[poorimpulsectrl]

and I'm not talking about the various threads pertaining to Fixup

How relevant is signal to noise ratio?

I mean I often see hardware manufacturers touting SNR over 90 as being evidence of pristine sound, but I just checked my Creek OBH-11 amp and it's SNR is 60 or 65. While the Creek isn't an Orpheus amp there are still many people who find it fine. So I'm wondering if SNR is an all or nothing measure of sound quality, or if it needs to be considered in conjunction with other measures.

Incidentally, what's the SNR of the Meta42 amps?

 

[ServinginEcuador]

To give a little electronics background on the subject, we must first understand about decibels. A decibel is a unit of measurement that is logarithmic in nature. Each unit of 3db represent a doubling of something, and a -3db cuts it in half. Every 10db represents a factor of 10x the reference/original. So, here's an idea of how quickly that can affect things:

0db= 1
1db= 1.3
2db= 1.6
3db= 2
4db= 2.6
5db=3.2
6db= 4
7db= 5.2
8db= 6.4
9db= 8
10db=10
11db= 12.8
12db= 16
13db= 20
14db= 25.6
15db= 32

These values are approximate as it's been a while since I last had to create this chart. Now, when someon says that a signal to noise ratio of something is 65db, what they are saying is that the level of the noise, when compared to the signal, is some odd 3200000 times lower in volume than the signal passing thru the circuit with it!!! The number gets MUCH larger when you go to 90+db, but you get the idea. If anyone claims they can hear a signal that is 3200000 times less in size than another, they would be rich beyond their wildest imaginations as they could detect sounds imperceptible to anyone else in the world. That is not to say that this noise isn't hearable when there is no signal and you turn the volume up a bit, but when there is music coming thru with it, not a chance!!

 

[poorimpulsectrl]

Hey, thank joo fo' splaining (said in ricky ricardo voice). So why is signal to noise ratio even stated if it seems so apparently irrelevant in most cases?

 

[ServinginEcuador]

Quote:

Originally posted by poorimpulsectrl Hey, thank joo fo' splaining (said in ricky ricardo voice). So why is signal to noise ratio even stated if it seems so apparently irrelevant in most cases?

I think it has more to do with the fact that you can hear it when the music is quiet or not playing. I don't know the exact cut-off to where a S/N ratio becomes completely irrelevant, but somewhere around 80-90db and above is basically so small it's considered a moot point. Even at 60db it is very difficult to detect.

For example, take you Creek and disconnect the inputs. Then put on your headphones and crank the volume all the way up. Do you hear anything like noise?? If not I guess you can say that the rated S/N ratio of your unit is mot?? Eh!!

 

[PinkFloyd]

In a nutshell Signal-to-noise ratio Describes the difference between the level of the audio signal and the level of unwanted noise. The larger the figure, measured in dB, the lower the noise will be.

Theoretically, the OBH-11 isn't classed as Hi-Fidelity as it's SNR figures fall below what is generally classed as "Hi-Fi" specs.

65db-70db SNR is pretty poor these days as is the fact Creek don't quote a frequency range for the OBH-11.. maybe they havent got round to measuring it yet, who knows

I have just sent my Creek OBH-11 back as I was absolutely underwhelmed with it and rate it as one of the poorest designs I have ever seen.. having said that, everyones ears percieve music differently so if it sounds good then sod the specifications.. plug your cans in and enjoy the sound.

Talking of SNR, the X-Can V2 quotes 108db "A" weighted and 96db unweighted and if you have got the chance to try the x-can V2 try it fast before you end up with buyers remorse with the Creek!!

Pinkie

 

[ServinginEcuador]

Just thought of something else. When you are trying to add volume to speakers, headphones, or anything else for that matter, to get more sound out of it, you also have to double the power supplied to get that volume change. Most people don't know this and think if they buy a more powerful amp it will be louder. That's not always the case. Let's say you own an amp that puts out 150 w/channel and you want your speakers to go louder. In order to do that you would actually need to buy an amp that can push at least 260 watts of power to get any appreciable increase in sound out of his speakers. At 22db you are pushing 128 watts of power, so a doubling of power is needed to make a noticable change in volume, so you have to shoot for 25db of gain, making the power needed 256 watts.
A 1db change, or 166 watts, is too small to detect, 2db, or 205 watts not enought, but can be done, but 3db, or 256 watts is easily noticed and should do the trick!

My brother ran into a similar problem when he wanted to run his 35wpc stereo into a set of Bose Am-5's. These have a sensitivity of only like 86db with one watt, so his amp would only drive these things to about 101db, at that would be straining and possibly damaging to the speakers since it's at max output he could clip the amp or overdrive it. I talked him into a pair of Infinity speakers with a whopping 95db sensitivity. That same amp was then capable of rocking the house with a whopping 110db of sound!! So sometimes it is cheaper and better to go with a more efficient set of speakers vice buying a more powerful amp. This at least gives you options as to which component to replace when wanted.


Sorry for rambling, but I thought you might like to know!!

 

[PinkFloyd]

Well said! sensitivity is far more important than wattage when it comes to speakers.

