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Multi-Way Conventional loudspeakers with crossovers

driver trade up to improve system performance
driver trade up to improve system performance
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Old 27th February 2014, 04:34 PM   #1
jimbones is offline jimbones  United States
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Default driver trade up to improve system performance

About a year ago I built up a pair of hybrid OB speakers using a RS270 10 inch woofer in a sealed box, a Peerless 830883 mid and SB29 tweeter 2nd order 300 and 2200. They sound good but I am always willing to improve on it.

If you were in my position to pick out the weakest link (driver), which if any do you think is a candidate and why?

Thanks for your advice.
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Old 27th February 2014, 05:10 PM   #2
Lojzek is offline Lojzek  Croatia
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The weakest link is always a DIYer and his approach. IMO

I don't like the idea of putting a Qt= 0,4 driver in a sealed box,
if we are talking about a passive one without EQing. Losing the
lowest octave without a reason.
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Old 27th February 2014, 05:51 PM   #3
sreten is offline sreten  United Kingdom
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Hi,

I'll guarantee the execution is more of a problem
than the drivers and swapping drivers won't fix it.

Vented might improve matters but is not the real
issue, and the large driver Vas suggests sealed.

The real issue in likely the bass to mid x/o, proper
EQing of the baffle hump, proper mid level and
then proper mid to treble integration and level.

Saying you just used 2nd order x/o's doesn't
begin to cover the issues. Done properly you
would know any new drivers would need
some x/o modifications and redesign.

OB mids are very tricky if you cannot measure.

For sure IMO you'll need a series (parallel LCR)
trap on the mid to start getting anywhere.

(e.g. https://sites.google.com/site/undefi...diy-sunflowers)

Its all in the x/o design, and once you've done that
properly thoughts will not wander to different drivers.

I cannot see any real point in changing any of your drivers,
except for the fact the bass unit is ~ the same sensitivity
as the mid, which will involve attenuating the mid quite
a bit. Another option is going active bass to mid and
mid EQ with a passive x/o mid to treble.

100W on the bass would be quite happy with a nice
25W (Death of Zen - class A) amplifier for mid/treble.

rgds, sreten.
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Old 27th February 2014, 06:41 PM   #4
jimbones is offline jimbones  United States
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OK, So I agree with the XO discussion. I wanted to leave that out of the equation because Dumptruck assisted me with in a lengthy design period (and measurements) and I am confident that with his experience and assistance it came out as good as it could based on our exchanges. Much thanks to him for all his help.

I did not want to bias your recommendations by stating what I believed to be the area to start with. And YES if I touch ANYTHING at all the whole design must be reviewed again!! I am on board with you on that!!

The mid is attenuated but I can tell you that it sounds very good.

If i were me I think it is the bass driver that I would change and revisit the XO. But what Bass driver to use? I want to stay sealed in approx 1.6 cu ft.
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Old 27th February 2014, 06:45 PM   #5
jimbones is offline jimbones  United States
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So i took a look at the sunflower link and basically the LCR addresses the dipole peak (in that case it was 375 hz) and I have to see what it is in my system. Thats not hard though.
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Old 28th February 2014, 12:15 AM   #6
jimbones is offline jimbones  United States
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One important fact I left out: I am using a Velodyne HGS 12 sub 50hz and below. The 0.4 Q driver should work in a sealed box no?
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Old 28th February 2014, 12:24 AM   #7
PeteMcK is offline PeteMcK
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get rid of the sub & put the RS270 in a vented box
__________________
Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 28th February 2014, 03:29 AM   #8
dumptruck is offline dumptruck  United States
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Hi, I'm that dumptruck, and I helped with this design via email during a time when I didn't have anything to work on, going back and forth with jimbones taking measurements. I had nothing to do with the speaker design outside of the xover, and I've never heard it.

Anyway, jimbones was just getting started with taking measurements, and the room was smaller than you'd want to get measurements of this driver layout, so I was never very confident in the design and probably drove jimbones nuts with requests to try to take reverse null measurements in various ways, but I did at least attempt to get all the basics right, and he declared it finished. I would not be the least bit offended if you guys want to try to dig into some more measurements and see if we screwed anything up. Just don't go into it assuming it's a random mess created by online calculators or something.
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Old 28th February 2014, 07:46 AM   #9
Lojzek is offline Lojzek  Croatia
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Dumptruck,

I think the chance of me getting involved into more measurements
would be like the chance of winning a lottery jackpot. It should also
be noted that newbies often strive to build over and over again and
it does not necessarily mean something was wrong with the speaker
project. It is only natural until everything settles down and enough
money is spent.
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Old 28th February 2014, 07:55 AM   #10
Lojzek is offline Lojzek  Croatia
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Quote:
Originally Posted by jimbones View Post
One important fact I left out: I am using a Velodyne HGS 12
sub 50hz and below. The 0.4 Q driver should work in a sealed
box no?
If you already had the sub, then I don't see why need for RS270.
You could have let the Peerless play all the way down to 50 Hz
and cross to the sub there.
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