Frank Stearns
April 9th 15, 08:56 PM
Thanks to all who responded to this thread...
To answer the questions/comments posed:
- The room is 1st order Eigentone, just like the last one, with double sheet rock
walls and ceiling, and a fairly dense floor. The Eigentone dimension means that LF
energy build up, while still present, is more even and tends to stay near the
boundaries. This is what the measurements show. +6 to +10 dB build-ups exist near
the boundaries (but by no means the unweildy +12 to +18 you'd find in a typical
room). No deep nulls exist at any place else in the room. The actual dimensions are
in the 11x15x8 range, but that's not exact.
- The room is well treated, with various modes of difussion, absorption, reflection
and LF trapping (19 traps of various depths and dimensions, including 6 angle traps
going up and down the rear corners and left/right upper sides -- probably the most
effective trapping considering the size of the trap).
(To Gary: no, this is not a case of overly damped HF leaving behind more LF. Plenty
of diffusion and reflection happening.)
- Neil and Scott's sub-20hz idea is interesting, and one wall-spanning rear-room
trap is quite large and deep and likely easily dipped into the sub 20 hz region.
However, I switched to a lighter-mass diaphragm to get a little higher usable range.
Saw no diff with the main issue of a slight and broad LF rise, nor in the sub 20 hz
region (but who knows if the measurements were of much use below 20hz). This
diaphragm change did yield some taming higher up, between 25 and 60 hz, at the
client couch toward the back of the room.
Any suggestions for a measurement system that might give me better data below 20 hz?
- Analog filters, passive or active, are non-starters for many reasons.
- Fortunately, the EQ required is not extreme nor with peaks and dips all over the
place. For my faux room EQ inside a PT session I've used three filters in two EQ
plug-ins. First, -3.5 dB shelved so that the transition to flat starts at 200 hz and
gets there by 300 hz. Then, one narrow -4 dB notch at 31 hz and one very narrow +4
dB peak at 300.
This measures closer to flat though not all the way there by about 1.5 dB. As one
poster replied (and I agree) making it absolutely flat might not be the practical
ideal nor sound the best.
(I was just listening to a mastering proof of a CD I finished mixing for a Sony
Records affiliate. This was on my cheapo shop boombox and things in the low end
translated very well.)
- I have indeed done many physical measurements trying to relate distances to
frequencies. (Years ago I wrote a handy little app that given wavelength, period, or
frequency, calculated the other two.)
But the relationship just is not there directly -- that's been one of the nutty
things. I suspect the problem might be one of those diagonal interactions I've read
about -- less obvious than the typical standing wave between untreated parallel
surfaces, but still a potential issue.
- it also might indeed be room gain; this room is slightly more solid than the old
room, at least in the flooring (old room was also double sheetrock, wall and
ceiling), so perhaps not as much is getting passed through the floor here.
- Problem with the DEQX or Trinnov is the expense (US$5K for the DEQX and the
Trinnov might be even more). I only need the digital portion of what they do -- so
that's a lot of money in those boxes that would be unused -- assuming they've given
the care they claim to the analog outs. (I already have a pristine and somewhat
expensive analog path from the monitor controller out to the crossover and
amplifiers that would be hard to match; don't want to lose that.)
- The main diff in this new room compared to the old room is the size and shape of
the soffits. These are toe'd in at less of an angle, are not down-angled, and are
somewhat deeper with a little more sheetrock thickness than in the old room. They
each also have way more sand in them than the old ones. It's conceivable the soffits
in the old room were performing some sort of trapping action.
- I shudder at putting a Behringer-anything in that room, but it might be a good
experimental item. It appears to have 10 programmable filter sets (I only need 3 per
channel), so that would be fine -- if I can stay away from their typically cheesy
analog signal paths. The only question is whether I can trust how well it handles a
digital signal in terms of jitter and doing the correct arithmetic...
Is there a similar product made by someone else with better build quality? (I
wonder which company/product was copied by Behringer for this product?)
Sorry to be so long-winded, but a lot of interesting questions and comments were
posted.
