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Jason Foi Studio Design - Tuning
Old 21st May 2019
  #31
That's an awesome garage, Jason. And I can't believe who's chiming in! What a great place to be a fly on the wall.

I like the table with decks by the way (although I sorely miss my Technics 1210's I am thinking about trying digital myself).
Old 21st May 2019
  #32
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Quote:
Originally Posted by Northward View Post
Each their channel L/R.
Ok, i'll check, but i dont think i have room to flush mount the subs. If not I'll get them as close as I can.
Old 21st May 2019
  #33
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Quote:
Originally Posted by thermal View Post
That's an awesome garage, Jason. And I can't believe who's chiming in! What a great place to be a fly on the wall.

I like the table with decks by the way (although I sorely miss my Technics 1210's I am thinking about trying digital myself).
Thanks man, yeah, Thomas is a good guy to get help from for sure.

This is my first controller, I've always used CD/Vinyl in the past, too. So far i like it, but it kinda feels like cheating at times.
Old 21st May 2019
  #34
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Quote:
Originally Posted by Jason Foi View Post
Ok, i'll check, but i dont think i have room to flush mount the subs. If not I'll get them as close as I can.
You don't have to! Like I said just put them against the wall under your mains on axis. Done. Set them up with a low LPF and play around with the Phase settings etc until they merge well with the mains.

The boundary / edge diffraction phase shift for such long wavelengths will be pretty much negligible.
Old 21st May 2019
  #35
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Could also turn the subs to face each other, drivers being perpendicular to the front wall? It buys a couple inches of distance.
Old 21st May 2019
  #36
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Quote:
Originally Posted by Northward View Post
To calibrate, bypass the monitoring section. Go from a good D/A straight to amps and use the same D/A output channel to calibrate so the source is absolutely the same. Select the flatest speaker and calibrate the other to match it.

Calibrate driver per driver until they individually match, which you can only do by accessing the trims in the amplifiers.
Thanks for further explanation. I’d never considered calibrating per driver, rather than per speaker unit (tweeter + woofer), but it makes very good sense if seeking a perfect match... albeit perhaps overkill for a small home studio like mine

Quote:
Originally Posted by thermal View Post
...I can't believe who's chiming in!
Aww shucks, you’re making me blush! Don’t mention it; I’m just happy to be here
Old 4 weeks ago
  #37
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Waiting for Jason to upload his new measurements...

Old 4 weeks ago
  #38
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You may be able to improve on it some by using the minidsp as a crossover, do you have it only connected as left and right or the subs on their own outputs from the 88?

To me it makes sense to also play with positioning the subs for best response with dirac running as well...You can set both subs to subwoofers in there IIRC. Possibly there is a placement that will have less resonances in the lowest octaves while still allowing the DSP to take care of the frequency response.

The only downside to that is DIRAC has a bit of latency...

Personally I would shoot for more a bass-up house curve, especially with both speakers playing together, the subs should sum to have a nice lift over the rest. You can also define a house curve in REW so the measurements still show as flat. I like the harmon curve, It's pretty bass heavy compared to flat, but I find mixes translate well. You can dial it back too.

You might also get some soft blankets to place on the desk etc (I think that fleece "cuddle" fabric works well to find where any ERs are coming from). Looking at the ETC and spectrogram it looks like there is a bit of reflections/diffractions in the first few ms.

Studio looks amazing and overall this is an great result!
Old 4 weeks ago
  #39
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Quote:
Originally Posted by Jason Foi View Post
Hello, for those of you who do not know, I have been in the process of converting part of my home's 2 car garage into a small home studio control room. I've finally finished construction and was hoping to get some help with the final tuning of the room.

My original design thread is located here at John Sayer's site: http://johnlsayers.com/phpBB2/viewtopic.php?f=1&t=20552
I have attached a Zip file which contains my SketchUp file for those who would like to download it.




Dimensions: 15.2 Feet (L) x 12 Feet (W) x 8.2 Feet (H)

Monitors: 2x Eve Audio SC208 Flush Mounted and 2x KRK KRK10S Subs.

DSP: MiniDSP DDRC88A-BM with Dirac Live

MIC: UMIK-1 with cal file.

For the attached *.mdat all speakers were playing. I have not yet used Dirac Live or any other DSP other than the onboard crossovers on the 2x KRK10S's (they can not be turned off, but are set to their max 90hz and 180hz) and a -6db low shelf centered at 465hz for baffle step compensation.

