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Old 13th September 2005, 02:04 PM   #11
simon5 is offline simon5  Canada
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Quote:
Originally posted by bobo1on1
How about a bandpass enclosure, the low bandwidth will attenuate the harmonics so the distortion will be lower.
True but you have group delay with a bandpass enclosure and group delay is bad.

Quote:
Originally posted by JinMTVT
what about the linkwitx thing OB enclosure?
is it one of the best way to get less distortion ?
Yeah open baffle bass is probably the best thing for SQ. Infinite Baffle is good also. The problem is to equalize the response to have enough SPL down low. It's expensive because you want many high excursion woofers.
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Old 13th September 2005, 09:24 PM   #12
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The best bass / sub quality I've had in my room so far was using my tempest subs from 40Hz down, with 2 x 10" scanspeak drivers per side from 40Hz up. Sounded a lot better than using the tempests up to 80Hz.

I've decided to keep the tempests below 30Hz, and am replacing the scans with 2 labhorns. (home theater - If my system was music only I'd have kept the scans)


Maybe a driver doing 15 - 40Hz has trouble keeping the 40 - 80Hz 'tight ' when its moving so much ?

If I get time I'll try using 2 of my tempests below 30Hz, and 1 from 30 - 80Hz. Maybe the bass will clean up nicely. Won't be for a while though - haven't got the xo to do it at the moment.



Cheers,

Rob
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Old 13th September 2005, 11:00 PM   #13
JinMTVT is offline JinMTVT  Canada
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the only problem i see with using a sub up to 40,
and then woofers from 40 up
is that you will end up with either woofers not doing a good job at 1KHZ + or at 80hz less ...
or with another XO near 1KHZ to have mid woofs before the twits.... and a 4 way system quite adds to the complexity of the thing i think ..
it'll be hard to setup, and hard to get right!
( and probably seriously costy )

since we are on a DIY site, and i dind't suggest that no cost was in the line ... we have to consider complexity and cost as up level priority ( after SQ of course in our compromises ;p )

I seriously thought that most 15-18" could play up to 100-200hz
quite nicely ...

what kind of woofers are then used to cross in between 40-80hz region ? size? throw ?

what is the most used range in sub 200hz bass in music?

and by the way ... what are the best quality bass from 100hz up ?
we've only talked about SUB bass for now ..
but i'd still consider the 80-200hz region as "bass"
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Old 13th September 2005, 11:53 PM   #14
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Maybe I should have given more details....

The 10" scans were crossed at 250Hz to my mids...

When I crossed the scans to the tempests at 80 instead of 40Hz the sound got worse.... But would go louder / bigger etc.

""

the only problem i see with using a sub up to 40,
and then woofers from 40 up
is that you will end up with either woofers not doing a good job at 1KHZ + or at 80hz less ...
or with another XO near 1KHZ to have mid woofs before the twits.... and a 4 way system quite adds to the complexity of the thing i think ..
it'll be hard to setup, and hard to get right!
( and probably seriously costy ) ""

Your original post asked about sound quality up to 100Hz... Why the assumption of an xo at 1kHz ? I answered regarding sound quality in low bass

You need to look at the scans + tempests as a 'subwoofer system' rather than a 'sub + bass' situation. ie - it's not a 4-way system, but a 2-way + sub where the sub happens to be a 2-way..if that makes sense

btw I don't see why a 4 - way is more difficult than a 3-way to set up.. as long as you've got basic measuring equipment.


To sum up - in a music only system I'd have kept my 3 x tempests from 10 - 40Hz, my 4 x scanspeak 8565-01 10" from 40 - 80 as a good sound quality bass system. I prefer them to my 3 tempests (10 - 80Hz). If I was doing this as a music system I'd probably cross at 30Hz though rather than 40Hz. (I only give my thoughts on what I've actually heard though) The only reason I'm building labhorns is my penchant for home theater...

Maybe you should set out your goals and the system you intend to put the subs into. Then our suggestions may be more useful.


Cheers,

Rob
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Old 14th September 2005, 01:55 AM   #15
JinMTVT is offline JinMTVT  Canada
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sorry if i derived from my personal topic
hihih

and also sorry if i turned my posts to look like questions for my personal projects ..wich it was not intended to!

ok so lets get back to the subject ..objectivly!

So from your experience, 2 types of drivers are needed to get the best quality under 100hz for a given system
( with the drivers you used of course ...)

so why do you think your tempests aren't good to work at higher than 40hz on your system ?
have you come to conclusions about the reason?
not fast enough ?

and hwat kind of crossover have you used in between both?
was it steep ? or they were permit to work considreably together???
( sorry if you mentionned alrady the type of crossover slope )
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Old 14th September 2005, 07:15 AM   #16
Coolin is offline Coolin  Netherlands
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My geuss would be the tempest get louder at the 80Hz end because of increasing radiation impedance.
So the low end is less compared to the upper bass creating an imballance.

This is also a problem of the driver manufaturers. Getting a balance in the bass responce. Using a heavier cone is one way but you lose effeciency.

Also at the higher bass frequencies the internal box geometry also becomes more important
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Old 14th September 2005, 07:17 AM   #17
Coolin is offline Coolin  Netherlands
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Oh forgot,

Room gain compensates for alot of this effect...
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Old 14th September 2005, 12:26 PM   #18
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The xo @40 Hz was from my av processor, 24dB. I added a 2nd 12dB to my mains to give a total 24dB slope on them (processor puts a 12dB highpass slope when speakers are set to 'small')

The tempests were eq'd flat in room before xo'ing, so played the same spl from approx 15Hz - 120Hz. The 10" scanspeaks were flat in room to 20Hz before xo'ing.

I'm guessing the main reason for sounding better is that the scanspeaks were just a lot higher quality drivers than the tempests. Although if I test the tempests as I said above I'll see if they 'clean up' when they're not doing the sub 30Hz stuff.

I'm not saying you must use 2 drivers to get 'good bass', just giving my experience with the tempests and the scans.

Cheers,

Rob.
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Old 15th September 2005, 07:54 PM   #19
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BTW The best subwoofer I've ever heard with music was the Martin Logan Descent. (3 x 10" servo feedback sub) In a room about 13' x 9'

Beautiful.

Rob
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Old 17th September 2005, 12:28 AM   #20
Retsel is offline Retsel  United States
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Default Best subs

I agree that servo subs can be among the best. I had a Genesis 900 sub that was pretty good. Genesis informed me that they had a mod to improve the attachment of the accelerometer to the woofer thus reducing distortion. I was skeptical, but sent the woofer off to them. When I got the woofer back into the subwoofer box, I was really, really impressed. The bass was perhaps the best I have heard. This shows how feedback devices can make an average woofer into a very high performer. The only other bass I heard that was better was a Genesis 200 system which had total of 16 eight inch woofers also servo controlled.

I was rolling the Genesis sub off at about 40 hz to Hedlund Horns, which used a Lowther DX4. The midbass of the Lowther driver in a back horn is also something to behold. The very flexible crossover provided by Genesis allowed me to provide a seamless crossover, which I am convinced is the reason why most don't get great bass.

I am playing around with Avalanche Audio 18 inch drivers in an W style open baffle. I have not yet got the system up and running yet, but it will be interesting to see how these drivers work in an open baffle arrangement and whether they can make music rolling them off at around 100 hz.

Retsel
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