Frequency response on amps?

[jay21112]

Do amps really have frequency responses?

I bought a Crown XLS2500 to power a sub, but I just noticed that the published frequency response is: "at 1 watt, 20 Hz - 20 kHz +0 DB, -1 DB."

Direct link: XLS Drivecore™ Series

Does this mean that the amp won't pass frequencies under 20Hz to the sub?

If so, it's not really of use for me for a subwoofer and I need to send it back.

 

[markw]

Do amps really have frequency responses?

I bought a Crown XLS2500 to power a sub, but I just noticed that the published frequency response is: "at 1 watt, 20 Hz - 20 kHz +0 DB, -1 DB."

Direct link: XLS Drivecore™ Series

Does this mean that the amp won't pass frequencies under 20Hz to the sub?

If so, it's not really of use for me for a subwoofer and I need to send it back.

It'll pass frequencies above and below that frequency range but they may not be within that specified 1 decibel variation. They may be a decibel (or more) higher or lower.

Now, I'd be more concerned about at what it says at higher power levels. I doubt any sub will be happy with just one watt.

 

[TLS Guy]

Do amps really have frequency responses?

I bought a Crown XLS2500 to power a sub, but I just noticed that the published frequency response is: "at 1 watt, 20 Hz - 20 kHz +0 DB, -1 DB."

Direct link: XLS Drivecore™ Series

Does this mean that the amp won't pass frequencies under 20Hz to the sub?

If so, it's not really of use for me for a subwoofer and I need to send it back.

That is a really good performance. To be within 1 db to 20 Hz is excellent.

It probably rolls of some below 20 Hz and pretty much all amps do. But I bet it is not more than 3 db down at 15 Hz.

You don't really need performance below 20 Hz any way and you can make very good arguments for placing a filter to roll off frequencies below 20 Hz.

 

[jay21112]

That is a really good performance. To be within 1 db to 20 Hz is excellent.

It probably rolls of some below 20 Hz and pretty much all amps do. But I bet it is not more than 3 db down at 15 Hz.

You don't really need performance below 20 Hz any way and you can make very good arguments for placing a filter to roll off frequencies below 20 Hz.

Well, I told a half truth: it wasn't exactly a subwoofer I bought it for. I bought a pair of Buttkickers and bought the amp to power it. And the claim to fame for a Buttkicker is the ability to feel the sound down to 5 hz. So, while I may not be able to hear 5 hz, the Buttkicker should make me feel it.

Therefore I was really looking for an amp that allowed a clean signal down to 5 hz. The Crown Amp had everything I was looking for - tons of power into 4 ohms, 2 channels, and low pass filters.....but then when I looked through the book I saw the 20 hz - 20 k hz deal and now I realize that it's probably not the best match for my application after all.

So since you say the amp is good, maybe I'll keep it and bi-amp my front L+R to give them a little more power and take some stress off the receiver.

But to power the Buttkickers I think I'll going to have to just buy the buttkicker amp....

 

[TLS Guy]

Well, I told a half truth: it wasn't exactly a subwoofer I bought it for. I bought a pair of Buttkickers and bought the amp to power it. And the claim to fame for a Buttkicker is the ability to feel the sound down to 5 hz. So, while I may not be able to hear 5 hz, the Buttkicker should make me feel it.

Therefore I was really looking for an amp that allowed a clean signal down to 5 hz. The Crown Amp had everything I was looking for - tons of power into 4 ohms, 2 channels, and low pass filters.....but then when I looked through the book I saw the 20 hz - 20 k hz deal and now I realize that it's probably not the best match for my application after all.

So since you say the amp is good, maybe I'll keep it and bi-amp my front L+R to give them a little more power and take some stress off the receiver.

But to power the Buttkickers I think I'll going to have to just buy the buttkicker amp....

You don't need a Crown Dive Core amp to drive dumb buttkickers! You just need a very crud amp for those. Those horrid things would likely destroy the Crown amp anyway.

Grow a pair, and build a sub that does not need buttkickers. Send back the buttkickers.

 

[jay21112]

You don't need a Crown Dive Core amp to drive dumb buttkickers! You just need a very crud amp for those. Those horrid things would likely destroy the Crown amp anyway.

