Will these speakers work?

[snails07]

I’m building my first set of speakers and I’m trying to work out if they are going to work and are going to sound any good.
Here is what I have so far...

Tang Band W5-704D 5” woofer (http://www.tb-speaker.com/detail/1208_03/w5-704d.htm)
Dayton dc28fs-8 tweeter (Dayton Audio - DC28FS-8 Classic Series)

For the crossover I want to do something simple (really simple) and would like to go for just a 6db crossover at around 3500hz. Not sure why, just a number that looked good

The enclosure internal volume comes to around 0.33 ft3 which after looking at some online calculators seems about right. This volume doesn’t take into account the space taken up by the back of the woofer or the port.

How does all that look, do you think this will work out ok or am I way off the mark?

Thanks!!

[wintermute]

A quick look at the response curves and specs of those two speakers to me looks like they would be good for a first attempt and designing your own speaker. The TB mid looks great (dip around 400Hz not withstanding) if the freq response curve is accurate. Don't expect great power handling with an xmax of 3.3mm but they look like they should be easy to work with!

I haven't done any calcs so can't comment on your box volume. As to whether they will sound good, I think someone who has used these drivers would have to comment on that

edit: looking at the tweeter again 3.5K is probably too low for a 1st order.

Tony.

[dabbler]

About 15 years when I was getting out of high school a friend of mine inherited some old speakers form his dad. We pumped those speakers full of some pretty offensive techno and promptly blew every driver. He decided to replace them with some decent jaycar brand drivers and an off the shelf crossover. We did no calcs of any sort, just tried to match the drivers from the FR graphs in the catalogue. The result was surprisingly great. We pumped alot more offensive techno through them and they survived to this day. My friend brought them out of storage recently and plugged them in for a listen, to see how our slightly aged and more experinced ears would recieve them. I was amazed that they still sound very good. Between us we have made a few of our own DIY speakers and owned lots of commercial designs. I would be happy to live with them and have to say they sound better then most of my own DIY adventures where I have used measurements, simulation, used active crossovers etc!

So what s the point of my story? I guess its that you may get lucky like my friend did. The drivers seemed to gel but really it was a fluke. If you dont have measuring equipment you wont really know what you'll get and how to fix it if all goes wrong.

But saying all that, its fun to experiment and a good learning process and you may end up with something good. Just dont spend too much money on your first venture

Introduction to designing crossovers without measurement

[chris661]

I see a problem.

Your midbass is of higher sensitivity than your tweeter (though not by much, you'll probably get away with it when baffle-step kicks in).

If you pick a tweeter with a higher resonance (that one is 800Hz - very low for a small dome tweeter), you'll get more sensitivity.

The problem is that simply putting a big resistor in front of a midbass will affect its low frequency response. For tweeters, this matters very little. So people tend to go with a more sensitive tweeter and pad it down (add resistors) to get the drivers in-line again.

Chris

[6.283]

Originally Posted by chris661

If you pick a tweeter with a higher resonance (that one is 800Hz - very low for a small dome tweeter), you'll get more sensitivity.

But less overlap, which is required for a 1st order x-over.
Also, the TB starts to roll off around 4KHz. That will add to the down sloping of the low pass and acoustically you will end up with a higher order x-over. No big problem as long as you account for that in the tweeter high pass.
1st order x-overs are not really simple. They look simple because you have less components but in the end they make things often times more difficult.

Have fun with the project !
Oliver

[DrDyna]

IMO, a 6db crossover for the midbass unit could work, but on the tweeter I'd probably use at least a 12db unless you planned to go up to a pretty high xo point. With the current plan of 6db@3.5khz, I'd be very careful with the volume knob. I ran my mains for a couple of years with a 6db around 4khz, but be ready to pretend your speaker's wattage rating is about 15w.

[wintermute]

Originally Posted by chris661

I see a problem.

Your midbass is of higher sensitivity than your tweeter (though not by much, you'll probably get away with it when baffle-step kicks in).

Hi Chris, are you looking at the same specs as me?

I see both drivers as being nominally 8 ohms. woofer is 88db 1W/1M and tweeter is 89db 1W/1M....

snails07, in the same price range as the dayton tweeter you might want to consider this seas unit THE ART OF SOUND PERFECTION BY SEAS - H1211-06 27TDF or perhaps this scan-speak http://www.scan-speak.dk/datasheet/pdf/d2606-920000.pdf

Hasaudio Speaker Components - International Suppliers of Speaker Components and Speaker Kits has the dayton, as well as both of the above.

Note I haven't heard iether, I have morel softdomes, and previously Phillips.

Tony.

[sreten]

Hi,

Depending on where you intend to place the speakers it will sound thin
with no baffle step correction (BSC) applied, this is usually done by
oversizing the inductor on the bass mid unit. If you apply BSC
then you will need to pad down the tweeter to match.

6dB/octave on a low Fs tweeter is usually not a good idea due
to distortion, excursion increases below roll-off right down to Fs.

Simple c/o's do not = a simple speaker, the result has complex issues.

Take a look at : HTGuide Forum - New project.....(The Noobsters) a bargain 2-way

rgds, sreten.

undefinition (see FAQs)
Zaph|Audio
FRD Consortium tools guide
RJB Audio Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
DIY Loudspeaker Projects Troels Gravesen
Humble Homemade Hifi
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design

[chris661]

Originally Posted by wintermute

Hi Chris, are you looking at the same specs as me?

I see both drivers as being nominally 8 ohms. woofer is 88db 1W/1M and tweeter is 89db 1W/1M....

...

Tony.

I put it down to a moment of insanity. ( I may have been looking at the frequency response charts. At a glance, the TB looks 90dB, the tweeter is more noticably below that. The scales on the graphs are different, so more care is needed on my part when looking at such things)

As a thought (this one may be insane too), is it work aligning the crossover so that they meet when they're both 6dB down over their nominal SPL? I'm fairly sure it's at 6dB down so when they combine, they add to full volume again. Could be 3dB.
I'd guess that to be ~9kHz.

Aha! Mr Sound Products to the rescue.

A conventional Butterworth 12dB/octave filter is still by far the most common crossover, but is now under threat from the Linkwitz-Riley alignment. The latter has a crossover frequency where the output of each filter is 6dB down, and this has the advantage of a zero rise in output at the crossover frequency. The 'conventional' crossover filter is 3dB down at crossover, and the summed output shows a slight peak of 3dB at the crossover frequency.

Rest of the article is here - might be of use.

Chris

[sreten]

Hi, quiite frankly beware advice from those who know as much as you do, i.e. not much, rgds, sreten.

Checkout the links I posted, if not game, go for the design I posted, it will save you lots of grief.