is the woofer on top the reason why measurements show a linear phase response at the crossover? since even 6db slope filters should introduce a phaseshift
tho im kinda confused since its quite unusual to not have the tweeter at earlevel
Typically, we would toe out a driver that has a rising response, so to balance the mids and the highs.
Having it lower achieves the same.
Also, to time align the woofer to the FR, by placing the FR lower, the distance to our ears is now longer than the distance of the woofer. Physical delay.
Having it lower achieves the same.
Also, to time align the woofer to the FR, by placing the FR lower, the distance to our ears is now longer than the distance of the woofer. Physical delay.
Woofer on top provides the time delay for the tweeter. If you put tweeter on top with a 75mm setback (stepped baffle) that would achieve same thing. 1st order (6dB slope) filters are linear phase.
Edit - Perceval is right about the mild off axis equivalent of toe out to balance a rising response tweeter. One of the reasons this speaker is non-fatiguing.
If you did tweeter on top with stepped baffle it would sound a little brighter. There would be diffraction effects of the tweeter in the edge of the baffle step “ledge”. It could be reduced somewhat by thick layer of felt in the ledge.
Edit - Perceval is right about the mild off axis equivalent of toe out to balance a rising response tweeter. One of the reasons this speaker is non-fatiguing.
If you did tweeter on top with stepped baffle it would sound a little brighter. There would be diffraction effects of the tweeter in the edge of the baffle step “ledge”. It could be reduced somewhat by thick layer of felt in the ledge.
are you using FIR ? normally 6db slope filters also introduce phaseshift
Ah.. understood thanks, this makes my plan to use a other wideband driver quite more challenging... i need one that also has rising highs i guess..
in my experience the pressure peaks in bass reflex (or other higher order resonant) enclosures exceeds that of sealed chambers by far.
Just have a look at the displacement of bass reflex driver at helmholtz resonance: the driver gets full power (because of impedance minimum) but still the diaphragm (nearly) does not move. That's result of the resonator pressure in the enclosure!
Thus any driver leakage induced chuffing noises would be much higher in ported systems than in closed ones.
Stv,
The TL has a very large vent cross section and velocities are never high enough to produce turbulence or chuffing noises. The TL opens up the back chamber of the driver and really reduces compressive distortion. The midrange sound of the RS225 in TL vs sealed is much more open and clear. Bass reflex may be different because the resonance is in a smaller chamber.
The TL has a very large vent cross section and velocities are never high enough to produce turbulence or chuffing noises. The TL opens up the back chamber of the driver and really reduces compressive distortion. The midrange sound of the RS225 in TL vs sealed is much more open and clear. Bass reflex may be different because the resonance is in a smaller chamber.
hi xrk, I was referring to sArj's question whether a sealed box in combination with the not perfectly air tight RS225 (air gap at the phase plug) may produce chuffing noises.
I agree that the TL cross section you propose will never produce any chuffing, it's sized to never do so!
Intuitively we think that the pressure in a closed box must be higher than in one with an opening (port, TL ...).
but at resonance the pressore in the cabinet is huge for ported/TL boxes!
just listen to a ported box at resonance frequency with just a tiny air gap, a screw not tightened for example!
Cheers, Xrk!
Then I think the current amount of stuffing is correct. I will try to fine tune once the speakers are warmed up abit more and see if theres a difference.
And I double checked and you are correct, got response up to around 16kHz.
This is my current frequency response from my listening position, with Dirac tuned. The teal/green is combined. Got a few dips here and there. Tricky room i guess.
Is it possible to use RS225 in a normal 2 way?
That is, with a treble. Split frequency around 1800-2000 hertz.
That is, with a treble. Split frequency around 1800-2000 hertz.
Yes (I've done it). But not, if you want to get the best from them, at that sort of crossover frequency: you really need to be crossing at 1.4KHz or preferably a little lower to avoid the distortion amplification of those massive bell modes (the current Dayton response data glosses over that somewhat given the smoothing applied), and ideally, you need a high impedance LC parallel notch in series with the driver to further help hammer it into submission when crossing >1KHz or so. It's still a great driver of its type two decades after its introduction, with a very good motor for the price, but it's not a straightforward unit to get the best from in a conventional 2-way design. The tweeter needs to be fairly robust, & you'll need LR4 minimum, but they exist: the TW29 Satori variations for e.g., which I've used many times.
Thanks!
I have 4 differnt tweeters.
Scanspeak 2905/930000
Seas Prestige 25tdfc
Peerless Xt25bg60
Fountek Neocd3.0
Can I use any of them?
I have 4 differnt tweeters.
