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-   -   Vifa Floorstanding Speakers (http://www.diyaudio.com/forums/multi-way/56325-vifa-floorstanding-speakers.html)

Big Kev ! 29th April 2005 08:08 AM

Vifa Floorstanding Speakers
 
Hi everyone,

I've got some bookshelf speakers at the moment but I've been hearing a few floorstanding speakers and they have so much more depth than my bookshelfs. Because I'm on a reletively tight budget I've been looking at making my own floorstanding speakers. I've done a bit of research but I'm still a bit confused. At the moment I've decided to go for a tower with:

Vifa Silk Dome Tweeter Flate Plate 4 [D27TG-35-06]
Vifa 6.5" Mid-Woofer [P17WJ-00-08]

and have the box at around 25 Litres tuned to 42 Hz (using WinISD).
I was looking at making a 2nd order crossover (using WinISD again) but if this crossover wont be that good or if I can find out how to make somthing better (like a 4th order) I would like to go with that. My only other concern is that the tweeter is 100W nominal while the woofer is only 40W. Does this matter? I was thinking of maybe going for two of the woofers in a TMM or MTM arrangement but only if its really nessesary or makes a huge imporvement as I want to keep costs down.

This is my first time at building a speaker by myslef from scratch so any advice, suggestions or anything at all would be greatly appreciated. Thanks a lot :)


Edit: Sorry, I've just done a search and I've found a few threads on the Vifa tweeter and woofer combo. (still have questions though ;)) Is it worth me saving up for more/better drivers because 25 litres isnt exactly floorstanding size and I'm looking for speakers that sound nice and deep without a sub (...for now :D). Could I make a transmission line box or would that have to be really big? Cheers

bjackson 30th April 2005 06:24 AM

Well...
 
You could do something like that, but it sounds like you either need to brush up on the finer points of speaker design (x-over topologies, bsc, etc), or do a pre-existing kit.

This kit reminded me of what you were wanting since it had a vifa woofer :-): http://www.speakerbuilder.net/web_fi...oject/eros.htm

If you want any more help drop me a line, and sometime when I am more awake, I'll do my best to help :-)

Noksukau 30th April 2005 10:02 AM

Kev, you seem to be on the right track so far and have selected some excellent drive units, certainly the tweeter's reputation stands it out from the budget crowd. I am not familiar with the woofer but looking at the specs and doing a few searches, it seems a sound choice. Of course you can spend more money and get something with more extension and resolution, but that would be almost doubling the woofer budget, and you already seem to have chosen an excellent unit that is within a price range you feel comfortable with.

Kits are often recommended for a first build, and I have recommended them too, but that's usually for those people who want to save money, have a bit of fun and have a reliable solution they can fit and forget for years. Just like if they'd bought them in a shop. The fact that you seem to be having such fun selecting drivers and considering what box alignment will suit them and your tastes best, and have been doing a lot of research, leads me to believe that you wouldn't be satisfied taking someone's else's design and copying it. I wouldn't be, for me the design was everything, and learning from mistakes is fun as it means you get to do ANOTHER design! :D

Certainly, it is unlikely your own design will be as good as someone else's with mountains of experience behind it, but I think you will feel greater pride and satisfaction by getting help to make your very own speaker. I've never built a kit and my first speakers, listening now, sound pretty rough compared to newer, pricier designs. At the time though, they were better than anything I could buy for the price and I adored them, and beamed with pride when I played them. Back then though my only resource was Radio Shack, who sold me the drivers and a book on rudimentary design, paired with 'a crossover' from the shelf! You are already way ahead of that, and have a fantastic resource here and on the web at large. Your first speaker, already, is way ahead of mine.

So, if you want a fail-safe speaker to whip-up on a budget and enjoy for years to come, build a kit. If you are liking the design element, and think you might want to continue this as a hobby then design, build, learn and have fun. They won't be awful, they will be damned good, just maybe not wringing the absolute best from the units in hand.

If you are tempted by a TL, many will say it's ambitious for a first project. There are certainly a lot more variables to consider, and the box building is more complex than a basic speaker. I think with help from people here though you will be able to come up with a satisfying design, and on preliminary calculations for your woofer, your cabinet won't be too massive either. Certainly bigger than 25l, about 50l I'd say. That is based on tuning to the 37Hz Fs (resonant frequency) of the woofer with a 3:1 line taper, should work out with about a 6ft line. With one fold you should have some perty looking floorstanders about 3ft tall and a foot deep say. OK, that's not subterraneous bass, but I doubt you'd feel the need for a subwoofer. As you say, for now! ;) No doubt you've already visited the sub design forum. As for adding a second woofer I think that budget would be better spent on a higher quality woofer (like Vifa's XG18WH00-08, glass fibre cone, lower mass, lower Fs, better basket etc), if it was going to be spent. A second cone would help bridge the sensitivity gap between the tweeter and woofer, but as long as you don't plan on splitting your eardrums a single woofer and some attenuation on the tweeter will be fine. Look how many commercial designs do the same after all.

Sorry to go on, don't know if any of that has helped solidify your goals. As bjackson said, do a bit more research and I think you'll be set. I think a series crossover (as opposed to the standard parallel) would suit those units nicely as both have extended bandwidth and the tweeter an exceptionally low resonance. Still, plenty of time for all that later! Have fun. :)

Ben.

