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Multi-Way Conventional loudspeakers with crossovers

New user. First speaker build. All the usual questions!!
New user. First speaker build. All the usual questions!!
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Old 14th February 2020, 09:11 PM   #1
jjams82 is offline jjams82  United Kingdom
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Default New user. First speaker build. All the usual questions!!

------------PREAMBLE / RAMBLING INTRODUCTION--------------


First post here. Hello, nice to be here. Seems like a good place to be!

This community seems to still be bustling along on old school BB forum whatever-it - and is and doing well. The only other forum I frequent that's doing well on a simple old style forum is very community based and quite the wonderful place which has had me end up many times in the dolomites, Italian alps, French alps, and even a helicopter (followed by an Italian hospital). I'm not expecting snow trips from here, but some noob help would be VERY MUCH appreciated.

That's all intended as quite the compliment, just to be clear. I do love a good old fashioned forum and the ones that still tick along nicely have to have something special in them.


Right ------ ON TO THE ACTUAL POINT OF THE POST! -------------


INTRO AND THE BASICS:
--So I'm making my first speaker. I have all the skills and tools needed, I'm a farmer, I can make anything out of anything (so long as you just need it to last till the end of the season). Point being, construction of almost anything is no problem at all. Hexagonal multi point wangjangling pressure canceling hyperwave cab, with a tapered horn poking out the bottom... I have the tools and the materials. All good. No probs.


THE DRIVER AND MY EXPECTATIONS:
--(see pics)-- I have a coaxial driver (I mean, it's all the rage nowadays after the ls50). It's a Focal 6.5" car audio driver. 165ca, they served me well in a MX5 which is no more. I have the two way with crossover version in my newer car and really quite like them (when I'm parked, not roof down on the motorway) I know what to expect, I'm not looking for perfection, just a speaker I can pair with my next project (A nice little mid/bass type sub) and put in a small bedroom. Enjoy the music, and don't fuss the details. Thankfully Focal provide a whole load of data on the speaker, Thiele/Small parameters and whatnot. I'm unfamiliar with what they mean, despite a week of lurking, googling, and generally hoping to find a calculator which would just tell me what to make and save me from having to use my brain


MY NEEDS:
What I lack is the knowledge. It's always the case eh. Traditional noob post right here. I have the driver, the skills, and my expectations are appropriately low for a car driver. Where do I start? I'd assume sealed, but ported perhaps? It'd have to be a front port. Long tapered horn thing? I'm keen to get as much bass as I can out of them (check out the frequency response graph in the pics) so my sub (Which I haven't built yet) can be focussed on lower frequencies. The good stuff. No way I'm sticking them in my good system with the good sub - I need a new sub! Again though, my expectations are appropriate for the driver! See what I get first.


SPECIFIC QUESTIONS:

-- Sealed or ported?

-- If ported, what sort? One thing I haven't got is a nice flared tube, but a slot port would be easy enough if ported is the way to go. Again, it must be be front firing though, they're gonna be close to a wall.

-- (see pics) -- I have a crossover from a previous car audio setup that, well, it's a real crossover not the little block on the coaxials. I'm not sure it's a good idea to mess with what Focal have decided is right though so probably not gonna introduce that potential bag of problems into the mix. But, if any real crossover is better than a little block on car audio coaxials, then so be it.

-- Volume of the enclosure. Try as I might I always seem to be missing one TSP that gets me the internet calculators working. Annoying. It's usually "Actual System Q (Qtc)" and "Resonance Frequency (Fb)". I have no idea how to calculate or find that. I've been messing about on diyaudioandvideo.com and their calculators. but my noob status prevents me from believing anything as I don't know the Qtc or Fb as mentioned.


FINISHING UP THE POST:
I could ramble on about this for ages, donkeys years, and eons. And I've already gone on too long. Basically I have some data, and I want to make the best of what I already have, but need help.

So... Here I am, asking the community that seems to be the place where people learn and experiment and build. Any advice or thoughts would be very very much appreciated.
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Old 14th February 2020, 10:29 PM   #2
jjams82 is offline jjams82  United Kingdom
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I've also realised that I've been overthinking it. A little knowledge is a dangerous thing.

Less funkyness. Simple box. Listen. Enjoy music where there previously was none.

