holes to pass through the piping from the inside unit to the condenser outside. I will make those parts easy to remove with a drill driver, to make this step as painless as possible. So the fresh air WILL BE there, and the conditioning will be temporarily provided by a portable electrical heater (if cold) and by opening the door from time to time (if warm). :oops: I know that it's by no means ideal (and I'm indeed disappointed :cen: ) BUT there's nothing else I can do as the money is simply not there at the moment and I have to think of alternatives to get me going and make all this effort worthwhile! I read many times the HVAC chapter of Rod's book, and I'm particularly aware of his introduction "Re-work is always a lot more expensive than doing it right the first time. So save your money, keep your sanity, and plan for this now". But by doing it this way, I hope that I'm minimizing any rework in planning for the air con to eventually be placed. … but what are your thoughts? Would that work? Any thoughts much appreciated as usual ! Simo

…the budget is drained !

Bummer! :( :cry: :!:

I AM going to do the fresh/stale air in/out system as I understand that step can't be skipped !

Yup! People have this silly habit: we like to breathe... :) If we could get over that, then we wouldn't need to ventilate our studios!

… but what are your thoughts? Would that work? Any thoughts much appreciated as usual !

As you say, it's not ideal, but if that's the only option you have, then that's what you'll have to do. It will work, but bare in mind that without A/C you won't have any de-humidification going on, so there's the associated risk of problems related to high humidity in your room. Especially considering where you live: London isn't exactly known for its extreme dry weather, and desert-like climate! :) :shock: So maybe consider putting a portable dehumidifier in there, if you notice humidity issues. Also bare in mind that when you do put the mini-splits in eventually, that will necessarily involve some destruction of your isolation walls: The installers will have to cut holes in them to pass the pipes through (normally two copper pipes for the coolant, plus a condensate drain pipe, plus an electrical cable), all grouped together. That's going to need a lot of attention when they do that, since that bunch of lines is a potential flanking path, and the holes are potential major weak points. So that part will need to be done with care, in order to get you back to the same level of isolation. You cannot just do what the HVAC installers will want to do, and are used to doing: Cut two holes through the two leaves directly opposite each other, and run the group of pies straight through! Bad idea, on all counts. The holes cannot be opposite each other: the must be separated by as large a distance as you can figure out. Since your walls are going to be inside-out, that presents a problem as to how you are going to isolate and decouple all of that! The electrical cable and condensate line are not too much of an issue for flanking, since they are usually light and flexible: you can loop the cable inside the wall and hang it from above, and you can route the condensate line carefully (making sure to keep it always sloping down, never up), but the coolant lines are a problem. They are probably copper, and usually at least the return line is wrapped in a thick thermal insulation cover. There needs to be enough space inside your wall to deal with all that, and stop them from creating a major flanking path between the two leaves. One way of dealing with that is to curve the pipes as soon as they get through the inner leaf, then route them over a long distance (up, down, sideways, maybe even in a loop or spiral), before curving them again to go through the outer leaf. And of course, do not let the copper contact the drywall directly: seal the holes really well with acoustic caulk. etc. It's much easier to do all that with the walls open, before you put the drywall on: doing it afterwards is a pain. Like Rod said: it's a pain to retro-fit! So all of that is going to need some careful planning in advance: How are you going to replace that section of drywall that you need to remove in order to do all of the above? That should be considered now, in advance, before you even start building the wall. It will be too late to do that once the wall is built. (Or rather, it can still be done, but there will be compromises, and it won't be easy, or cheap.) - Stuart -

Thanks for your input Stuart, all good points as usual ! I had a sort of idea of how to minimize the destruction and replacement of my isolation walls, but that actually involved cutting a hole through the two leaves directly opposite each other. :oops: …what you say (curving the pipes as soon as they pass through a leaf in order to have the two penetrations as far away as possible) makes a lot of sense, and I now understand why it is not a good idea doing it the way I was planning. Thanks for pointing that out ! I guess my only option now is to see if I can securely plan it taking that into consideration, or otherwise wait and stop the build for some funds to do the installation before the access to the gap between the leaves is totally obstructed. ciao Simo

