Amplifier Noise Floor

[RTally]

The hissing is white noise of course all amplifiers make it to some extent but the Crowns have more than I wanted it's only threw the tweeters on any set of speakers. The one amp is connected directly into the wall socket and the other is connected in a different room on a power strip but no matter where they are plugged in with or without an audio source they do it I just think they are designed this way. The gain has been all the way down and makes no difference it's not defective since I have been using one amp for over a year and the other for 6 months or so. And they are pro audio amplifiers people call them budget amplifiers which i would agree with but as far as I know they do their rated RMS power. I think someone should dyno the Crown XLi series I really want to know if Crown is true about it.

If that is the case, then you need to get some good amps. Or at least get amps suited for your near field listening pleasure.

It seems like you are using pro amps in an application that they were never intended to be used. They may be great for public performances, but it sounds like they suck for home use where sound quality rules. Their noise floor is too high for quiet environments like a home. I am sure that they are fine for use in public spaces where the background noise is high.

 

[audiotemp]

I use two pairs so that's 4 speakers

Try connecting your speakers in series instead of in parallel. This may (?) reduce the noise floor by 6 dB.

 

[Audiofreak71]

It's strange I've never really paid attention to white noise from my amps except when the volume is pretty high with nothing playing, however my current amp has zero noise at any volume with my ears directly to the speaker, absolutely nothing even at full tilt, so I guess some amps don't have noise.

Audiofreak71

 

[whoaru99]

If that is the case, then you need to get some good amps. Or at least get amps suited for your near field listening pleasure.

It seems like you are using pro amps in an application that they were never intended to be used. They may be great for public performances, but it sounds like they suck for home use where sound quality rules. Their noise floor is too high for quiet environments like a home. I am sure that they are fine for use in public spaces where the background noise is high.

FWIW, I use a number of pro amps for home audio, with no noise concerns. A couple differences though; they have better s/n ratio and I'm more like 10-12 ft from the speakers.

 

[Billy Dio]

Since you seem to be using a bi-amp set up, you could always try and get a smaller amp with excellent SNR, and let it power the mids/highs separately. A 35-50wpc amp can push 90 SPL (like 105-108 db) loud enough to be heard over whatever else the bigger amp might be doing on the other speakers i.e. a pair of 15's, 12's, 10's etc.

FWIW, I have a 9620b which was made by AB, and marketed as a "Pro Series" (825wpc @ 8ohm). I had repairs done by the new owners after getting it, and the guy stated "they have a high noise floor" while referring to the "Pro Series" line. This particular amp was designed to play loud venues, etc., and not marketed as a home amp per say. With that said, it's really quiet so unsure what reference he might have been comparing to.

For your gear, it might be inherent to the "Pro" line.

 

[Northwinds]

It's strange I've never really paid attention to white noise from my amps except when the volume is pretty high with nothing playing, however my current amp has zero noise at any volume with my ears directly to the speaker, absolutely nothing even at full tilt, so I guess some amps don't have noise.

Audiofreak71

Same thing with the WOPL's, absolute black hole which is why preamp selection is so important when using a high quality amplifier(s). I have found a lot of amp's noise floor can be cleaned up by looking at the wiring inside and moving it away from noise sources (if possible). Shielding around a transformer is another good thing

 

[RTally]

It's strange I've never really paid attention to white noise from my amps except when the volume is pretty high with nothing playing, however my current amp has zero noise at any volume with my ears directly to the speaker, absolutely nothing even at full tilt, so I guess some amps don't have noise.

Audiofreak71

Same thing with the WOPL's, absolute black hole which is why preamp selection is so important when using a high quality amplifier(s). I have found a lot of amp's noise floor can be cleaned up by looking at the wiring inside and moving it away from noise sources (if possible). Shielding around a transformer is another good thing

A properly designed and constructed amp should have ZERO audible noise with no input. Eliminate all external sources of noise. If an amp still has noise, it needs to be repaired or replaced with a more suitable amp.

