Long ago when I was more concerned with rock and roll volumes, my vision was to build up a P.A. rig that was bi-amped, with a pair of 15" drivers in boxes with mid/top boxes on poles. It sounded OK but I hardly used it and never needed anywhere near that volume even with a 6 piece band. Plus it was a pain in the a$$ to stack!
The boxes (.063m³ or 2.2ft³) had been "disco" speakers with cheap drivers and a piezo horns on top . Inside there was some kind of cross over network. I was obviously not thinking straight so:- I bought 15" 500W Eminence Kappa drivers - 4Ohm (because those extra 2db must count.) and the crazy bit was, I wound a high-pass filter possibly set to 4KHz, which was really dumb since it was driven from an active crossover anyway!
Now that I'm not playing in 6 piece bands I want to revert to single full range boxes, so some de-modding is required. Assuming I keep the boxes; I could bin the crossovers and have a 15in with the piexo in the top. Its nowhere near HiFi but pub audiences don't mind. Piezos can get by with a cap so its all good ....
Except a single piezo can't handle 500W.
I could put in a conventional compression driver but who makes a crossover that handles that kind of power. And anyway, a 8Ω and a 4Ω crossover would need to be custom.
Is this impossible?
The boxes (.063m³ or 2.2ft³) had been "disco" speakers with cheap drivers and a piezo horns on top . Inside there was some kind of cross over network. I was obviously not thinking straight so:- I bought 15" 500W Eminence Kappa drivers - 4Ohm (because those extra 2db must count.) and the crazy bit was, I wound a high-pass filter possibly set to 4KHz, which was really dumb since it was driven from an active crossover anyway!
Now that I'm not playing in 6 piece bands I want to revert to single full range boxes, so some de-modding is required. Assuming I keep the boxes; I could bin the crossovers and have a 15in with the piexo in the top. Its nowhere near HiFi but pub audiences don't mind. Piezos can get by with a cap so its all good ....
Except a single piezo can't handle 500W.
I could put in a conventional compression driver but who makes a crossover that handles that kind of power. And anyway, a 8Ω and a 4Ω crossover would need to be custom.
Is this impossible?
Last edited:
Eminence have stock high pass crossovers for their compression drivers, 400 watt no problem and protection circuit, works well with the PSD2002 and surely fit Kappa 15 if you make a 4 ohm LPF - ditch the piezo. Still 60 liters is a bit short for a 15” but for the pub should be ok.
PXB:1k6 - Crossovers | Eminence Speaker
PSD:2002S-8 - Drivers | Eminence Speaker
H 290S - Horn Flares | Eminence Speaker
If you have active try to cut the Kappa 3 or 4 order at 1000-1500 Hz as it has a nasty peak at 2kHz.
PXB:1k6 - Crossovers | Eminence Speaker
PSD:2002S-8 - Drivers | Eminence Speaker
H 290S - Horn Flares | Eminence Speaker
If you have active try to cut the Kappa 3 or 4 order at 1000-1500 Hz as it has a nasty peak at 2kHz.
Last edited:
I have a pair of Peavey SP2 (2004) rated at 500 W that has a 70 W rated compression driver. The pink noise they rate PA speaker with does not have that much energy in the treble. These crossover @ 2000 hz. A previous model rated @ 300 W with the same drivers, crossed over @ 1200 hx. SP2-XT.
I had a Peavey 1210 with dual 10" woofers & triple Motorola piezos pointed in 3 directions. Sounded pretty good IMHO, if light on 54-100 hz.
You can modify your existing cabinet if you wish. Tweeters are usually protected with 8 to 16 ohms series since they are more sensitive than woofers, usually. The art to two way building is protecting the tweeter from blowing if the singer drops the mike or the 1/4 phone cord from the mixer pulls out making a big high frequency pop. Incandescent bulbs for the series resistor are one common practice. A diac or voltage protection device after the series resistor is also common in models designed to maintain a good reputation for reliability.
