Powering LFR's

Posted by: brwsaw

Powering LFR's - 03/20/13 01:46 AM

Can LFR's be powered by a 2 channel ADA1500 and 2 of 4 channels on a ADA1000 without SQ issues at typical party levels?
Posted by: JohnK

Re: Powering LFR's - 03/20/13 02:26 AM

Certainly; they'd be more than sufficient.
Posted by: tomtuttle

Re: Powering LFR's - 03/20/13 08:33 AM

Make sure the gain is the same. I.e. i hink you need 4 identical channels of amplification for the stereo pair. I'd check with Axiom.
Posted by: Ken.C

Re: Powering LFR's - 03/20/13 08:34 AM

I'd check with Axiom before taking advice from anyone on these forums regarding this.
Posted by: dakkon

Re: Powering LFR's - 03/20/13 09:45 PM

I am going to guess that Andrew used the same % gain across all of the new amp series. You "could" use amps of different gains.. The problem with that is that the different speakers would bet getting power increases at differing rates.


I am using 2 different amps, that have different power ratings, but the same gain.
Posted by: JohnK

Re: Powering LFR's - 03/20/13 10:17 PM

Alex, no need to guess; the Axiom amplifiers all have a 29dB gain spec(i.e., the incoming voltage is increased about 28 times). Although if different amplifiers are being used it would be desirable to have them be of the same gain so as to keep the front/back balance of the LFR1100s at the intended level, it would be possible to still achieve that balance with amplifiers of different gains if at least one of them had an independent level control which could be adjusted so as maintain the balance despite the different gains(this is adding a complication, of course).

As to whether the amplifiers have to be of identical maximum power output, the answer is no, as Andrew pointed out here about a year ago.
Posted by: brwsaw

Re: Powering LFR's - 03/20/13 11:52 PM

Thanks for the link.
Posted by: cohesion

Re: Powering LFR's - 03/21/13 07:53 PM

FWIW I am using a 4 channel ADA 1500 with my LFR's and this works very well indeed. I do think this is overkill for the rear channels but on the other hand only 2 channels in an ADA 1500 is overkill in a different way. I once tried to spark some interest in a hybrid solution with mixed channels of 1500 and 1250 but got no interest.
Posted by: brwsaw

Re: Powering LFR's - 03/21/13 10:24 PM

Anyone ever meet the 400 watt limit and measure the db at any given distance?
I don't know that I'll need the extra power in my next room.
Posted by: cohesion

Re: Powering LFR's - 03/22/13 07:47 AM

You mean the recommended max power for the LFR's? That is only a guideline rather than a hard limit. I wouldn't worry!
Posted by: Ken.C

Re: Powering LFR's - 03/22/13 07:51 AM

And, knowing Axiom, an EXTRAORDINARILY conservative guideline.
Posted by: cohesion

Re: Powering LFR's - 03/22/13 07:54 AM

Exactly. In fact it has been said that even the M80's are tested up to 1000 watts/channel.
Posted by: Ken.C

Re: Powering LFR's - 03/22/13 08:10 AM

"Even" Heh.
Posted by: J. B.

Re: Powering LFR's - 03/22/13 08:19 AM

in fact, for the M80's, the article says 700 Watts continuous with peaks of 1100 Watts; for a duration of 100 hours. (of course, no clipping of the amp's output).
Posted by: AdrianD

Re: Powering LFR's - 03/22/13 11:29 PM

As others pointed out, with a high quality music source and clean power you can go way beyond the 400W.
I've never measured the wattage, but went to over 100dB with peaks at ~110dB in a 5000 cubic feet room; then people started to leave as it was too loud. No signs of distortions or any other artifacts. I LOVE my M80s!
All I can tell you (although this doesn't mean much) is that I had my volume at 6/10 on my preamp with monoblocks rated at 350W but with high gain - 32dB.
I would much rather keep an eye on the amp than the speakers.
Posted by: brwsaw

Re: Powering LFR's - 03/23/13 02:39 AM

Is there a device available that will remove artifacts and or control the output volume so all media can be played without worrying about sudden spikes in volume?
Posted by: brwsaw

Re: Powering LFR's - 03/23/13 02:48 AM

I haven't found the limit of my ADA1000 and my M80'yet.
The only distorion I've heard related to the recording.
Posted by: Ken.C

Re: Powering LFR's - 03/23/13 07:53 AM

brwsaw, that function is currently available on Audyssey equipped receivers and is called Dynamic Volume. I've had middling success with it, and mostly use it as a night mode.
Posted by: AdrianD

Re: Powering LFR's - 03/23/13 09:20 AM

Originally Posted By: brwsaw
Is there a device available that will remove artifacts and or control the output volume so all media can be played without worrying about sudden spikes in volume?

Device: a decent pre/pro will have that feature, even without Audyssey.
Software: JRiver.
Posted by: brwsaw

Re: Powering LFR's - 03/23/13 10:29 AM

I really like dynamic range, most movies wouldn't be the same without it.
I'm refering to the difference in volume when songs and or channels are switched.
Would DRC control this as well?
Posted by: J. B.

Re: Powering LFR's - 03/23/13 10:31 AM

this is done with an adjustment in the receiver named Input Level Adjustment or something similar.
Posted by: brwsaw

Re: Powering LFR's - 03/23/13 10:36 AM

Thanks.
I take another look.
Posted by: dakkon

Re: Powering LFR's - 03/24/13 06:44 AM

Originally Posted By: brwsaw
Anyone ever meet the 400 watt limit and measure the db at any given distance?
I don't know that I'll need the extra power in my next room.


The amp i am using for my front drivers is rated for 1200W @ 2ohm, the amp i'm using for my rear drivers is rated for 500W @ 4 ohms.

The front amps is a Krell FBP300cx, the rear amp is a krell KAV 250A. My normal volume is about 90-95db in the room, with peaks well over 100db... My room is a great room that is about 17feetX18feet..


Clean power is the most important thing, Clipping is what does damage to speakers, not power....

With that being said, i will admit, i have way more power than i need... But, i'm ok with that :~)
Posted by: brwsaw

Re: Powering LFR's - 03/24/13 12:42 PM

Would the artifacts added from a scratched cd or bad PVR recording be considered clipping or is there another word for it?
I always worry about the times when the audio signal is interupted for a moment.
Iphones and Ipods connected by wire are the worst.
Posted by: dakkon

Re: Powering LFR's - 03/24/13 02:19 PM

read the below link.


http://en.wikipedia.org/wiki/Clipping_(audio)
Posted by: brwsaw

Re: Powering LFR's - 03/24/13 04:51 PM

Thanks. I've got a handle on clipping because of too little power.
I wonder if the issues mentioned above have the same effect. They can happen at any volume.
Posted by: dakkon

Re: Powering LFR's - 03/24/13 06:28 PM

not if your amp (voltage source) can handel the input signal. The only time you would have a problem is if you are trying to push the amp beyond it's operating parameters.. You mentioned sudden increases in volume, and artifacts within the source. These are just inputs, if you have a substantial enough amp, you're LFR's will play much lounder than you would ever want them to.. I usually listen to my system at 12-15 or so.. Reference level on my processor is 32.. If that gives you a gauge as to how loud it gets... 12-15 will result in about 90ish db within the room... The only way i would measure the DB in the room at reference level would be with hearing protection. At that point, it would just be an exercise to get a number..