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Multi-Way Conventional loudspeakers with crossovers

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Old 16th August 2004, 11:27 AM   #11
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Seems like a few people are doing their best to scare you off Jennice. From what you describe, it appears you have far more resources at your disposal than many other DIYers.

If you are a passion for music, a desire to learn, time on your hands and don't mind getting them dirty, then I see no reason why you can't build yourself a great pair of speakers. Remember it's as much about the music as it is about learning and enjoying the journey.

There will be some initial investment in tools, materials and books. It's a bit daunting at first, but the satisfaction of building your own one-of-a-kind speakers and hearing music through them is immense.

Personally I'm not really into kits, because that leaves the fun part of design in someone elses hands, but if you're a little afraid to jump in head first , this may be an alternative.

I suggest you build yourself a couple of small 2 ways to start with, using, say, Vifa drivers and see how you go. Later, if you get more ambitious, you can build a big pair of MTMs, 3 ways, or transmission lines, and use your 2-ways as surround units.
And remember there are infinite resources on the net, and software available that makes it easier than ever.
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Old 18th August 2004, 09:09 AM   #12
Jennice is offline Jennice  Denmark
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Hi David and Mark,

I agree... It seemed that people tried to tell me my ideas are deemed to fail.
Yet, why would so many be discussing DIY speaker projects if it is next to impossible to make anything decent? That question kept nagging me, as I couldn't find an answer to it.

It's interesting to hear what sort of quality/price range is possible with trained DIY. However, my target would be a pair of speakers, probably a tweeter and two bass/mid's (2-way), in the range of UKP 200 per speaker.

I don't have "the JIG" (yet?) as I don't have a soundcard with enough output power to drive it. I understand that it needs some power from the sound card. I have an old SoundBlaster 16 PCI available, if that's suitable.

The other gear I have access to, includes microes and a measurement system: http://www.bksv.com/pdf/Bu0228.pdf

Thus, my idea was to build the speaker, as I imagine it to be, but keep an access to the cross-over. Then I'd apply a noise signal, and measure the spectrum. Based on this spectrum (and my ears), I'd adjust the values of the x-over.

Would that work?

Jennice
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Old 18th August 2004, 12:05 PM   #13
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The only problem with that plan is that good crossover parts aren't very cheap, so don't plan on buying a variety and trying different values until you get the right one.

Building, then measuring to determine the XO components to buy will work.

For 400 UKP you can build much better than a "decent" pair of speakers. You should check out Planet10's site and see what Dave builds for next to nothing.
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Old 18th August 2004, 12:32 PM   #14
Jay is offline Jay  Indonesia
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Quote:
Originally posted by Jennice
Yet, why would so many be discussing DIY speaker projects if it is next to impossible to make anything decent? That question kept nagging me, as I couldn't find an answer to it.
First, because speaker DIY is fun and challenging. If you design your own speaker for the first time and your objective is merely to have the best possible speaker out of available budget, forget it. Even with those advance hardwares and softwares you won't make anything decent.

But if you don't really need the fun and challenges, then build somebody else's works that had been proven. Lot's of hours, experiences and tools have been invested in good designs. And you don't need to invest another work to get the result.

Quote:
Originally posted by johninCR
For 400 UKP you can build much better than a "decent" pair of speakers. You should check out Planet10's site and see what Dave builds for next to nothing.
That's the positive side of speaker DIY
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Old 18th August 2004, 12:50 PM   #15
dvdwmth is offline dvdwmth  Canada
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I was recently wondering the same thing. After lots of reading I ended up building something using a radio shack fullrange (fostex 103 type) and a 12 in driver I salvage from an older speaker with a simple inductor on the woofer. It sounds better then I ever expected a home build with 50 bucks worth of parts could ever sound.

It was a great way to learn and since there are lots of interesting designs for drivers like this I am finding lots of opportunities to experiment with various cabinet types and electrical wiring.

Full range driver are, IMHO, an excellent way to jump in without getting overwhelmed with complex crossover issues. They're cheap (well some are anyway), well documented, and sound good. You can always add more drivers to fill out the extreme ends if you want to experiment with crossovers.

The important thing from my point of view is do something simple and cheap that will get you excited about what can be done, and then tacke a more complicated project. There are tons of projects that will fit the bill
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Old 18th August 2004, 01:46 PM   #16
Mark25 is offline Mark25  United Kingdom
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Hi Jennice,

David recommended starting with a 2-way, i'd second that, you can always add an extra driver later.

The link you gave looks like a industrial data measurement system. Probably overkill, ruler flat F response is not essential. It appears to be only measuring in the F domain, for that lots of people here use Speaker Workshop by Audua. I use dazy web labs tms1, myself (no logic in that, just because!). These all need a decent mic, like Linkwitz modded panasonic module or a B&K if you have one to hand !!

