Or a FR on top. XO at 200Hz, top is in an aperiodic midTL and sealed on the bottom. Designed to get away with afirst order PLLXO.
dave
Passive bi-amping — most of the advantages of bi-amping go away. You are just adding more power, which is not a primary benefit, that being losing the passive XO.
dave
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And yet ... even today - after several decades - people still don't get this basic fact!! 🙄
Losing the passive XO (which goes after the power amp) means each power amp channel is directly connected to its driver. That's where the advantage lies.
These are beautiful cabs!!
The top could be FR cab arrangement that naturally rolls off the bass.
But is the lowest driver of the pair the 'sub' driver.... ???
Actually the sub in a separate cab, speaker not facing the listener could also go without xover (sub drivers start roll off about let's say 200 hz...). That's how I first made it and you get all the extended bass range, but using active xover to cut the top is better. (In my case there was an overlap between sub and top in a not very pleasant range 😄😄)
Passive xover for low frequencies would be bulky, expensive, poorer performance both for the driver and the amp.
That's why almost ALL passive 3 way speaker cabinets on the market SUCK compared to a lame home put up bi-amping, provided there are suitable drivers and amps for the bi-amping.
The bass (sub) amp and speaker should handle the power and spl needed to cover the 'top'.
'Top' is whatever size you intend to use. The accent there is on detail, clarity, stereo imaging, sound signature u like.
Using an amp the same power for the 'top' is an overkill, but might be easier and convenient (uniformity) for small systems.
Going for a lower xover point (no more than 90hz) makes it easier on the sub alignment with the 'top' speakers.
Chosing other xover point is to get the best of the drivers u use I guess.
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Just to add, using ported enclosure both for the 'sub' and 'top' is a bad idea - two different resonant frequencies and their detrimental effects.
It is best to move the resonant frequency as low as possible - less probability to hear it's quirks.
So it is the 'sub' to be ported, mainly cause it is cheaper and much easier to implement than other options.
(I would do sealed + linkwitz transform if I am willing to spend the money and time on this).
I don't know much about transmission lines and their quirks, but sealed is a safe bet and much easier to implement for the 'top'.
It is best to move the resonant frequency as low as possible - less probability to hear it's quirks.
So it is the 'sub' to be ported, mainly cause it is cheaper and much easier to implement than other options.
(I would do sealed + linkwitz transform if I am willing to spend the money and time on this).
I don't know much about transmission lines and their quirks, but sealed is a safe bet and much easier to implement for the 'top'.
2 SDX7eN in parallel, subwoofers operate below 40 Hz.
Chrisb put over 200 hrs into those cabinets.
dave
With active crossovers being so cheap [ S/H Behringer??] and older but still good poweramps being sold at bargain basement prices why wouldn't you Bi, Tri or Quad amp?
Even when paying full retail price for a digital XO to cross your subwoofers a Behringer Ultradrive is almost cheaper than a passive XO using a coil with a sufficiently low resistance to not cause power loss in the bass
Locally a Jantzen P-Core 25mH with a DCR of 1.15Ohms is $60- plus shipping but shopping around a DCX can be had for $399- new and I bought my last DBX 234xs for $99- where somebody local had just upgraded to digital. Personally it is a no-brainer where space isn't at a premium and you want to crossover to the bass low in the 80 to 120 Hertz region
Even when paying full retail price for a digital XO to cross your subwoofers a Behringer Ultradrive is almost cheaper than a passive XO using a coil with a sufficiently low resistance to not cause power loss in the bass
Locally a Jantzen P-Core 25mH with a DCR of 1.15Ohms is $60- plus shipping but shopping around a DCX can be had for $399- new and I bought my last DBX 234xs for $99- where somebody local had just upgraded to digital. Personally it is a no-brainer where space isn't at a premium and you want to crossover to the bass low in the 80 to 120 Hertz region
Dave it is at a minimum no worse that the equivalent passive network but with no insertion losses as a bonus
While not the best practice, it is the practice being spoke of. Bi-amping is viewed from the speaker cabs prospective. It's not a rack count as many suggest. Nor specific to active or passive. It's just what the cab see's. This is evidenced by the vast majority of speakers having two sets of binding posts. These are for bi-wiring or bi-amping. As per the instructions. The reason is to use identical amps, but give the psu of the hf amp an easier time. This is more benefit than additional outboard psu's, as the work needed to just drive a tweeter and maybe a midrange, is a fraction of that needed to drive bass. The bass wasn't really improved by this though, as the bass amp was still under a similar duty.
In all, it's a similar improvement to improving the power supply. One amp barely see's a difference, but one is unloaded a lot.
Hello,
I am largely in agreement.
I sometimes sneak in a passive part or two for a bit of equalization.
I almost always use a protection capacitor for the expensive tweeter compression driver. Keep the DC accidents out of the tweeter. Also keep the hum and buzz out of the tweeter
For the JBL M2 they use a hardwired L-Pad to operate the D2 compression driver amplifier with a bit of resistive load to lower the effective noise from the waveguide. Without the hardwired L-Pad a 100 watt amplifier has a higher SNR operating at 7.5 Watts than 0.5 Watts. You know that % THD+N thing, as watts go up % Noise goes down.
Thanks DT
I use a Rane Mojo MX23 active crossover for a 2-way + sub on my bench. The mid to sub crossover frequency is set at ~120Hz. Keep the long stroke Low Frequencies out of the driver that produces voice frequencies.
Do you a 31-band analog equalizer? Old school, I know.