Building new speakers!

FelixAUS

Member
2010-11-25 5:44 am
Hi, sorry if this is in the wrong area of the forum, move around as you please =)

A few months ago I bought a set of home theatre speakers (8" splits) from a garage sale for $10, one worked the other didn't :( (Get what you pay for I spose).

I pulled my dad's old Luxman L-30 out of the garage and set the one up, sounded great (drivers are AKAI).

However since only one of them worked I went into Jaycar and bought two new drivers (http://www.jaycar.com.au/productView.asp?ID=CW2196).

They sound really good, except with the new driver's I have realised one of the speaker box's is stuffed and is letting air out somewhere it shouldn't as deep bass through them sounds disgusting (however the other box is beautiful).

So then that leads me to building new vented box's for them!,

I've been reading a lot of stuff on the internet about speaker box design's etc, but thought I should ask for a specific opinion given my case...
Okay here's the questions:


1. For the boxes MDF or Marine Grade Ply? 18mm? 22mm?
2. Should I stay with a 2 way setup? or is 3 way better? I could buy the 4" of the same speaker. (I listen to all sorts of music, but do love bass, so getting low dirty amounts would be good.. :) )
3. I have put it all into WINISD and it gives you a recommended box size and port length, gain, phase plot etc, what should I be looking for on those graphs? or any good websites to explain it all?
4. If I chose a 3 way setup, and given they are all 8 Ohm speakers, and my amp is a 2x50w (4 ohm) or 2x40w 8ohm, What would be the best way of wiring it? Would running a 3 way crossover in parrallel damage my amp (by dropping it to 2 ohm) or because it is a crossover is this not a problem?

Any help will be appreciated since I want to do a proper job and build some speakers that will last a long time!

If you need anymore info to help please ask :)
Cheers,

Felix.
 
Hi Felix,

I'm assuming the home theatre speakers you have comprise of two drivers, an 8" woofer and a tweeter? (The term 'splits' is a very Australian term and may not be understood by many of the forum members outside AU. I've only ever heard it used in car audio circles too.)

Anyway, this speaker enclosure contains a passive crossover? If so this crossover will have been designed specifically for the two Akai drivers. By swapping the woofer, unless it has exactly the same specs as the one it replaced, you may not get optimum results.

To be honest, the first thing I would do is simply repair the leaking enclosure. This way you can use your amp at 8 ohm. You said the one that works sounds good.

If you really want to build new speakers because you're up for a challenge, I would seriously recommend a tried and true design where somebody else has made all part selections and calculations for you. There are plenty of great examples on this website, or on the web in general. This way your results will be MUCH more predictable!
 

FelixAUS

Member
2010-11-25 5:44 am
Lowpoke, yes 8" driver and a tweeter (I've only ever had a bit of dealings in car audio :) )

Yes the current ones have a passive crossover and AKAI tweeter, which is one of the reasons I was thinking of starting from scratch (new tweeters, crossovers, and boxes).

In terms of fixing the box, that was my original thought, and it seems everything I have done just won’t fix it! I've even gone way overtop with screws, hot glue etc at every possible place where I suspect it is losing compression and it still puts out this nasty muddy sound! It’s not the drivers either since I have swapped them, and it’s not the amp. They also look a little less than average so I think I will start again... :)

Thanks for the tip about pre-tested designs, I will look into it!
Although considering I have already bought the new drivers wouldn't it be better taking the box specs out of WINISD?
I am using the downloaded one and that has calculated optimum enclosure and port size/length for my drivers. Should those measurements be correct?

Seeing as this is my first attempt at boxes should I stick to a 2 way speaker? or are the extra complications a 3 way that much more work?
I do want to do a good job which will hopefully last many years. I had my last exam today (YAY!) so time and resources for building boxes are not a problem as I have access to a tablesaw, timber, router, jigsaw etc so I dont mind putting in a lot of work if I get a fantastic speaker out of it!
:)

Also any good audio websites which explain gain, phase plot curves etc would be appreciated! I have done pre-tertiary electronics and physics so I think it shouldn't be too hard to get and understanding of once I know the basics =)


Thanks again - really appreciated!

Felix
 
Felix, I used these drivers 2/side in a 3-way, search this forum for details. IIRC, you'll need 24- 30 Litres per driver, & IMHO, these are really only suitable for use in a 3 way, they sound a bit nasty high up (I think I crossed them over ~ 400Hz 2nd order).
Sorry this is a bit breif, got do actually do some work today!!!
 
Hi,

See the links, sometimes you are lucky and the new drivers
work with the box and crossover, in that case repair the
duff box and count yourself lucky, otherwise start from
scratch, keep the AKAI boxes c/o and tweeter, with
some experience you may be able to find suitable,
i.e. very similar bass drivers, I have done this.

rgds, sreten.

http://sites.google.com/site/undefinition/diy
Zaph|Audio
FRD Consortium tools guide
RJB Audio Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
Humble Homemade Hifi
Click below to go to
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design
 

FelixAUS

Member
2010-11-25 5:44 am
Looking up my old Unibox sims, I used 24L/ driver tuned to ~40Hz; If you want a smaller box, 18L @ 48 Hz looks good, 13L @ 50Hz is the point below which where there isn't quite enough low end for me...