Not a lot of people know that.

Pinkie

 

[ServinginEcuador]

Quote:

Originally posted by PinkFloyd Well said! sensitivity is far more important than wattage when it comes to speakers. Not a lot of people know that. Pinkie

Pinkie,

Thay will if they frequent this site!! Wattage can be just as important, BUT you run into problems with power handling of the speakers. They can be fried if you try to run too much into it!!

OBTW, do you have a really smart friend bent on taking over the world.

 

[PinkFloyd]

Quote:

Originally posted by ServinginEcuador OBTW, do you have a really smart friend bent on taking over the world.

Fraid not mate but I can point you in the direction of a great water garden lighting firm that punts out cheap 12Vac / 50VA transformers

 

[ServinginEcuador]

Quote:

Originally posted by PinkFloyd Fraid not mate but I can point you in the direction of a great water garden lighting firm that punts out cheap 12Vac / 50VA transformers

Make sure to start a new thread under the tweaks section and put the info, pricing, and seb site to these as I'msure there are lots of X-Cans users who would love to get their hands on some upgraded PSU device!! Thanks for doing the research on this!!

 

[Orpheus]

serving,

"If anyone claims they can hear a signal that is 3200000 times less in size than another, they would be rich beyond their wildest imaginations"-- that's not exactly true. your ears can hear that difference... that is because your ears do not interpret sound linearly. your ears judge volume logarithmically, exactly like the dB scale. so, a 65dB s/n ratio is pretty much a 65/1 ratio the way you hear it. don't believe me?--play something at 50dB... raise the volume to 70dB... is it 100x louder? nope.... it's not. it's just louder by a mild amount. mathematically you are correct... but that's not how your ears/brain works.

poor,

equipment with higher s/n ratios have more self-noise. turn down your preamp all the way. now, listening to your headphones, you'll hear some hiss.... that's the result of your bad s/n ratio on the creek. listen to a unit with a higher ratio, and it'll have less hiss. now, at higher listening volumes, this isn't a problem... but when you have quiet passages, or you listen to music softly... welp, it's very distracting in those situations.

 

[ServinginEcuador]

Orpheus,

I agree and stated this in my second post here, but thanks for helping make the point to Poorimpulsectrl about self-noise and being able to hear it under certain circumstances. I think it is good to hear things from multiple sources to reinforce what is said as fact, not opinion.

But, you're wrong about the difference between 70db of sound not being 100x louder than something at 50db. It is not only 100x louder, it is 100 times more difficult to produce than the same sound coming from the same source at 50db. Sound works exactly the same as anything else that used db's to express it. 20db of sound is 100x the amount of volume!! Period. Every 3db is a doubling of gain in an amp, sound out of a speaker, power going into the speaker, and sound heard with the human ear! The difference from 50db to 80db is 1000x the volume, whether you think it defies logic or not is irrelevant. It is a stated fact of physics. The sound pressure, which is how we read sound hitting our ears, is 100x greater at 70db than at 50db. It's just a matter of being so small at 50db, like a whisper, that when it is multiplied by 100 it is still pretty insignificant. 100 times .00001 is still a small number, but it is still 100x the original factor.

I don't want to pick a fight or nit pick this to death, but I want to amke the point that this is correct.

 

[Orpheus]

yes serving, the sound pressure IS many times "louder" hitting our ears when comparing say a 50db signal to 70db. but THAT IS NOT HOW YOUR EARS JUDGE VOLUME. ...my near field monitors have a special amp with a db SPL readout.... if you want, and i know you live near by, you can come over and i will prove it to you. i will play for you something at 50db. and something at say 90db. that is a difference of 10000* in sound pressure. true. but to your mind, it is only about 2x-5x (kinda hard to interpret as a number... but definately no one would say is anywhere near 10,000* louder) as loud. that is because you hear logarthimically. i could also play for you something at 87db and 90db. the sound pressure is about 2x as loud right? but i truly doubt you can even hear a difference in volume AT ALL. need proof?--then i shall prove it to you.

you are confusing two measurements: sound pressure level, and the perceived volume in your head. they are not the same.

 

[ServinginEcuador]

Orpheus,

Gotcha!! I was talking about actual calculations and you were referring to perceived loudness changes!!! Thanks for clarifying that for me as I was confused. Far too often here these minor disagreements end up in name calling, cutting each other down, etc, but I am glad that we could communicate these things clearly in the public forum so that all who read this will be helped also!!!

I agree that your brain will only think it is a small amount louder than before and not 10000 times louder!!! It is, as you stated, that much louder, but your brain can't tell that exact amount.

Good talking with ya!!

And if you wanted to hear the Sonic Adventure Reality headphone amp, or whatever cables I have, just PM me and we'll set-up a time to let you hear it with whatever music you wnat to bring!! Or if you want to have me bring some cables to meet and have you try them out, that would also work out also!!

 

[Orpheus]

don't worry man. i have never started calling anyone names on a discussion forum before. just wanted to clarify to Poor that though you are correct in what you said about physics, it isn't necessarily what we hear.

...but anyway...

later.