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Old 27th April 2007, 03:47 AM   #1
navin is offline navin  India
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Quote:
Originally posted by felixx
If you will try in time....open baffle....you will never look back to enclosure sound.
Never thought open baffles can look so good and so compact.

BTW how does one determine if the woofers one has are suitable for open baffle? High Qts? How high? 0.7? or more?
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Old 27th April 2007, 06:52 AM   #2
felixx is offline felixx  Romania
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No ..I don't use a subwoofer.....I don't need that.
I have another setup only for home theater.

Martin King have the same woofers into open baffle and the active setup provide 97db on 35hz.He tryed first Dayton woofers but the personal taste was Alpha's.
About qts...in fact is a matter of personal taste.
You should try to listen first woofers with 0,4-0,7 and after that you should go to Alpha's 1,26....but do that quiqly.
Some have a good reports using 0,5-0,7 and have a personal taste because use so called "quality of the bass"....but loose that cream of music.
But...I myself,Martin and many others owners have tryed all these qts.
The Alpha's do the job stunning.Bass is clean,full,a little soft,(that I appreciate to Alpha's)avoiding interference with Supravox,the instruments in right in my face.....

You should try to listen to have a good impression.
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Old 27th April 2007, 10:35 AM   #3
navin is offline navin  India
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This is OT but related to felix's OB subwoofer so forgve me if I post this here.

Felix,
I have a 4 12" woofers handy.
Qts 0.44
Qms 5.1
BL 7.8Tm,
Fs 17Hz
Vas 380 liters
MMs: 73gms
Voice coil height: 30mm
Air gap Height: 10mm
Resistance: 3.1 ohms (4 ohm nominal).

Presently they are in large sealed boxes (about 65-70 liters each) and I was hoping to reconfgure them into smaller boxes. I was thinking Apreioic till I saw your OB speakers. I understand OB will drop the Max SPL I will get by about 6db bot the bass should have better definition.
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Old 27th April 2007, 10:54 AM   #4
felixx is offline felixx  Romania
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4 pieces of 12" into (two) open baffle don't think it goes very well.
First I wanted to try Peerless 12" sls ....but I wanted to make a very short compromise....and that is really woofers.

Another option will be if you will use 4 piece 12" only into one open baffle or dipole sistem.That means 8 drivers only for bass.
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Old 27th April 2007, 05:18 PM   #5
v-bro is offline v-bro  Netherlands
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I think OB lets a driver play more or less as intended by the manufacturer (most drivers are measured in an OB). It just needs to be large enough and it works... I do have the impression that large bass drivers perform better in such small baffles (I tried several small drivers and even with eq. I didn't like the results...).

I just built one proto (lucky I got the wood for free...) and immediateley loved it. After that I measured and saw it also measures fine...

I would always recommend building some kind of proto first...

The drivers I use (JBL 2220A) have very very low QTS, so after all the stories I expected it to need lots of EQ. But it doesn't!

I don't know what to believe anymore, right now I think there are many drivers suitable for the job....(more than people claim...)

Also I think there are many ways to rome, if you have more from this you can have less from the other. It's the balance that counts.

For instance if you have a smaller baffle, use larger drivers or eq. If your driver has high Qts it can be a smaller driver/less eq.
I'm starting to think if you just build something on a good hunch you're close enough to get it right anyway.

I must add that I presume most of the above (and a bit of experience) but I didn't try everything yet, and certainly don't claim to be some kind of OB guru....
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Old 27th April 2007, 06:21 PM   #6
felixx is offline felixx  Romania
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@v-bro
Absolutly true.
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Old 27th April 2007, 10:01 PM   #7
v-bro is offline v-bro  Netherlands
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Quote:
Originally posted by felixx
No ..I don't use a subwoofer.....I don't need that.
I was surprised about this myself! I bought 30 year old, but recently reconed drivers for 50EUR./each. containing the ingredient 'alnico' I started with the baffle only, than added 15cm sides to make a small u-frame, than made the real thing larger than necessary and it turned out precisely right My woofers have Qts somewere way under 0.30, effieciency about 100dB (if I was well informed...) So I expected shallow bass response. I figured since the top end is only 85db it could be well filtered. And since they are sort-of PA drivers they could handle serious power. Boy was I surprised Offcourse the fact that the baffle touches the floor makes a lot of difference. It completely eliminates the acoustic shortcut on the path to the listener, but even outside the socalled 'beam' (way off-axis) they appeared to show pretty good tonal balance, only less loud.

Quote:
Originally posted by felixx


I have another setup only for home theater.

Martin King have the same woofers into open baffle and the active setup provide 97db on 35hz.He tryed first Dayton woofers but the personal taste was Alpha's.
About qts...in fact is a matter of personal taste.
You should try to listen first woofers with 0,4-0,7 and after that you should go to Alpha's 1,26....but do that quiqly.
Some have a good reports using 0,5-0,7 and have a personal taste because use so called "quality of the bass"....but loose that cream of music.
But...I myself,Martin and many others owners have tryed all these qts.
The Alpha's do the job stunning.Bass is clean,full,a little soft,(that I appreciate to Alpha's)avoiding interference with Supravox,the instruments in right in my face.....

You should try to listen to have a good impression.
You sure have more experience than I have with OB, your speakers are quite compact for an OB. But I don't even doubt they sound like heaven...anymore....

Be building more of 'em, much much more next with a really high Qts driver
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Old 28th April 2007, 04:10 AM   #8
navin is offline navin  India
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Quote:
Originally posted by felixx
4 pieces of 12" into (two) open baffle don't think it goes very well....
I thought your system also had 2 drivers (albeit different ones) per side.

So 2 12" per side is not a good idea. well plan b for me was a isobarik box.
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Old 28th April 2007, 04:12 AM   #9
navin is offline navin  India
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Quote:
Originally posted by v-bro
...with a really high Qts driver
Even I assumed that a really high Qts (Qts > 1) was required.
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Old 29th April 2007, 06:50 PM   #10
v-bro is offline v-bro  Netherlands
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Quote:
Originally posted by navin


Even I assumed that a really high Qts (Qts > 1) was required.

Well from the measurements and from the experience I have nothing to complain about. I think a higher Q driver could have been smaller size and lower sensitivity. I just thought I'd start with overkill to create the necessary headroom to clean it up afterwards. But I don't feel I should change anything, like I said I'm totally satisfied! I don't even feel like using eq to boost the lowest freqs up. The driver has 40hz Fs and the system goes well below 50hz, which I find deep enough...

Bottom line is that the balance here seems quite allright, eventhough I think some adaptations are needed with low Qts drivers. But I see no problem in using low Qts drivers. High Qts will perhaps only give slight benefits...

I can only speculate on this for the moment, perhaps someone can explain it better or give a few nice examples? Pictures or measurements...or a link to....
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