Pete, thanks for your thread! So you would reccomend running these just for lows and buying a separate midrange? Maybe the 5" of the same style? The tweeter you used, is this the RSN1005 Piezo Tweeter?

In terms of box sizes WINISD "Optimum" is a 44L tuned to 35 Hz? Is this a little exessive then?


Sreten, thanks for those links, I will begin trawling through them today :)

Moondog I will post some pics up soon!

Cheers,

Felix.
 
'So you would reccomend running these just for lows and buying a separate midrange?' yep; 'Maybe the 5" of the same style?' - No, this would be much better :5.5" - 4 Ohm - Ferrite - WF138WA02 - Soundlabs Group

'The tweeter you used, is this the RSN1005 Piezo Tweeter?' - well, it's the old Motorola version, pretty much the same I think

'In terms of box sizes WINISD "Optimum" is a 44L tuned to 35 Hz? Is this a little exessive then?' - yes, Jaycar's 'parameters' are notoriously dodgy. Mine will be closer, but these drivers need a few hours break-in before Fs settles down. FWIW, Unibox is a bit better than Winisd.
 

FelixAUS

Member
2010-11-25 5:44 am
Ok thanks, looks like I will go a 3 way then!

Would those RSN1005 tweeters be fine? (they are only $10....) (Also it says they dont require a crossover, is that correct since they are peizo? I assume that would simplify things slightly...) , or should I go a Titanium dome tweeter? (25mm Titanium Dome Tweeter - Jaycar Electronics). Or something else you would reccomend? :).


Ill check out Unibox also!, thanks!

Tried to upload some photos but it tells me there is an error! maybe because im new to the forums? Ill try again later! anyway i think it is the front baffle that may be loose or something, because I know its not:

1. The drivers (Have swapped them)
2. Wires (have checked every one)
3. Amp (have swapped channels and cables)
4. Rear panel (chucked some more screws in just to be sure!)
5. Connectors

So to be honest I think I am just better off building new ply boxs which will look and sound better...

Cheers,

Felix
 
I'd go 2.5 way - much easier if it's your first crossover... (this is a 2 way with a 'helper' woofer) Or, to make it even easier, you could go 'Full Range' + woofer', Check out the Mark Audio & CSS drivers on the Darcher site
Drivers : Darcher Audio
(Hope I'm not overwhelming you with choice...:)

The Piezo tweeters are only good as 'supertweeters', I'd avoid them... I only used them because i had them, & my mid was 'wide-range', I think I crossed these at ~ 8KHz.
(& to work well they DO need a crossover, but not a conventional one...)

The Wavecor drivers from Soundlabs are much better bang-for-buck than Jaycar drivers, their tweeters are the same price as the Jaycar ones (go for the ones with ferrofluid)
 

FelixAUS

Member
2010-11-25 5:44 am
Did a bit of googling on the 2.5 way, and that sounds pretty good!

This is my understanding of it (Please correct me if I am wrong )
It would work by having the 8" jaycar and the 5.5" midrange from soundlabs working the low frequencies up until (400Hz?), then the 8" dropping out and the midrange holding its own up until it reached the crossover to the tweeter (Soundlab one) at around 1.5 KHz? (That’s assuming I understand the graphs on the pages).

For the actual cross over type, would one similar to this be suitable?
Zaph|Audio - ZRT - Revelator Tower
Or is this looking a tad complicated?

For the graphs:
Tweeter page: 4 Ohm - Ferro - TW030WA02 - Soundlabs Group

Midrange : 5.5" - 4 Ohm - Ferrite - WF138WA02 - Soundlabs Group

Thanks!,

Felix
 
I'd go 2.5 way - much easier if it's your first crossover... (this is a 2 way with a 'helper' woofer)
(Hope I'm not overwhelming you with choice...:)

The Piezo tweeters are only good as 'supertweeters',

I'm with Pete here, 2.5 way is much easier than a full blown 3-way and sound almost as good until pushed hard
 
Felix, You've grasped the general idea of a 2.5 way, I cross the helper woofer over at the Baffle step frequency (115/width in meters).

Zaph's crossover for his 2.5 way gives the general schema for a 2.5 way with 2nd order crossover to the tweeter; however, parts values for your crossover need to be calculated using the impedance of your drivers at the crossover frequencies
 
I can vouch for the W130S, it's a decent midbass driver. Needs a large ported box for full extension (~17L tuned to ~42Hz), but sealed will give some bass output, with a smaller cabinet. If you were also adding an 8" bass driver, I'd be tempted to save the smaller driver the distortion and go for 3-way, cross to the bass driver ~100Hz.

Chris
 
Hi Felix, should have checked price first.

Chris I agree in principal but a 2.5 way is so much easier for a beginner, and taking some of the bass to the big woofer makes the full range driver play with less distortion and therefore greater ability to handle power.
I think Rabbitz has used a Vifa P-13 with a Vifa M-22 in this configuration with good results
 

FelixAUS

Member
2010-11-25 5:44 am
Thanks for you input guys!

Chris thanks for that, although I am thinking of sticking with the 2.5 way!

Now in your opinions would the better option for a midrange be the visation driver over the wavecor one? And if so should I also go with a Visation tweeter? or something else?

Once I have decided on that I can start drawing some plans... :)