Thanks again for any add-on comments/suggestions,
Frank
Mobile Audio
--
To answer the questions/comments posed:
- The room is 1st order Eigentone, just like the last one, with double sheet rock
walls and ceiling, and a fairly dense floor. The Eigentone dimension means that LF
energy build up, while still present, is more even and tends to stay near the
boundaries. This is what the measurements show. +6 to +10 dB build-ups exist near
the boundaries (but by no means the unweildy +12 to +18 you'd find in a typical
room). No deep nulls exist at any place else in the room. The actual dimensions are
in the 11x15x8 range, but that's not exact.
- The room is well treated, with various modes of difussion, absorption, reflection
and LF trapping (19 traps of various depths and dimensions, including 6 angle traps
going up and down the rear corners and left/right upper sides -- probably the most
effective trapping considering the size of the trap).
(To Gary: no, this is not a case of overly damped HF leaving behind more LF. Plenty
of diffusion and reflection happening.)
- Neil and Scott's sub-20hz idea is interesting, and one wall-spanning rear-room
trap is quite large and deep and likely easily dipped into the sub 20 hz region.
However, I switched to a lighter-mass diaphragm to get a little higher usable range.
Saw no diff with the main issue of a slight and broad LF rise, nor in the sub 20 hz
region (but who knows if the measurements were of much use below 20hz). This
diaphragm change did yield some taming higher up, between 25 and 60 hz, at the
client couch toward the back of the room.
Any suggestions for a measurement system that might give me better data below 20 hz?
- Analog filters, passive or active, are non-starters for many reasons.
- Fortunately, the EQ required is not extreme nor with peaks and dips all over the
place. For my faux room EQ inside a PT session I've used three filters in two EQ
plug-ins. First, -3.5 dB shelved so that the transition to flat starts at 200 hz and
gets there by 300 hz. Then, one narrow -4 dB notch at 31 hz and one very narrow +4
dB peak at 300.
This measures closer to flat though not all the way there by about 1.5 dB. As one
poster replied (and I agree) making it absolutely flat might not be the practical
ideal nor sound the best.
(I was just listening to a mastering proof of a CD I finished mixing for a Sony
Records affiliate. This was on my cheapo shop boombox and things in the low end
translated very well.)
- I have indeed done many physical measurements trying to relate distances to
frequencies. (Years ago I wrote a handy little app that given wavelength, period, or
frequency, calculated the other two.)
But the relationship just is not there directly -- that's been one of the nutty
things. I suspect the problem might be one of those diagonal interactions I've read
about -- less obvious than the typical standing wave between untreated parallel
surfaces, but still a potential issue.
- it also might indeed be room gain; this room is slightly more solid than the old
room, at least in the flooring (old room was also double sheetrock, wall and
ceiling), so perhaps not as much is getting passed through the floor here.
- Problem with the DEQX or Trinnov is the expense (US$5K for the DEQX and the
Trinnov might be even more). I only need the digital portion of what they do -- so
that's a lot of money in those boxes that would be unused -- assuming they've given
the care they claim to the analog outs. (I already have a pristine and somewhat
expensive analog path from the monitor controller out to the crossover and
amplifiers that would be hard to match; don't want to lose that.)
- The main diff in this new room compared to the old room is the size and shape of
the soffits. These are toe'd in at less of an angle, are not down-angled, and are
somewhat deeper with a little more sheetrock thickness than in the old room. They
each also have way more sand in them than the old ones. It's conceivable the soffits
in the old room were performing some sort of trapping action.
- I shudder at putting a Behringer-anything in that room, but it might be a good
experimental item. It appears to have 10 programmable filter sets (I only need 3 per
channel), so that would be fine -- if I can stay away from their typically cheesy
analog signal paths. The only question is whether I can trust how well it handles a
digital signal in terms of jitter and doing the correct arithmetic...
Is there a similar product made by someone else with better build quality? (I
wonder which company/product was copied by Behringer for this product?)
Sorry to be so long-winded, but a lot of interesting questions and comments were
posted.
Thanks again for any add-on comments/suggestions,
Frank
Mobile Audio
--