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F.A.S.T speaker design questions?
F.A.S.T speaker design questions?
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Old 11th October 2017, 05:08 PM   #1
Cintronic is offline Cintronic  United Kingdom
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Default F.A.S.T speaker design questions?

I am curious to try a F.A.S.T set up and before even thinking of speaker types and details I need to understand some basics first.

I am concerned about matching output speeds from different types of designed. I prefer the sound of sealed subs, can the full range be a horn/ TQWT or would it not be a good match?

Is it advisable that the FR speaker design needs to cut off at same frequency as the crossover cut off point e.g. Port tuning/ TQWT length or does this not matter?

Any other advice to get a coherent design to work would be welcome.
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Old 11th October 2017, 05:24 PM   #2
Bob Brines is offline Bob Brines  United States
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There is no such thing as "speed" in speakers. There is poor integration of bass and mid frequencies.

If you like a sealed sub, fine. Use a sealed full-range. Pick a sub that can cross at 300Hz give or take. Ideally no higher to preserve the linear phase characteristics of the full-range. Pick a full-range as small as you can that will cross at 300Hz.

Of course reality dictates moving the cross-over to match the choice of drivers. My personal speakers use the Audax HM210C0 and the Scan Speak 10F-8424G0 crossed at 500Hz with a Harsh phase linear XO.

Bob
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Old 11th October 2017, 05:24 PM   #3
planet10 is offline planet10  Canada
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F.A.S.T speaker design questions?
Usually a WAW (Woofer assisted wideband… there is finely a move to lose the FAST moniker) has an XO high enuff that one does not need to attempt to extend the LF and sealed or aperiodic midTLs (or OB) are commonly used.

Like any XO the cutoffs need to create a smooth hand-over. That is specific to the exact implementation.

I am rushing away at the moment, i can post a lot more on the subject including examples we have built.

dave
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Old 11th October 2017, 05:36 PM   #4
scottjoplin is offline scottjoplin  Wales
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We may have to put the TLA to a vote
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Old 11th October 2017, 06:44 PM   #5
Jerms is offline Jerms  United Kingdom
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Have a look at the Nautiloss topic if you want interesting "sealed" and damped TL.
Or The Dagger. Both by XRK971

Sealed plus a Linkwitz transform seems a good idea for bass. Should result in a smaller package but excursion is king.

J.
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Old 11th October 2017, 06:48 PM   #6
scottjoplin is offline scottjoplin  Wales
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Small sealed box EQ'd for bass is only worth considering if small is the priority
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Old 11th October 2017, 06:54 PM   #7
chrisb is offline chrisb
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As usual, Uncle Bob's advice is right on the nose.


OK, Scott, I'll bite "TLA" = Transmission Line, Aperiodic ? I see Dave is still catching up to your new testament acronym

Jerms - doesn't the LT suck up a lot of power? Mind you, thanks to classD, that's probably never been cheaper per watt.
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Old 11th October 2017, 06:57 PM   #8
scottjoplin is offline scottjoplin  Wales
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Old 11th October 2017, 07:47 PM   #9
chrisb is offline chrisb
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Old 11th October 2017, 10:22 PM   #10
Jerms is offline Jerms  United Kingdom
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Quote:
Originally Posted by chrisb View Post
As usual, Uncle Bob's advice is right on the nose.


OK, Scott, I'll bite "TLA" = Transmission Line, Aperiodic ? I see Dave is still catching up to your new testament acronym

Jerms - doesn't the LT suck up a lot of power? Mind you, thanks to classD, that's probably never been cheaper per watt.
Vs a ported or TL, much more power would be required to extend low response. It all has to come from the front wave.

How the driver response scales vs power becomes an issue possibly. Assuming two woofers rather than a single sub....

Last edited by Jerms; 11th October 2017 at 10:27 PM. Reason: Minor brain fade
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