 

[VYNULADIKT]

Same thing with the WOPL's, absolute black hole which is why preamp selection is so important when using a high quality amplifier(s). I have found a lot of amp's noise floor can be cleaned up by looking at the wiring inside and moving it away from noise sources (if possible). Shielding around a transformer is another good thing

Second that! My WOPL is dead silent. Can only tell its on because of the lights, until you throw a signal to it, then you really know.

 

[whoaru99]

A properly designed and constructed amp should have ZERO audible noise with no input. Eliminate all external sources of noise. If an amp still has noise, it needs to be repaired or replaced with a more suitable amp.

There are many "properly designed" amps that exhibit some noise through the speaker.

That said, I have no disagreement with the recommendation of a more suitable amp if one is going to listen at 2 ft from the speakers in a low noise environment.

 

[whoaru99]

An interesting little experiment since I happen to have a Crown XLS 1000 that has even a slightly worse SNR rating at >97dB (vs. from memory 100 and 103 for the OPs amps).

Using the ultra-sophisticated Iphone SE and SPLnFFT measuring app , the ambient noise in my basement "test" was 27.2dB. The noise floor increased to 30dB @ 2ft with the amp switched on (connected through ADS L420 speakers).

Could I hear the hiss? Yup, even at a bit farther than 2ft. But that is in a very, very quiet room.

If I did the test upstairs where the ambient level is about 32dB (between increases from passing cars and gusts of wind), would I even hear the hiss at that same distance? (no, I'm not lugging the stuff upstairs to try it)

 

[Powertech]

These Crown amps are P.A. units, not hifi amps. I'm not saying that they cannot reproduce sound well. If you had them running at anywhere near their design output would you hear any hiss? At those levels in a P.A. environment, which would also probably have lots of background noise from crowds of people, could you even get close enough to the speakers on stage to hear the hiss? A hifi on the other hand is designed to be used at low domestic levels, in a quiet environment, and as such needs to have a very low inherent noise levels.

 

[Cody AOC]

These Crown amps are P.A. units, not hifi amps. I'm not saying that they cannot reproduce sound well. If you had them running at anywhere near their design output would you hear any hiss? At those levels in a P.A. environment, which would also probably have lots of background noise from crowds of people, could you even get close enough to the speakers on stage to hear the hiss? A hifi on the other hand is designed to be used at low domestic levels, in a quiet environment, and as such needs to have a very low inherent noise levels.

A hifi amplifier well also depends on how much money you might spend on one my dad has a Yamaha preamp [CX-A5100] and a yamaha amplifier [MX-A5000] one of the newest ones that they currently make and it has some white noise and it's home audio hifi since it's designed for home theater use. He paid almost $6k for it not including the speakers or wiring or $500 in XLR cables but white noise is still there but are we 2 ft away from them NO.
Those yamaha's sound really good but the higher you turn it up the white noise does get much more present. If you need or want proof of pictures on the Yamaha's i'll include them both. Now the Crowns i'm changing them in what job they are going to be doing the Crown XLi 2500 will be powering a 15" subwoofer it's rated 1000 watts RMS. I've already put it to the test and it will push the subwoofer WAY more than enough I got 500 watts RMS to spare from the amplifier. Then I'll throw my other Crown XLi 800 for the front desk speakers might be a little downgrade from the 2500 but sounds the same just with less power. It might a a little while but i'm making this system the best thing I can afford to do i'm not rich that's why I own what I do I never liked class D amplifiers and Class ab is what i've always used they will last longer and I can repair them at home if I needed to. The class D amplifiers NOT CAR AMPS but pro audio ones will never last s long as class ab how do i know i've owned my fair share over the years class D amplifiers are made to throw away when they get a problem because of how small the compounds are. I've owned 2 different class D amplifiers in the last 4 years. i'll name them off in order, crown xls 2500 this one was my first one I really liked it sounded great and all no problems until 2 and a half years later the thing started to get a weird buzz sound when you turned it on after it was warm you know you it was running for a few hours and then I shut off to go leave and come back and hour later then it would buzz at me it never did have the fault lights never came on but very shortly after that it kinda just gave up seemed not right. I sold it to someone who knew how to fix it I had it looked at by 2 different repair shops and they wanted $250 just for the repair I decided ad just by a different amp I went with a Behringer iNUKE NU6000 it was and still is priced well $350 can't beat that but just last year the output transistors went out they blew up I always ran it clean no clipping at almost full power and it killed my two 15's I had in my room I had to get recones for them. I must either have bad luck with class D amps or they are made poorly. Your probably thinking this guy is full of sh*t i'm not full of it I do buy everything new.

