HAPPY NEW YEAR!!!
I could use some advice please...
I have a pair of radian 475 PB-8 compression drivers in Altec 511B ( I think ) or 811B horns, atop a JBL AL6115. Not sure if this is a great match....
Radian says the lowest recommended x-over freq is 1.2 K, but fails to mention the slope.
Since this is for home use, so it will likely only ever see 1 watt or less of power... maybe 2 if I'm nuts.
Would the Radian 324/1594 be a decent crossover to use in this installation? ( 1.25KHz crossover frequency ).It is 12 db per octave.
Radian says: NEW 2-Way 1.25kHz Crossover
Phase, Frequency, Time Delay & Volume Compensation
For Use w/ A 8 Ohm High Frequency Driver & 8 Ohm Woofer
Time Aligned For Use w/ A 90°x 40° Horn <- this looks ok
Any help here would be most appreciated!
I could use some advice please...
I have a pair of radian 475 PB-8 compression drivers in Altec 511B ( I think ) or 811B horns, atop a JBL AL6115. Not sure if this is a great match....
Radian says the lowest recommended x-over freq is 1.2 K, but fails to mention the slope.
Since this is for home use, so it will likely only ever see 1 watt or less of power... maybe 2 if I'm nuts.
Would the Radian 324/1594 be a decent crossover to use in this installation? ( 1.25KHz crossover frequency ).It is 12 db per octave.
Radian says: NEW 2-Way 1.25kHz Crossover
Phase, Frequency, Time Delay & Volume Compensation
For Use w/ A 8 Ohm High Frequency Driver & 8 Ohm Woofer
Time Aligned For Use w/ A 90°x 40° Horn <- this looks ok
Any help here would be most appreciated!
The crossover frequency and slope for a compression driver is somewhat open, depending on the use. As you say it's for home use and you'll get away with a lot in that regard.
What will be more important for choosing this is the behaviour of the horn, the breakup of the woofer, and the physical separation.
What will be more important for choosing this is the behaviour of the horn, the breakup of the woofer, and the physical separation.
ALTEC LANSING 811B HF HORN MANUAL Pdf Download | ManualsLib
https://cdn.shopify.com/s/files/1/0111/0324/0254/files/475PB-data_sheet_051317.pdf?771
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A distortion sweep at 1W from 500Hz on up will tell you lots about the drivers behavior at the low frequency end. I would also do a polar plot of your horn and bass driver. With this data you should be able to make a sensible decision about your crossover frequency. Don't use a pre canned Radian Crossover. It will not work with your horn or be optimal in a domestic environment.
In the old days standard here would be 12dB/oct, 18dB/Oct would certainly be safer, 6dB/Oct would be dangerous, definitely insufficient.
IF horn and driver "can" reach 1200Hz, out of safety or caution I woud use about 50% higher, say 1800Hz or so.
On the PE website, there is a mention of the power rating being at 1khz with a 24db slope. I'd say this would be a safe start.
Seeing a quick chart showed it dropping off at 800hz or so. Crossing at say 1000hz, a steep drop at 800hz may be audible with too shallow a crossover slope. As previous mention suggested I've seen people give a 50% safety margin as well.
Fortunately home use usually gets you a little more flexibility if not reproducing crazy SPLs and the driver has the steam to do what you need.
Seeing a quick chart showed it dropping off at 800hz or so. Crossing at say 1000hz, a steep drop at 800hz may be audible with too shallow a crossover slope. As previous mention suggested I've seen people give a 50% safety margin as well.
Fortunately home use usually gets you a little more flexibility if not reproducing crazy SPLs and the driver has the steam to do what you need.
As JMFahey suggests compression driver vendors are pretty optimistic in their low frequency cut off suggestions. A driver rated to work to 1k2 is likely going to sound pretty harsh if used below 1k6 in my experience. Likewise the high end of a 2226 is realistically much lower than the rated 2k. I'd suggest turning your system into a three way with a 10" or 12" as a mid driver in a sealed box and cross out of the 2226 at 300-500 and into the Radian driver at more like 1k6. Probably have to build custom crossovers to accomplish this it you want to stay passive.
