I know the following is the not most scientific way to ask this. I have been trying to estimate how many VA or watts a single driver will take from an amp, and used every imaginable tool out there (short of actual measurement), but because the drivers are prepietary no TS params are to be found.
Can someone give me a ROUPH ESTIMATE of hamy many watts about it will take to drive a 7 inch aluminum cone woofer with a huge magnet structure to about 90 dB at about 40 Hz (its Fs?) in a medium sealed enclosure. If thats too hard, then what about 103 dB at 120 Hz? The driver is 4 Ohm nominal I know that. What can I expect with a 50 W current-limited little chip amp, driving just one driver? Here is a pic:
Can someone give me a ROUPH ESTIMATE of hamy many watts about it will take to drive a 7 inch aluminum cone woofer with a huge magnet structure to about 90 dB at about 40 Hz (its Fs?) in a medium sealed enclosure. If thats too hard, then what about 103 dB at 120 Hz? The driver is 4 Ohm nominal I know that. What can I expect with a 50 W current-limited little chip amp, driving just one driver? Here is a pic:
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What you have here is a severe lack of information. Just looking at the driver is not enough. You need at the very least T/S parameters including the driver sensitivity, then you can model the driver in your intended enclosure with something such as Unibox, and get a rough estimate of how much output you get with how much input at what frequency, how much excursion at what frequency with how much input power, etc.
T/S parameters can be measured, with a tool such as the Dayton WT3 available at Parts Express. I'd say that device is a bit of an investment though if you only intend to measure a single driver with it.
T/S parameters can be measured, with a tool such as the Dayton WT3 available at Parts Express. I'd say that device is a bit of an investment though if you only intend to measure a single driver with it.
I agree! just trying to get a general idea if a singele 3875 is sufficient to drive such a unit.
One detail I left out is that the manufacturer rates the entire tower as 90 dB sensetivity, thats using third order passive xo on the woofers. I suppose its safe to assume at least that much sensetivity using active xo. Does it make sense to say then that only about 20 watts will drive this thing to about 103 dB above FS?
One detail I left out is that the manufacturer rates the entire tower as 90 dB sensetivity, thats using third order passive xo on the woofers. I suppose its safe to assume at least that much sensetivity using active xo. Does it make sense to say then that only about 20 watts will drive this thing to about 103 dB above FS?
I took a closer look at your picture. Looks like you have some excursion available. Adding a Linkwitz Transform with an F3 point at 4 shows about 10 mm of excursion with the AV8. Your driver off course will require more since it is a 7". The bad news is you need 6 dB of gain which means you need 80 watts (20*2*2).
Rodger, thanks so much for your help! I am not trying to push these to their limit for this application. I am infact sealing up the enclosures and addiding dedicated bass up to 40 or 50 HZ to take the pressure of these woofers (2 per tower), since I tend to listen to loud bass.
My main concern is whether the woofers will be able to keep up with the mid and tweeter given all drivers are eating off of identical 3875 amps. It will be far easier to put together 8 identical amps if you know what i mean. And it seems that the 3875 should not clip at higher volumes, even though the woofers are only 4 ohm nominal, as each has its own "engine". I hope my assumptions are all correct here, cuz the trigger is about to be pulled
thank you for your help!
My main concern is whether the woofers will be able to keep up with the mid and tweeter given all drivers are eating off of identical 3875 amps. It will be far easier to put together 8 identical amps if you know what i mean. And it seems that the 3875 should not clip at higher volumes, even though the woofers are only 4 ohm nominal, as each has its own "engine". I hope my assumptions are all correct here, cuz the trigger is about to be pulled
thank you for your help!
An active setup with 8 chipamps sounds like a lot of fun.
If you like how the mid-bass of the 7" sounds, I say use it but maybe loss the eq and rely on your subs for below 80 Hz. Only testing will tell if they can keep up with the rest of your system (SPL specs sometimes aren't exactly "as advertised") but at least you won't have to worry about bottoming out and you won't need the extra power.
If you like how the mid-bass of the 7" sounds, I say use it but maybe loss the eq and rely on your subs for below 80 Hz. Only testing will tell if they can keep up with the rest of your system (SPL specs sometimes aren't exactly "as advertised") but at least you won't have to worry about bottoming out and you won't need the extra power.
By loosing the eq i suppose you mean to rely on the sealed box attenuation of the low end, which you estimate to be at 80Hz, right? I guess thats what I am doing. The midbass on these is great, and will be even better when I finish lining the enclosures with solid oak on the inside and adding studio foam to really make it dead.
This realy is a fun project, and I am taking the easy route, using B&W 803 as a starting point and using chip amps with readily available PCBs, the only hard part will be replacing the passive XOs with actives from Rod Elliot, and that is not so hard after all. This is a large scale "test" and if it sonds good, I will have no choice but go with all DIY high end design, maybe 12 class-A "heaters" driving some enormous TAD subs and bass, with ATC mid thrown in for good measure Picking a tweeter will be fun too. Now THAT will be fun!!!!!!!!!!
One interesting thing I am finding is that first order slopes, as implemented in the 803 passive, require VERY SERIOUS matching of drivers, and often times, 4th order sounds way better, even when the drivers are wide-ranged. That is one thing I am trying to prove with this design as I take it from 1st and 2nd order to 4th.. Using 4th order and wide range, the XO points can be placed at strategic positions to not impact the phase at critical points. I am understanding that majority of drivers are just not beefy enough to overlay one another and still sound transparent.
Is first order XO over-rated
This realy is a fun project, and I am taking the easy route, using B&W 803 as a starting point and using chip amps with readily available PCBs, the only hard part will be replacing the passive XOs with actives from Rod Elliot, and that is not so hard after all. This is a large scale "test" and if it sonds good, I will have no choice but go with all DIY high end design, maybe 12 class-A "heaters" driving some enormous TAD subs and bass, with ATC mid thrown in for good measure
Picking a tweeter will be fun too. Now THAT will be fun!!!!!!!!!!One interesting thing I am finding is that first order slopes, as implemented in the 803 passive, require VERY SERIOUS matching of drivers, and often times, 4th order sounds way better, even when the drivers are wide-ranged. That is one thing I am trying to prove with this design as I take it from 1st and 2nd order to 4th.. Using 4th order and wide range, the XO points can be placed at strategic positions to not impact the phase at critical points. I am understanding that majority of drivers are just not beefy enough to overlay one another and still sound transparent.
Is first order XO over-rated
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