 

[whoaru99]

We never know quite how individual situations compare to the big picture, but pretty much all top line pro amps are switching amps these days. Crown, QSC, Lab.gruppen, Powersoft and other big names stake their reputation on reliability of switching amps.

Personally, in addition to the relatively new XLS 1000, I have three Crown CE4000 amps that are also switchers. They're roughly 16 years old, no problems at all.

 

[Nixxuz]

These Crown amps are P.A. units, not hifi amps. I'm not saying that they cannot reproduce sound well. If you had them running at anywhere near their design output would you hear any hiss? At those levels in a P.A. environment, which would also probably have lots of background noise from crowds of people, could you even get close enough to the speakers on stage to hear the hiss? A hifi on the other hand is designed to be used at low domestic levels, in a quiet environment, and as such needs to have a very low inherent noise levels.

It's generally not the noise floor from the amp itself, so much as the active cooling fans that most Pro amps have. That can be mitigated with aftermarket fan mods or a fan controller, although there are a few "crossover" pro/consumer amps that have what's pretty much just a giant heatsink instead of fans nowadays.

 

[tarior]

Try not to be too disappointed to find that when you buy inexpensive, outsourced PA amps that they have an audible noise floor at two feet away from the speakers.
They were not made with nearfield listening in mind.

 

[Nixxuz]

Try not to be too disappointed to find that when you buy inexpensive, outsourced PA amps that they have an audible noise floor at two feet away from the speakers.
They were not made with nearfield listening in mind.

Well, I wouldn't think so either, seeing as they are in no way intended for nearfield. The thing that weirds me out is this; supposedly, class D amps in general are accused of having a "hiss". This subject has been brought up a lot since a certain review out there gave the JBL LSR305 studio monitors glowing praise for being THE one stop buy for budget audiophiles just starting out. Complemented over and over because of their flatness and accuracy.

But they hiss. Apparently not ALL of them, but enough that it's been commented on quite a bit. The popular opinion floated around a bunch of theories from noise floor of the integrated D amps, to ground loops, to interference from other components. Eventually it just was thrown out as a given that class D amps just hiss. That it's part of the way they are built.

This doesn't sit right with me. I've heard many a crappy HTiB and PC speaker setup that NEVER hissed, and they are all using class D. And PC speakers are almost universally nearfield.

Maybe I'm just missing something? I don't have the right setup to test anything now as all my amps are A/B. Is it really a thing?

 

[tarior]

I don't the the O/P's amps are class D. Looking at the pic he provided with the top off, it looks like a class AB amp with a linear power supply. Should be reliable enough and sound good. Just not quiet.

 

[Nixxuz]

I don't the the O/P's amps are class D. Looking at the pic he provided with the top off, it looks like a class AB amp with a linear power supply. Should be reliable enough and sound good. Just not quiet.

Oh I understand that. I'm running a QSC ISA280 right now myself for a power amp to my sub. But because I am insane and can't leave well enough alone I'm getting a D class to roughly triple the wattage. I'll have to see how the D sounds with my towers at some point though.

Edit: after checking the Crown specs they pretty much have to be A/B as they weigh in the neighborhood of 30+lbs. Most of the D class pro amps come in under 10.

 

[tarior]

Class D amps are great for subwoofer duty.

 

[Nixxuz]

Class D amps are great for subwoofer duty.

I am excited. Should be pushing in excess of 2K to my 18". I've still got a bunch of crap to do to the box, but I just can't seem to stop listening long enough to get down to business.