IF..... the B&K equipment you linked measures in the time domain too, and you have access to an an anechoic chamber, then you're a long way ahead of most of us already!


Eric Wallin's JIG is a popular jig for measuring driver T/S parameters, there is another one with a built in power amp too, sorry; i can't find the link at the mo'

Rod Elliott's article about passive X-overs may be interesting to you, if you haven't already seen it.
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Old 18th August 2004, 07:37 PM   #17
Jennice is offline Jennice  Denmark
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Quote:
Originally posted by Mark25
[B]Hi Jennice,

David recommended starting with a 2-way, i'd second that, you can always add an extra driver later.
Yes, I'm thinking of a 2-way, probably with parallelled woofers - maybe of smallish size, to keep the baffle less wide, yet have the speaker move some air for bass.

This brings up (yet) another question... isn't it possible (and preferrable) to match the baffle step response with the cross-over frequency?


Quote:
The link you gave looks like a industrial data measurement system. Probably overkill, ruler flat F response is not essential. It appears to be only measuring in the F domain, for that lots of people here use Speaker Workshop by Audua. I use dazy web labs tms1, myself (no logic in that, just because!). These all need a decent mic, like Linkwitz modded panasonic module or a B&K if you have one to hand !!

IF..... the B&K equipment you linked measures in the time domain too, and you have access to an an anechoic chamber, then you're a long way ahead of most of us already!
Yes, I do have access to an anechoic chamber, but I do wonder about it's use, since the speaker will never be used in such a chamber. Another thread somewhere mentiones this issue also.

Yes, the PULSE measurment system is industrial grade
...and it can be made to use time records.
Why, by the way, is this needed, when I really need the frequency-depencency of each driver? I don't intend to monitor it long enough for it to cook it's voice coil.

Yes, I also have a 3Hz - 50kHz mic at hand, although the measurement assembly I normally have access to, has a 25kHz BW.
Then again, I can probably borrow the 200kHz versions in the week-ends if needs be. (speaking of over-kill). It's not always that exciting, but at times it does help to work at B&K.

One of my thoughts was to use a white noise generator, a power amp, and series resistor, to get a response spectrum of each driver. This is basically what Rod talks about with his sweeps, isn't it? (To obtain driver parameter knowledge).

Another thought of mine is also mentioned by a fellow DIY'er in some thread elsewhere: The parameters we measure are on a non-broken-in driver. The thread stated somewhere, that once the driver was broken in, the specs got rather close to the manufacturers specs (within 2%), whereas they're way off when the speaker is new. So if I'm not going to rely on specs, I should break the drivers in, right? (letting them play noise for a number of hours).

Enough new questions for now... time to find my bed and call it a day. Tomorrow is a new day full of opportunities and duties at the QA office. Hopefully I'll get the task of breaking stuff again!
Well, officially, it's called QA testing according to standard test schemes, but if the designers haven't done their job well enough, it get's really fun!
Imagine... getting paid for breaking stuff!
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Old 19th August 2004, 08:37 AM   #18
Mark25 is offline Mark25  United Kingdom
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Generally, the better the inherent driver quality, the nearer they end up to their advertised T/S specs, when run-in.

User Vikash has some interesting stuff about running in the Audax AP100Z0 on his site. http://www.vikash.info/audio/audax/index.asp, it's also covered in the thread Maplins close-out on AP100Z0 but that's about 55 pages long or so........

Sorry i wasn't clear about the time thing, I meant the ability to measure the phase output of a driver. A drivers o/p changes in phase with F, driver physical position and X-over slopes also effect phase. This becomes important when you are summing the outputs of two drivers. There's some info on Rod's site here but as usual it's all thoeretical. For the beginner (like me) it's hard to determine the audable effect of these factors, weight them if you like. I guess that's where experience comes in. I'll stop now, before i dig myself into an even bigger hole............and mention something like; dispersion patterns.
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Old 19th August 2004, 08:47 AM   #19
Jennice is offline Jennice  Denmark
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Mark,

I don't intend to hold anything against you, in case my project shouldn't be successful. I appreciate any input, and any suggestions/advice I can get, but there's only one person to hold responsible for my project and progress - and that's ME
I'm trying to find as much material and info on this subject as possible, before getting out the wallet, but nhere's nobody else than me to weigh in the arguments and suggestions before deciding if/what to build.

Jennice
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Old 19th August 2004, 08:53 AM   #20
Mark25 is offline Mark25  United Kingdom
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i'm more worried about getting over my head technically and getting flamed for it...........i was rather hoping that someone else would have "picked up the reigns" by now, so i could learn too.
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