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Multi-Way Conventional loudspeakers with crossovers

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Old 30th June 2009, 03:41 PM   #11
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Quote:
Originally posted by oaristys

I don't have lot of experience but when you put a speaker tested with a graph on specsheet and you put it on a same volume boxe, you will get what you paid for. You will not change all the things in making another box 1 inch taller and 1.5" less deep.

Changing the volume of the cabinet doesn't change the sound of a speaker much unless you are way off. However, changing the cabinet baffle dimensions or the driver placement on the baffle does impact the sound anywhere from a little to a lot. This is due to the diffraction effects of baffle. So a cabinet that is 10"x10"x10" will sound and measure much differently than a cabinet that is 7"x15"x9.5. And a XO which is designed for the 10x10 baffle will not work as well on a baffle which is 7x15.

Quote:
Originally posted by oaristys

I know the better thing will probably to measure ourself the drivers in like 1 cuft and design the box and crossover with our result instead of the manufacturer one. But sound a bit funny to me. If you have to do that. How can you be sure of you driver choice !? Anybody check the manufacturer specs for choose.

Manufacturer's data is a guideline to go by when shopping for drivers nothing else. The other thing to consider is that the mfg posted frequency response is usually taken on an infinite baffle, which will quite a bit different than the frequency response of the driver once it is mounted on your baffle. That is why for best results you need to measure your drivers in your enclosure.

Quote:
Originally posted by oaristys

Or why DIY community don't create a consortium who test itself the most popular and pertinent drivers available ? One place where all the specs and curve are real and trustable !

There are numerous sites that post driver measurements, Zaph Audio being one of the more popular. But even then, John's measurements are only good for comparisons between drivers measured under similar conditions. Once you mount them on your baffle, those measurements will change.

Look at the raw measurements of the Scan Speak 6600 tweeter in his ZRT design enclosure:

http://www.zaphaudio.com/ZRT-2way-me...R-rawinbox.gif


Then compare that to his other measurements of the 6600 tweeter in his tweeter measurements section.:
http://www.zaphaudio.com/tweetermishmash/compare.html

Note the big differences between 500 and 2500 Hz. This is all due to baffle diffraction and should be accounted for in the XO.

Regards,

Dennis
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Old 30th June 2009, 04:31 PM   #12
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Ok...

Manufacturer specs. It's like look at reviews of 4x4 truck on highway first and after, review yourself the truck in your domain or backyard. But you cannot review it on your favorite trail before buying it. Maybe the truck is more efficient in dry mountain trail but you have to go in mud and wet plane in higher speed as possible. So you cannot trust the manufacturer high way specs, and cannot trust your mountain friends too.

The market speaker is adapted. I think,s it's why the manufacturer order specific speaker just for specific enclosure and why 26 prototype enclosure are in a backs tore. Just for doing a good sounding loudspeaker with basic enclosure with cheap brich wood, cheap tole and plastic materiel drivers and basic crossover with cheap component.

Me, DIYer need to buy high quality stuff all the way, use MDF and reinforcement, ultre big air core inductor and onerous inductor for build a 20W bad sounding speaker. After what, need to be the same problem than cheap mini sound system like panasonic : add a filter to made it sounding good. But with quality parts.

The day i will be able to make this kind of test, i will buy under 15$ drivers with cheap NP inductor and small coil. I will use brich or " mdf. I have a voice in my mind who saying that will sound good overall after appropriate filtering and crossover design.

If it's true, it's a good news for my friends who will be interested about 85$ budget hi-fi speaker pair. Every guy who finding basic PolkAudio, Energy, PSB, or no name speaker sold at bestbuy and cie.
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Old 30th June 2009, 05:26 PM   #13
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it's a bit frustrated because when i pay 39 to 350$ for a driver, i ask for accurate and honest service and specs.

350$ Scan Speak cost just a bit more than 25$ one to build on a shop. No magic here. It's just a driver.
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Old 30th June 2009, 05:37 PM   #14
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I have Mission 701. Build with a ... less than 5mm plastic baffle ! And it's a big bookshelf. Plastic chassis driver. Sound prety good. Better than a pioneer. sony, or any basic speaker.

I have klipsch computer speaker mad with 2 or 3mm plastic. The size of a spagetti sauce bottle and do 60hz bass with not equally sound quality on this price range and size.

