Signal to noise ratio question

[speakerdude123 10+ year member]

How much of a difference does the signal to noise ratio (dB) make on an amplifier. I see some with 70dB and others at like 110dB?

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[gunz4me2 10+ year member]

How are they rated? Some use the old school rating and rate SNR at max power whereas others use the CEA rating and rate it at 1 watt. Generally, SNR is higher at maximum output!

Lastly, if this is on a subwoofer amplifier, it won't make that much of a difference.

 

[speakerdude123 10+ year member]

Yes this would be hooked up to a woofer.

So I shouldn't make a decision based on a higher dB rating?

PS: what makes a good amp? (for a sub that is)

 

[gunz4me2 10+ year member]

Oddly, I go for efficiency these days when looking into subwoofer amplifiers. As long as they do rated power, you'd be hard pressed to tell one amplifier from another in the subwoofer frequency range. After all, the sub bass part of the audible spectrum is the area where the human ear is least sensitive to changes in frequency.

So, what I am saying is don't fall for the marketing hype. You can't hear damping factor and if it is over 50, it won't matter on your subwoofers. Also, as long as the distortion is 1% or less, that isn't all too important either when it comes to a subwoofer.

Signal to Noise ratio can be important because some subwoofers are known to reproduce hiss if the SNR is too low. That only makes a difference if the subwoofer is mounted inches from your head versus a sub in the hatch or trunk area.

 

[speakerdude123 10+ year member]

So then why would anyone buy an amp for $600 when a $100 amp has the same same output? I see amps that produce the same numbers but one will be 2 maybe 3 times as much... Can you explain this? Is the money worth it?

Thanks for the input so far.

 

[ExplsvCookie257 10+ year member]

The more expensive amps sometimes do rated power and then some, also they usually have better build quality more flexibly crossovers, as well as bigger inputs. other then that I really dont know what makes them better. im sure they have better sound quality to some degree if you have a good enough sub to be able to tell the difference with.

 

[gunz4me2 10+ year member]

Customer service, support, build quality, etc. generally come along with the higher price tag, but not always. Then again, I couldn't detect a sound quality difference between a $150 Clarion DPX1851, Soundstream Reference 700s, JL Audio 500/1, Linear Power 5002 (at 8 ohms with the coils in series), the sub channel on a 25 to Life Power 1000, and a few other amplifiers used on my subwoofer. As a result I decided to go with the lower cost amp that gave me the power I needed with the better efficiency. Contrary to the old school belief, great sound does not have to cost big $$, but you really need to know what you are looking for when it comes to the lower cost alternatives!

 

[ExplsvCookie257 10+ year member]

ever thought that if you had the best sq sub not sure of which that is but would you then notice a difference lol.

 

[gunz4me2 10+ year member]

ever thought that if you had the best sq sub not sure of which that is but would you then notice a difference lol.

IDK, the 13w6v2 loaded JL Audio Stealthbox in my Mustang has a pretty flat transfer rate in that particular vehicle. There are very few after market options that came anywhere near flat.

This is my RTA response with my sub cranked all the way up.:

I normally run it between 0 and 10 on my Alpine 9887, depending on what material I am listening to and how much bass it has in it.

 

[helotaxi 5,000+ posts]

IIRC the old school companies that actually made good amps rated s/n referenced to 1W. Its only be more recently that noise to rated output has been used to inflate the numbers.

As previously mentioned though, s/n isn't a spec I'd give much weight to for a sub amp unless it was just insanely low compared to 1w.

 

[gunz4me2 10+ year member]

IIRC the old school companies that actually made good amps rated s/n referenced to 1W. Its only be more recently that noise to rated output has been used to inflate the numbers.
As previously mentioned though, s/n isn't a spec I'd give much weight to for a sub amp unless it was just insanely low compared to 1w.

That was the major PROBLEM with old school measurements because companies didn't disclose how their rated specs were measured. Orion, for example, was guilty of rating their damping factor at the circuit board versus the molex plug and those were significantly different numbers! //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif Also, I just picked Orion as an example BUT they are not the only old school company guilty of doing this back in the day!

 

[helotaxi 5,000+ posts]

Well with damping factor simply listing output impedance would be much more informative.

The one thing that I found amusing was that the current magazines test amp s/n against rated power. What a worthless test! The old CSR tests gave numbers always agains 1W and IIRC with the gain control at min and max. That is actually a telling test. I seem to recall the original Soundstream REF300 being the quietest amp they ever tested at around 98dB to 1W.

There are some reasons to go with a more expensive amp but whether it's worth it or not is up to the person. I don't buy into the whole mystique surrounding high dollar SQ amps. Where I can justify spending more money for the same power is in the tolerances in the components, the quality of the spec'd components and the overall QC from the company. A warranty is all well and good but I would much rather buy a solid design made with good parts and not have to use the warranty.

With a quality amp built with quality parts from a quality design, the variance between s/n, THD, power output and efficiency between a randomly selected sample of amps will be very small. The same can't be said about budget amps. One sample might destroy its ratings while the next barely make spec or not make spec at all. One might be really noisy and another amazing. It all comes down to luck of the draw and I'll pay a bit more to stack the deck in my favor on that one.