file SD15

12 years 3 months ago #415 by guest
Replied by guest on topic SD15
Nah that's fair enough. I'm just being lazy init.

Yeah, agreed on the JBL.

What about P.Audio, or Celestion maybe, one of those might be accessible in the USA?

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12 years 3 months ago #606 by jsg
Replied by jsg on topic SD15

CalmIt wrote: Nah that's fair enough. I'm just being lazy init.

Yeah, agreed on the JBL.

What about P.Audio, or Celestion maybe, one of those might be accessible in the USA?


Well, I'll pass on P.Audio due to this: http://freespeakerplans.com/forum/forum_posts.asp?TID=51 at least until I learn that any manufacturing issues have been resolved.

Aren't celestion based in UK? Anyway, the BL on all their pro 15 drivers seems to be less than 24 which is too low (PD is 30 and Fane is 32).

Ars est celare artem

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12 years 3 months ago #607 by jsg
Replied by jsg on topic SD15
Here's a question. Does anyone have plots for HD15? Also, and perhaps more interestingly, does anyone have an impedance measurement of an HD15? Does anyone have HD15 lying around and fancies doing this? It would be super-cool to get 1, 2, 4 and 8 unit stacks in half-space. 1, 2 or 4 in quarter-space would be roughly the same as 2, 4 or 8 in half-space respectively.
I plan to build a model of HD15 so I can co-design the SD15 and take into account xover and high-pass - for seamless integration and max efficiency!


Ars est celare artem

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12 years 3 months ago #791 by guest
Replied by guest on topic SD15
I would absolutly love a high efficiency cab to go below my HDs... no matter the driver, something that excels in the 30hz-70hz band would be perfect.

If you let me know how to do an impedence plot of the HDs I will have a go.

Cheers,

Adam.Edited by: Adambomb

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12 years 3 months ago #808 by calsystems
Replied by calsystems on topic SD15
Would be good to have the Same Footprint. but im guessing thats what you are aiming for.


Edited by: CalSystems

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12 years 3 months ago #816 by jsg
Replied by jsg on topic SD15
Same fromt panel dimensions so it stacks nicely, but might go back a little further (which would make the stack less likely totopple over!)

Adam, you need to feed sinewaves into the sub through a resistor. Measure voltage and current at lotsa different frequencies. Impedance is voltage divided by current. Let's leave it for a while in case someone already has this info, that would save your effort. Thanks for offering though!

Cheers, John


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12 years 3 months ago #817 by calsystems
Replied by calsystems on topic SD15
Im sure this would be hard, but maybe design it so the when SD and HD are time aligned when the fronts/backs are flush to each other. Im sure this would be a Nightmare. Just a Thought

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12 years 3 months ago #831 by jake_fielder
Replied by jake_fielder on topic SD15
Good project!

(The bandpass king is back!!! )

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12 years 3 months ago #873 by sks01
Replied by sks01 on topic SD15
"im sure this would be hard, but maybe design it so the when SD and HD
are time aligned when the fronts/backs are flush to each other. Im sure
this would be a Nightmare. Just a Thought"
correct me if im wrong but wouldn't the only way to do that to have the horn path the same length? in which case that wouldn't work even vuagley, im thinking this will need a long horn path and a nice slow expansion rate?

do it for the love of the music

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12 years 3 months ago #922 by jsg
Replied by jsg on topic SD15
Well, SD15 will be a bandpass, either 6th order or 8th order depending on what comes out best. This means it'll have a much larger group delay than the HD15, and so to get phase alignment the HD15s will have to be delayed.




One way of doing it is to just have a crossover at something like 70-80Hz, but another possibility is to let the HD15s run down to 0Hz (or the infra filter) and overlap the sub up to 70 or 80Hz. If we do this, we can use the shallow (12dB/octave) rolloff of the HD15 by running the sub in phase to get coupling (probably needs diagrams to explain this properly).


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