Site Links
Howdy, Stranger!
It looks like you're new here. If you want to get involved, click one of these buttons!
Quick Links
Categories
In this Discussion
2.5 way XO feedback
Haven't tried a 2.5 XO earlier, and the cascaded 2.5 way is over my head - not sure changing what changes what in the response - will need a lot more fiddling around with it to understand. to provide some context, this is a TMWW where the WW is in isobaric configuration and ported and the Mid is sealed.
I have taken the 3 way XO in PCD and in the mid, left out the high pass on the midrange blank. Anyways this is what I got - anything i can try quickly to improve something. Haven't yet listened to it or taken off axis. This is a temp XO for the contest only, so ok with doing something crazy or throwing the kictchen sink at this - long term this will live as a 3 way.
Also, there is no BSC - but I am hoping the 2.5 way coming in at 800hz would take care of it and provide full BSC, but the selaed mid will fall off around 100-80Hz and there is a sling bump up at the 200hz area - so under 80hz it would be lacking - any ideas how to passively bump up the lower end?
Inverted:
Couple of things to note:
The tweeter has a dip around 7khz and 3 khz
The mid has double peak breakup at 6khz and 7khz
The ISO woofers goes wonky around 1.5k
Comments
Gets hard to do much electrically down there since the resonance spikes will dominate. Though if you model the cabinet with some added series resistance from inductor DCR it tends to give a nice little kick in the pants to the response down low. It might not end up as bad as you might think.
Whenever I simmed 2.5ways it seemed best to use a 12db/oct lowpass on the .5way. But was easy to run into trouble low passing the .5 woofer too high to where it's response started to mix with the tweeter response and create cancelation.
2.5way on 4ohm drivers is usually a no go unless you have an amp that can hack it. But this is a special workaround for the Ft wayne meet if I remember correct?
Crown is 2 ohm stable.
InDIYana Event Website
it's definitely above 2 ohms throughout, I can always add 4 ohms in fromt of the XO to keep it at 4 ohms, if needed... but the crown should be ok. i'll try the additional resistors if my measurement amp goes into protection - it's rated min 4 ohms
I have done exactly one 2.5 way and found the juice isn't worth the squeeze, at least with woofers with a breakup.
I have 4 more Mac05 - I might try a TMM 2 way with a more robust tewwter such as the peerless beastmode - I am finding it difficult to push down the double peak breakup of the woofers. The breakup starts just under 5k, and crossing around 1800 or a bit lower would be swell.
So I was way off the simulation when i tried it out - the TM section was very close but hte 2.5 was not. anyways after a lot of trial and error which included making some minor changes to the TM section too, this is what the final version looks like.
This a comparision of the TM section to the 2.5 way. The red is the TM only without any BSC, and the blue is the .5 ISO woofers filling in below 1khz.
the response for the TM is offset by 10Db. I don't know how to fill in the respose under 80hz or so when the M will start rolling off and the ISO woofers will most probably be 6db lower on thier own - so low bass may be a bit lean?
this is measured? do they sound bass light?
This is measured - Bass doesn't seem light - I don't usually build full BSC, so this seems to fall in the right space. Sounds full and my tiny emotiva a2 mini seems to drive them fine, though it's 4ohm min rated - this defintiely dips down to 2ohms.
Related: the Dreadnaught is basically an arc welder - I shouldn't be afraid of low impedance speakers. It took a minute for it to blow a 10amp fuse when we shorted the nanners at Iowa that year.
I was thinking it was some sort of measurement error as I'd have a hard time believing it is near 10db down by 100hz. If you are using a typical gated measurement setting it will drop off below ~200hz no matter what and can be ignored.
it is gated at 300hz, see towards the bottom of the graph at the 300hz mark - it says gating. I have added +10db to the TM to make it easier to compare - the measurement are at the same votage level at the amp. the measurement is blind to anything below 300hz.
Most well build amps can take a bit under the min rated amp, but I was suprised the little amp was able to drive a 2 ohm load for a couple of hours at a pretty loud clip.