Three-Way Active System with 15"

[RussianBlue]

Be kind to me, this is a rough experimental setup, a 15' for the bottom, 6' for midrange and a tweeter on top, active setup. The 15" is a JBL 2235H, the 6" midranges are Audax PR17MO (I am using one of them on each side at the moment, 100dB 1W/M !!), the tweeter for now a VIFA XT25. I am currently working with different crossover frequencies with the Behringer Ultracurve(mostly 4 th order L-R, 2nd L-R) and slopes. 220Hz seems to work well for the mid/bass and 4.5kHz for the mid/highs. An interesting combination is a 18dB/oct Butterworth for mid/high and a 24db oct L-R for bass/mid. I have been listening to various X over frequencies, slopes and filters, but anything higher than 300Hz seems to reflect unfavorably on the clarity. I would agree with all the benefits that people have mentioned about professional 15" drivers - low distortion, high SPL, fast response. Drawback only in the size requirements for room and cabinets.
Now I am looking for a suitable sub for the first and second octaves. I also found that one AUDAX midrange is quite enough and I am considering replacing the second one in each cabinet by a PHL 1120 which will cover ONLY the octave between the JBL 2235 and the AUDAX. Also, the tweeter will be replaced by something better eventually, possibly a Morel MDT 33.
BTW, this system already shakes the house. The Audax midranges are unbelievably efficient, the JBL horn is not connected at the moment. I would appreciate any comments/suggestions concerning tweeters and/or low midrange drivers (6").


Cheers


P.S.: this is an older photo, I now have the XTs "dismantled" (no faceplate) and sitting on top of the midrange cabinets.

[454Casull]

Nice puppy.

[Branwell]

Hello RussianBlue,

I did a system with a Eminence Kappa Pro 15LF 2, PHL 1120, and a verity of different tweeters ranging from the G2 ribbon to the Scanspeak Revelators.
The crossover was a Behringer DCX 2496 and the speakers sounded great.

One thing I cant over stress enough is to do some appropriate cabinets.
Having the tweeter mounted as you do is going to result in a nasty frequency response that cant be eq’ed with out messing up the off axes response. It'll sound much beter in a proper cabinate.

Branwell

[RussianBlue]

Thanks for your comments,
Yes, you are right Branwell. The tweeter of course is no longer where it was on the photo. I took off the faceplates and mounted it on top of the mids. I was experimenting with physical placement and time alignment. My question now is whether to mount the tweeter into the space of where the second Audax is sitting and/or whether to replace one AUDAX with a PHL to run a 3.5 way system, ie. PHL covering only the 150 - 300 Hz region. This would then effectively make it a 4 way system and I would need two DCX 2496. Also, eventually the cabinet with the JBL woofer will be turned upsidedown to place the speaker in closer physical proximity to the mid. Also, has anyone had experiences with using the DCX to tune a speaker system and then replacing it with a passive crossover network?


Cheers


Branwell, which tweeter did you end up liking best?

[BobEllis]

Looking for a sub?

Those 2235s will go at least to the mid 20s in about 4.5 cubic feet tuned to 24 Hz. Build a 2nd order variable Q high pass filter at 24 Hz, and tune for flat in room response. (One of Sreten's favorite implementations )

Try it, I think you'll like it. If you can handle that much floor space taken up by the bottom

[kingdaddy]

I would let those Vifa XT’s play down much lower, for a high order slope like a LR24db. I would go no higher then 2.8K and as low as 2K, also don’t play them with the faceplate off, the faceplate is what holds the diaphragm and VC in the gap. Also try letting the mids play down lower and overlap the mids with the woofer, you might find that your missing out on a lot of program material. A speaker designer that I trust once told me that its always better to run the tweeter lower then to have the mid play higher, and I can confirm this with my setup using the Vifa XT and SS8530 mids.

[Branwell]

RussianBlue,

The PHL 1120 is very similar to the PR170MO, in that it was designed by the same fellow and intended for the same purpose more or less. The only difference is it’s a newer design…….The above is what I have heard, I don’t know it to be fact…

Its range is about the same as the PR170MO and crossing it over at 150hz ( right around its resonance frequency ) is not really a good idea, IMHO.