Not super high-end big sonus faber or Nautilus speaker i know. But it's the proof that sometime, yes, we can build small, cheap or real life simple satisfying sounding speaker.

I don't want to integrate the minding of you should buy onerous component to build a speaker as good as a 450$ monitor on market.

and yesterday, i see by accident the inside of my Monitor Audio from the back port. I can see the tweeter from the back... .. no realy don't need onerous component to produce good sound lol

Big woh ! WWow! look at this quliaty driver and "yeah a beer can size capacitor is what you need". - as nothing to do with the real result !
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Old 1st July 2009, 04:01 PM   #15
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Since you're such an expert, I don't understand why you're asking for help.
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Old 1st July 2009, 04:33 PM   #16
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Quote:
Originally posted by Face
Since you're such an expert, I don't understand why you're asking for help.
An expert ?

This is what i "see" from my angle point of view. An expert can come here with measurement material and help me to make my two project "definitive" and "sellable" (is it the world for "it can by sell").

Maybe i misunderstood the origin of this forum too. Not just diyAudio but diyHi-EndAudio. It's a good thing. It exist race car forum, luxury car forum and authentic collenction car too ! But don't go to race one to find help how to fix something on a 40mph max 1915 old car ...

Hey i love you guys ! You want to push my pleasure trough best hi-fi sound et prestige. It's very noble and generous !

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Old 1st July 2009, 04:40 PM   #17
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Or like, going to PolkAudio forum to search how to do better sounding and looking speaker than Sonus Faber...

I think it's better to come here

You are good experienced diyer and hifi serous technician. Like the Solen tech guy who simply cannot admit it's possible to use this or that parts (cheap or small gauge). It's like NO PASS in is head lol. But the true is that will work ! Just not as good as 2 500$ bookshelf speaker.

I'm a serious experienced amateur photographer and if someone ask me "Hey can i but this Olympus DSLR with a basic Sigma 125$ lens to do good picture of my trip to Mixico ?" i will fall on the floor and ask "what do you think about the idea of taking no picture at all ?"
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Old 1st July 2009, 07:04 PM   #18
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Can I assume you are looking for a simple solution to a simple question?

The problem is that crossover design is very complex.

But for beginners on a budget there are quick and easy solution. No they aren't by any means 'audiophile' solutions. But for a beginner, the get the job done.

One solution might have been a simple straight forward off-the-shelf crossover. The problem is, you have an 8 ohm woofer and a 4 ohm tweeter. That complicates things.

The next solution is to use the crossover calculator link to earlier. Make sure you put in 8 ohms for the woofer and 4 ohms for the tweeter.

http://ccs.exl.info/calc_cr.html#second

Also a similar calculator at -

http://www.apicsllc.com/apics/Misc/filter2.html

Next, you need to select a crossover frequency.

At the crudest most rudimentary level, we can say about 2khz. Without a frequency plot, we can't be sure how clean the woofer is near that frequency. The spec sheet says it is usable up to 10khz, but frequency specs are notoriously unreliable.

Now is 2khz the prefect place to crossover? Well, we don't really know. At this level of design, it is simply a matter of picking something in the working range of both speakers - 1.8khz, 2.0khz, 2.2khz ... made a decision.

Though since the tweeter resonates at 1.1khz, we might go one octave above that for the crossover, making it 2.2khz. But again, the problem is we have no information to determine who well the woofer is doing at the frequency.

But, if you don't want to be buried in all the technical details, then pick a frequency. If 2.2khz appeals to you, then chose that and move on.

But with the limited information you have, that is about the best you can do.

I suggest a 12db second order crossover of the Linkwitz-Riley variety.

Now there is certainly room for variation. You could use a 6db first order crossover. Though I think the higher the crossover the better.

Since the woofer claims it is functional to 10khz, you could use a simple single 6db capacitor on the tweeter. Again, I think the higher the crossover the better, but not too high.

How any of these will sound is somewhat unpredictable. You can buy a pile of components and try all variations of the crossovers and see which you like best.

But personally, I see the 12db/second order as the general all-purpose crossover.

Again, how any of these will sound is somewhat unpredictable.

When you find the values from the crossover calculator, find the nearest equivalent values at Parts Express.

