Axiom Home Page Forums General Discussion Stereo Triggered pulled - Active LFR-1100's are on order!

Steve, according to Craig, we won't need centers when we all upgrade to active LFRs. Just sayin'...

Understood, Craig. Thanks.

They will be my last. I expect them to be less of a speaker and more of an audio platform. I look forward to driver upgrades, amp upgrades and DSP upgrades.

Hi Rich,

The insane amp stack (2 x ADA1500-1 and 4 x ADA1500-2) is really for one application, the dance party. There just seems to be no end to everyone wanting to progressively keep turning the system up in direct relationship to the bar getting drained. But this application aside, something like a combination of an ADA1500-2 for the LF sections and an ADA1250-8 for the rest sounds like a smart combination. It saves money compared to two ADA1500-5s and you can still run balanced everywhere if you want. As to how much power is needed for the mids and tweeters compared to the bass it is tough to nail down an exact number as the content plays a big role. But we do know that you want to avoid any clipping at all cost as just a minor amount taints the performance.

Ian,
I think it might be easier to consider what max voltage is needed at each speaker section rather than power..

There are two parts to consider: the driver section needs (voltage/SPL/freq) and the max content peak voltage over frequency relative to a reference (say 1kHz). The driver part you have and I’ll bet that the content part has to be known if you don’t know it already ... ( if not, it would not be a hard reasearch project given all the online content. Know of any a grad students who might need a topic?)

Armed with this info we can talk about relative amp clipping and power.

It's pretty simple in my mind. We already know the woofer array can take in excess of 4500 peak Watts. We know this because Axiom is selling systems with a 1500-1 for each woofer array. So if the woofer array is sized for 4500W, what should the mid and tweeter arrays be sized for? Well, if we make the reasonable assumption that 60% of the musical power is bass (that's 4500W), 34% is mids and 6% is highs, that brings us to 0.36*4500=1530W peak required for mids and 0.06*4500=270W peak required for highs. So as a maximum system size, you'd need:

- 4500W peak for bass
- 1530W peak for front mids
- 1530W peak for rear mids
- 270W peak for front highs
- 270W for rear highs

I've made the assumption that front and back are fed the same amount of power. This may or may not be the case depending on the design of the filters and how the BGC switch is set.

If we go with what I have above, then each active LFR needs:

- ADA 1500-1 for bass array
- ADA 1000-2 (one for the front mids and one for the back)
- ADA 1000-2 (one for the front highs and one for the back)

But how do you optimize the power delivery for a system of two? You'd do the following:

- Two 1500-1 for the woofer array per LFR
- Two 1000-3 for the front mid and the two tweeter arrays per LFR
- One 1000-2 for the rear mids per LFR.

One last thought. The above is maximum system sizing for absolute max SPL that these things can deliver. Keep in mind that I can blow my brains out with an ADA-1000-2 and M100v4 in my 4,200 cu. ft. room sitting 12 feet away.

I'm starting off with a 1500-3 and a 1000-8. All Watts in the following discussion are peak Watts.

The 1500-3 will give me 4500W to share between the LFR and 160v2. The 1000-8 will give me 3000W to share with the remaining LFR channels. I also plan to test a 1000-3 in place of the 1500-3.

I think all this will be over-kill; even with the 1000 in place of the 1500. Here's why:

- 0 dB on my Onk is really LOUD in my room through my M100v4 and (any) ADA.
- if I play a 60Hz tone, 0dB on my Onk is 441W across the woofer array. I know this because that triple woofer array is 4 Ohms and 0dB on my Onk is 42V out of an ADA. 42 squared divided by 4 is 441W.
- let's assume the bass signal in my music is really 441W. That makes the mid 36% of that or 159W and the highs 6% of the lows or about 26W.
- for stereo listening, with the 1500 for the lows, I have over 2000W of head-room per channel. Even with an ADA-1000-2, I'd have over 1000W of headroom per channel.
- with the 1000-8, I have over 150W of headroom per channel for mids and 350W per channel for highs...LOL!

So I think for those who are just sitting on the sidelines and aren't sure about what to get for amplification, go with a 1000-2 for the lows and a 1000-8 for everything else.

Keep in mind you'll likely be running an active LFR system with a sub. So that's load that's lifted from the amps.

I still like how clean 2.0 sounds.

I'll try it for sure.

I just want to add another thing about the amps with active LFRs. I really like the clipping protection circuit in the ADAs. Without being overly-offensive, the channel shuts down. I like this much better than a compression circuit because it lets me know if I need more amp power.

So far, I've never had a need for more than a 1500 for any of the Axioms. The only time I've been able to activate the 1500 clipping circuit is when I had two stacked M5s (a 2.5 Ohm load) and also an M5 stacked on the M100 (again a heavy load). I was still able to pull 112 dBC peaks on the stacked M5 and 109dBC peaks on the stacked M5/M100 at 12 feet away before shut-down.