More than once surfed your great website and by that seen the DEQ2496 mod. Have a feeling it's EQ some kind of linear phase, if it is then by that you could try make a 2 way filter for one speaker where phase is not damaged as you write. I mean in "Utility" menu set it's channel mode up to "Dual mono" HP and LP now via left and right channel and two DEQ2496 needed for stereo speakers but here meant just as a trial to see if a higher order XO is linear phase for one speaker or your dual woofer thoughts and how that sound. Only use the PEQ's 12dB HP or LP and as example put two HP PEQ right channel and two LP PEQ left channel and you now has HP/LP 4.orden with no phase turn. Up to 10 serialized PEQ HP or LP 12dB could be used for a whooping 120dB/oct, though frequency point would have to be exercised and not necessary be same for HP/LP as summing when serializing the unknown Q of the 12dB HP/LP filters influence summing.
1: RC filters of first order are fine for phase outside the xo region. But 90 deg phase rotation at xo frequency,is not ideal either.
Or...just use active 4th order, get phase alignment, and accept the cycle lag (which is debatably inaudible)
I have found that first order is largely a pipe dream, and has far more drawbacks than benefits, especially through the xo region...unless partnered with a 3rd order section
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Mini dsp is certainly flexible and highly useful, however I'm yet to be totally convinced of its quality and usefulness to me, especially in regards the gain issue.
Id also imagine any phase issues between 400-600hz would be pretty detrimental to spacial cues, which i believe (not professing to know) are located in exactly this area. Unfortunately all the first order designs ive done sounded phasey, yet the higher even orders didn't, which is something which surprised and delighted me at the same time.
Here's the deal. The minDSP is an entry level product has shortcomings. I highly recommend it for anyone just starting out with DSP and bi-amping. Soon or later you need to step up and it gets moderately expensive. The miniDSP has two features that affect the SQ. First, it is analog in, so you need a DAC to feed it. It then does a analog >> digital conversion. Second, the output DAC's are not the greatest.
I am using the nanoDIGI. This product is digital in and digital out. You feed it SPDIF and preferably 24/96. Do the sample rate conversion where ever you get the best SQ. The output is 24/96 SPDIF, so you need 2-4 DAC's depending on how many channels you are using and and equal number of amps. But you get to use the best equipment you can justify. I am just using two channels with Topping D20 DAC's, a TPA3116D2 amp on the tops and a Crown XLS 1500 on the bottom.
Have fun.
Bob
Picture attached captured from an old KEF note. Phase plot 1.order at left 3.order at right and the strait line shows filters final damage to system phase when acoustic summed and is actual ideal for 1.order.
Maybe it ain't easy getting it right, a quote Bob Richards #10 "Getting a passive crossover to be accurate is a bigger project than many realize" unquote.
Some specs that seems needed is drivers need plenty overlap, if drivers not linear inside overlap needs EQ someway, at XO frequency point depending the wavelength the physical spacing of drivers needs attention for correct summing, on axis acoustic arrival from both HP and LP drivers need offset by physical distance them or use delay (allpass or digital).
Baffle difraction design at both HP/LP, drivers not fire from same place in space, room boundary modes, all has possibility degrade the multiway 1.order design.
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Without knowing a guess is it has 180º or 360º phaseturn around center frequency in bandpass. The speaker science/knowledge material i've seen express all drivers and boxes has equality electric filters and this way can be simulated. If if has a 180º turn it still can sound very good, a friend has some +20 years old KEF where bass drivers running as bandpass is hidden inside, only a narrow tall baffle with middle/tweeter visible, and they sound really good.
Thanks for the compliment on my website. Sadly I couldn't justify the cost of keeping it up there, so as of last week it's only on my hard drive now.
Linkwitz is using the miniDSP thing if anyone wants to see an apparently good example of its use. I personally know nothing about it.
Getting back to the original question; Can a 2nd woofer be added to a fullrange driver without some kind of phase addition issue? If the added woofer is physically far enough away from the wideband driver, room acoustics may dominate and make the phase addition a small thing.
In the interest of keeping things simple and low cost, I'd just try it and see. I'd give the 2nd woofer a lowpass with -3dB at about 50HZ. I'd also try using a second order passive filter and see if that didn't work even better. Ideally there would also be a highpass on the wideband driver, possibly a bit higher in frequency, maybe 100HZ. It might be better if the wideband driver is attenuated relative to the 2nd woofer, to make up for losses in the coil and to beef up the low end amplitude a bit. In that frequency region most rooms are going to cause pretty significant phase issues just from room reflections, so adding one more effective reflection (differential phase delay) may be hard to even see with pink noise and a decent RTA. How the speakers will interact with the room will be different, but not necessarily worse, and could be better.