I'm still ery curious wether to go ported or sealed?

The rest, I'm sure it'll sound like something we can enjoy music on.
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Old 14th February 2020, 11:35 PM   #3
AllenB is offline AllenB  Australia
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New user. First speaker build. All the usual questions!!
Some traditional thinking says closed for sound quality, vented for extension. This is far from the whole story though, and I don't like to perpetuate stereotypes.

You want resonance and Q data. Fs is the resonance frequency of the speaker. Fc is what you'd call it once it's been modified by a closed box. Vented is a little different, Fb would be the resonance of the vented box but the box resonates independently of the speaker in this case (with closed they work as a team).

Qts is the speaker Q, Qtc is the Q once put in a closed box.
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Old 14th February 2020, 11:47 PM   #4
Galu is offline Galu  Scotland
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The Qts of your driver indicates that it is not suitable for a ported enclosure, so design for a sealed enclosure.

Qtc is chosen by you. A value of 1.00 will give strong bass.

The resonance frequency if the box, fb, is not required to be inputted into this calculator if designing for a sealed box: Speaker Box Enclosure Designer / Calculator

Remember to change the volume unit to litres. I used an effective cone diameter of 140mm.

If you do it correctly, you should come up with an enclosure plan.
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Old 14th February 2020, 11:59 PM   #5
Galu is offline Galu  Scotland
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I get a sealed box volume of 27 lires (0.95 cu ft) with the bass response 3dB down at 66Hz.

How did you get on?
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Old 15th February 2020, 12:52 AM   #6
jjams82 is offline jjams82  United Kingdom
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Thanks for the replies so far. Especially the explanations of what Fc and Fb are.

I'm going to go sealed. If it's designed for sealed and that makes it simpler to make, i'm in. Can't argue with that.

I'm wondering how big a 27 litre box would be... -3db at 66hz would be quite acceptable considering what I'm working with. I've been playing about on speakerboxlite.com as they have the non-coaxial version of the woofer already in there as a preset. Haven't got anything quite that low, but not far off. And of course playing about with cheap 10-12" subwoofer boxes to see where they could potentially meet up... A bit of a waste of time but I'm sure I can get a relatively compact sub to meet with these.

I'll have a play on the Speaker Box Enclosure Designer / Calculator now I know what's what.

Thankfully WAF isn't a factor as when I told the GF that WAF/SAF is a thing on audio/cinema forums and the like she laughed and said "you put your speakers wherever you like, I don't care... You have fun with 'em!" But... These would ideally be going in a smallish bedroom so size so no one is whacking them constantly while walking past so I'm trying at least to keep them relatively thin. Or, sod that and put 'em in the other room, I don't know. Performance vs convenience, the age old compromise of everything ever.
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Old 15th February 2020, 12:57 AM   #7
jjams82 is offline jjams82  United Kingdom
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Yeah... Hmmm. Looking at the room again, it's a goofy shape and who knows where they'll go so performance it is. If they sound any good I'll manage to fit them in somewhere, and a sub, maybe under the bed? That could be fun.
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Old 15th February 2020, 01:08 AM   #8
AllenB is offline AllenB  Australia
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New user. First speaker build. All the usual questions!!
On the spec sheet, Vas =9litres. Vas is the measure of air that compares to the speaker. Normally a closed box is smaller than Vas so that it has an influence on the speaker.

Your Q=0.87, this is a little high. This speaker was probably designed to work best into the boot of a car, which is big enough that the speaker doesn't 'feel' it. In other words it has its bass already pumped up without the help of an enclosure.
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Old 15th February 2020, 01:15 AM   #9
planet10 is online now planet10  Canada
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New user. First speaker build. All the usual questions!!
Quote:
Originally Posted by Galu View Post
...with the bass response 3dB down at 66Hz.
What are F6/F10.

Toole has shown F3 to be meaningless to the human ear/brain.

dave
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Old 15th February 2020, 01:17 AM   #10
planet10 is online now planet10  Canada
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New user. First speaker build. All the usual questions!!
Quote:
Originally Posted by Galu View Post
A value of 1.00 will give strong bass.
Qt of 1 will give a slightly underdamped response and trades smaller box size for a bit of a peak and less downward extension.

dave
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