Big Kev ! 30th April 2005 11:23 AM

Quote:

Originally posted by Noksukau
I wouldn't be, for me the design was everything, and learning from mistakes is fun as it means you get to do ANOTHER design! :D
:D


Thanks a lot for the reply Ben :) I've already built a kit a while ago, some M5's from TLSK, for the price I paid I'm quite happy with them and there nice for little bookshelfs. Back when I had my receiver and my sub they were a quite nice setup, but you know how it goes ;) I was looking at some kits but here in Australia the floorstanding kits are now a bit expensive and I want to desgin my own speakers to suit my room and my price range. (plus they sound so much nicer when you can say you made them ;))

I'm leaning away from starting off with a TL design and just sticking with a vented box. I'm still a bit confused with the crossover design and everything but I'll keep reading :)

I'll post more later but at the moment I'm in the middle of fissling with WinISD ;) Thanks for the posts, any other help or ideas definalty wouldnt go astray, cheers :)

Big Kev ! 30th April 2005 01:06 PM

Well I've been having a look at the Peerless 850122 driver which seems to be pretty similar to the Vifa but has a nicer gain slope in a larger box. However it isnt as sensitive and it still has very high group delay at the tuning frequency (although I'm not sure if this matters if I have a sub???). I think I'm gonna stick with the Vifa because I've only heard good reports about it and its meant to have a nice midrange.

I also had a look at this design:
http://www.mass.com.au/pdf/designs/mp17h.pdf
which is very similar to what I'm making, the only difference is the tweeter which is the Vifa D25AG-35-06. Its the same price as the D27 I was looking at and its aluminum compare to silk. To be honest I'm not really sure which is the better tweeter. (sensistivity on the D25 is only 90dB so I wouldnt have to dampen it as much) If I used the D25 I would have a nice crossover design (making the crossover - well a good one - is kinda confusing me. I dont really have the experience to know what actual difference to the sound it would make)

One other concern I have is the Vifa woofer only has a nomial power rating of 40watts which seems a little to low to me. I want the music to be able to go loud as well as sounding good. I may be on the wrong track here though, just wanting some clarification :)

Cheers

mwmkravchenko 30th April 2005 01:22 PM

Size Does matter!
 
Hi Kev

I'm writing this in front of two boxes with the same woofers. THey are floor standing. One hundred liltres, shelved low end. Decent reponse to 30 hz. And thats where it is tuned. You don't always have to go with a so called optimal alignment. Try fiddling with the numbers and see what happens!

MArk

chainenoble 30th April 2005 02:27 PM

i put together a low price mtm using the silver flute 6.5" woofers and the seas tdfc tweeter.i was very impressed with the sound for what they cost.check out the silver flute woofers,they are a low priced jem.

Big Kev ! 30th April 2005 03:40 PM

Re: Size Does matter!
 
Quote:

Originally posted by mwmkravchenko
Hi Kev

I'm writing this in front of two boxes with the same woofers. THey are floor standing. One hundred liltres, shelved low end. Decent reponse to 30 hz. And thats where it is tuned. You don't always have to go with a so called optimal alignment. Try fiddling with the numbers and see what happens!

MArk

Any other pictures or info?

Cheers

Edit:
Quote:

Originally posted by chainenoble
i put together a low price mtm using the silver flute 6.5" woofers and the seas tdfc tweeter.i was very impressed with the sound for what they cost.check out the silver flute woofers,they are a low priced jem.
I'll have a look but to keep costs down I would prefer to use drivers I can easily get over here. I'll have a look around.

mwmkravchenko 30th April 2005 03:58 PM

Pics?? what pics??
 
No digital camera!

They are 10" wide ( 245 mm ) by 56" tall ( 1422 mm) by 17" deep ( 416 mm ) deep. Double port 3" ( 75 mm )

Driver complement is two vifa 6 1/2" and a BGcorp Neo 8 set up in a MTM. The tweeter panel is crossed over at 700 hz. The tweeter driver is set at ear height 34" ( 833 mm ) on centre. Great sound and imageing. Not the best X-over point theoretically but tuned with a lot of thinking and listening. It's a first order electrically but quickly turns into an acoustical third order at 300 hz so it's not that bad of a choice. It's soon to go active.

The interior is shelf braced and there is a shelf at a level to install a massive 15" I picked up. So the box will have a side firing 15" sub. I'm going to go with an equalised box design alla graham maynard ebass. And the rest will be in the listening. The two 6 1/2 approach the displacement of a decent 10" so the bass is not all that bad. With the larger box as it is there is decent low bass response with a shelf starting at 60 hz dropping by 3db and then rolling off around 35 hz. It has scared more than one person. Do a simulation and see the total possible output. Use x-max plus 10% for your calculations as it is a little more realistic. If you want to go with an MTM only a high pass filter or low cut would be a good idea. It would give you a lot more headroom.

Mark

GM 1st May 2005 04:58 AM

Quote:

Could I make a transmission line box or would that have to be really big?
Greets!

They have to be large to go low with any authority. A ML-TL is much more flexible though. Here's a proven design that's slightly <25L for a single P17 tuned to ~Fs using these averaged measured specs of several units:

Fs = 46.17Hz
Vas = 21.93L (0.774ft^3)
Sd = 135.62cm^2 (21.021"^2)
Qes = 0.6
Qms = 1.28
Qts = 0.40851
Re = 5.83ohms
Le = 0.92mH
BL = 6.35 N/A
Cms = 8.3067e-04mm/N
Mms = 0.0143051Kg

L = 30.22"
pipe area (CSA) = 46.017"^2
vent = 2.5" dia x 4.5" long near/at the bottom
driver down from top 11.53"

Extend the bottom of the cab as required to get the desired tweeter height and fill the resultant cavity with kitty litter or similar to to keep it from resonating/mass load it. I recommend mass loading the top also with either a filled cavity, triple thick top plate, heavy potted plant, etc.. Of course allow for a tripod base to keep it from easily being knocked over since it's so tall/'skinny'.

WRT the XO, make the cab the same width with the tweeter location the same as John's (note they're mirror image) and clone his XO: http://www.audiodiycentral.com/sd200_johnk.shtml

GM


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