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In the Forum: Audio Discussions
In the Thread: A listening room for a domesticated Cat?
Post Subject: Some thinking required…Posted by Romy the Cat on: 10/23/2017
Yesterday I finalized everything, made the crossovers permanent,
arranged the cables, check the phases and levels per each channel and officially
declared to my wide that the listening room setting up is over. Then as the kids
went to bed I decided to spin some music in a comfort of my new re-acquired
listening room. I put the scherzo
from Mahler Second, tuned the light off, stretched
in my chair and pushed play. Instead the customary timpani strike opening the Macondo barked to me with
some horsey fart. That was more than unpleasant.
I took my own “test tracks”
the recordings that I know for years very well and that I use the debug playbacks.
Played it and it was very obvious that the playback was very seriously sick.
The sound has very undecided lover end and overall super brittle it was almost
like waking barefoot over crash glass. The setting the tweeters lower did not help,
so it was obvious that something in my LF was out of phase. It is not very much
publicized fact in audio that there is a lot of conception between upper HF and
lower LF. I wrote about it a lot in past at my site. So, in this case when the whole
upper end was brittle like very rusty knife and lower bass was as ugly as it usually
come from open baffle I instantly recognized that one of my LF section is out
of phase.
There was however two dilemmas. I just checked all my individual
channels and made sure that they are in proper phase. Also just a few days
back, even last morning I had great sound with no signs of upper range harshness
of bass problems. The environmental problem are out of picture, so what is
going on?
I do not have a definitive answer yet even though I was thinking
about it whole evening and whole morning today. The most likely is that my playback
proper configuration is what LF channels need to be set that right LF side runs
in opposite polarity then left LF. Most likely it is what I had before my last setting
up. You see, I can’t check the polarity of my left LF and it runs 20Hz
filtration and I have no gain to excite my phase miter. I did not bring scope to test it but rather I
set with RTA each side LF in max gains to Midbass and Upperbass in max gain to
Upprabss. Since the Midbass and Upperbass
are in phase with R and L side I was under presumption that LF will be in phase
if they in max gain to own Midbass. So apparently, and probably because they
have deferent filtration my R and L LF channels runs max gain to midbass in opposite
phases to each other. This is the only explanation I have.
If it is so then it will be VERY strange configuration with
R-LF and L-LR to be in opposite phase. Sure, they are in very different acoustic
environments and runs different crossovers (20Hz and 45Hz second order), they
run different impedance change. So there are a lot of explanation why to be in opposite
phase would be reasonable. Still it would be strange and unusual.Rerurn to Romy the Cat's Site