Scanspeak 2905/930000
Seas Prestige 25tdfc
Peerless Xt25bg60
Fountek Neocd3.0
Can I use any of them?
have a look at
https://heissmann-acoustics.de/en/hochtoener-mit-waveguide/
while your tweeters are not exactly what heissmann tested, e.g. your peerless ring radiator should probably be very similar to XT25TG.
That’s a nice tweeter on paper. I have not had a chance to hear one in person but have wanted to try a dual ring radiator. Not crazy about the nipple look though. 🙂
As far as using RS225 in conventional 2 way crossover, I did a simulation once to pair it with a waveguide dome tweeter (can use RST25F-4 as replacement for RS28F) here:
https://www.diyaudio.com/community/...ligned-rs225-8-and-rs28f-in-waveguide.360445/
I think I crossed at 1.5kHz:
The best thing is that it is time aligned and has a close to transient perfect step response.
As far as using RS225 in conventional 2 way crossover, I did a simulation once to pair it with a waveguide dome tweeter (can use RST25F-4 as replacement for RS28F) here:
https://www.diyaudio.com/community/...ligned-rs225-8-and-rs28f-in-waveguide.360445/
I think I crossed at 1.5kHz:
The best thing is that it is time aligned and has a close to transient perfect step response.
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FWIW (from somebody who's been there & got the bruises) -be a bit careful with the XT25 / R2604-832[3]0. Notwithstanding its narrowing polars with frequency, which can be an advantage in some cases, it's a lovely tweeter in many ways: very low linear distortion, and generally low non-linear distortion down to about 2.5KHz. Because it's a ring radiator, elevated HD2 is the dominant profile throughout the range: from a functional POV it's basically like having a diaphragm made from two flexing surrounds -there is no piston operation at all in its operation. Not in itself an issue since HD2 is within reason the least problematic. Now comes the caveat: HD3 & > climb sharply below about 2.5KHz or so, and depending on application, it's audible - very audible. You can take it below 2KHz, but there are a few things you need to keep in mind:
1/ You will need an Fs LCR Zobel to prevent it ringing. If you cross low, a damping shunt resistor isn't likely to be sufficient, & depending on exactly what you're doing, it may not be even if you cross higher.
2/ LR4 or > is basically required. Forget anything less
3/ You will likely be limited in SPL & distortion terms even with that in many cases -if it's a system with limited headroom, you may get away with it, but unlikely otherwise.
1/ You will need an Fs LCR Zobel to prevent it ringing. If you cross low, a damping shunt resistor isn't likely to be sufficient, & depending on exactly what you're doing, it may not be even if you cross higher.
2/ LR4 or > is basically required. Forget anything less
3/ You will likely be limited in SPL & distortion terms even with that in many cases -if it's a system with limited headroom, you may get away with it, but unlikely otherwise.
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Quickly looking over the others mentioned:
Fountek Neocd3.0 = forget it with the 225. It's a traditional ribbon, so marketing notwithstanding, 3KHz is likely to be the LF 'performance' limit, as typically distortion rockets in most of these ribbons below roughly that point.
Scanspeak 2905/930000 = still pretty good after all these years (the 9000 series arguably being the first 'modern' high-end tweeters). Pushing it for this application, but there are worse options
Seas Prestige 25tdfc = ditto. Like the 9300 it should be able to handle it if (if) you go to town in the filter & aren't aiming for high SPLs
Peerless Xt25bg60 = as discussed. It can be done, but as with the above domes & probably a touch more so, you need to put some effort into the filtering & we're working on the assumption you're not planning on high SPLs.
Fountek Neocd3.0 = forget it with the 225. It's a traditional ribbon, so marketing notwithstanding, 3KHz is likely to be the LF 'performance' limit, as typically distortion rockets in most of these ribbons below roughly that point.
Scanspeak 2905/930000 = still pretty good after all these years (the 9000 series arguably being the first 'modern' high-end tweeters). Pushing it for this application, but there are worse options
Seas Prestige 25tdfc = ditto. Like the 9300 it should be able to handle it if (if) you go to town in the filter & aren't aiming for high SPLs
Peerless Xt25bg60 = as discussed. It can be done, but as with the above domes & probably a touch more so, you need to put some effort into the filtering & we're working on the assumption you're not planning on high SPLs.
The SB ring radiators are basically designed by the same man who did the XT25 & have a similar response & general behaviour, so if you're not sold on the looks, they are a potential option. Because the XT25 design was still under patent he came up with the internally pinned dome solution, so they avoid the 'unique' appearance of their ancestor & having more radiating area they often beat it on the low end in terms of non-linear distortion, although the original still probably has the slight edge in terms of linear distortion. Name your poison really.