Volume control is digital in the music player. As long as you upsample to 24 bits, you have lots of dynamic range before significant bits get cut.
Set the volume to max in your music player (and Windows if you are going to use Direct Sound). Turn up and balance your amps for as loud as you will ever go. Now set your volume in your music player.
Bob
Set the volume to max in your music player (and Windows if you are going to use Direct Sound). Turn up and balance your amps for as loud as you will ever go. Now set your volume in your music player.
Bob
In every FAST I've done, and every 3 way I've done, that doesn't use a high order (4th order) XO, I've had to flip the polarity. If not, there's a broad deep null right around the XO with tons of ever lap.
The difficulty of getting a passive XO to work with a FAST is multi faceted. The impedance peaks at Fb are a nightmare meaning first order does not work, unless you deal with those peaks some how. Parts are expensive, so high order is not feasible. Low Oder means more excursion and extension into the break up region from the woofer. And crossing low means bigger XO parts which again adds to the cost and put the designer into the impedance peaks again.
The difficulty of getting a passive XO to work with a FAST is multi faceted. The impedance peaks at Fb are a nightmare meaning first order does not work, unless you deal with those peaks some how. Parts are expensive, so high order is not feasible. Low Oder means more excursion and extension into the break up region from the woofer. And crossing low means bigger XO parts which again adds to the cost and put the designer into the impedance peaks again.
I suspected this was the solution, but I was hoping for an alternative. This is precisely what prevents me from switching from miniDSP to nanoDIGI. I use an analog preamp for both volume control and source switching, and the nanoDIGI simply won't integrate. Or, at least I can't imagine how it would.
For example, how do you integrate a turn table or other analog source into your setup?
You are not going to like my answer, but....
Digitize your analog inputs to 24/96. Proceed as above.
It is my opinion and i do not intend to get into a food fight defending my opinion, is that the difference between vinyl and redbook is not the medium, but the mix. The mix on vinyl (and SACD) is often at least different if not better than what gets put on a CD. So, buy that great mix on an LP, digitize it on the very first play and you have the best of both world.
Bob
I don't dislike your answer at all, in theory, and I'm not looking for a fight at all either. I am looking for answers and you provided a perfectly sufficient one.
I'm just not ready to put away the vinyl. I like the smell and feel too much. To me, it is like a time machine back to my youth. These days, I'll take what I can get when it comes to feeling youthful.
Sorry for the OT, all.
Recently I've been having fun simming fullrange drivers crossing over to supporting woofers in various implementations. Practicing on different simulations has shown me that making a 1.5-way or even a proper 2-way (with the fullrange driver crossed around 4-500hz) will take more science than just slapping an inductor on the helper woofer, for example. While the phase issues might be less tricky than when you cross at higher frequencies, it still needs to be done with some care and the natural phase of the drivers being used has to be taken into account. That being said, I would still say it's much easier than your typical 2-way being crossed between 2-3khz. One last thought: making a 1.5 way with two identical drivers might not be too difficult, but crossover designing software will still be a big help in determining the appropriate value inductor.
Just want to add something to what tuxedocivic mentioned: he's absolutely right that crossing in the 100-200hz region, where most of us with full-range sensibilities want our woofers to take over, has also struck me as being prohibitively expensive and complicated if you want to buy quality components. ($100+ for ONE capacitor? No, thanks.) Crossing over between 400 and 500hz is more feasible. Additionally it means more protection for the full range driver and offers the possibility of using smaller drivers with better treble and dispersion.
That isn't gonna work... if you ar eXOing high enuff to get away with a (practical) inductor then the FR needs to be high passed.
If you are only low passing the helper woofer, it needs to be at or below the low end of the FR which is going to require another amplifier (often a plate amp in practise).
A 1.5 way system is a completely different beast. You are adding the 2nd driver to compensate for baffle step, or if you don't need BSC, then wire in series using a bypass cap to share the load at LF (assumming a voltage amp)
dave
Just do it at line level with PLLXO and bi amp. The cost of good class D amps is way less than an inductor and fat capacitor to achieve the same thing.
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