I have spent a bit of time measuring and repositioning subs and I think I have found the best possible starting point, but I would like to hear some opinions on my results before I move forward and implement DSP.

Thanks for your help!
would you mind showing the positions of the subs in a small diagram (including dimensions of the room) and the x-over settings you're currently using?
Old 4 weeks ago
  #40
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Quote:
Originally Posted by deedeeyeah View Post
would you mind showing the positions of the subs in a small diagram (including dimensions of the room) and the x-over settings you're currently using?
Sub position has changed dramatically from first measurements. Room measurements are in the first post, 15.2'Lx12'Wx8.2'H. I'll post new measurements tonight hopefully. I've been trying to implement Thomas's advice, successfully i think, but we'll see.
Old 4 weeks ago
  #41
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Quote:
Originally Posted by Skol303 View Post
Waiting for Jason to upload his new measurements...

Lol, soon
Old 4 weeks ago
  #42
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Quote:
Originally Posted by RyanC View Post
You may be able to improve on it some by using the minidsp as a crossover, do you have it only connected as left and right or the subs on their own outputs from the 88?

To me it makes sense to also play with positioning the subs for best response with dirac running as well...You can set both subs to subwoofers in there IIRC. Possibly there is a placement that will have less resonances in the lowest octaves while still allowing the DSP to take care of the frequency response.

The only downside to that is DIRAC has a bit of latency...

Personally I would shoot for more a bass-up house curve, especially with both speakers playing together, the subs should sum to have a nice lift over the rest. You can also define a house curve in REW so the measurements still show as flat. I like the harmon curve, It's pretty bass heavy compared to flat, but I find mixes translate well. You can dial it back too.

You might also get some soft blankets to place on the desk etc (I think that fleece "cuddle" fabric works well to find where any ERs are coming from). Looking at the ETC and spectrogram it looks like there is a bit of reflections/diffractions in the first few ms.

Studio looks amazing and overall this is an great result!
Thanks for chiming in! I have been using the minidsp for crossover and im using 4 channels L,R, L sub, R sub

Still havent added dirac yet, i'll keep it as a last resort.

For now, i'm going with a flat FR, but might add a house curve in the end. I just want to get a good calibration first.

I've been trying placing 703 over sections of the desk, and i really dont get a change in FR. Position of the desk doesnt do anything to the bigger nulls either. I've narrowed some phase cancellations, the only deep nulls in my FR, to the top slats on my backwall, but im pretty sure those will be blocked by my chair when im at LP. If not, f it, or i can add something to the slats to help scatter it if i must.
Old 4 weeks ago
  #43
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Comb filter

Quote:
Originally Posted by Jason Foi View Post
... I've narrowed some phase cancellations, the only deep nulls in my FR, to the top slats on my backwall, but im pretty sure those will be blocked by my chair when im at LP. If not, f it, or i can add something to the slats to help scatter it if i must.
Sorry,

but I guess you don't measure a listening-position with a back of a chair some
20 cm behind the microphone.

So why listening that way?

Best
Old 4 weeks ago
  #44
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Quote:
Originally Posted by akebrake View Post
Sorry,

but I guess you don't measure a listening-position with a back of a chair some
20 cm behind the microphone.

So why listening that way?

Best
I feel like i'm misunderstanding you. Why listen to music while sitting in a chair? Im not at LP for measurements either, should i not be in the room when i listen either?
Old 4 weeks ago
  #45
Quote:
Originally Posted by Jason Foi View Post
I feel like i'm misunderstanding you. Why listen to music while sitting in a chair? Im not at LP for measurements either, should i not be in the room when i listen either?
I have been measuring with my mic on a stand in the LP and moved the chair away. Just occurred to me that I would probably get a more realistic measurement if I'm actually sitting in the chair (somehow with the mic where my head is normally at)..? Or at least keep the chair behind the mic.
Old 4 weeks ago
  #46
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new *.mdat file attached

Measurements include the following:

L Main
R Main
L+R Main
L Main + L Sub
R Main + R Sub
L+R Main + L+R Sub
L Sub
R Sub
L+R Sub
Attached Files
File Type: mdat JFStudioV2.mdat (12.87 MB, 20 views)
Old 4 weeks ago
  #47
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Frequency response again looks excellent to my eyes

What stands out here for me is the excessive decay ‘bloom’ in the very low end around 27Hz (example plot below), which shows up no matter what combination of speakers you're running. In some plots it peaks at 65dB, which is significant - is it audible when the room is quiet; or during measurement sweeps?

