Hi everyone, I made a pair of this speakers a while ago. I always though that's a transmission line or a "quarterwave" design. But is it really ?
They are made around the Tang band W8-2145 driver, blanda bowl (the large one 28cm) and a PVC pipe (about 210cm long and 6.3cm diameter). All of this sealed in a concrete base which incorporates the connectors. Sorry, I don't have graphs and mesures, but they sound good-ish to my ears.
First I designed this speaker with the 1/4 wavelenght type of enclosure, but now I'm wondering if it is a transmission line or a very long ported design.
Thank you by advance for your reply and feedback.
Hi Guillaumemonochrome
your prototype is also a transmission line, in the frequency response there is certainly the resonance frequency at L/4. The simplest way to detect resonances is to measure the impedance as the frequency varies.
The presence of a large enough spherical volume should also activate a second resonance at L/2 as in waveguides open on both sides.
The reduced section of the waveguide compared to the surface of the cone introduces a resistance that reduces the movement of the cone. It's no wonder he feels good.
On the site https://www.claudiogandolfi.it you can see the prototypes I have developed, they use multiple transmission lines with L/4 and L/2 resonances, the last one is cl08a2 https://www.claudiogandolfi.it/cl08a2.html#.
Claudio
your prototype is also a transmission line, in the frequency response there is certainly the resonance frequency at L/4. The simplest way to detect resonances is to measure the impedance as the frequency varies.
The presence of a large enough spherical volume should also activate a second resonance at L/2 as in waveguides open on both sides.
The reduced section of the waveguide compared to the surface of the cone introduces a resistance that reduces the movement of the cone. It's no wonder he feels good.
On the site https://www.claudiogandolfi.it you can see the prototypes I have developed, they use multiple transmission lines with L/4 and L/2 resonances, the last one is cl08a2 https://www.claudiogandolfi.it/cl08a2.html#.
Claudio
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Thank you Dave. maybe I should forget about the spherical enclosure and start from a tapered quarter wave tube design.
Guillaume
Guillaume
Thank you Claudio, I don't think that I'm capable of understanding all the Multi Delays Diffraciton concept and details, but from what I understand from your site and prototypes, it looks impressive. It makes me think that it's maybe possible to adapt this on the same spherical enclosure, but with multiple pipes going up and down from it. Only one direct source may not be enough for the 3D effect. Aesthetically and sonically, it could be really interesting.
Guillaume
Guillaume
Spherical enclosures are good.
A TL needs to be properly modeled if you want a good result. Otherwise it is a crap-shoot.
dave
A TL needs to be properly modeled if you want a good result. Otherwise it is a crap-shoot.
dave
I ment "forget about" for this particular design mixing spherical and TL. It's maybe not possible to bound the two for an effective speaker. Not with my capabilities.
Your prototype (module behind the direct radiating loudspeaker) indeed use pure L/4 and L2 resonances, but it is completely different from what the OP have built.
No.
As member planet10 pointed out, it is a vented box with too long bass-reflex tube - presuming that the cube at the bottom is not empty chamber with two separate tubes (in and out) attached to it. That is a wrong design.
It is not big enuff to be a TL. What is the volume (a bit less than 7 litre?) and length & diameter of the vent is 6.3Dx21 cm?
First guess on the response. Does not account for the vent resonances that will happen. And the noise.
dave
It's big/long enough to impact the driver's performance over a much wider BW than a simple 'one note' reflex vent (34400/4/21 = ~410 Hz) as your sim shows, so TL seems an appropriate moniker to me and why I used the reflex math that the local Altec Dist. designers recommended to design high aspect ratio 'column', 'tower', TLs beginning back in the late '60s.
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The sphere intern volume is 9 litres, pipe diameter 6.3cm and the pipe length is 210cm. Like you said, it remains far from optimum.
It is in french, but it's really well made. There is a huge drivers data base, and each driver can be used to calculate all types of enclosures (with volume port size length etc..). All on browser.