Grow a pair, and build a sub that does not need buttkickers. Send back the buttkickers.

Haha, that's why I didn't mention the Buttkickers in my first post. I was afraid I wouldn't get any response.

No worries, I'm slowly building towards an 11.4.4 setup. It's not super high end, but for my salary it's high end. I'm running Polk LSI all around in an Onkyo 7.2 setup right now, and need to purchase the Yamaha A-3000 receiver to plug in my other 4 height speakers that are just collecting dust right now.

I have two subs in the front and I'd like to even out the room with 2 more in the rear, except I'm running Polk Audio MicroPro 4000's which have been discountinued and I'm not sure what to get to match them, so I'm sitting on that for a bit.

And as for the final .4, I'm in the process of buying new seating and hooking up 2 buttkickers to the LFE and 2 Clark Synthesis Platinum Transucers to the L +R Channels.

So, I feel like I'm heading in the right direction, it's just that I'm really discovering as I go....

 

[dwh]

Therefore I was really looking for an amp that allowed a clean signal down to 5 hz.

What source material do you have that goes down to 5hz? Or are you going to sit in your chair with the buttkickers and play a 5hz test tone?

 

[mtrycrafts]

.... I doubt any sub will be happy with just one watt.

Oh, the sub will be very happy but the listener will not be.

 

[mtrycrafts]

...

Therefore I was really looking for an amp that allowed a clean signal down to 5 hz.....

You really don't need such an amp just one that you can feel. I doubt your butt will know if the amp is distorting at 1% or 100% or 200% for that matter at 5 Hz.

 

[jay21112]

You really don't need such an amp just one that you can feel. I doubt your butt will know if the amp is distorting at 1% or 100% or 200% for that matter at 5 Hz.

I don't know enough about amps, transducers, and frequency response...but if the Crown amp rolls off at 20 hz (that was the terminology Crown used), then what kind of signal is left down to 5 hz? Wouldn't that mean that a 5 hz signal would barely be passed compared to the 20 hz signal?

Since the transducers produce motion and not noise, to me that sounds like to calibrate the tranducer to produce (and not overproduce) a vibration at 20 hz, it would barely produce anything at 5 hz. However, if I calibrated the transucer to accurately produce a vibration at 5 hz, it would greatly overproduce vibration at 20 hz. Don't I need an amp that will pass a consistent signal from 5 hz to like 80 hz (the crossover point for the LFE)?

Again, I have no idea what I'm talking about, but this is what I'm piecing together.

 

[Grador]

I don't know enough about amps, transducers, and frequency response...but if the Crown amp rolls off at 20 hz (that was the terminology Crown used), then what kind of signal is left down to 5 hz? Wouldn't that mean that a 5 hz signal would barely be passed compared to the 20 hz signal?

Rolloff doesn't mean response falls off a cliff, just that it'll start dropping off at some rate. Even if it did fall off a bit, we're still talking bout your butt here, I kinda doubt that it's that great at determining power level differences. Furthermore as stated at some point above me in this thread, there isn't really going to be much in the way of source material that actually goes down to 5 hz.

 

[mtrycrafts]

... Furthermore as stated at some point above me in this thread, there isn't really going to be much in the way of source material that actually goes down to 5 hz.

And at sufficient level to matter much.

 

[GranteedEV]

if the Crown amp rolls off at 20 hz (that was the terminology Crown used)

The exact terminology suggests the crown does not roll off until below 20hz. 20hz is just a de facto standard for bass depth.

then what kind of signal is left down to 5 hz? Wouldn't that mean that a 5 hz signal would barely be passed compared to the 20 hz signal?

Most amps will be around ~3db down by 8hz or so, and roll off 6db/octave somewhere below 10hz. The exact measurements must be measured.

Since the transducers produce motion and not noise, to me that sounds like to calibrate the tranducer to produce (and not overproduce) a vibration at 20 hz, it would barely produce anything at 5 hz. However, if I calibrated the transucer to accurately produce a vibration at 5 hz, it would greatly overproduce vibration at 20 hz. Don't I need an amp that will pass a consistent signal from 5 hz to like 80 hz (the crossover point for the LFE)?

