my room designer designed a whole ceiling bass trap into my room. it was 15" deep and covered the whole 21' x 29' ceiling. except for -6- inset 6' x 8' chambers. these chambers had fabric covered vertical openings with Corning 709 fiberglass in the openings. you can see the chambers in the ceiling of my room pictures. the idea was that this bass trap would control the bass; but clearly in retrospect it was a huge mistake. now 11 years later that mistake has been rectified.....finally.
4 years ago I did have a contractor remove the fabric panels from 4 of the 6 chambers and glue and screw 3/4" finished maple plywood over these openings; which did improve the bass response. I thought that fixed my issue. I was wrong.
last May, 14 months ago, my speaker designer was here for 2 days to do the final tweaking to my Evolution Acoustics MM7's. when he measured the room he found a fairly wide -12db suck out at 30hz, one that the room dimensions did not logically predict. he strongly suspected that the remaining openings in those center chambers were the likely cause. since the MM7's are so powerful and adjustable, he was able to minimize the effect of the suck out with adjustments, but at the cost of ultimate performance. he did strongly suggest I get those openings covered. he even gave me two sets of settings sheets for the 4 sets of adjustments (2 sets on each bass tower).......one for the 'compensated' adjustments he made, and another for 'flat' adjustments anticipating my getting those openings sealed up.
since last May I have given a good amount of effort into finding a contractor to do that work, but was not successful.
then this spring I went thru the experience with the fabric treatments that really took things up a few notches. I had quite a few people thru the room and the feedback was very positive. I knew that somehow I needed to do this final thing and hopefully that would allow the bass performance that was already amazing to go to the optimal level. I was fully motivated to get this done with my excitement from the big step forward from the fabric treatments.
I realized if I wanted to get this done i had to do this myself.
finally I was able to convince my son (I bribed him by giving him one of my bicycles) to help me do this nasty job. I spent last week buying -3- 4' x 8' sheets of finished 3/4" maple plywood, another 8 foot step ladder (we would be working at 10'-11'), a good quality circular saw, saw horses, and all the other bits and pieces we would need. my son had a 208 mile one-day STP (Seattle to Portland) bike ride on Saturday and did not get home till late, so Sunday morning a spent 2 hours clearing out the room.....everything to the sides....racks moved, tape decks moved. big job. tarp laid. ladders set up. neither of us are carpenters; could we rip the panels without chipping? could we even cut a straight line?
would it actually make a positive difference?
we did not know exactly how we would remove the fabric panels or how they were attached. would we be able to get them out without removing the trim pieces? we did not posses the skills to properly replace the trim.
he showed up around 10:30am and we first removed the 8 deflector panels with in the chambers and then got to work pulling off the fabric panels, 4 per chamber, 8 total. we were able to get them out with considerable caution and effort without disturbing the trim. then we measured and started ripping the sheets and cutting to size. I had a work commitment mid afternoon for 2 hours, and returned. finally about 9 that night we screwed and glued the final plywood sheet. then he left and I spent 2 hours reassembling the room. I'd had a listening visitor from California the previous day (HiFi Guy) and then the previous night I'd had a work dinner till midnight. I'm not a young guy. I was gassed. I tried to listen. was it boomy sounding? if that 30hz -12db suck out was solved to a significant degree that old set-up would cause the lower bass to be boomy. I thought it was boomy but fell asleep right away. the next morning before work I was not yet recovered enough to listen.
finally after work that night I had recovered enough to listen and went thru my digital listening references and the lower bass was clearly boomy, if not quite a bit more energetic sounding. I had spoken to my speaker designer earlier and he said I should shut off the amps in the bass towers and see if it sounded clean. if it did that indicated that the closing of the openings had not likely caused other issues. I did that, went thru my references again, no problem, sounded very clean. so then I turned the bass towers back on and adjusted both the 'bass level' and the 'bass quality' (Q) halfway to the 'flat' positions and listened to the references again. better, less boomy. much more energy. some magical things happening. then I went 3/4 to the flat positions and again listened. now it was a big WOW! everything was now at a whole new reference level. all up and down the frequency range. a whole new level of coherence and naturalness. vocals were superb sounding. much more holographic. bass impact a couple orders of magnitude better. so I just listened late until early morning Tuesday and again after not much sleep in the morning. I was stoked.
that night I first listened as it was; then found a good cut and moved the 'bass quality' the last little bit to the flat position. clearly better. then I moved the 'bass level' the last little bit to the flat position and it was super clean and right. it sounds perfect to me now; I've been listening for 2 days now to it and I'm just beside myself. as good as it had been; it's not only much better but much different than even Saturday night. what is so crazy to my mind is how much different vocals and the mid range is simply by eliminating a 30hz suck out. it was very interesting hearing how much detail had been covered by those adjustments which were pegged to cover the suck out when taken to flat all that detail jumped out.
the MM7's are now fully unleashed and are something to behold!
how close to absolutely flat is it? don't know. I hope it can get better from here.....but maybe not. is the suck out all the way gone? once I measure it I may or may not post it. we all know how much I love graphs.
I suppose I have a persecution complex posting about discovering my personal mistakes. I know from time to time that comes back to haunt me when ner-do-wells want to give me some crap. but so what. I feel that these sort of experiences contribute to the collective knowledge. and one has to be open to learning and going farther down the road.
my goal 11 years ago with my efforts was to get the room and system out of the way of the music; I think I've essentially done that finally.
oh and btw, this job cost me about $250 in materials and I did acquire approx. $450 worth of tools and a ladder. I was going to give the bike to my son anyway but he did not know that. so between the fabric and this job about $500-$600 and the effect is off the charts.
