New Design

[gullfo]

on the duct size - if you use 16" duct, then expand into a 24"x24" soffit plenum and 24" flex if routing, then you'll have a 3:1 on the plenum or 2.25:1 on the duct so basically a 2x-3x speed reduction in the room. so even if you went with a 12" duct in the ceiling w. 20x20 plenum or a 20" duct in the room - it's still a 2x-3x reduction... so if you make the smaller attenuator boxes (12" vs 16") and get the air velocity to say 300fpm, then you're going to get down to 100-150fpm in the room side and further reduction based on the vent openings.

[1970428scj]

OK yes , So I am now down to building just 4 baffle boxes per room, once through the 2nd ceiling leaf , to Plenum, and from there I can spread the vents out via the soffit.
The units I decided on ( in stock locally) Mitsubishi PUZA36NKA/PEADA36AA8 This is the P Series which is a light industrial series. Have you ever used these? M series was backordered for 3 months, or at least that is what they say

[gullfo]

it probably doesn't matter M or P -- although keep in mind they're running 100% of time your rooms are occupied... so check for continuous operation specs.

why 4 per room? why not 2? supply and return. you only need the attenuator at the interior junction. then route via soffit ducting in the room. or am i missing something in your mass layering?

[1970428scj]

Glenn, you are correct that is my bad. I was thinking 4x for both rooms 2x iso booth,
As for vent lay out, supply and return, what would you think is best for live room and control room, 2 large? 4 mid size? or does this need to be calculated? And what vents/ register brands have you used or do you?

I see Mitshubishi has ERV but they are way more than a Panasonic? Do the Mitsu ERv since with the thermostat vs on a separate on off

[gullfo]

the ERV should simply be on when the AC is on. and the fans on the AC should be running 100% whether or not the compressor / cooling / heating is running so the air is circulating (not only efficiency but also fresh air). on the venting - if there is enough linear space on the soffits, i'll go with several medium (32") to large (48-60") 5-slot slot diffusers to ensure as even a distribution as possible and to ensure best cross-flow so no dead corners etc. you need air volume moving at a glacial pace vs smaller volume at a faster pace.

you cannot hear it but your microphones can. in the CR, if you're not regularly doing live recording in there (e.g. guitarist on the couch, vocalist etc) then you can accept a bit more air noise there -- ensuring it's symmetrical to the listening spot. live room and isolation room -- low, and very low respectively.

[1970428scj]

Thanks Glenn, So if my room is 19'x27' Is it better for both supply and return to be on opposite sides running the long way?
Should the baffle box, Plenum be in the center of the soffit ? In other words the supply/return soffit is a T?
Off the in soffit plenums I would take 4x 8" ducts to 4 vents on both supply and return?
Soffit vents should face sideways of down?
The reason for the ERV question was the Mitsubishi brand is $2700 compared to a Panasonic at $1000
Mitsu is 300cfm and probably has integrated control with their Hvac, where as the Panasonic will require its on separate control. At this point spending $25k on the system not sure if its worth the extra $$ , Money is getting tight but I am not about to stop over $1700 more

[gullfo]

i would run, facing down, 4 24" diffusers spaced 36" apart, group centered along long walls. run the attenuator at middle above the ceiling if possible so you can tee off that entry to the 2 slot diffusers on either side.
example: https://www.linearslotdiffusers.com/col ... ear-3-slot
https://www.linearslotdiffusers.com/col ... lot-plenum (or build your own)

[1970428scj]

If the supply is centered , 4 every 36" or T'ed where is best for return

[gullfo]

sorry - 36" vents on 72" for the large room. tee in the middle. might need some baffle or sizing to even the distribution.

[1970428scj]

Awesome! What size inlet duct is being used?

[gullfo]

in this example? 16" I.D. w/ 24"x24" duct board or lined ducts (technically 22"x22" inner measures w/ 1" duct insulation).

[1970428scj]

What is the best duct to use when piercing through a leaf? Flex duct or metal?

[gullfo]

for larger projects, i like to use 2 inter-leaved duct board "sleeves" with the air channel being flex duct. this keeps the flex duct from contacting the rougher materials and the duct board is more easily sealed to it's respective layer. the inter-leaving allows for shifting and remain decoupled. for smaller jobs - i add a larger size flex duct around the air channel one and seal layers to the wrapper - using round take-offs to form the edges on the wrapper ends.

[1970428scj]

From my Hvac space I will go up through the ceiling to the vented roof, this will not effect the 2nd leaf wall or ceiling to the studio. So I assume this is flex duct or metal duct , isolation at this point is as normal home install?

Do you have any examples of drop ceilings (leaf 2) for Live room and control room?

[1970428scj]

There seems to be no edit button on earlier posts I made , Is there a way to edit ? Am I missing something?