Introducing the Sierra-LX!!!

[hometheater]

An amplifier channel under full range load will be under more stress from lower frequencies than anything else. I think this is the motive for your question.

But, if we presume that the power recommendations per distance for a reasonable listening level already presume that the amplifier being used isn't under stress at full range, then the wattage indicated gets all frequencies out the door to the listening distance at the level indicated. Crossing over the speaks higher has the potential to remove stress from an amp, but doesn't make everything in the high pass louder necessarily.

I'm just going by Dave's table for suggested min amp power for various distances. So if I crossed over the LX at 60 hz, how much would the suggested amp change for each distance?

Of course, I'll be using a sub to play the frequencies below the crossover point.

[davef]

I'm just going be Dave's table for suggested min amp power for various distances. So if I crossed over the LX at 60 hz, how much would the suggested amp change for each distance?

Reducing / removing deep bass from an amplifier does not increase its power rating. It can provide additional headroom, but every amplifier is different and this can not be determined without actually testing the amplifier under load.

In simpler terms, you are asking how much more horsepower a car will generate by removing weight from the car.

Hope this makes sense and please feel free to reach out to me directly.

[hometheater]

Reducing / removing deep bass from an amplifier does not increase its power rating. It can provide additional headroom, but every amplifier is different and this can not be determined without actually testing the amplifier under load.

In simpler terms, you are asking how much more horsepower a car will generate by removing weight from the car.

Hope this makes sense and please feel free to reach out to me directly.

I know eliminating deep bass from a signal is not going to increase the power rating from an amplifier. But by doing so, whatever power it has can would be more focusd on the reduced frequency range.

On your table, you suggested 90 watts minimum at a distance of 15 feet. I presume that's for running it full range. If I crossed over at 60 hz, would the suggested power be less than 90 watts? If so, what would be your guess by how much?

[djDANNY]

In simpler terms, you are asking how much more horsepower a car will generate by removing weight from the car.

I think the analogy is more akin to: If a certain car needs 1000hp to hit 250mph and I reduce the weight of the car by 500 lbs, how much hp do I now need to hit 250mph?

So, if a subwoofer will handle frequencies 80hz and below (and is assumed to be able to hit reference levels for those frequencies), how much recommended power is needed for the Sierra LX’s to take care of 80hz and above? What about 60hz and above if the sub is crossed over at 60hz? (Crossovers aren’t brick walls but I think you get the point).

[davef]

I think the analogy is more akin to: If a certain car needs 1000hp to hit 250mph and I reduce the weight of the car by 500 lbs, how much hp do I now need to hit 250mph?

So, if a subwoofer will handle frequencies 80hz and below (and is assumed to be able to hit reference levels for those frequencies), how much recommended power is needed for the Sierra LX’s to take care of 80hz and above? What about 60hz and above if the sub is crossed over at 60hz? (Crossovers aren’t brick walls but I think you get the point).

Interesting analogy but it isn’t correct in this context. You are stating that by removing weight from a car, that car can then reach the same speed with a lower horsepower engine. That is true but weight and speed are directly related to each other. Wattage (power) and frequency bandwidth have no relation to each other, which is why I mentioned two unrelated factors. Horsepower relies on speed (RPM) and force (Torque) to calculate. Wattage relies on knowing any of the 2 following variables to calculate, voltage, current, resistance. Frequency bandwidth is not a factor and is completely unrelated to wattage.

Our amplifier power recommendations (for a pair of speakers) are based on the ability of that amplifier to provide enough wattage to that pair of speakers to reach peaks of 96dB, including typical room gain, at the given distance.

Typical in-room sensitivity of our LX = 87dB which means 2.83 volts into the speaker will produce 87dB SPL measured at 1 meter (or 90dB with a pair of speakers)

Using Ohms Law, 2.83 volts into an 8-ohm load = 1 watt. This is entirely independent of what frequency or frequencies the amplifier is being asked to reproduce.

If we want to hit 107dB at this same distance with one speaker (or 110 with 2 speakers), thus 20dB louder, it will require a 10x voltage gain which = 28.3 volts into the speaker. 28.3 volts into an 8-ohm load = 100 watts.

Wattage = Voltage squared / Resistance. In the context of this discussion, resistance is fixed (speaker impedance) and the voltage gain of an amplifier is also fixed. The only variable is the voltage level being sent to the amplifier (volume level) Frequency bandwidth is not a factor.

