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In the Forum: Audio Discussions
In the Thread: A listening room for a domesticated Cat?
Post Subject: Kind of LF depression…Posted by Romy the Cat on: 9/24/2017
The kids are growing up and twins sleep fine and walk already.
So, the Bessnow’s household is calming down, a live-in nanny for sure helps…
With more time at my heads I am trying to finalize my playback in our new home.
I spent a few hours today to experiment with different lower octaves solution
for Macondo. There is something better and something worse but frankly none of
the solutions, looking the result I am getting, not worthy from my point of
view. I mean I can make it to work but it all is a stretch and just a substitute
of my desire to return my playback to the day of former glory. None of the solution that I have are neither
good sonically or elegant technically, not to mention inspiring as a “last
solution”.
Her are just a brief overview of my thoughts, juts to organize
them for myself.
Here is the Left channel response with no bass of any kind. It
is RTA 48 measurements per octave. The microphone is approximately 30 inches
closer then I presume the sweet spot should be. The MF/FH a bit attenuated compare to upper
bass and the microphone extended further from the horns axis. I have done it intentionally
to see the upper bass output more prominently. The resolution is quite high 2dB
per square and the entire sweep is from 10Hz to 2kHz.
The channel does somewhere what is expected. The 50Hz large
peak I am sure coming from the corners the left channel located. I was moving the speakers and was changing the
position but it is still there. It would be necessary to play with the lowers channels
to mask it out. The most typical solution from the way how I deal with the
problems like this (means do not fight with room but design channels to fit the
idiosyncrasies of the room) is it to
make one channel from 125Hz to 60Hz and another from 40Hz and all the way down.
The problem then how to drive the damn sub 40Hz section. The Milq will not do
it unless it will be over 100dB sensitive. So, just based upon the sweep below
the design of the LF solution organically flows: 60-125Hz a tandem of vintage
woofers and then LF section. For the LF section would do an array of 10 of my beloved
pimpled Scans Speak drivers. For 60-125Hz will do pretty much anything. It might
be sealed solution of something similar to Altec 815A. How to position 10 drivers
array and a tandem of 15” woofers in time aligned position is bit dilemma but
addressable I think. The advantage of
this solution that I can very prissily to factor the crossover for midbass and
lower bass to fit the profile of each channel. Take a look at the right channels it is slightly
different. 
It is the room gain and is and at 100Hz. So, I might plays with flooding
or phase tuning the midbass in a different way than the left channels and it might
work. What this solution lacks of elegance and there is something else. The
room responses to my current Macondo and it might or might not be the response
to 100 inch tall LF line array. It is very difficult, if ever possible to predict
what will happen after I put a huge amount of boxes in the room. I can model it
to degree using juts one sub 40Hz unit and drive it with a powerful SS but it
will not be the same. So, there is no way to say how the sub 40Hz array will
behave until you built the damn things and put it into THIS room. Now very
promising…
Anyhow, here is the response of Macondo complimented by a
pair of 15” Vitovoxes in small and shitty sealed boxes. It is very nicely cover
the desired region but it drops like a rock. I think with larger, let say 6-8
cube feet per driver, enclosure and a proper
damping it might have a slightly smother decay. Something that I would very
much need, regardless how much it will be supported by next LF channel. I would
like to have in there 12dB decay and I might not get it with Vitovoxes.
Here is the Macondo Right Chennal supported from the bottom
my Scans Speak 72” line array, 4 drivers. I brought it just for illustration.
If discard the 50Hz peaks then we are good 6-10 dB lower in amplitude of to cross
at sub 40Hz.
The last one is my Left Channels with a single Klipsch
corner horn crossed at 115Hz with default K30 driver. When I first connected it I hated it and now I
play with it a bit and I like it more. I
lost the time-alignment which is unpleasant. I can make the Klipsch horns to
sound much better: better driver, better crossover dialing, better corner
loading… it is a bit stiff solution but it does decay nicely in the room. In
fact it decays too long, that 12Hz peaks is a bitch and it is very auditable. I
need to play with corner loading to get rid of it I guess…
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