Time Alignment

[alskinner]

I know this subject has been covered in other threads, but I found this interesting. I recently aquired a pair of 2360H horns with 2445J drivers. My thoughts were to start another project using my Altec A7 bottoms with the 2360 setup. Anyway, just to test the 2360s out I hooked them up in place of the 2397/2441 combo on my hybrid 4345s. The sound was amazing, the speakers dissapeared and the whole room seemed to become the speaker with sound coming in 3D. Of course it is somewhat impractical to have a horn the size of the 2360H mounted 30" in front of the rest of the drivers but it is a great sound. I am going to experiment with these a few days or until my wife gives me the "evil eye" to move them. I guess one of my questions is is there an analog way of time alignment and if so is there any links on how to accomplish this?
Thanks for any help

AL

[RacerXtreme]

Did you just win those on EBAY? How would you describe their sound as compared to the 2441's ? I'm leaning towards buying the exact same setup to run on top of eight JBL 2225's in 4 Altec 210 VOTT cabinets. They do eat up a lot of room don't they..... I know some people feel the 24 db slope in my Rane AC23 electronic x-over makes the sound seem "squashed" (is that the right word???) but the time alignment feature is really helpfull. Are you familiar with Rane gear?

Nice horns. Let me know if you're wife ever convinces you to sell them. I've been watching Ebay and there has been a few sets of them up there lately. Some guy in Florida has a bunch of them.

c-ya

Guy

[alskinner]

Thanks for the reply,

I did win these on e-bay from ABrown in Pensacola, Florida. Fortunately he lives about 100 miles from me or I don't know if I would of bought them. They looked a little dingy but when I go them home and cleaned them up they looked great. The drivers were also in great shape. He has 2 pairs up for auction right now. I don't know what the shipping would run due to their size.

As far as the sound against the 2397/2441. They are two completely different sounds. 2441 has a smooth sound but is rather pinpointed far as listening posistion. If you move from a seated position to a standing position you can tell a difference in the sound because of the horizontal dispersion.

On the other hand the 2360H/2445 the sound is also very smooth. I was at first concerned with the sound of titanium diaphrams due to the expression by some of their harshness. On the 2360H they are extremely smooth and because of their dispersion characteristics will fill the room without a paticular sweet spot in the mid-range. When I close my eyes I cannot tell where the speaker is as it appears to be coming from everywhere, yet it is still coherent with the instuments and vocals seeming to come from different places.

Of course these are first impressions and I have them very crudely set up at the moment, but if I had the real estate to put these horns in I would certainly give them strong consideration. One thing I have pondered is hanging them from the ceiling in order to get the physical placement right without taking up a lot of floor space.

As for Rane, I am familiar with their products and personally don't care for the sound. I know their are a lot of people that do and I respect that. I use an Ashly 4001 4 way crossover and absolutely love it. That's why I am trying to see if there is an analog time-delay that will work for the midrange only.

[Earl K]

Al

Re; Time Alignment

Just use a physical alignment topology, ( ie start by aligning the voice coils of the horn driver with the woofer below it ).

Horns like this are not going to get "flush-mounted" into a box ( to look nice & vacilitate portability in the SR business ) . Since they exist "outside of the box" you have the flexibility of shifting it around in depth until you obtain the best "summing" at the crossover point .

A simple tone generator ( sine wave ) & Radio Shack SPL meter are all that is needed to accomplish this alignment task .

I think that there's a paper on the procedure , over at Todd Whites' Unofficial Altec site - buried somewhere in the archives.

[alskinner]

I am about to come to the same conclusion. Physically aligning the drivers until the SPL is the same is a good basic approach and I know that will work. I am working on getting an RTA, O'scope and SPL meter as far as signal generator I have one based on software that has worked well for me aligning Compression driver diaphrams. Since aestetics are not as much an issue with me than the sound I want, I don't mind putting the horns any where they need to be. I do have the driver on the Horn almost lined up with the bass driver on my 4345 Hybrids but as I said it is going to stick out anywhere from 26 to 30 inches from the rest of the drivers, this will probably not be as much an issue with the A7 cabs as the driver magnet on the 416 woofer is already about 27" back from the mouth of the bass horn opening. Again thanks for the input. I still have a lot of homework to do before I can draw some final conclusions and I do need the equipment where I can somewhat validate what my ears are telling me.

Regards
AL

[Mr. Widget]

I am working on getting an RTA, O'scope and SPL meter as far as signal generator I have one based on software that has worked well for me aligning Compression driver diaphrams.

I don't know what you were planning of paying for all of that, but the Clio Lite version will do everything you need and more and is $700. This includes a calibrated mic... not just a test mic that is sorta calibrated like the Behringer, Rane etc. but a mic that has calibration data files for it.

I really haven't scoured the internet, but it is possible that Soundeasy or one of the many other even lower cost options might do what you need. For time alignment using Clio you can shoot an impulse response of each driver and then physically move them or digitally move them until they are all at the same position in time. Here we see that this driver is 3.6 milliseconds from the mic.

Widget

[Earl K]

Al

- I'd recommend you buy an old Behringer CX 2300 crossover . Pay as little on eBay as possible.

- Just use the LF output on it to drive the woofers. This is a "tunable" crossover.

- The analog delay section on the woofer section allows you to electronically shift the woofers back approx. 23 in. So, that's your maximum allowed physical horizontal spread between the voice coils. Also, make sure the Horn Driver is behind the woofer for this woofer delay to work.

- Drive your horn amp with something else that is more transparent sonically.

- I use a Passive Line Level HiPass ( 2 caps per balanced XLR input on an amp ). This gives a 6 db slope.

- Get more slope ( say 6 or 12 db more ) by using some passive parts after the amp - before the horn driver.

- Since you really want to protect any compression driver from DC ( offsets from the amp ) - this caps' inclusion represents a 6 db "opportunity" for a crossover. Pick a value that is actually working as part of the crossover. Choose a value that is small enough so its' Fc point that is dead-on to your desired crossover area.

- Follow this DC blocking cap/ crossover by creating an ad hoc High Frequency Lift section/CD Horn EQ that really just consists of an 8 ohm resistor ( in series to a 8 ohm JBL driver ). A cap ( paralleled to that resistor ) allows High Frequencies to "bipass" the resistor . At high frequencies ,this caps uf value is "in series with the previous cap" so you need to adjust its size ( upwards ) to account for this fact.

- Follow this "EQ" setup with an approprite sized coil and you've got a CD compensated 3 pole crossover ( that is as "transparent sounding as your amp is ). Keep the coil "after" the EQ section . Coil size in this position is minimized by it's proximity to the low impedance of the driver ( or being situated after the impedance of the resistor ). The coil is quite effectively isolated from the DC blocking cap by the resistor - allowing greater freedom of choice in value selection ). Translation ; coil size that is based on a low impedance is smaller than a coil working into a higher impedance ( for the same crossover frequency ) The smaller coil size saves money .

- With all the electrical "spreads" occuring between the 3 poles of this sort of crossover topology - you're now essentially listening to a 3 pole Bessel arrangement. The maintenance of the Bessels' superior transient response is worth the (minimal) effort of deviating from a more classical arrangement.

- Do all this and I think you'll soon forget the inclusion of that lowly "Behringer" part into your system .

Oh , buy the older CX 2300, not the 2310 or 3400. The newer Behringer stuff is "Surface Mount, Wave Soldered" stuff that is all quite goofy on the inside and virtually impossible to fix since SMD stuff is ,"just so teeny-tiny" .


( a few thoughts )