Whether we send a single 20Khz signal to the amplifier or a single 60Hz signal, or both at the same time – to reach that 107dB level I mentioned above, will still require 28.3v volts (100 watts.) You can even try this yourself… Use a voltmeter across the positive and negative inputs on the speaker, fix the volume level on the receiver and play some pink or white noise. Record the voltage level. Now do the exact same test but set the speaker to small, thus limiting the bandwidth. Any change in that voltage reading? (hint: no) The reason for that is simple, because that voltage level is determined by the fixed gain of the amp and fixed volume level you set. Wattage is then calculated by using that voltage and the impedance of the speaker (also fixed)

Technically, the spec should be voltage requirements for the speaker, and that would add some clarity, but amplifiers aren’t spec’d this way. It is important to understand that this is voltage requirements for the speaker to reach a specific volume level at a specific distance, converted to wattage. This is different from maximum wattage an amplifier can provide and/or headroom – that is fully up to the amplifier manufacturer as to how they publish specifications, there is no firm standard yet and who knows if they would even be adhered to.

What is really being asked here is that if we recommend a certain amount of power to reach a volume level at a specific distance with our speakers, if someone’s amplifier is rated under that power rating but they then limit the frequency bandwidth – would that amplifier then be able to provide enough power? As I have previously mentioned, I cannot answer that question because there are dozens of factors involved that only the amp designer and maybe the manufacturer would know, and I cannot provide an answer without actual testing of the amp. I am not one to simply throw out arbitrary numbers.

Let's bring the discussion back to the LX... Thanks!

[natetg57]

Let's bring the discussion back to the LX... Thanks!

I just did the LX upgrade on my front three, 2EX. Right away, listening without a sub, I noticed a huge amount of bass. Like many others have noted, much more than you'd expect from a compact bookshelf. Later, when I ran Audyssey, I noticed that I'm getting a huge bump around 50hz in my room. I think I'll need to experiment a bit with placement to try to get a more even response. After using Audyssey to tame the bass peaks and integrating my two L12s, I'm not noticing a huge different in midbass, from the 2EX, but again, I think I need to play around with speaker placement. The biggest improvement for me was with vocals. Male vocals have a fuller, more natural sound, and female voices in particular feel like a real person in the room with me. It's striking and my wife noticed the difference as well. On certain songs, the soundstage is extremely big...both wider and taller than before. And yes, Audioslave sounds much better now. I'm looking forward to trying out some more material and cranking the volume when I have the opportunity. There are a few times when I miss the extra detail from the Raal ribbons (acoustic guitar and violin), but overall, these are the perfect speakers for me, since I listen to 'everything'. Thanks Dave for speakers better than what I ever thought I would be able to afford!

[curtis]

...After using Audyssey to tame the bass peaks and integrating my two L12s, I'm not noticing a huge different in midbass, from the 2EX, but again, I think I need to play around with speaker placement....

Also try different crossover settings to the sub. In my room, changing from 80hz to 60hz made the bass a bit more visceral even with room correction.

[natetg57]

Also try different crossover settings to the sub. In my room, changing from 80hz to 60hz made the bass a bit more visceral even with room correction.

Thanks Curtis. I think 60 is a bit better for me as well. Here's a screenshot of what the MultiEq Audyssey App is picking up. I was thinking about trying to pull the speakers a bit farther away from the wall and see if it smooths the bass out any. IMG_20221106_195643.png

[curtis]

Thanks Curtis. I think 60 is a bit better for me as well. Here's a screenshot of what the MultiEq Audyssey App is picking up. I was thinking about trying to pull the speakers a bit farther away from the wall and see if it smooths the bass out any.

How does it sound with Audessey handling that bump?

How much space do you have behind the speakers? I only have about 16" before a sound panel. I have the Anthem Room correction EQ 400hz and below. My room/positioning has a significant boost in bass at about 60hz and another peak at about 35hz(same issue with the Sierra-2, just more significant with the LX). I am grateful for room correction.

[natetg57]

How does it sound with Audessey handling that bump?

How much space do you have behind the speakers? I only have about 16" before a sound panel. I have the Anthem Room correction EQ 400hz and below. My room/positioning has a significant boost in bass at about 60hz and another peak at about 35hz(same issue with the Sierra-2, just more significant with the LX). I am grateful for room correction.

It sounds good, I probably only have 8" behind mine.