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LDS 2x12 Large horn

#21
The driver stuff is not nearly the issue it's getting here - proper tuning of porting makes ANY of them work well, after all.

The crossover thing is really where the issues arise and that's time time time. It's pretty easy with active crossovers especially of the DSP variety to get good voicing, and crossovers that act well off-axis - all without any impedance/reactance issues. But it takes a lot of measurements and man-hours to do a splendid passive for ANY drivers. To do the level of design I'm talking about a one-offs box would have to be sold for a MUCH higher price than a box that's had that level of attention put into it but has gone into mass production.

It doesn't matter how good Ralph Patterson is or whether he has a good measurement suite if he can't justify putting that major investment into time time time that someone like Duke does for each and every one of his products.
 
#23
Refresh me on what Yamaha boxes you are talking. Does Ralf use a good test measurement suite? Most of the companies involved in SR enclosures do box-specific crossovers with a fair amount of time and attention behind them for at least some of their product lines. Even in the cheaper lines, ferinstance, you'll often find driver and enclosure specific designs that make good FR and polar plots. Why? Because those plots are part of the product literature.

What Duke is doing is very much akin to that level of design and data aquisition. But since bass players are "a different breed" he has less reason to publish the actual data, although it informs him and keeps him honest.
 
#25
Yeah, even with those c112v you see 6-band polars and FR and impedance sweeps in the manual. The economy of scale for these huge companies - AND the professional engineer protocols and expectations and facilities in place at them - make it realistic and practical to work on even the cheaper products' crossovers to a level that has hardly ever happened in bass product circles.
 
#27
I dunno guys. There are a lot more things to correct for in a horn crossover than a woofer to woofer crossover. If you look at the resonant peaks on horns and the way horns change impedance and all that it's a lot more complex to get the info you need to in the first place.

There also tends to be a lot more padding on a horn; many horns are padded back 10db or more in good designs.

Mix those two issues and it's a lot more likely someone will get a midrange crossover functional by just going generic than using a horn and driver. Fewer variables in play and sensitivity matching is far easier too.

Just as an example, say, a 3012LF and an Alpha 6a - you could get a workably decent sounding system just going with a generic eminence 800hz PCB.

Try doing a 3012LF to a horn with the stock 1200hz or 1600hz Eminence Xover and your results will likely be much different. You'll at the very least have to add a serious lpad for any decent horn that goes that low and is in the right size.

I realize that midrange xovers are still complex, but I'm convinced it is a bit more difficult to get it right with the low crossed horn, at least based on what I've seen so far. In parts count at the very least.
 
#28
You are wrong. If you want GOOD crossovers it's not about being merely functional. Either type of scenario is easily handled with generics and variable L-pads if you don't actually car about more than "functional". But if you care about quality it's going to be just as tough in either case. For one thing, you can get to a pretty good place with compression drivers just by taking Wayne Parham's methodology to heart. Also note that many potential deciBels of padding actually gives you MORE to play with concerning other component selections and topology arrangements.

For the midcones you are also living in an area where you usually have to deal with far worse impedance / reactance issues, difficult loads are a hair breath away due to both woofer and mid driver, and it's in a region where the amplifier driving it "cares" a lot more. And then there are those huge response spikes that make a comp driver on a Constant Directivity device seem very textbook.
 
#29
rpsands said:
I dunno guys.
Click to expand...

Exactly, you don't.

Both are extremely non-trivial to do well and both can be bodged with varying degrees of success. The spare sensitivity with a horn and thus the resonance damping the padding can add actually makes things much easier. All in all, if you want to do a proper job that gets the best out of the design it will take a long time, whichever approach you choose.
 
#31
kringle77 said:
Im having lds build me a cab using a pair of kappalite 3012ho woofers, an eminence psd:2002 driver and a 12x6 horn crossed over at around 1.6khz.

I don't really care for the extended low end of the 3-ways and some sound too smooth in the upper mids so, I think this design could be better for me. Any thoughts a horn lens? Any other thoughts?
Click to expand...

I like the overall approach you're taking, assuming the 3012HOs do what you want in the bass region.

The Pyle PH612 lens is what I use in several home audio cabs and my bass cab, and JBL and Parts Express both offer essentially the same thing. I tried a whole bunch of different horns and this one stood out from the pack in its price ballpark, as far as radiation pattern uniformity goes. In fact, at first I questioned my measurements as they looked too good to be true.

With a rectangular-pattern horn, imho it makes a lot of sense to go with a rectangular-pattern woofer section. In that regard, your format offers improvement over what I'm currently doing.

kringle77 said:
Ralph is definitely doing the x-over.
Click to expand...

Good call. I think you'd have left a great deal of potential on the table if you'd gone with a generic crossover.
 
#32
I actually am very interested in dukes 2x12 cab and could just decide to go with that. If it was still going to have the same midrange character that kjung describes the 1x12 as having, I'd probably just go with that. Again, Im not trying to do a knock off of Dukes design at all. There are some features that Im looking for that he probably won't offer, not that it's a big deal. So Duke, when is the 2x12 coming?:)
 
#33
Alex, I'm impressed with your Super Twelve and curious why more builders haven't used the 3012HO in bass cabs, given the strength of this driver and that there are a number of players who like a bit more mid forward tone. Given the 2.5 kHz peak in the 3012HO response I wondered what a slightly larger enclosure (Vb = 3.85 ft3) with a lower crossed mid horn might sound like?