Near the bottom of the crossover calculator page, you will find a calculator for an fixed L-Pad. Determine how much you want to attenuate and enter the correct impedance value for your tweeter, and it will give you the resistor values. Power resistors also available at Parts Express.

If you just want a basic no-hassles, no-fuss, no-muss crossover, this is how to do it.

That is a functional crossover. An ideal crossover is much more complex.

I think sometimes it is possible to know too much. One of the problems I have with this group is the tendency to always offer a $1,000 solution to a $100 question. Or, in this case a $500 solution to a $20 question.

This isn't the ideal way to build crossovers, but it is a place to start, and we all need a place to start. We all need to make those first few mistakes, so that we can live and learn, and move on to build again.

If this person wants to spend lots of time and money to learn the infinite art of crossover design, then fine. More power to him.

But if he simply wants a basic functional beginner crossover so he can get his speaker up and running, I've shown him the way to do it. Such as it is.

Steve/bluewizard
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Old 1st July 2009, 07:57 PM   #19
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Quote:
Originally posted by BlueWizard
Can I assume you are looking for a simple solution to a simple question?

The problem is that crossover design is very complex.

Though since the tweeter resonates at 1.1khz, we might go one octave above that for the crossover, making it 2.2khz. But again, the problem is we have no information to determine who well the woofer is doing at the frequency.

Steve/bluewizard
Ok is it the principal reason for not buying an already done crossover ? What do you do with parts when you change the frequency after measurement ? Crossover is like 60$ - 150$ in parts !! Inductor cannot be refund because you need to use the extremity and solder it... It's the more expensive parts i think...

Probably the reason for use a active xo for speaker development.

Like you say, it's problematic for the guy who just like to do lot of things himself. Patio deck, chairs, furniture, renovation, speaker etc. this guy love to get something as good as what in store but for less and with the proudness. Tweek and change the crossover cost a lot !

This is why you advice to take already existing and proven design available on few website ...
Please read and correct me if i misunderstand


I understand now the first basic job of a crossover is to split the spectrum in 2 (for a two way) and attenuate one of two driver to make it same SPL.

I think we get "as is" sound from chosen driver without fatal problem.

First opportunity to limit the use of driver in the range where he sound better. (change to xo frequency)

For guy who want to limit the xo at this level, an completed crossover can be buy (!). If you have two 8 ohm drivers and want to split to 2500hz. Buy 8ohm 2500 two way crossover and there will do the job. I see not other than frequency and Ohm taken in count for parts calculation.

And why doing ourself this crossover with pricey component if you will need to adjust frequency later .. !? And it's easier to refund this crossover than each parts separately !

So i understand better the second and more tough job of a crossover too. This job is to add basic circuit made from inductor, capacitor and resistor, for attenuate one part of the spectrum. Manipulate the impedance too. The more attenuation zone you need, the more this kind of circuit module will be added. Crossover cannot "fill a hole"... It can just attenuate all around it.

There is the more impressive sound update to reach studio monitor fidelity. Now, it's impossible to find just the right crossover to fit with your driver except if you find a crossover already done for specific project.

Other work can be done by crossover ? Delay, phase shift ? Don't really understand phase shift.
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Old 1st July 2009, 09:16 PM   #20
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A quick estimate of the 'text book' crossovers for your project is about US$22.00 per crossover (coils and capacitors only).

If you can't get into the minute details of crossover design, which are near infinite, then use the nominal impedance ratings on the speaker, and whatever values the calculator gives you, and hope it averages out reasonably.

For a more precise match of crossovers, you need to have some measuring equipment. First a computer with a decent sound card, then a bunch of software (some of which is free), a reference microphone, a small mixer, and maybe a basic stereo amp. Add to that, a test box, of which there are many design plans on the Internet.

Total costs assuming you have a computer, between $250 and $500, depending on how far you want to take it.

One simple tool for basic testing of speakers is the Dayton Woofer tester available from Parts Express. Cost about $100.

So, I see two routes to follow, either raise the level of your skill, knowledge, and equipment, or lower your expectations for this project.

Though a little research might help. You might be able to find cabinets designs that use this woofer if you search the Internet or search the Peerless website. Frequently the specs sheets will have some basic cabinet design information on them.

Steve/bluewizard
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