BigE,
The actual acoustic crossover frequency is determined by the impedance curve of the woofer and the driver/horn combination and the passive components used. The JBL 2226 in the AL6115 impedance rises from around 8 ohms at 200 Hz to 20 ohms at 1600 Hz.
The Radian 324/1594 was designed for their 2" coaxial, it might "work", but probably won't result in very good response with your driver/horn combination.
The recommended minimum 1200 Hz crossover frequency rating for the 475 PB-8 driver comes with the expectation that most users will use small horns with a Fc far higher than the horn you have, they measure on a 90x40 horn only 8” wide, 7” high, 8” deep.
For low level home use the polymer surround 475 PB-8 would certainly be OK with a proper 12dB crossover as low as 500Hz with the 511B, or 800 Hz for the 811B- measure the horn size to see what you have.
The response of the JBL 2226 is pretty ragged above 900 Hz, been so long since I've heard 511 or 811 horns, can't say whether I'd prefer them or the JBL 2226 in the 500-1kHz range.
Anyway, check out this sticky:
Introduction to designing crossovers without measurement
Cheers,
Art
The horn is a 511b.
At this point, I am guessing I should get the 808b compression drivers fixed? A was hoping for a full range two way, but it seems the radian does not go low enough. And a 15" will start beaming just north of 900 Hz.
At this point, I am guessing I should get the 808b compression drivers fixed? A was hoping for a full range two way, but it seems the radian does not go low enough. And a 15" will start beaming just north of 900 Hz.
You might want to look see if Radian makes diaphragms for the 808s. They do make nice sounding stuff but not every item meets every requirement. You may need to tweak the crossovers if you go that route. If you wind up having the buy Chinese knock off diaphragms be prepared to go thru four or five before you find a matched pair - if you do.
I don't like the sound of any metal diaphragm compression driver below 1k hz but clearly lots do.
I don't like the sound of any metal diaphragm compression driver below 1k hz but clearly lots do.
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Old Alnico drivers can be a crap-shoot as far as magnetic strength, and good diaphragms are expensive.
Have you tested the 475PB on your 511b?
On the little horn Radian uses for testing, it is only -3dB around 800 Hz- output in that range should be quite a bit more with your 500 Hz horn.
Riley, the 475PB uses a Mylar surround, it's not "all metal".
It also has more extended HF response than the Altec 808b.
Art
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If going that route, I could use the jan didden modded Behringer dcx2496, to test slopes at least. Old Yamaha p2200 down low and f5turbo on top.
But isn't 800 too low for the 475pb?
I also have a buttcheek JBL. Gonna dig it out and look at the model.
New year's is on us though. So i will resume with trials tomorrow at earliest.
Thanks and HAPPY NEW YEAR TO ALL
But isn't 800 too low for the 475pb?
I also have a buttcheek JBL. Gonna dig it out and look at the model.
New year's is on us though. So i will resume with trials tomorrow at earliest.
Thanks and HAPPY NEW YEAR TO ALL
Experimenting with a digital crossover is my preferred way of learning what crossover characteristics are best for any speaker combination regardless of the final crossover plans. The full size JBL 2344 butt check horn will load a driver down to 1 kHz while the smaller 2342 is only good to around 1K2. The 2344 is a great sounding horn for home stereo use, thats what I listen to in my living room crossed over at 1100 in 2206s with 24db per octave slopes.
Big E,
Any HF driver will have two limiting factors- excursion and power.
Excursion on any HF driver is limited to a bit under 1mm before the diaphragm contacts the phase plug, which sounds horrible, and will crack aluminum diaphragms after a fairly short period.
800Hz could be "too low" on a horn that does not provide loading below 800Hz, but just fine on a horn like the 511B that does.
In the "olden days" of horns that provided loading down to 500Hz, drivers would often have two power ratings, lower power at a lower frequency, double that at a higher frequency. Those ratings have mostly been eliminated, since they are horn dependent- the driver might be able to take 25 watts at 500 Hz before the diaphragm hammers the phase plug on the 511B, but only several watts on the JBL 2342.
Art