| 4real |
Well, since the standard Loudspeakers forum doens't give me a lot of response, I'll try to get some help here.
Well, I'm about to make a nice small speaker for the kitchen with a Vifa BGS 119/8, based on the Picolino tml speaker, for the german DIY magazine HobbyHifi (HH).
The problem is, that this thing is just a bit to big :( So I have to make them smaller, thus a shorter TML. I know it will not get as deep down as the orriginal, but that is nog so important.
Ik should look something like this:
The box is about 20x25x16 cm
The problem is, that I cannot het a decent simulation of this tml. I used the mathcad worksheets to simulate the original design, wich can be found here:
http://www.audiocomponents.nl/speak...xt-line_eng.htm
TSP of the Vifa (according to HobbyHifi):
Re: 5,5
Le: 0,20 mH
Fs: 61 Hz
Qms: 3,4
Qes: 0,62
Qts: 0,52
SD: 36 cm^2
VAS: 4 L
Cms: 2,2 mm/N
Mms: 3,1 g
Rms: 0,35 kg/s
BL: 3,3 N/A
Xmax: 0,65 mm
The problem is, I cannot reproduce the results that HobbyHifi has measured, no matter what I try :( The steady drop starts @ about 150 Hz with mathcad, while HH has a steep drop at about 60 Hz:
They use AJHorn to simulate, and the results are very close to the actual measurements: http://deepspace9.xs4all.nl/~christiaan/10bgs-7.jpg
Sadly, I don't have AJHorn, so I'm hoping that someone can help me with some simulations, or maybe give me some other hints, so that the mathcad worksheets work...
Please help me :bawling: |
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| joensd |
Hmm, even in a straight TL it sims down to ~60Hz.
How did you simulate the Picolino with the mathcad sheets?
Did you put in the proper geometry with all the bends/area changes?
If so, you could send me the file.
:D
It´s a bit of a contradiction to scale down a TL but you should get nice results with your size restrictions.
One fold should fit nicely. |
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| 4real |
Yes, sure, you're cheating with a TQWT ;) Yes, with that one, i can get to 60 Hs, but there is no defference with a BR response (just a extra peace of MDF ;)
I want a real TML ;) |
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| planet10 |
| quote: | Originally posted by 4real
you're cheating with a TQWT ... I want a real TML |
IMHO, a TQWT is just another flavour of TL...
dave |
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| 4real |
well, in this case, there realy is no difference with BR, so IMHO not worth a try (I would just make a BR then).
I would like to make a tapperd tml, like in the picture. The point is, mathcad cannot reproduce the measurements HH made (and also what AJHorn simulated) |
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| planet10 |
| quote: | Originally posted by 4real
well, in this case, there realy is no difference with BR, so IMHO not worth a try (I would just make a BR then). |
A mass-loaded quarter-wave line will behave different than a similar volume (but more evenly proportioned) BR.
| quote: | | I would like to make a tapperd tml, like in the picture. The point is, mathcad cannot reproduce the measurements HH made |
I would guess that the parameters have not been input correctly -- i've seen too many simulations get real close to spot on the resulting measure.
dave |
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| 4real |
Well, as i see it, it the parameters were not wrong, but that is why I need your help...
Well, I tried again, and now, I do get something similar to AJHorn, so I'm on the right way :D |
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| joensd |
with the MJK-sheets or another software?
would you mind posting your results?
Cheers |
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| 4real |
| quote: | Originally posted by joensd
with the MJK-sheets or another software?
would you mind posting your results?
Cheers |
Yep the sheets. I'm now about to make a 100 cm line like this:
Simulates like this:
-8 dB @ 40 Hz is not bad, and I even have room for my amp and FM receiver :) |
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| joensd |
| Did you put in the proper geometry or simulating with a 100cm line and constant cross-section-area? |
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| 4real |
| quote: | Originally posted by joensd
Did you put in the proper geometry or simulating with a 100cm line and constant cross-section-area? |
I simulated with a *SD from 3,6 tot 0,38 (as in the picture) . An constatnt cross section line is not very good, and won't fit the box ;)
I might do a more detailed sections simulation, but I think this one will do :) |
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| joensd |
| quote: | | and I even have room for my amp and FM receiver |
now, where are you going?
wasn´t that supposed to be a christmas present for your parents?:D
| quote: | | An constatnt cross section line is not very good, and won't fit the box |
you can fold the line and still keep the CSA constant. |
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| 4real |
| quote: | Originally posted by joensd
now, where are you going?
wasn´t that supposed to be a christmas present for your parents?:D
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Yes it is :D, active wireless speaker, but I think I'll put some real terminal on it, too, for a real amp :). The thing I'm going to use now is 6 W TDA chipamp, not the best, but it will do...
| quote: |
you can fold the line and still keep the CSA constant. |
Sure I could, but it will not fit in the box. The resulting curve does not look very good either! |
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| kyote |
Have you build this thing alreay?
