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Old 9th June 2008, 09:11 PM   #1
Bluto is offline Bluto  United States
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Join Date: Sep 2007
Location: WI.- near the Dells
Default OB XO Design

Wasn't sure if this belonged here or not. FR is primary attribute but OB is subject.

In last couple days I've run into several designs that people have DIYed that I happen to own same drivers for. I bought them simply to play with or felt they were deal enough I'd get my money back if I couldn't use them. Frankly I was surprised to see others had similiar thoughts.

XO design is something I'm going to have to learn should I continue in this hobby. All software I've seen for design is box oriented.

Is there such a thing as OB design software or if not can anyone lead me to what I should be reading?

Some of these drivers were purchased without even knowing TS and despite many still on market sellers not offering such yet others are using them even as I'd envisioned.

Thanks - Bluto
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Old 9th June 2008, 10:56 PM   #2
tinitus is offline tinitus  Europe
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http://www.quarter-wave.com/OBs/OB_Theory.html
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Old 10th June 2008, 12:16 AM   #3
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Hi,

this is a nice tool for simulating effects
of different baffle sizes and placing of drivers.

For first tries it works cheaper than cutting wood.

Concerning XO the tool makes proposals for
baffle step compensation.

http://www.tolvan.com/edge/

Note: This tool works with idealized drivers.
The drivers effects on bass response e.g.
have to be taken into account by yourself.


Here is much OB theory and practical hints too.
It is a "must read" to me ...

http://www.linkwitzlab.com/

There is an Excel Spreadsheet e.g. which is able to calculate
displacement volume needed dependent on radiated
frequency and distance of the dipole sources.


Best regards
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www.dipol-audio.de
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Old 10th June 2008, 12:29 AM   #4
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Being that open baffles are so easy to design and construct, the
crossover is by far the biggest hurdle.

OB crossovers are a lot like other crossovers. You can start with
a textbook value, and then the work begins, tweaking it, starting
over, tweaking that....

Keep in mind that a flat OB has a different character with regard
to baffle step correction and diffraction.

It can be a very rewarding activity if you have patience. Sometimes
a crossover gets nailed pretty quickly, sometimes it takes months.

Commonly a crossover that measures pretty flat still doesn't sound
right, and you have to try something else.

Life is easier if you have an active crossover and some capacity for
equalization, and is easiest if you have some measurement
equipment.

Of course the fastest way is to find an example with your drivers
that's been worked out.

What drivers and baffle are you considering?
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Old 10th June 2008, 03:59 PM   #5
Bluto is offline Bluto  United States
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Location: WI.- near the Dells
Thanks Guys -

Some of this I'd read and forgotten it existed so I'll go back and re-read. Some of these links are new to me so will be helpful.

Nelson ... Somewhat difficult to nail it down as I'm doing a bunch of experiments including 'augmenting' FR's with different drivers such as guys running both large Eminence with Visiton B200's .

I've got some Misco J9 series 5 x 7's that have a 95db SPL. I could provide you the link if you'd want it. Right now I have 4 of them wired together and they sound great but FR is only about 75 - 12000. The closeout Onkyo tweets P.E. had wake them up pretty good. Qts not provided by them but I've spoken to them in past and they do allow you to talk to Engineers so I know I could get the stats. I'm guessing it's above .9.0 . Also playing with Pioneer A11, Sammi cast 4" FR that I'm having trouble finding numbers for, Pioneer FB11 is a mid but Qts has to be high as they integrate terrifically with other 8" and above FR's I have that do have high Qts and SPL is decent so considering a decent baffle for them , MTX/Oaktons , now defunct and will never get numbers for as well as a few I'd have to dig out of boxes as it's been awhile.

All of these experiments have me considering if buying testing equipment would be worthwhile.

As with all, I'm looking for the 'Holy Grail' and have been astounded that several dirt cheap drivers I've purchased have outperformed drivers of reputation that cost me as much as 5 times more.

I'm really enjoying FR OB and simply thinking there are likely many good 'low buck' drivers out there that may never have been intended initially for this purpose but would serve very well.

Bluto
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Old 10th June 2008, 05:36 PM   #6
The one and only
 
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Alas, I have no experience with Visatons, so I can't help you directly,
but if you are persistent, you'll be able to get them tweaked in.

And while you're looking a low buck bargains, don't forget the
Pioneer BU20FU20.
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Old 10th June 2008, 05:42 PM   #7
Kensai is offline Kensai  United States
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Send a message via AIM to Kensai
Which is on sale at PE for $20 right now.

Kensai
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Old 10th June 2008, 11:45 PM   #8
ttan98 is offline ttan98  Australia
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Location: Melb
Quote:
Originally posted by Nelson Pass
Being that open baffles are so easy to design and construct, the
crossover is by far the biggest hurdle.

OB crossovers are a lot like other crossovers. You can start with
a textbook value, and then the work begins, tweaking it, starting
over, tweaking that....

Keep in mind that a flat OB has a different character with regard
to baffle step correction and diffraction.

It can be a very rewarding activity if you have patience. Sometimes
a crossover gets nailed pretty quickly, sometimes it takes months.

Commonly a crossover that measures pretty flat still doesn't sound
right, and you have to try something else.

Life is easier if you have an active crossover and some capacity for
equalization, and is easiest if you have some measurement
equipment.

Of course the fastest way is to find an example with your drivers
that's been worked out.

What drivers and baffle are you considering?
Nelson,

I have similar experience.

That's very good advice, there is no substitute for experience.
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Old 11th June 2008, 12:13 AM   #9
Bluto is offline Bluto  United States
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Join Date: Sep 2007
Location: WI.- near the Dells
Experience is likely the best Teacher.

Wish I hadn't have gotten out of Audio for as long as I did.

I am having some Fun but even low buck experimenting gets expensive.

What bothers me but also makes me laugh is that I see even Guys with bigger wallets are never satisfied and always looking for more.

I swear I'm gona put together a system that keeps me happy for at least a few years but I think I'm kidding myself.

I'll likely not be happy until I build something the whole County can hear without distortion with less than 20 watts of power. Then I'm gona play it until I get arrested! Buddy Holley and Bo Diddley.

I keep envisioning Noriega looking for blankets to cover his ears when they blasted him with Rock n Roll n Panama.

Bluto
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Old 11th June 2008, 01:09 AM   #10
DaveCan is offline DaveCan  Canada
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Location: Moncton NB
Bluto, I'd guess that the bigger wallets always looking for more, either have not taken their room into account, or just enjoy serial upgrading..

The crossover ? I would think the best bet would be to get the best active crossover one could afford, not sure why most go the passive way as I'm no speaker designer but it just makes sense to me somehow.. Dave
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