Troels has measurements. The woofer is 10" sealed (acoustic suspension)
http://www.troelsgravesen.dk/SnellA3i.htm
Nearfield of individual drivers. Room response remains a mystery... (30Hz peak must be room mode)
Stereophile has measured Type A Reference https://www.stereophile.com/content/snell-acoustics-type-reference-loudspeaker-measurements
I have made two pairs of speakers with closed box 10" floor-coupled downfire and I like them very much. I use dsp.
http://www.troelsgravesen.dk/SnellA3i.htm
Nearfield of individual drivers. Room response remains a mystery... (30Hz peak must be room mode)
Stereophile has measured Type A Reference https://www.stereophile.com/content/snell-acoustics-type-reference-loudspeaker-measurements
I have made two pairs of speakers with closed box 10" floor-coupled downfire and I like them very much. I use dsp.
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Yes it is the room response + loudspeakers here, so hard to see but where the acoustic cut off is. He has a 17 (or 20?) squaremeter room iirc. All his loudpseakers are tailored in room for the bass as far I know, so we don't know really cause soundcard delay doesn't allow measurement really below a certain threshold (200/300 Hz ?).
He uses a grossly approximation of room gain from a ScanSpeak Excel spreadsheet. He doesn't use REW to measure room response alone as far I am aware of... (and even so the excitation of the room whatever REW is certainly not an easy precise task. Needs high spl level and capable drivers in thelows for that)
He uses a grossly approximation of room gain from a ScanSpeak Excel spreadsheet. He doesn't use REW to measure room response alone as far I am aware of... (and even so the excitation of the room whatever REW is certainly not an easy precise task. Needs high spl level and capable drivers in thelows for that)
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I believe the Hypex FA-xyz will give you the capability to transform the 2-ways into an excellent full range 3-way. This is a difficult transformation to do with a purely passive crossover, but with 3-channel active amps and DSP, it is quite achievable.
I have a similar setup, with woofer cabinets on the floor, and the mid-tweeter "top units" on a stand. The stand also contains the Hypex FA253. I have made 3-different mid-tweeter "top-units", all with different sonic characters
More...
Some sources say A3 has 12" some 10" woofer - even TG writes both ways...
The measurement in my previous post is true nearfield with long gating. Notice that also mid and tweeter responses show similar peak at 30Hz
"Nearfield response of drivers driven from crossover. Disregard the relative level between drivers as I was only interested in rendering possible points of crossover. The bass response was measured with the microphone as close as possible to front grille. The bass upper roll-off more seems like 6th order acoustically from this measurement."
Here an example how my MR183 nearfield vss. room response look (SB29NRX)
Some sources say A3 has 12" some 10" woofer - even TG writes both ways...
The measurement in my previous post is true nearfield with long gating. Notice that also mid and tweeter responses show similar peak at 30Hz
"Nearfield response of drivers driven from crossover. Disregard the relative level between drivers as I was only interested in rendering possible points of crossover. The bass response was measured with the microphone as close as possible to front grille. The bass upper roll-off more seems like 6th order acoustically from this measurement."
Here an example how my MR183 nearfield vss. room response look (SB29NRX)
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how about using 2 drivers, one at the top (close to the mid) firing forward , one at the bottom firing down.
That's what I proposed before like a Kef 104/2, Kef 104/2 has a central rode but you can use the fixing screw holes for the task to allow close coupling and vibration cancelation.
I've built a center channel using the FA 153 (I think?) and my experience with that was a major reason why I'm considering this project.
I think Troels surmises it's a combination of the crossover plus the slot loading, which I'm not sure this is even the right term. It's not a substitute resonant port... but you know what I mean.
I will add that at the time of this design LR 4 filters were a hot topic, to the point where THX made it part of their equipment, whether or not it would acoustically sum correctly or not.
Given how easy it was to implement an LR4 with my 3-way center channel I am absolutely jonesing to do this again here.
🙂
Ah, yes of course.
The question you might be asking yourself is actually still asked today in the form of whether it's ok to use DSP to EQ any woofer to any response.. even if it's below the woofer resonance, so that there's no need to add mass.
a) Is there a difference in sound quality between that and added mass.. is there any magic? and,
b) What measurable difference will there be.
Firstly, a system of this type is ordinarily expected to be single amped and used without necessarily any EQ. Passive tricks to correct the response to something usable is no different really than something like choosing to use a vented box.
Extra mass may reduce sensitivity, reduce high frequency response and modify cone breakup behaviours, but being a woofer, just the former would be of interest. Cone excursion for a given response will be the same with or without the mass so over-excursion, while it may be it's own issue, wouldn't be an issue just because of the mass.
There is also the question of the minimal weigth of the cone (in stifness behavior I mean) for bass purpose. At 100 Hz we are not far from a subwoofer design.
It was the active crossover and separate bass amp driving the sealed-box 12 inch woofer!
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@Andersonix I was pretty sure the one I saw did not have an active crossover... but I know mine will!
About 30Hz peak in TG measurements, it must be ambient noise that induces a room mode.
Slot height in downfire - it makes basically a waveguide like effect. Perhaps one can calculate it with Hornresp ( I am not smart enough). But another effect comes from the nearness of the wall - no front-wall interference nulling but delayed max amplitude in impulse/step response which is easily corrected with dsp by adding delay to mid and tweeter unless the xo is very low alike a subwoofer.
Another interesting trick is used in D&D 8c - put woofer(s) on the backside of the box! So, this kind of speaker calls for dsp and a competent installer who makes in situ settings based on measurements! D&D and my AINOgradient xo at 150Hz, Snell and my MR183 around 250Hz.
Slot height in downfire - it makes basically a waveguide like effect. Perhaps one can calculate it with Hornresp ( I am not smart enough). But another effect comes from the nearness of the wall - no front-wall interference nulling but delayed max amplitude in impulse/step response which is easily corrected with dsp by adding delay to mid and tweeter unless the xo is very low alike a subwoofer.
Another interesting trick is used in D&D 8c - put woofer(s) on the backside of the box! So, this kind of speaker calls for dsp and a competent installer who makes in situ settings based on measurements! D&D and my AINOgradient xo at 150Hz, Snell and my MR183 around 250Hz.
@eriksquires I don't think it's a secret; Large low(ish) Q sealed woofers with boundary reinforcement are pretty good for low-end music reproduction. Time to build those Snell type AIII clones!
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Yes, it is too late to do anything else besides a 2 woofer sealed box with 3-way plate amp. You are killing me people. 🤣