Your room dimensions suggest that your lowest mode is at 37Hz, so my guess is that it’s something vibrating - e.g. drywall or the cavities in your soffits. Either that or it’s perhaps caused by your air con, or an external sound leaking into the room. If it's the latter, then you should be able to hear it as a constant, low background hum. If there's no audible hum, then it's likely caused by a resonance that's being triggered at that specific frequency.

During your next set of sweeps, I’d suggest trying some 'control' measurements with everything switched off apart from your speakers and computer - i.e. no lights, no air con, no Cadillac idling in the garage space next door This will help to determine what's causing some of the noise.

Hope that helps and again, I think you've done a great job here. I only wish my room had such a good response pre-DSP!

Jason Foi Studio Design - Tuning-l.jpg

[EDIT] minor point... but I'd also suggest boosting your subs and adjusting the crossover a little, so that their output better complements that of your mains (you can easily remove any excess if/when you run Dirac):

Jason Foi Studio Design - Tuning-subs.jpg
Attached Thumbnails
Jason Foi Studio Design - Tuning-l.jpg   Jason Foi Studio Design - Tuning-subs.jpg  
Old 4 weeks ago
  #48
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Quote:
Originally Posted by Jason Foi View Post
I feel like i'm misunderstanding you. Why listen to music while sitting in a chair? Im not at LP for measurements either, should i not be in the room when i listen either?
The aporia of the measure: where the body, the kind of seat (with the back behind the head) change drasticly what it's heared and what it's measured.
Old 4 weeks ago
  #49
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Personally, I always get myself and my chair out of the way when measuring.

I also swapped from a high-backed chair to a cheap office chair with a low backrest (similar to the photo below), because I figured it wouldn’t impede reflections from the rear and mean that my measurements (without chair) are more closely matched to what I hear when sat at the listening position (with chair).

But that’s all guesswork... I’m not an expert

Jason Foi Studio Design - Tuning-2d656be3-f659-42b0-bd4e-00e679ff3d98.jpg
Attached Thumbnails
Jason Foi Studio Design - Tuning-2d656be3-f659-42b0-bd4e-00e679ff3d98.jpg  
Old 4 weeks ago
  #50
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Quote:
Originally Posted by Skol303 View Post
Frequency response again looks excellent to my eyes

What stands out here for me is the excessive decay ‘bloom’ in the very low end around 27Hz (example plot below), which shows up no matter what combination of speakers you're running. In some plots it peaks at 65dB, which is significant - is it audible when the room is quiet; or during measurement sweeps?

Your room dimensions suggest that your lowest mode is at 37Hz, so my guess is that it’s something vibrating - e.g. drywall or the cavities in your soffits. Either that or it’s perhaps caused by your air con, or an external sound leaking into the room. If it's the latter, then you should be able to hear it as a constant, low background hum. If there's no audible hum, then it's likely caused by a resonance that's being triggered at that specific frequency.

During your next set of sweeps, I’d suggest trying some 'control' measurements with everything switched off apart from your speakers and computer - i.e. no lights, no air con, no Cadillac idling in the garage space next door This will help to determine what's causing some of the noise.

Hope that helps and again, I think you've done a great job here. I only wish my room had such a good response pre-DSP!



[EDIT] minor point... but I'd also suggest boosting your subs and adjusting the crossover a little, so that their output better complements that of your mains (you can easily remove any excess if/when you run Dirac):

Thanks for your input again. The LF bloom and noise floor are the only things that bother me too. I tried playing pink noise from from REW at 10hz to 40hz and walked around the room listening and touching, and i dont really hear/feel anything vibrating. The only source of LF noise that i hear is my pc isolation cabinet. I'll try bringing the mic closer to it too see if the noise floor level changes at those frequencies. I also wonder if it has something to do with the umik-1 usb mic giving feedback some how. When i stay in the room for sweeps and while listening to music, i just dont hear anything ringing out, and i expect that i should at those levels.

I lowered the curve on my mains crossover from 48db to 24db and that fill out the low end a tad more.

In all honesty, the room sounds freakin fantastic as is, and at this point i'm not even sure if i want to use dirac or not. The measurements look better than i expected them to look without it.

