I just came across your thread again, Dave, and was wondering how it all turned out in the end? It's been a while, so I guess the studio is completed by now?
I must admit, it was looking pretty darn good in the end: both the photos of the room and the REW data. A huge improvement over the way it was originally!
Got any "final" photos and data? I'd really love too add your thread to the "Finished Studios" hall of fame... Your thread is a testimony to what can be accomplished in a small room on tight budget, with careful analysis and careful design.
Krakadon wrote:Here is my latest update. I'm not sure how much more I will do until I replace my KRK 10S (planning to buy an Adam Sub10) and measurement mic. Hopefully over the holidays I can find time to empty the room for baseline characterization. How much I do now depends on the feedback I get from people. I am pleased things are moving in a positive direction but there is still a lot of room for improvement...
UPDATE 171118
Completed:
• Repositioned subwoofer (after testing many positions) to optimize low end response
• Repositioned sidewall broadband absorbers to get into reflection zone
• Added equidistant 1.5” vertical slats (70% coverage) set 1.25” from face of rear broadband absorber on each side which is not in reflection zone
• Added 2’x4’x3/16” wood panels (horizontal orientation) with equidistant 2.5”d circles (70% coverage) to the face of the top corner treatments on the side walls and rear wall
• Added 2’x4’x3/16” wood panel (vertical orientation) with equidistant 2.5”d circles (70% coverage) to the face of the top corner treatments on front wall (they curve up over the top of the ceiling cloud)
• Took new REW measurement.
• Updated slides.
Planned:
• Upgrade RadioShack SPL meter and Behringer ECM8000 calibration mic
• Replace KRK 10S sub with Adam Sub10
• Remove everything from room and do baseline characterization (this will take several days and take my studio off-line so I don’t know when I can get to this. All of the other stuff I can do in the margins so to speak, maybe over holidays).
• Solicit input
Hi Krakadon!
Impressive improvements!
How did you manage to tackle that sharp 100Hz dip? And what was it's origin?
Great work. I recommend you taking a moment to ceremonially smash the RS SPL Meter. An utter POS.
The Behringers vary wildly at HF, and I just skim reading I don't know if you pointed the mic 0 or 90 degrees? So let's be sceptical about absolute HF data.
That aside, a Flat Response at the listener position would be similar to listening to speakers in an Anechoic Chamber. Or using Audiometric Headphone. i.e. Brighter than a normal domestic response by 1dB per octave. i.e. 6-10 dB tilted out of whack with reality.
Also, it is quite common in fibre treated rooms to see that dryness in the warm low mid region.
This seems to be compounded by you including a lot of HF reflection. Your decay spectrum is boom and tizz.
I would recommend immediately using the Eq on your speakers to get something close to a 6dB tilt between 100Hz and 10KHz. The Bruel and Kjaer Curve. I had S3A's for years. +6dB LF -4dBHF. This sounded absolutely crystal clear, don't be afraid to turn knobs, they are only an extended crossover.
I spoke with Adam and they said the acoustic center (in their parlance, they won't say "acoustic axis") is between the tweeter and woofer and that they couldn’t be more precise than that (basically they said it was proprietary).
That's pretty dumb of them! It's a key parameter for correct speaker set-up! Take a look at other manufactures, such as Genelec, Barefoot, and K&H; They put out publications that show the exact location of the acoustic axis for all of their speakers, because it is important!
[...]
So anyway, since Adam doesn't want to help one of their customers with important information, we'll guesstimate intelligently. Or cheat! I've used the A7X in several studios, so I already have a model with my best guess:
EQUIPMENT--SPEAKER--Adam_A7X-S03.jpg
I emailed Adam support with the same question about my S2X, this was their reply: "the acoustic axis is located directly under the tweeter, at the level of the lower screw."
It may not be directly applicable to your A7X, but hopefully it can help others.
ADAM are by no means dumb. I asked about vertical orientation of the S3A some years ago. Within hours they generated polar plots both horizontal and vertical, including rotating the tweeter which is easily done. Afaik since then they have included vertical orientation in their writing. It is way better in terms of horizontal dispersion. I am not sure how Acoustic Axis is defined, but most things Acoustic or Sonic become clear when Frequency is introduced. Clearly at HF where sound is coming from the tweeter only, the AA IS the tweeter.
Similarly LF.... In between is a sliding scale obviously. But in the crossover region both drivers will overlap, thus a mid point notion.
There is an idea that these components 'sum' at a little distance away from the speaker. Really? Well even it one accepts that idea, the sources are certainly not coincident, but rather occupy an area. Again the Spectrum, HF radiation is ray like, LF is balloon. In dealing with specific areas of reflection I would focus on the tweeter and a circular area around it.
Your thread is a testimony to what can be accomplished in a small room on tight budget, with careful analysis and careful design.