>>> The goal is to get the port terminus action closer to ear level.
Why not simply flip it over?
Why not simply flip it over?
Godzilla said:
Curiously I did that with a Tangband W821s (whatevs.) It seemed to work well. but I still didn't like the Tangbands. anybody wants to buy 'em for cost and shipping can have them
This opens the question of a passive radiator which is usually used with larger speaks. Like Schultz, "I know nothing" of passive radiators. But I don't suppose the mass loading of the MLTL is effected by gravity with the flip.
Right side up or upside down, the terminus is still in a different plane
and not as close to ear level.
And if there is a boundary from a tv stand or the like, maybe the effect would be enhanced. I'm not even sure what the effect is at this point. Just thinking out loud.
Re: FE127 bipole TQWP
All EnaBLed up, Scott's bipoles replaced a set of Magnepans. He likes the pipes a lot better.
dave
SCD said:
All EnaBLed up, Scott's bipoles replaced a set of Magnepans. He likes the pipes a lot better.
dave
loninappleton said:
Hmm, according to my notes it's a 6" long vent. Regardless, raising the vent up to the driver midpoint will raise Fb a bit, flattening the response some and 'sharpen' the vent's response plus increase its harmonics' effect on the ~300 Hz - up BW, so technically increasing harmonic distortion.
It changes the vent's end correction factor, ergo its tuning frequency, but on such a small vent it's negligible/inaudible.
GM
GM said:
I don't think I'd raise it up to driver midpoint but get it off the bottom and use an elbow inside the confined space. The reason for the bottom install was to have the full cavity available for loading. I never play anything loud so I don't know if that's just my sense of proportion or what.
Driver in the middle ??
Why is the driver in the middle on this one? Most enclosures I've seen like this, it is most of the way to the top.
http://homepage.mac.com/tlinespeakers/FAL/box-plans/diyA-FRref-monopole.gif
Why is the driver in the middle on this one? Most enclosures I've seen like this, it is most of the way to the top.
An externally hosted image should be here but it was not working when we last tested it.
http://homepage.mac.com/tlinespeakers/FAL/box-plans/diyA-FRref-monopole.gif
Hmm, not sure why it's this low on a straight pipe, I calc ~11.09" i.d. down from the top for smoothest response with least stuffing. Regardless, when the driver's at the top and vent at the bottom you get max pipe loading that often results in some peaking at Fp, though it can be damped down with additional stuffing if desired and as the driver moves down the pipe the vent loading is reduced until you reach a point of causing severe notching in the response due to the long reflections back to the top of the pipe.
If you want the driver at the top, then move the vent up to smooth it out and increase the vent length to lower Fp back to where you want it and damp any Fp peaking at the vent.
GM
If you want the driver at the top, then move the vent up to smooth it out and increase the vent length to lower Fp back to where you want it and damp any Fp peaking at the vent.
GM
As best as I can recall, there were quite a few variations theorized and drawn during this cooperative project, not all of which were necessarily built - this might well be one of them.
I've frequently opined that while it takes a bit of work to get the most from the FE127E, it's hard to make them sound crummy. Designs like this might fit into that latter category.
I've frequently opined that while it takes a bit of work to get the most from the FE127E, it's hard to make them sound crummy. Designs like this might fit into that latter category.
GM: I've put off building metronomes or straight thin boxes for my 127s because I need the drivers to be 48" off the floor and the top of the cabinet to be "not a great deal higher". How close to the top dare I put them, is straight sided better at the top because of more volume, and what port adjustment would I make?
Oh, what the hell, recommend dimensions. Thanks.
Oh, what the hell, recommend dimensions. Thanks.
GM said:
Tim Forman's design. he chose midpoint on a few designs. We need to getthe above note into the diyA FR Ref thread. That offset sure would make for a more conveiient build.
dave
edgebc said:
Well, you can put the driver at the extreme top if you like, it just may require more stuffing than if located further down. Anyway, driver location at the top works best with a high aspect ratio TQWT (reverse taper) and slides down as it shifts to straight, then to horn taper. Another thing to consider is the driver's Qts. For the TQWT we want a relatively low Qts, increasing with increasing flare with straight taper being around 0.4 Qts. Obviously, any flare can be used with any reasonable Qts, just there seems a synergy of sorts using these rules-of-thumb (ROT).
WRT the FE127E, its highish Qts would require a horn flare, ergo lower driver location, so the ROTs won't work here and a MLTL this long for such a small Vas driver poses some problems, but this doesn't look too bad once EQ'd if the published specs are reasonably close:
L = 49.5"
W x D = 7.312" x 4.5"
zdriver = near/at the top
zport = 35.125"
port = 2" dia. x 1.75"
All dims i.d. and stuff as required down to just above the vent (0.25 lbs/ft^3 shown).
GM
Attachments
planet10 said:
?? Assuming TF doesn't mind, seems like it should be listed as a note on the drawing as an alternate driver location.
GM
Clarification please, sorry.........
Is the port 35" down from the center of the driver, the top or 35 " up from the bottom?
Would a reverse taper(behind the driver) stuffed trap, like in the BiB, help?
Is the port 35" down from the center of the driver, the top or 35 " up from the bottom?
Would a reverse taper(behind the driver) stuffed trap, like in the BiB, help?
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