You crossover details depend on cabinet venting, if any, and how much of the signal you want to divert to the tweeter. As above, same 2 drivers, different watt rating, different crossover design.
I had a Peavey 1210 with dual 10" woofers & triple Motorola piezos pointed in 3 directions. Sounded pretty good IMHO, if light on 54-100 hz.
You can modify your existing cabinet if you wish. Tweeters are usually protected with 8 to 16 ohms series since they are more sensitive than woofers, usually. The art to two way building is protecting the tweeter from blowing if the singer drops the mike or the 1/4 phone cord from the mixer pulls out making a big high frequency pop. Incandescent bulbs for the series resistor are one common practice. A diac or voltage protection device after the series resistor is also common in models designed to maintain a good reputation for reliability.
You crossover details depend on cabinet venting, if any, and how much of the signal you want to divert to the tweeter. As above, same 2 drivers, different watt rating, different crossover design.
The XOs are on order (to be imported from the USA). I bought one driver to mod one cab at a time. Damn thats heavy! I'm going to have to suport it inside the cab somehow or the first time it gets bumped it'll rip the horn out of the cab! 
The HF is seldom rated for LF power, and is often close to a tenth, especially when it's a compression driver.
A 50-100W driver like PSD2002 would do very well in a 500W PA system, as already mentioned by fabricadetabaco. Other inexpensive drivers include BM-D450 (PAudio), D220Ti (JBL Selenium) etc. The ASD1001 may not be sufficient, though it's probably the cheapest one you could get.
A 50-100W driver like PSD2002 would do very well in a 500W PA system, as already mentioned by fabricadetabaco. Other inexpensive drivers include BM-D450 (PAudio), D220Ti (JBL Selenium) etc. The ASD1001 may not be sufficient, though it's probably the cheapest one you could get.
So you are saying to keep the 4KHz Low pass filter I have and wire in the HPF in parrallel, or wind a new one?
Do crossovers affect each other?
As for pictures, I'm most of the way into the butchery on the first one already but I can take pictures of the second as I do that one.
Last edited:
You bought the 1600hz HpF right? That is for the PSD2002 only. Crossover connects parallel to the speaker terminal. What type of terminal do you have? You could have a dual terminal setup that allows bi-wiring or bi-amp/active crossover.
Looking at the datasheet of the Kappa I would cut lower for LPF. Maybe around 1,2kHz. You want to do this passive or active? With a first order passive you could actually cut as low as 500hz making it acoustically match the PSD as the response of the kappa is increasing towards its breakup at 2kHz. but you would need to attenuate the tweeter level with say -10dB using an Lpad as the sensitivity of the kappa cut at 500hz is maybe 95dB while the PSD will be 105 or maybe even more. Hope it make sense. What you want to avoid is the peaks of the kappa (look at the data sheet and you know what I mean). If you cut at 4,5kHz today I’m sure it’s screaming. Unless you have active crossover with eq that is. We need to know a little more about your total system.
Looking at the datasheet of the Kappa I would cut lower for LPF. Maybe around 1,2kHz. You want to do this passive or active? With a first order passive you could actually cut as low as 500hz making it acoustically match the PSD as the response of the kappa is increasing towards its breakup at 2kHz. but you would need to attenuate the tweeter level with say -10dB using an Lpad as the sensitivity of the kappa cut at 500hz is maybe 95dB while the PSD will be 105 or maybe even more. Hope it make sense. What you want to avoid is the peaks of the kappa (look at the data sheet and you know what I mean). If you cut at 4,5kHz today I’m sure it’s screaming. Unless you have active crossover with eq that is. We need to know a little more about your total system.
Last edited:
Its 2 boxes, each with 2 drivers. A 4 ohm 15inch and now the 8ohm PSD2002. They are driven by a 2 channel amplifier. It a mobile system. It can't afford to be more complicated than that. The problem always has been to make them work together using the components that are available. I don't know if its possible to use a HPF and a LPF in the same system circuit. If not, the project is down again.
