For my new 12" coaxial tops, I'm considering NOT using a passive crossover.
I'll need a third, low power stereo amp, for the HF.
I've never done this before, but I assume that an amp could be designed specifically for use above 1 KHz, so as to get excellent performance at a reasonable price point. I would assume class D can be avoided, since HF doesn't pull a lot of amps. (Do any low-powered class A live amps exist?)
I will probably be using a DriveRack Venu360, so I don't need any onboard DSP.
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Can anyone recommend a particular unit or brand?
It would have to be rackable, of course, 2U maximum, very light, and I guess around 200-300 watts per side @ 8 ohms.
I'm only interested in "very good" to excellent quality. (My other amps are Lab Gruppens)
I'll need a third, low power stereo amp, for the HF.
I've never done this before, but I assume that an amp could be designed specifically for use above 1 KHz, so as to get excellent performance at a reasonable price point. I would assume class D can be avoided, since HF doesn't pull a lot of amps. (Do any low-powered class A live amps exist?)
I will probably be using a DriveRack Venu360, so I don't need any onboard DSP.
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Can anyone recommend a particular unit or brand?
It would have to be rackable, of course, 2U maximum, very light, and I guess around 200-300 watts per side @ 8 ohms.
I'm only interested in "very good" to excellent quality. (My other amps are Lab Gruppens)
What do you consider "low power"? I have a Yamaha P3500s powering comps in my big rig.. but those are 2" exit drivers, the smaller P2500s would do fine for 1" comps. These are excellent sounding amps IMO, they have even found some acceptance in home theater circles due to that sound quality and for being silent operating.
Thanks. I've read good things about the P3500S with HF drivers on another forum as well.
However, 33 lbs is getting up there!
One amp that looks promising is the QSC PLX1802. Still A/B, very low distortion, and only 13 lbs. $900, but what can you do?
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As for how much power -
Radian doesn't yet spec the HF driver separately, It's a brand new coax, but I know it's a 2" throat / 3" coil, so it has to be their 760NEOPB / 760NEOBePB driver.
They spec the 16 ohm version at 105w from 500 Hz up, so the 8 ohm, at the 900 -1200Hz point I'll be crossing, must be at least 125w.
113dB sensitivity.
Of course, I'll likely never get close to maxing them, since the 8 ohm 12" maxes out at about 131 dB continuous. (They spec the 16 ohm only, and at 128dB continuous)
However, 33 lbs is getting up there!
One amp that looks promising is the QSC PLX1802. Still A/B, very low distortion, and only 13 lbs. $900, but what can you do?
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As for how much power -
Radian doesn't yet spec the HF driver separately, It's a brand new coax, but I know it's a 2" throat / 3" coil, so it has to be their 760NEOPB / 760NEOBePB driver.
They spec the 16 ohm version at 105w from 500 Hz up, so the 8 ohm, at the 900 -1200Hz point I'll be crossing, must be at least 125w.
113dB sensitivity.
Of course, I'll likely never get close to maxing them, since the 8 ohm 12" maxes out at about 131 dB continuous. (They spec the 16 ohm only, and at 128dB continuous)
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Another good choice.
Yes, I have my amp limited at 6dB below full output and I'm not sure I have never seen it activate, if it did it would only be a momentary flicker. Any amp this size is overkill for a compression driver but I have sometimes found it advantageous to split the amp racks and place one behind each speaker stack. In that case I use this amplifier for mids and highs and here it is a little undersized for the mids so a smaller amp wouldn't be sufficient at all.
For what it's worth, when I really opened it up, I found I could hit the limiters on 300w/ch into the 18Sound ND1460 drivers I used in my PA system.
That was also hitting the limiters on a pair of Faital Pro 10FH520 midbass units, which were getting about a kilowatt each.
Crossover was LR4 at 1.1kHz. Usually I run it at 750Hz but that would've been rather abusive.
Everything sounded fine, though - a testament to the drivers, I think.
YouTube
That was 85dB C-slow at the camera position, with peaks around 18dB higher.
The PLX amp mentioned further up would do a fine job, I expect.
Chris
That was also hitting the limiters on a pair of Faital Pro 10FH520 midbass units, which were getting about a kilowatt each.
Crossover was LR4 at 1.1kHz. Usually I run it at 750Hz but that would've been rather abusive.
Everything sounded fine, though - a testament to the drivers, I think.
YouTube
That was 85dB C-slow at the camera position, with peaks around 18dB higher.
The PLX amp mentioned further up would do a fine job, I expect.