How does it sound?
And would you mind to put a detailed plan (with angles and width) in here?
It looks real interesting.
And perhaps some Pictures? |
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| 4real |
I hope te get the units this weekeind, and I might even get started with building it :)
Detailed plan with angles? Well, I'm not shure If there is realy going to be an actual detailed plan, but I might try to make something up tonight...
If it is realy going to sound as well as the simulations say, is just a matter of building and listening ;)
It will be my first TML project, so I'm very excited to get started with it :D
Pictures will be there when I have them :P |
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| 4real |
Just for the fans (and for my own ease), some drawings :angel:
I had to find a fairly decent pice of free CAD software to help me. I found QCAD, and it works very nice :D
At first a small png of the desgin:
 (don't expect to see any measurements on that picture ;) )
But here some PDF's
A2 format: http://deepspace9.xs4all.nl/~christiaan/picolina.pdf
A4 format: http://deepspace9.xs4all.nl/~christiaan/picolina_a4.pdf
All measurements in mm's
The lines are very thin, so your printer might not print very well.. I'll have to look into that.
I recommend that you don't build the thing befor I have no good results. You never now how bad I'm at designing stuff :smash:
I'll keep you posted! |
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| kyote |
Ok. Im staying tuned in excitment of your results.:cool:
I hope my english is not too bad. |
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| 4real |
| quote: | Originally posted by kyote
Ok. Im staying tuned in excitment of your results.:cool:
I hope my english is not too bad. |
No, I don't think so. I hope mine is not bad either :D . You can write in German to me, but I don't thinks that the majority of the diyaudio readers would understand that ;) |
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| kyote |
| quote: | | You can write in German to me, but I don't thinks that the majority of the diyaudio readers would understand that |
Yeah, that's what I hink, too.
But it's a bit weird to write to e.g. Joens in english.
Lucky that there are german DIY forums.:D |
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| earsandeyes |
4Real,
How did you wordk around the 10 minute timelimit on the free software?
Regards,
E&E |
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| 4real |
| quote: | Originally posted by earsandeyes
How did you wordk around the 10 minute timelimit on the free software?
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I did not, I'm just very quick :D
... no ..., I use the linux version, that one is GPL'ed and can be build from source and used unlimited :angel:
Oh, befor I forget: I received the unit's today, and they look great! Also I bought some MDF. Sadly no 15 or 10 mm, but I had to go for 18 and 8 mm. No need to panic, it will do just fine! |
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| 4real |
Yesterday I started building. Sadly I coudn't het 15 mm MDF, so I had to take 18 mm. Also 10 mm was not present, so 8 mm will have to do :(
Oh, well, I'll manage...
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| 4real |
Some new pics:
Still lots of work to do, but I'm getting there ;) The filter is already installed and can't come out again. It bearly fits :P |
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| navin |
2 questions.
1. does the lower part of the front baffle have to be sloped inwards?
2. Can this box be used for other 4-5" fullranges like the fostex or jordan? |
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| 4real |
| quote: | Originally posted by navin
1. does the lower part of the front baffle have to be sloped inwards?
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I don't know. I used the design of the orriginal picolino as a basis, and it has this slope, too. I would have to look in the article to check...
| quote: |
2. Can this box be used for other 4-5" fullranges like the fostex or jordan? |
Well, that's hard to say, you sould simulatie what those things do. |
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| navin |
| BTW where did you get the vifa fullrange. madisound does not carry it? |
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| 4real |
| quote: | Originally posted by navin
BTW where did you get the vifa fullrange. madisound does not carry it? |
By Ebay for a mild price :D |
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| navin |
| your wood work probably costs more :-) |
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| 4real |
| quote: | Originally posted by navin
your wood work probably costs more :-) |
Oh, no way! The Vifa's were not that cheap. It's not realy a low budget unit. I paid 45 Euro's/unit, normaly its about 55 euro's here in the Netherlands. |
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