A biamp solution like the Crown XTi2000 with built in active LR24 filters and DSP would seem sensible given the design difficulty of a passive crossover, but when the Peavey ECS-1800X crossover was brought to my attention in a previous post I wondered if it was a good enough off the shelf solution to get a decent sounding cab with that nice Pyle PH612 lens and Eminence NSD2005 driver? [Invalid or Expired Link Removed]

3012HO_LargeTwin.jpg

(For a dual 3012LF with horn I'd just wait for Duke's new cab.)
 
#34
rpsands said:
I dunno guys. There are a lot more things to correct for in a horn crossover than a woofer to woofer crossover. If you look at the resonant peaks on horns and the way horns change impedance and all that it's a lot more complex to get the info you need to in the first place.

There also tends to be a lot more padding on a horn; many horns are padded back 10db or more in good designs.

Mix those two issues and it's a lot more likely someone will get a midrange crossover functional by just going generic than using a horn and driver. Fewer variables in play and sensitivity matching is far easier too.

Just as an example, say, a 3012LF and an Alpha 6a - you could get a workably decent sounding system just going with a generic eminence 800hz PCB.

Try doing a 3012LF to a horn with the stock 1200hz or 1600hz Eminence Xover and your results will likely be much different. You'll at the very least have to add a serious lpad for any decent horn that goes that low and is in the right size.

I realize that midrange xovers are still complex, but I'm convinced it is a bit more difficult to get it right with the low crossed horn, at least based on what I've seen so far. In parts count at the very least.
Click to expand...

I'm not so sure when it comes to "stock" crossovers. Just using part values based on free air impedance curves and such will get you better even with the changes that happen when you load them in a cab and put power to them. The "in the cab" part is still a bit above my paygrade to say the least and can't honestly give a definate yes or no but my ears tell me it is. It also has a lot to do with the crossover frequency and the impedance curve of the driver used. I don't think it's any coincedence that a few of eminence's 12/6 combinations are an ohm or so away from their curve @800hz and they happen to sell an "8ohm/800hz" 2way crossover, 2nd order LP/3rd order HP but look at what happens to the same (or different) drivers at 500 or 1.6 and it's way off, you'd be much farther ahead making something from scratch.
 
#35
kringle77 said:
I actually am very interested in dukes 2x12 cab and could just decide to go with that.
Click to expand...

I don't think my 212 would be a good choice for you. It would be lower efficiency than you want, and would have more low-end output than you want (both as a consequence of using the 3012LF instead of the 3012HO).

It looks to me like you've done a good job of defining what you're looking for, and also of sketching out a very promising solution.
 
#38
5StringPocket said:
Alex, I'm impressed with your Super Twelve and curious why more builders haven't used the 3012HO in bass cabs, given the strength of this driver and that there are a number of players who like a bit more mid forward tone. Given the 2.5 kHz peak in the 3012HO response I wondered what a slightly larger enclosure (Vb = 3.85 ft3) with a lower crossed mid horn might sound like?
Click to expand...

I did spend some time considering this approach in 2009 but once I'd built, listened to and tested the Super Twelve I felt it didn't make sense, especially as the Big Series cover the ultra accurate approach so well. I'm currently working on a PA cab which uses a big horn tweeter and will be interested to compare the performance of this for bass. I do like cabs to be bombproof and that means handling really LOUD rock gigs even if the bassist wants to lay on a ton of fuzz and noise, and low crossover points and horn tweeters and fuzz can be rather risky. DIY is different because the users tend to be better informed and thus less likely to kill things - plus it's their own problem if they do!

It's all too easy to look at an on-axis measured plot and believe that a break-up peak as in the 3012HO will be really obvious and prevent you getting a smooth clean tone. In reality once you figure in the total power response and thus the tone at the listening position it's pretty insignificant on the gig, and thus a higher crossover point works very well and results in an arguably more versatile cab than one with a large horn, fixed attenuation and a low-pass on the woofers. Look at the on-axis plots for other bass guitar drivers and you'll see much more uneven response around the cone break-up than the 3012HO exhibits, yet these drivers and ones like them are still very popular with bassists that love clean clean tone.

I should also add that the 3012HO works extremely well with 5-string bass, despite what simple T/S modelling might lead you to assume!
 
#39
alexclaber said:
It's all too easy to look at an on-axis measured plot and believe that a break-up peak as in the 3012HO will be really obvious and prevent you getting a smooth clean tone.
Click to expand...
+100. Break-up mode is 100% responsible for the tone love for EVMs. For that matter most of the tonal differences between single driver systems, both bass and guitar, are related to break-up modes. Crossing over below the break-up mode has its benefits from a dispersion standpoint, as break-up typically takes place where the driver is beaming. But tonally there's no reason to fear the break-up mode. Celestion owes its existence to it.
 
#40
Got an LDS 2x12 with the 3012HO's, couldn't afford the Barefaced... someday... But anybody who thinks the 3012HO will be limited tone-wise in its use as a bass guitar driver hasn't spent time with one. I'm quite confident in stating that both James Jamerson and Geddy Lee could get their signature tones out of one. It's up to the player and many other gear factors. I also feel that the vast majority of bassists would be more than happy with the low end you can get out of a 3012HO-stocked cabinet. It's really up to how hard you want to push the speakers and whether you're smart enough to make the correct EQ adjustments.
 

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