Given the power involved I can see myself winding my own coils again. I don't think I will be able to buy them.
Given the power involved I can see myself winding my own coils again. I don't think I will be able to buy them.
Yes HPF and LPF can be parallel connected. That’s how all biwire speakers are set up with the parallel at the terminal. You can try with the coils you have, what values are they? I’d cut them low if you have the chance to get some more parts 4 ohm crossovers are a little less common. Here’s one that I think might fit your setup.
Shopping
Shopping
By the way the 1,6kHz high pass filter includes a light bulb automobile fuse which acts like a peak voltage compressor - saved my day a few times. You should play with it before you assemble everything you will see it start blinking when you play too loud. Gives an indication of system tolerance. It gets hot too so make sure you don’t put in near some wool inside the speaker. If you have a bass reflex perhaps but it on the opposite side of the bass reflex so you can watch the bulb from outside. Great way to keep control over the load. When it blinks it’s time to turn it down a little. Protects the expensive driver and the crossover. If the bulb burns a new one cost 2 dollar. You can also reduce the tolerance with only one bulb. The prefit comes with two I believe.
Thanks for the link but even if it wasn't discontinued it would only be rated at 250W - Half as big as I need. Custom coil time.
The first thing I need to know is the wire thickness which comes from the current. Check my numbers please:
Assuming 500W and 4ohm driver:
P= I²R or I= √P/R = √500/4 = 11.1 ish Amps
V= IR - 11*4 = 44V
Now, I can only guess length of the wire (3M) or the volt drop (4v) but the calculators that I can find point me at 16AWG or 1.3mm². Does that make sense?
The first thing I need to know is the wire thickness which comes from the current. Check my numbers please:
Assuming 500W and 4ohm driver:
P= I²R or I= √P/R = √500/4 = 11.1 ish Amps
V= IR - 11*4 = 44V
Now, I can only guess length of the wire (3M) or the volt drop (4v) but the calculators that I can find point me at 16AWG or 1.3mm². Does that make sense?
Remember that 100 watt is +20dB from 95 = 115dB/1m.
500 watt is another +6 or 7dB while 250 watt is +3 or 4.
How loud do you intend to play? The difference between 250 and 500 is only 3dB and almost not audible.
You’re approaching 120dB here in both cases!
Without a subsonic filter I believe the 15” would break mechanically from over excursion way before from heating. I don’t think a 250watt crossover would be a problem. To be honest it might actually give you the protection you need to protect the more expensive driver. Making a new is fun for sure but I don’t see the point.
It’s up to you. The calculated values is what’s important. I think a crossing at 800 hz would work good. Second order.
500 watt is another +6 or 7dB while 250 watt is +3 or 4.
How loud do you intend to play? The difference between 250 and 500 is only 3dB and almost not audible.
You’re approaching 120dB here in both cases!
Without a subsonic filter I believe the 15” would break mechanically from over excursion way before from heating. I don’t think a 250watt crossover would be a problem. To be honest it might actually give you the protection you need to protect the more expensive driver. Making a new is fun for sure but I don’t see the point.
It’s up to you. The calculated values is what’s important. I think a crossing at 800 hz would work good. Second order.
Ha ha! well, Out doors for instance, sound disilpate quickly. I have a 1000 what amp and the drivers are 450W. Well I certainly wouldn't want to limit to ability to use that by cheaping out on wire size. with a custom wound coil. 1.6mH coil from: Jantzen | HIFICollective
and a cap I can get anywhere, I can build a LPF for under £25. Twice as much as the one that I can't buy and ship from the USA, but at least I can get this.
and a cap I can get anywhere, I can build a LPF for under £25. Twice as much as the one that I can't buy and ship from the USA, but at least I can get this.
1,6mh sounds right yes. You could try without the parallel cap first and just listen if the 2kHz peak is still audible.
Remember to add a LpAd to the HF to attenuate it by -10dB at least or get a variable LPAD rotary like the good old days.