It seems to me you're making this way more convoluted than necessary and confusing yourself. In essense - no. Whether a system is flat to 5hz or down 30db at 5hz, does not appreciably affect performance at 20hz beyond acoustic phase, if 20hz is at the same SPL. The acoustic phase really should not be audible at 20hz, given that... 20hz is not really audible unless accompanied by it distortion harmonics 40hz and 60hz.

Now being able to reproduce infrasonics is a difficult task.

Since most systems are unable to reproduce even 20hz cleanly, and most amps tend to even be flat to below 10hz, most systems are best suited to implementing low cut filters. Often there is an electrical rolloff before the amp stage, which is put in place to protect the driver from receiving information below a given frequency.

All in all, amps can go really deep by themselves.

However your entire analog signal chain does not necessarily go to 5hz all that easily. Let's say you've got a CD player, a preamp, and an amp. Each of these is likely to roll off 6db/oct around 10hz. So your system as a whole is probably 15-20db down by 5hz.

 

[jay21112]

However your entire analog signal chain does not necessarily go to 5hz all that easily. Let's say you've got a CD player, a preamp, and an amp. Each of these is likely to roll off 6db/oct around 10hz. So your system as a whole is probably 15-20db down by 5hz.

I didn't even think to look at what the frequency ranges for everything else were....
This is getting more and more complicated.

 

[GranteedEV]

This is getting more and more complicated.

Well, just stop concerning yourself with 5hz. The content ain't there, and even if were, it can only realistically be reproduced by eight LMS-5400s + thousands of watts each, or a Thigpen Rotary.

I agree with whomever said to take these buttkickers out of your system and focus on improving the system as a whole... "get your priorities straight!"

 

[jay21112]

Well, just stop concerning yourself with 5hz. The content ain't there, and even if were, it can only realistically be reproduced by eight LMS-5400s + thousands of watts each, or a Thigpen Rotary.

I agree with whomever said to take these buttkickers out of your system and focus on improving the system as a whole... "get your priorities straight!"

Haha, I always seem to be both the person that makes things harder than they should be, and the person going against the grain all the time. But, I've had dreams of my butt shaking to movies for years, so my priorities are as straight as they can be.

Again, I may not have anything able to audibly reproduce 5 hz, but tactile reproduction is another story (no?). I admit not a whole lot of movies probably have anything down to 5 hz, but I'm sure I have a few in my library that do, and to me, it's worth it for those.

I've decided to just buy the buttkicker LFE kits. They are the same price as buying the buttkicker amps by themselves, so it's like getting the buttkickers for free. And the amps advertise a frequency response to 5 hz.

Then I'm going to use the (2) 2-channel crown amps to power the clark synthesis transducers which I'll have hooked up to the rest of the system. I have my mains crossover over at 40hz (they each have powered subwoofers attached to them) and everything else crossed over at 80 hz. So that's perfect specs for the crown amps.

And then I'll have 2 amp channels left over, which I'll use for the height channels to convert 9.2 to 11.2 with the Yamaha receiver.

So, it might not be everyone else's preferred solution, but I think I have a solution that fits my needs now.

...I think.

 

[GranteedEV]

5hz is not audible. You have to consider what 15, 10, 5hz feel like.

...like a gust of wind going over your entire body. It's not "rumble". "rumble" is closer to 30hz - 50hz.

So, no, you won't "feel" it correctly. In fact with those devices, it'll be the same as 50hz. Just your *** being vibrated. I ain't into that sorta thing.

 

[mtrycrafts]

Haha, I always seem to be both the person that makes things harder than they should be, and the person going against the grain all the time. But, I've had dreams of my butt shaking to movies for years, so my priorities are as straight as they can be.
...I think.

If you really want that shaker, just install it, hook it to an amp and don't worry about frequency response, especially being clean.

 

[mtrycrafts]

...

All in all, amps can go really deep by themselves.

....

I bet one could follow James Cameron's sub all the way to the bottom of the trench.

 

[markw]

So, no, you won't "feel" it correctly. In fact with those devices, it'll be the same as 50hz. Just your *** being vibrated. I ain't into that sorta thing.

Betcha his lady friends get a "kick" out of his system, though.