Its intended lower range is 300hz and judging from its frequency response, 300hz is about as low as you would want to cross it. In my setup, I had it set at 300hz and 3,500hz.

If you want a PHL driver to cross in the 100hz to 200hz range, you might consider one of there 10” mid drivers or alternatively, one of there 6” bass / mid drivers like the 1340.
Believe it or not, if you don’t need to extend the top above 3000hz, a decent 6” bass mid driver like the PHL can make a very nice midrange driver if you cross it over like a midrange driver. Another point would be that bass / mid drivers can be crossed as low as you like.

For example, my current setup consists of the Seas Millennium tweeter crossed over at 1440hz, 24 LR, to a Seas Excel W22 8” bass / mid driver. The W22 is crossed over to the Eminence Kappa Pro 15LF-2s at 100hz 24LR. This setup sounds incredibly good and technically speaking, the W22 is not a midrange driver, but a bass / mid.

Getting back to the tweeter, unless the tweeter was specifically designed for it, crossing a tweeter over at less then 7K ( rule of thumb ) without a baffle generally causes diffraction problems which effects not only the sound, but also the imaging.

Branwell

[RussianBlue]

Originally posted by BobEllis
Looking for a sub?

Those 2235s will go at least to the mid 20s in about 4.5 cubic feet tuned to 24 Hz. Build a 2nd order variable Q high pass filter at 24 Hz, and tune for flat in room response. (One of Sreten's favorite implementations )

Try it, I think you'll like it. If you can handle that much floor space taken up by the bottom

Bob, can I implement this with the DCX? It has a highpass function for the low drivers as well. You say 12dB/oct at 24Hz? No problem. Right now I have it set for 27Hz but at 24dB/oct.

Branwell, thanks for the advice on the tweeter - I did know the theory behind all of this, but it is always different when experiencing the sound in the room. I am not too fond of those tweeters crossed over around 2.5kHz, but perhaps the baflle diffraction effect (mounted on a baffle) will solve that issue. I will check it out.

Cheers

[av_affected]

RussianBlue
Bob is referring to an 2nd order highpass that can be adjusted for underdamped alignment. This provides some boost at the cutoff frequency (typically 3-6 dB) an extends the system low-frequency cutoff point. Essentially it creates a sixth-order alignment.

This is exactly the configuration JBL used in their B380 commercial subwoofer: 2235H in 4.5 cubic feet with "boost" network/crossover (JBL marketed it as the BX63). And Bob is correct, the F3 of the system is about 24 Hz.

This woofer works very well indeed. I'm using one as a sub in my dedicated theater/listening room teamed up with some very high performance DIY Dynaudio mains. I built the crossover/ boost network with some simple Sallen-Key opamp filters. The combination of high efficiency and low distortion of this woofer creates one of the tightest, cleanest, most musical subs I've heard.

[RussianBlue]

Originally posted by av_affected
RussianBlue
Bob is referring to an 2nd order highpass that can be adjusted for underdamped alignment. This provides some boost at the cutoff frequency (typically 3-6 dB) an extends the system low-frequency cutoff point. Essentially it creates a sixth-order alignment.

This is exactly the configuration JBL used in their B380 commercial subwoofer: 2235H in 4.5 cubic feet with "boost" network/crossover (JBL marketed it as the BX63). And Bob is correct, the F3 of the system is about 24 Hz.

This woofer works very well indeed. I'm using one as a sub in my dedicated theater/listening room teamed up with some very high performance DIY Dynaudio mains. I built the crossover/ boost network with some simple Sallen-Key opamp filters. The combination of high efficiency and low distortion of this woofer creates one of the tightest, cleanest, most musical subs I've heard.

The standard 4430 box that I am currently using is a little over 4 cubic feet I think. Any idea of how to lower the "apparent" volume without building a new box?
I think the electronic high-pass could be implemented quite well with the DCX. Full four-band parametric on every output... .
Cheers, thank you for all of your kind responses.