Another floorstander help thread

[{icebox425}]

Hey guys,

I know you see a lot of these but I'm a noob and looking to build my first set of speakers. I've read a lot of threads and guides etc but I want to make sure of everything before I buy the gear.

I'm using this design as my point of reference seeing as I've never done this before.

Basically, each floorstanders utilizes 2 x P17WJ-00-08 woofers and 1 x D27TG-45-06 tweeter.

Using the recommended volume of 47.3 litres, I came up with the dimensions of:

W = 22cm
H = 91.3cm
D = 32cm

However, how should I align the drivers, MTM or TMM? and how do I know how far apart to space the drivers or whether I should change the alignment of the port or tweeter etc?

For the crossover I'm planning on just using the one provided in the design sheet.

If anyone could help answer these questions, or point out any flaws in my design I would be most appreciative.

Thanks,
Sam

[yertzl]

hey {icebox425}

im a noob 2, but ive read speaker buildin 201.

so from my understanding with speaker alignment if you go TMM you will get lots of lobes in the sound on the vertical axis.

with MTM- geometric approach to eliminating lobing errors in multiple speakers
with MTM you get a couple of bonuses depends on the cross over you choose:
3rd order: basically a lobe that waves with a slight arch down with a bit of a bigger bump in the middle.
3rd order high pass 2rd order low pass: this is straighter than the above aproach(still wavey). i guess you would use this in big spaces where wall reflections arnt an issue.
2nd order Linkwits Riley: looks like 1 big bubble blown from bubble gum, with the speaker been the mouth.- this confiq is useful with reducing wall/floor reflections.

and with space concerning MTM.
-to work properly dist b/n centres of adj drivers should b kept close to 1 wavelength of the cross over freq.
ie distance d =speed of sound/cross over freq

though no matter what your spacings are you will get some of the benifits from MTM.

hope this helps. and im only saying what the book told me. im yet to actually make my speakers.

[{icebox425}]

Thanks for the response. You have confirmed my initial desire to go for the MTM setup, theyre what most people seem to make around here so it makes sense.

I'm looking at using a 3rd order butterworth crossover as shown on the last page of the link in the original post.

Regarding the distance between drivers, using the V=F*W equation, the distance I calculated to be ~10cm which is obviously not possible as the drivers themselves have an 8cm diameter. The crossover point is around 3300Hz. Also, where does the tweeter fit into this?

Thanks again.

[yertzl]

yeah id probable use the crossover they have designed.

(arnt ur drivers 6.5"=15.9cm diameter and i assume the tweeters overall d =10 cm, therfore min dist apart ~13cm)
i think i forgot to put that the formula is from the centre of the adj drivers but that still doesnt help, since the min distance for the drivers will be~13cm

but if ur driver are 8cm diameter then this is easilly possible.
4cm from driver+5cm from tweeter = 9cm with 1cm left over.

but hey if you cant quite get them to separate thats why the book said you will get some benifit from the MTM no matter what the spacin. so just keep them close i guess. while keeping aesthetics in mind.

(i guess with not having all that fancy testing equip and programs you just have to take a punt, thats what i feel im going to have to do anyway.)

[{icebox425}]

Sorry about the confusion, I meant 8cm radius, not diameter.

I guess I'll just have to make it up as I go though.

Thanks.