Computer speakers Thought experiment help

[Moondog55]

So here I am getting tired of my current computer speakers.
Which BTW are some cheap shielded Sony woofers in a tin can filled with BAF.

Using the drivers I have on hand I am thinking of a small 3-Way
Jaycar CW2135 6 inch woofer
Which according to the Jaycar catalogue has a 6dB peak at 2k.


I also have a quad of cheap but reasonable Full-range 80mm drivers from a HTIB system for which I have no data but were used full range with a tweeter that used a 1.5uF cap and a pair of the Audax Mylar tweeters.
Initial thoughts are a small sealed box WMTM and XO points at approximately 400 and 6k

questions, will I be OK with just a second order L/R XO at 4oo or should I also use/need a notch filter at 2k?
Should I cross over the Audax tweeter lower and use a second order on that with a first order on the mids. Bearing in mind I want to keep the cost down so the cheaper and simpler the better this would be

[DUG]

Bi-amp

Then it is easier to change your crossover point.

Just a thought.

[Moondog55]

True, but I only have the one amp available for this ( the Alesis RA-100 ) even if I do have a spare Behringer unit

[head_unit]

What if you added a little Tripath chip amp from eBay? Then, if the levels between the 6s and 4s are quite different, you can adjust easily.

Be sure the 6s and 4s are physically acoustically isolated from each other.

Do you have any way to measure actual frequency response and impedance curves? If not, crossover design will be a total crapshoot while wearing a blindfold in a dark coal mine. That's not to say the results will be bad, but you can't just use textbook values for real-world crossovers.

[Moondog55]

Approximate impedance curves are close enough for this speaker.
After all most woofers are at or near their DCR around 300/400Hz and I can always use Zobels if needed, the LG have a natural roll-off that should work with a tweeter cut high enough and I know that a 2uF capacitor works fine with the little 12mm Audax.
More a question I guess on whether or not to use a small sealed box or go for a bigger box and rear port it

Quick testing tells me the 2 * 80mm in parallel should equal the woofer almost

[picowallspeaker]

Which Audax tweeter ? The poly casted one-body ?
I'm in the making of a little (?) 2 way with a 4"....4Ω-7W
and I used the 2nd order crossover suggested in the Audax datasheet of the product, which crosses at 6 KHz. Some attenuation to match different SPLs

[mondogenerator]

From what I recall (i.e. I could be wrong, it is 15 years ago) of the Audax tweeter (tw10**?) I think it suits a 1st order hi pass (combining to produce a 3rd order acoustic roll off), there is probably no reason why you couldnt go 2nd order, however.

The slight peak of the woofer at 2k is more than 2 octaves away from the Fc @ 400hz. going 1st order here may just be OK, although you're correct in thinking a notch may be necessary. Try both? I have a similar woofer for a similar application, and im using (or planning to) a XO a little higher up (~600hz) for similar reasons (hoping to avoid the notch)

[Moondog55]

Hmm Good question on the tweeter, I can't find the data , must be on the laptop. Two piece with the square face plate the Audax AW010E1
Google is my friend
Actually 10mm tweeter which is better match with 80mm mids
http://www.audax.com/archives/aw010e1a.jpg
http://www.audax.com/archives/aw010e1.jpg

So even second order I would not cross below 5k

[mondogenerator]

yeah data on those audax is a bit sparse, but there is some still around. All i recall is that there are several interchangable faceplates for the same 10mm dome and neo motor and formerless VC. Their Fs is 2.8k from memory, 5k is an absolute min, just for some reason i seem to recall that recommended, OR that it combined nicely to give a near perfect 3rd order roll off. 2nd order would be safer, i agree, but at low-ish SPL it may be a non issue

[picowallspeaker]

Yes, I've also recovered the 'Tw010' file from my HD
Fs is 3 KHz ...it has ferrofluid; these are the data for suggested xover circuit
Fc ------ S -------- L ------ C ------ P

6KHz 6dB/oct ----- - --- 3 uF ---- 25 W

6KHz --- 12 ---- 0,12 ---- 3,3 ---- 45


I've also did some WG experiments, indeed I'll use a little one I've made ( from elliptic tv speakers), but the tweeter is more like an on/off device rather
than one 'rich and full of nuances'