I have wondered about Charlie's suggestion - a small full ranger. Everyone knows about the TC9 3.5" full range - I'm listening to some now! There are some nice smaller drivers that I consider using as a low tweeter. 2.5", 2", 1.5" ... TC5FC07? I haven't tried building up a pair of speakers like this yet, but it's on my list of interesting ideas...
I built an MTM using a Tang Band 2" aluminum (concave) dome fullranger and two 7" woofers once. Crossed over at 750Hz. It worked out pretty well. That's why I suggested it.
People interested in the Morel CAT378 could get Mike Chua to email them his first order circuit in the Finch design:
https://ampslab.com/blog/2018/03/12/finch/
Very nicely done. I cannot show you the circuit here, out of respect to Mike's intellectual property.
https://ampslab.com/blog/2018/03/12/finch/
Very nicely done. I cannot show you the circuit here, out of respect to Mike's intellectual property.
mike's other stuff on 378 (i hadn't realized how much he likes it)
https://ampslab.com/blog/2018/02/21/morel-cat-378/https://ampslab.com/blog/2020/08/31/enlightenment/https://ampslab.com/blog/2021/04/19/thrush/https://ampslab.com/blog/2021/04/08/kookaburra/https://ampslab.com/blog/2021/04/23/thrush-cat/
https://ampslab.com/blog/2018/02/21/morel-cat-378/https://ampslab.com/blog/2020/08/31/enlightenment/https://ampslab.com/blog/2021/04/19/thrush/https://ampslab.com/blog/2021/04/08/kookaburra/https://ampslab.com/blog/2021/04/23/thrush-cat/
A more expensive alternative to the CAT378 and also used in A26 / Orangutang speaker is the Seas T35C002 tweeter. In the A26 it is run with just a capacitor and a resistor and a crossover point of 2600hz. As said both of these tweeter already have an inbuilt first order roll off there for adding a capacitor makes it a second order acoustic.
Not possible, if you mean 1st order acoustical high-pass filter all way down to low frequencies.
It is possible to manage the filter slope to be first order acoustically from 2500Hz down to the tweeter resonant frequency, but below that, slope downward will be about 18dB/octave.
Ahhh, i see your point.
-6db at 2k, then -15db near 1k, not -12.
True 6db would be 6db per octave, but i sort of agree with bob brines. I think he said it would be ok 6 down then 12 down, then you can roll faster.
-6db at 2k, then -15db near 1k, not -12.
True 6db would be 6db per octave, but i sort of agree with bob brines. I think he said it would be ok 6 down then 12 down, then you can roll faster.
The Morel CAT378 is used a lot in 1st order crossovers, even way lower than you plan to do so it should be fit. I don't like the sound of it altough. The SB26ADC can be crossed at 1300Hz with a second order (altough i would cross it a bit higher) so it would also fit your plan at 2500Hz with a first order.
Let me cite Beranek on pulsating spheres here. It is an oversimplification, OK. But what you see here is that a source of given dimensions needs rising excursion to keep acoustic (power) output. E.g. for this example the excursion at 100Hz has to be four times that at 200Hz just to keep the same output. Think of that before you want to establish a 1st order acoustic highpass.
Yeah, I reckon 2 octaves of true 1st order rolloff should suffice.
With the TW30WA12 and a 2500Hz XO we've attenuated 15 db electrical at FS.
Enough to keep excursion down? Maybe 😅
The way I see it there's two options if I were try 1st order acoustical:
1. A beefy tweeter mated to a small woofer at 2500-3500 Hz
Pros:
- Broad dispersion / wider sweetspot (could be considered a con)
- Less mass (greater resolution?)
Cons:
- Crossover lobing over a wide area
- Less output capability due to limited excursion capability of tweeter
2. A small full ranger crossed much lower (the WAW/FAST way)
Pros:
- Less lobing due to low XO
- More output capability due to higher excursion capability
Cons:
- Narrow dispersion / smaller sweetspot
- More mass (less resolution?)
There might be some confudlement. When typifying a driver, you look at how much SPL/ distortion a given input power generates. Thus measured, most tweeters start falling apart above 94 dB. Go to 100 dB and smoke may start coming out. However, if you want 2 way speakers that play music at 100dB C weighted, most SPL is generated by the mid bass driver, so a tweeter that does 94 dB would be fine.
Your assumptions are not absolute. I’d start simulating things in Vituixcad or Boxsim. Both do adequate directivity plots (although the first rules, I think). And look at designs like Mark K’s ERDXT- design, which deliberately uses 1st order electric X-over functions because of smooth directivity control.
Try ESS AMT as it can go down to 700Hz. This lets you cross at 2800Hz with shallow slope easily and have 2 octaves below to work with for the shallow slope to extend into. The GRS 8in planar is similar with a wide reach and goes low.
Alternatively, use a good full range driver. A ScanSpeak 10F sounds quite nice (only 18kHz top) but crosses over wonderfully first order at 900Hz even.
https://www.diyaudio.com/community/threads/10f-8424-rs225-8-fast-waw-ref-monitor.273524/
Alternatively, use a good full range driver. A ScanSpeak 10F sounds quite nice (only 18kHz top) but crosses over wonderfully first order at 900Hz even.
https://www.diyaudio.com/community/threads/10f-8424-rs225-8-fast-waw-ref-monitor.273524/
The old Peerless HDS (now Scanspeak D2608/9130) is still around: ferrofluid, 1mm x-max, 700Hz Fs, low mass soft dome, looks great on paper? Isn't it 20 years old by now?
https://www.madisoundspeakerstore.c...covery-d2608/9130-1-textile-dome-hds-tweeter/
https://www.madisoundspeakerstore.c...covery-d2608/9130-1-textile-dome-hds-tweeter/
Lots of good full rangers work here.
B80, 10F/8424 or 10F/8414, SB65WBAC25-4, TG9FD, FR88EX, FR55EX, 3FE25 or 3FE22, RS100, PS95-8 all sound pretty good.