Ps. My chair is lower that i thought it was when i wrote the other post. The back stops at my shoulders. I'll still have that dip at +/-650hz
Old 4 weeks ago
  #51
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Quote:
Originally Posted by Jason Foi View Post
I also wonder if it has something to do with the umik-1 usb mic giving feedback some how.
I think you could be right! I just had another looks at your waterfall measurements and extended the time range to 1 second, and many of those peaks (including the big one in the low end) are still ringing out, with no noticeable drop in strength - pretty much steady signals, like an electrical hum. So this noise could indeed be caused by a fault in the mic or somewhere else along your signal chain perhaps - ?

I don’t suppose you have another mic to test with? Might not even need to be a measurement mic for the purpose of this test (ie. checking whether the same peaks appear in the noise floor and decay plots).

Might also be worth a message to the miniDSP devteam to check whether it’s a know fault.

Two other tests I found useful when tracking down hum in my room:

1) Separate RTA measurements with the speakers turned on and off to check for hum.

2) Run a frequency sweep in REW with the speakers turned off. If it’s a problem with the mic, then I’d expect the same pattern of decay peaks to be clearly visible even when the room is silent.

Hope that helps. Keep digging!
Old 4 weeks ago
  #52
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Attached is a new set of measurements which include processing by DiracLive

Attached Files
File Type: zip JFStudioV3WithDirac.zip (11.83 MB, 16 views)
Old 4 weeks ago
  #53
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double
Old 4 weeks ago
  #54
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Measurements looks great to me
Old 4 weeks ago
  #55
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Quote:
Originally Posted by JayPee View Post
Measurements looks great to me
Thank you
Old 4 weeks ago
  #56
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Quote:
Originally Posted by JayPee View Post
Measurements looks great to me
Ditto! Looks great Jason.

Interesting to note that Dirac has significantly reduced that low end 'bloom' in your waterfall plots, which suggests it must have been an acoustic issue after all.

PS: I reckon that desk reflection at ~650Hz is so narrow you won't even hear it.

Time to crack open a cold one and start making some music! *

*cowbell optional
Old 4 weeks ago
  #57
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Quote:
Originally Posted by Jason Foi View Post
For now, i'm going with a flat FR, but might add a house curve in the end. I just want to get a good calibration first.
For sure, my only thought there would be to play with both. It's been my experience that sometimes with DSP you can place subs in a way that has for instance a worse FR, but a better sliced ETC or spec etc. If the FR can then be corrected, the sum can be more than the parts type of thing. YMMV of course.

Quote:
Originally Posted by Jason Foi View Post
I've been trying placing 703 over sections of the desk, and i really dont get a change in FR.
I've never gotten 703 to work for diffractions or high incidence angle reflections, as Thomas mentioned I think the surface impedance is too high. I've had better luck with dacron or cuddle fabric (the super plush fleece). Also terrycloth seems to work- even wedge or egg foam doesn't work. I have a cool looking fabric above my tweeters covering a cloud/soffit and was getting reflections off of it, the cuddle fabric took care of it.
Old 4 weeks ago
  #58
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Quote:
Originally Posted by Skol303 View Post
Interesting to note that Dirac has significantly reduced that low end 'bloom' in your waterfall plots, which suggests it must have been an acoustic issue after all.
Lol, i had the pc audio out being sent to the dj controller to the scarlett. When i switched pc audio out to the scarlett, it dropped considerably.
Old 4 weeks ago
  #59
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Quote:
Originally Posted by Jason Foi View Post
Lol, i had the pc audio out being sent to the dj controller to the scarlett. When i switched pc audio out to the scarlett, it dropped considerably.
Aha! Even better. Good to finally know what the cause was
Old 4 weeks ago
  #60
I didn't manage to open that file in REW, says it's not in mdat format?

Quote:
Originally Posted by Skol303 View Post
Personally, I always get myself and my chair out of the way when measuring.

I also swapped from a high-backed chair to a cheap office chair with a low backrest (similar to the photo below), because I figured it wouldn’t impede reflections from the rear and mean that my measurements (without chair) are more closely matched to what I hear when sat at the listening position (with chair).

But that’s all guesswork... I’m not an expert

This confirms what I have been noticing for a while - that I hear sound more clearly when I move my head further away from the headrest. I didn't understand it because I thought the headrest would be a positive rather than a negative, but it evidently is not! When practicing on SoundGym I found myself constantly moving my head forward in order to hear things better. I'm going to check if I can take it off right now.
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