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I read somewhere (Bullock?) that it makes the port effectively a bit longer = deeper bass.
If true, by how much?
QB3 alignment FB 38hz, critically damped.
TIA
Note that a post in response is preferred.
Warmest
Timothy Bailey
The Skyptical Mensurer and Audio Scrounger
And gladly would he learn and gladly teach - Chaucer. ;-)!
'Still not saluting.'
Follow Ups:
My Avalon Acoustics Eidolons have a down firing port that is surrounded on three sides by the cabinets short pedestal and the speakers come with mounting cones.
My experience with these speakers backed up closely to the rear wall is that every aspect of their intended presentation is compromised greatly including bass performance. Placed at 1/3 of the rooms distance from the back wall everything opens up including the bass performance.
Unfortunately, I never ran the frequency test CD which may have provided me with a more helpful answer other than, 'opens up,' sorry. I currently use two 12" subwoofers that control that region.
I would suggest placing three small pieces of 3/4" hardwood under your speakers which should provide more than enough air flow from he port. Two inches seems excessive and raises the tweeters location.
About it. I do prefer it but can be a bit hard to tune.
?
Note that a post in response is preferred.
Warmest
Timothy Bailey
The Skyptical Mensurer and Audio Scrounger
And gladly would he learn and gladly teach - Chaucer. ;-)!
'Still not saluting.'
CAlculate the area of the cone vs the area from the bottum edge of the speaker box parimeter and find the compression ratio. a little air compresion can be a good thing.
Yes?
I have sufficient board cut into circles to do that.
Some experiments ahead.
Thanks.
Note that a post in response is preferred.
Warmest
Timothy Bailey
The Skyptical Mensurer and Audio Scrounger
And gladly would he learn and gladly teach - Chaucer. ;-)!
'Still not saluting.'
more likely a mistake than a design.
If you could do the math right, the area bounded by the bottom of the enclosure to the floor would resonante, like a slot port, then yes, it could be possible that you changed the tuning FB from the enclosure port to the enclosure port/area under enclosure/slot port.
Although the area might normally be larger for 6th order, this might help invision what might be going on.
It makes sense what you're saying though.
Sounds like a DIY project. Is the vent removable such that you could just measure the box tuning frequency via voice coil impedance measurements and tweak the vent length to get it to the desired value?
Andy,
It is a DIY project a 3-way column with two bass enclosures, BUT ... the enclosures were OEM'd, concrete spheres. ?*
The ports (PVC plumbers pipe) are cemented in, so all I can do is turn one pair over (on the blocks I have made) onto a 24inch round paver and measure how deep they go.
If I decided to tune the down-facing pair lower I'd not be going any lower than 2/3rds the Fs of 38hz = 27Hz. A right-angle bend to fit over the back end of the port is a snap. How low will depend on what effect the acoustic loading has. May not have to retune.
* the second matching pair of spheres? one of each will sit on top of a down-facing sphere. ???? Cut-down basketball hoops on an adjustable column on rollers, and gravity will hold them in place, plus a small ball of blutak.
The third smaller sphere on top running from ~400-6kHz will be mounted in the same way. Moving them will be doable, as will be working on them.
Note that a post in response is preferred.
Warmest
Timothy Bailey
The Skyptical Mensurer and Audio Scrounger
And gladly would he learn and gladly teach - Chaucer. ;-)!
'Still not saluting.'
I was trying to picture what each complete system would look like, and then I thought... a snowman? Would be interesting to see pics of these.
It will be tri-amped.The current single pair in use is biamped.
Note that a post in response is preferred.
Warmest
Timothy Bailey
The Skyptical Mensurer and Audio Scrounger
And gladly would he learn and gladly teach - Chaucer. ;-)!
'Still not saluting.'
Edits: 06/13/12
Go used, buy a Class A or B Stereophile recommended pair from 5-10 years ago.
TWO pairs in fact.Don't know anything about the effect loading the port with the floor has?
Then why post?
Note that a post in response is preferred.
Warmest
Timothy Bailey
The Skyptical Mensurer and Audio Scrounger
And gladly would he learn and gladly teach - Chaucer. ;-)!
'Still not saluting.'
Edits: 06/13/12
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