Chris
The 18Sound ND1460 drivers I use are decent 3" diaphragm units, which are rated for 100W AES above 1.2kHz.
I don't think they're exceptional, either.
I have some 1" exit drivers with 1.75" diaphragms that are rated for 35W.
The BMS coaxials can take even more IIRC.
Chris
I can't feed digitally, unfortunately. My live rig entails combining three stereo sources into a tiny submixer, and that feeds the front end.
You've given me an interesting idea for the future, though, since the DriveRack I may purchase has digital in & out. That would be downstream of the submixer, so there you go.
Of course, right now I have no planes to use plate amps.
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Thanks for the tip on the PLD. - But why is that your preference? I don't need / want that onboard DSP, if I'll already have a DriverRack. - Or do I? - And the PLD is class D. Maybe technology is improving, but I have yet to head a class D amp that sounds as "right" in the HF as even a mid-level A/B amp. (Including my $4300 Lab Gruppens)
Hence this thread.
So... if you can elaborate on your choice, I'd really appreciate it.
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Maybe class D has improved, I dunno. Or maybe I should spend more time listening to the plx/pl3 vs the PLD. .... because i've always shared your opinion re class D.
But the ice amp run digitally is the only time I think I hear better HF (within the amps under discussion).
And I think the PLD's channel combining flexibility, DSP, and USB control/monitoring make them a much better value than the plx/pl3.
For PA, I also like the RMS and peak voltage limiting in the amp itself.
(I don't use the PLD's DSP for anything else, not that it's bad, it's just very limited to my processing setup.)
If the PLD's had AES input I would really love them !
But the ice amp run digitally is the only time I think I hear better HF (within the amps under discussion).
And I think the PLD's channel combining flexibility, DSP, and USB control/monitoring make them a much better value than the plx/pl3.
For PA, I also like the RMS and peak voltage limiting in the amp itself.
(I don't use the PLD's DSP for anything else, not that it's bad, it's just very limited to my processing setup.)
If the PLD's had AES input I would really love them !
Class D can sound very nice if you're not trying to get a gazillion watts out of it. Switching losses in class D go up like crazy when you up the voltage and current (power) , and you either have to build them less reliable or have high distortion - or both. But at only 200 watts a class D can be built to be reliable, relatively inexpensive, and have low distortion. There is no technical reason why it can't be done. You do have to spend more on it than an iNuke, but certainly not $4300 - to get 200 clean watts to drive tweeters. There are good reasons why you can't get .00x% THD20k at 5kW in class D regardless of price, and why a $350 3kW sounds poor and goes kabang after the warranty runs out. But neither applies for the application.
^ Didn't know that. Thanks.
I have a spare Fp6400. It's "only" 21 lbs.
It's a crazy amount of power for HF
, but maybe I can use that, dialed way down.
It would sure be nice to have a spare amp on stage that could handle the subs, if needed. I guess I could put a passive xover in for the HF for such emergencies, with a bypass switch. (As suggested earlier.)
Like I wrote, it doesn't sound as good as my old Crest, to my ears, driving a 2-way cab with passive crossover, but it's not far off. Maybe I was listening with false preconceptions & didn't make a fair judgement.
I have a spare Fp6400. It's "only" 21 lbs.
It's a crazy amount of power for HF
, but maybe I can use that, dialed way down.It would sure be nice to have a spare amp on stage that could handle the subs, if needed. I guess I could put a passive xover in for the HF for such emergencies, with a bypass switch. (As suggested earlier.)
Like I wrote, it doesn't sound as good as my old Crest, to my ears, driving a 2-way cab with passive crossover, but it's not far off. Maybe I was listening with false preconceptions & didn't make a fair judgement.
IIRC, the Labgruppen amps are not true class D. They are a quality class AB with a tracking downconverter like the Yamaha EEEngine. It's in between class H and class D for efficiency, and does not inherently suffer from the typical hockey-stick switching loss increase as you approach full power (which thermally stresses lower priced amps). Conduction losses dominate, and it is heat sinked accordingly.
The magic of the FP series amps (and most of the cost) is in their power supplies. Resonant mode, fully regulated, power factor corrected, and capable of supplying the amp's current demand at full sine wave output (the AC mains is not but the supply itself is). And "you get what you pay for" works both ways - they aren't cheap.
The magic of the FP series amps (and most of the cost) is in their power supplies. Resonant mode, fully regulated, power factor corrected, and capable of supplying the amp's current demand at full sine wave output (the AC mains is not but the supply itself is). And "you get what you pay for" works both ways - they aren't cheap.
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