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Multi-Way Conventional loudspeakers with crossovers

Vas Question
Vas Question
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Old 31st December 2017, 09:21 AM   #51
multi is offline multi  Australia
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i have 515 8ghp qts .195; I use tube amps damping factor about 10 to 12DB. At the moment I am trying Chinese speakers with QTS of 0.283 sensitivity of 99 db
phil
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Old 2nd January 2018, 01:17 AM   #52
head_unit is offline head_unit  United States
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Originally Posted by 33Polkhigh View Post
Can anyone tell me if you add series resistance to a driver to raise its qes, does this affect its VAS. I would assume that vas takes qes into account when its calculated, but does anyone know how this works?
To rephrase what Ron E said, Vas is just determined by the suspension (spider + surround).
Generally I'd say adding series resistance is not a good way to achieve things, to me it indicates the driver is not the right driver.
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Old 2nd January 2018, 11:00 AM   #53
33Polkhigh is offline 33Polkhigh  United States
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Generally I'd say adding series resistance is not a good way to achieve things, to me it indicates the driver is not the right driver.
Yea, I was looking at some full rangers like the audio nirvana classic 5". Raising the qes you can easily get sealed -3db in the 70-80 hz range, which is decent, plus the other benefits of sealed. I always use equalizer APO anyways so dealing with the changes to frequency response wouldn't be a big deal, but I haven't tried it.
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Old 4th January 2018, 03:50 PM   #54
head_unit is offline head_unit  United States
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Originally Posted by 33Polkhigh View Post
Yea, I was looking at some full rangers like the audio nirvana classic 5". Raising the qes you can easily get sealed -3db in the 70-80 hz range, which is decent, plus the other benefits of sealed. I always use equalizer APO anyways so dealing with the changes to frequency response wouldn't be a big deal, but I haven't tried it.
You mean this thing
Audio Nirvana Classic 5 Fullrange Speaker Driver
I presume. So in a small sealed box, if you made the Qts 0.7, the Fc becomes like 150 or whatever-and it seems to me what you want to do is raise the Q so you get the Q you want without raising Fc. Hmmm. Maybe...sticking a resistor in series just sticks in my engineering sensibilities, since it wastes power and my gut feel is "it doesn't really work like that" though I cannot definitively say that is so because it's a long time since I thought about doing that.

It becomes kinda sorta like a high output impedance tube amp, screwing up the frequency response, and around resonance screwing it up in a dynamic way since the Thiele-Small parameters change with the drive signal magnitude. It would also reduce the whole sensitivity since you're padding down the whole speaker. But it is easy enough to try as an experiment.
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Old 5th January 2018, 12:36 AM   #55
GM is offline GM  United States
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Originally Posted by 33Polkhigh View Post
Raising the qes you can easily get sealed -3db in the 70-80 hz range......
Right, trading efficiency for a wider effective bandwidth [BW], so EQ can only do so much before running out of power handling.

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Old 5th January 2018, 12:44 AM   #56
globalplayer is offline globalplayer  Germany
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Right, trading efficiency for a wider effective bandwidth [BW], so EQ can only do so much before running out of power handling.

GM
Or running into xlim/xmech even.
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Last edited by globalplayer; 5th January 2018 at 12:50 AM.
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Old 5th January 2018, 01:00 AM   #57
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True, these are normally the dominant part of 'power handling' in the LF.

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Old 13th January 2018, 01:47 PM   #58
33Polkhigh is offline 33Polkhigh  United States
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Using series resistance to change impedance lets you use drivers with powerful magnets and light cones in alignments that wouldn't normally suit them. Even using an over damped full ranger in an open baffle. I'm assuming you get the dynamics and detail. A lot of high q drivers have heavier cones or somewhat weak motors.
I wouldn't mind trying it and audio nirvana classic, maybe with a ribbon tweeter on the side. But I don't have room for any more speakers.
Yea the shorter xmax limits max volume, or requires a sub.
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