One option that comes to mind, is to do one single stud bay "conventionally" instead of "inside-out". In other words, the two studs right next to where the A/C unit will go could have their drywall on the room side, instead of the cavity side. You could then use that location to do all the "pipe mangling", have good access for sealing everything carefully and making sure it doesn't touch structures, plus you'll have an extra 3-1/2" of depth to work with, and the final drywall can be attached easily from inside the room. If you run your pipes almost vertically in the wall, that should give you plenty of room to keep the inner-leaf and outer-leaf penetrations far apart. The only drawback is how you fit that single "conventional" stud bay into the overall acoustic plan for the rest of the "inside-out" wall. But I reckon that should be easier than the alternative! :) If you plan things carefully, there should be no acoustic problems from having just that one small section of wall the "other" way around. - Stuart -

Great idea Stuart !! and fitting that "conventional" section into the rest of the build shouldn't be too difficult… I think it's just a matter of having one additional stud on the left and one on the right (screwed and caulked to the ones already there) (pic 2) and then attach the drywall to those from the inside of the room (pic 3) Simo

Great idea Stuart !!

That's what you're paying me so much for! :)

I think it's just a matter of having one additional stud on the left and one on the right (screwed and caulked to the ones already there)

You could do that, but you don't really need to, unless you were planning on more than two layers of drywall for your room. The goal is to retain the same surface density throughout the wall: Drywall and wood are roughly the same density (around 700 kg/m3), so as long as you have the same thickness all the way around, you are fine. Two layers of drywall (32mm) is actually thinner than one stud (38mm), so you are fine with just one stud. Of course, adding the extra one certainly won't do any harm! It's always nice to have a safety factor in there, and ensure a better seal too. But in theory you could get away with just the single stud that's already there. Your diagram looks exactly like what I had in mind! :) - Stuart -

Thanks a lot for your steady assistance - much appreciated - really!!

Soundman2020 wrote:

That's what you're paying me so much for! :)

:oops: :oops: I'll be the first buyer of your book though :D :D

:thu: - Stuart -

Hi While planning a strategy for my HVAC, I'm trying to get on with other things (no time to loose!), so now I'm about to start building the speaker boxes. Here is a sketch of my plan: - frame with a 18mm OSB plate attached to the back of the front studs - 18mm plywood plane (with vent) - speaker box (lined with a 5mm sorbothane sheet) - vents on the speaker box at the top and the bottom - opening for the cables (on the back of the speaker box) - 18mm baffle plate (plywood or OSB), levelled with the speaker box. The speaker is 12mm out in order to be levelled with (BUT not touching) the next "finishing:" layer, which is a 12mm timber plate (see next pics) - 12mm timber finish - 2mm gap between the speaker and the timber finish plate (filled with acoustic caulk or soft rubber), in order to decouple them Is this ok? or there's something I'm missing or that could be improved / changed? Also (I know I already asked this :oops: , but :lol: …), I'd like to have a packing strap or heavy string around the speakers (in order to be able to pull them out if needed), but how would you hide their ends for a neat finish (so they don't hang out from the 2 mm gap between the speakers and the timber finish) ? Thanks! ciao Simo

…or another option would be: - the speaker front is flush with the case - which is 12mm out from the baffle plate - the 12mm timber finish will end against the speaker box edges - a 2mm wood trim will cover the remaining visible part of the speaker box It's a slight variation from my previous sketch (everything else remains as posted on the post above). This one seems to hold the speaker more securely (and perhaps it'd be easier to build too with less margin of error). Don't know whether the 2mm wood trims would compromise the soffit effectiveness, even being just 2mm thick? Which one would you recommend? Thanks ! ciao Simo

the 2mm trim should not be an issue and you can tuck the packing strap ends under it to hide them. you might increase the depth of the padding around the speaker to at least 12mm.

Here's an off-the-wall idea: Maybe attach the trim with Velcro strips behind it, so you can get take it off easily to get access to the packing straps? Not sure if that would work: It just came to mind when I saw Glenn's post. - Stuart -

Thanks Glenn for your clarification and Thanks Stuart for the Velcro strips idea ! Much appreciated ciao Simo