4 years ago I did have a contractor remove the fabric panels from 4 of the 6 chambers and glue and screw 3/4" finished maple plywood over these openings; which did improve the bass response. I thought that fixed my issue. I was wrong.
last May, 14 months ago, my speaker designer was here for 2 days to do the final tweaking to my Evolution Acoustics MM7's. when he measured the room he found a fairly wide -12db suck out at 30hz, one that the room dimensions did not logically predict. he strongly suspected that the remaining openings in those center chambers were the likely cause. since the MM7's are so powerful and adjustable, he was able to minimize the effect of the suck out with adjustments, but at the cost of ultimate performance. he did strongly suggest I get those openings covered. he even gave me two sets of settings sheets for the 4 sets of adjustments (2 sets on each bass tower).......one for the 'compensated' adjustments he made, and another for 'flat' adjustments anticipating my getting those openings sealed up.
since last May I have given a good amount of effort into finding a contractor to do that work, but was not successful.
then this spring I went thru the experience with the fabric treatments that really took things up a few notches. I had quite a few people thru the room and the feedback was very positive. I knew that somehow I needed to do this final thing and hopefully that would allow the bass performance that was already amazing to go to the optimal level. I was fully motivated to get this done with my excitement from the big step forward from the fabric treatments.
I realized if I wanted to get this done i had to do this myself.
finally I was able to convince my son (I bribed him by giving him one of my bicycles) to help me do this nasty job. I spent last week buying -3- 4' x 8' sheets of finished 3/4" maple plywood, another 8 foot step ladder (we would be working at 10'-11'), a good quality circular saw, saw horses, and all the other bits and pieces we would need. my son had a 208 mile one-day STP (Seattle to Portland) bike ride on Saturday and did not get home till late, so Sunday morning a spent 2 hours clearing out the room.....everything to the sides....racks moved, tape decks moved. big job. tarp laid. ladders set up. neither of us are carpenters; could we rip the panels without chipping? could we even cut a straight line?
would it actually make a positive difference?
we did not know exactly how we would remove the fabric panels or how they were attached. would we be able to get them out without removing the trim pieces? we did not posses the skills to properly replace the trim.
he showed up around 10:30am and we first removed the 8 deflector panels with in the chambers and then got to work pulling off the fabric panels, 4 per chamber, 8 total. we were able to get them out with considerable caution and effort without disturbing the trim. then we measured and started ripping the sheets and cutting to size. I had a work commitment mid afternoon for 2 hours, and returned. finally about 9 that night we screwed and glued the final plywood sheet. then he left and I spent 2 hours reassembling the room. I'd had a listening visitor from California the previous day (HiFi Guy) and then the previous night I'd had a work dinner till midnight. I'm not a young guy. I was gassed. I tried to listen. was it boomy sounding? if that 30hz -12db suck out was solved to a significant degree that old set-up would cause the lower bass to be boomy. I thought it was boomy but fell asleep right away. the next morning before work I was not yet recovered enough to listen.
finally after work that night I had recovered enough to listen and went thru my digital listening references and the lower bass was clearly boomy, if not quite a bit more energetic sounding. I had spoken to my speaker designer earlier and he said I should shut off the amps in the bass towers and see if it sounded clean. if it did that indicated that the closing of the openings had not likely caused other issues. I did that, went thru my references again, no problem, sounded very clean. so then I turned the bass towers back on and adjusted both the 'bass level' and the 'bass quality' (Q) halfway to the 'flat' positions and listened to the references again. better, less boomy. much more energy. some magical things happening. then I went 3/4 to the flat positions and again listened. now it was a big WOW! everything was now at a whole new reference level. all up and down the frequency range. a whole new level of coherence and naturalness. vocals were superb sounding. much more holographic. bass impact a couple orders of magnitude better. so I just listened late until early morning Tuesday and again after not much sleep in the morning. I was stoked.
that night I first listened as it was; then found a good cut and moved the 'bass quality' the last little bit to the flat position. clearly better. then I moved the 'bass level' the last little bit to the flat position and it was super clean and right. it sounds perfect to me now; I've been listening for 2 days now to it and I'm just beside myself. as good as it had been; it's not only much better but much different than even Saturday night. what is so crazy to my mind is how much different vocals and the mid range is simply by eliminating a 30hz suck out. it was very interesting hearing how much detail had been covered by those adjustments which were pegged to cover the suck out when taken to flat all that detail jumped out.
the MM7's are now fully unleashed and are something to behold!
how close to absolutely flat is it? don't know. I hope it can get better from here.....but maybe not. is the suck out all the way gone? once I measure it I may or may not post it. we all know how much I love graphs.
I suppose I have a persecution complex posting about discovering my personal mistakes. I know from time to time that comes back to haunt me when ner-do-wells want to give me some crap. but so what. I feel that these sort of experiences contribute to the collective knowledge. and one has to be open to learning and going farther down the road.
my goal 11 years ago with my efforts was to get the room and system out of the way of the music; I think I've essentially done that finally.
oh and btw, this job cost me about $250 in materials and I did acquire approx. $450 worth of tools and a ladder. I was going to give the bike to my son anyway but he did not know that. so between the fabric and this job about $500-$600 and the effect is off the charts.
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