I'm considering using a pair of Tannoy ~4" dual concentric drivers - the ones used in the Autograph Mini - in Metronome cabs. The obvious one(s) to choose as a starting point, based on the size of the driver, would be the original one designed for the FE108e or the one designed for the FE127e. The Tannoy driver is a tad deeper than the Fostex - about 78mm from the back of the mounting flange - but the smaller cab could work if I use an additional thickness on the front face (possibly just a "power bulge"). The larger cab would be easier to mount the driver in. Any opinions as to the most fruitful direction to take here, and what cab dimensions I should be looking at? I've measured the midbass driver params using DATS V2 - see pic.
Looking at #18, one aspect of this quadratic taper design that surprises me is that it appears from what is said that it is a 1/4 wave resonator. I ask because my understanding is that this expansion results in a half wave fundamental resonance. (Like a saxophone)
Many apologies if this has been covered, or it is a dumb question.
Many apologies if this has been covered, or it is a dumb question.
A line open at one end is a quarter-wave resonator, one open at both ends or none is a half-wave resonator.
dave
dave
.........though when tapered it's some form of 'closed cone', i.e. a 1/2 WL resonator with a 1/4 WL fundamental. It's this seeming conundrum that me n' MJK are perennially at 'head knocking' odds with in describing them in that his '1/4 WL pipe' is technically correct whereas I prefer to use '1/2 WL resonator' as it describes it better to the casual DIYer and provide a link to graphically 'prove' both and let the 'gentle reader' choose his own.
Any advice on how to model this - choice of software etc...? I've used Basta! so far, which is probably not suitable for this...
I am I admit anything but an expert, but that link seems to me to show clearly that a closed cone is a half wave resonator. It has the same length and harmonics as the open pipe.
I have previously asked why a saxophone's lowest note is an octave higher than a clarinet's of the same length: The answer:
Because a saxophone is conical, and a clarinet is tubular.
Apparently (for reasons I cannot pretend to understand) this makes the saxophone a half wave resonator, and a clarinet a 1/4 wave resonator.
It has been discussed before. It's exponential
https://www.diyaudio.com/community/threads/the-metronome.85410/post-5520037
https://www.diyaudio.com/community/threads/the-metronome.85410/post-5520037
Scott just models them as ML-TLs. The slight difference has not made significant differences.
dave
dave
The plan in this post was meant more as an illustration of how to fold a Met, a member has reached out an di have made it a useable plan. I do hope to see it built.
https://frugal-horn.com/downloads/Folded-Betsy-K-Met-290524.pdf
dave
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Dave, FYI the PDF is cutting off the bottom of Page 2, thus obscuring some of the panel measurements. It looks like the illustrations are too far down the page.
Not to be obtuse but where does the driver mount exactly? In the top so it becomes omnidirectional and might work best near a wall boundary? Or in one of the symmetrical sides?
It mounts upwards, the rest is up to the builder. You could always mount them on the wall so the driver faces the listener ;^)
As i said the original work was to show how you would fold a Met.
dave
As i said the original work was to show how you would fold a Met.
dave