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Mike Anderson
2006-03-10, 22:48
Some claim that if you don't play the SB at full volume (40), you're losing sound quality. I'd like to know if that's true, because when I run my SB2 at full volume it is too hot for the device receiving the signal (Behringer DEQ2496), and I seem to get clipping, at least as displayed on the Behringer meter (it goes into the red).

Thus I have to turn the SB volume down to 35-37 to avoid clipping. Is it true that I'm losing sound quality by using the SB at volume 35 as compared with 40? It tends to sound better at 40 (at least when there's no clipping) but I can't tell if it's just because it's louder.

BTW, I'm using the SB2 with optical digical output, Slimserver 6.2.2 6245 - Windows XP - EN - cp1252 and firmware version 33.

max.spicer
2006-03-11, 04:59
Isn't this what the preamp volume control is for?

Max


Some claim that if you don't play the SB at full volume (40), you're losing sound quality. I'd like to know if that's true, because when I run my SB2 at full volume it is too hot for the device receiving the signal (Behringer DEQ2496), and I seem to get clipping, at least as displayed on the Behringer meter (it goes into the red).

Thus I have to turn the SB volume down to 35-37 to avoid clipping. Is it true that I'm losing sound quality by using the SB at volume 35 as compared with 40? It tends to sound better at 40 (at least when there's no clipping) but I can't tell if it's just because it's louder.

BTW, I'm using the SB2 with optical digical output, Slimserver 6.2.2 6245 - Windows XP - EN - cp1252 and firmware version 33.

Mike Anderson
2006-03-11, 12:23
^^^ My signal is going from the SB2 into the Behringer before going to the pre-amp. At 40, the signal is too hot for the Behringer.

Mark Lanctot
2006-03-11, 13:03
^^^ My signal is going from the SB2 into the Behringer before going to the pre-amp. At 40, the signal is too hot for the Behringer.

He meant the preamp feature in SlimServer, Player Settings - Audio - Preamp Volume Control. I'm not sure if it's in 6.2.1 but it's in the latest 6.2.2. However, this only applies to analog.

radish
2006-03-11, 14:00
What I don't get is how a digital signal can be "too hot". It's just 16 bit PCM right? So the range is fixed. Surely a 16 bit DAC which clips converting 16 bit values to analog is kinda broken?

crooner
2006-03-11, 14:03
Perhaps its the analog stages after DA conversion that are "too hot" and clip the signal...

JJZolx
2006-03-11, 14:46
Some claim that if you don't play the SB at full volume (40), you're losing sound quality. I'd like to know if that's true, because when I run my SB2 at full volume it is too hot for the device receiving the signal (Behringer DEQ2496), and I seem to get clipping, at least as displayed on the Behringer meter (it goes into the red).

Thus I have to turn the SB volume down to 35-37 to avoid clipping. Is it true that I'm losing sound quality by using the SB at volume 35 as compared with 40? It tends to sound better at 40 (at least when there's no clipping) but I can't tell if it's just because it's louder.

BTW, I'm using the SB2 with optical digical output, Slimserver 6.2.2 6245 - Windows XP - EN - cp1252 and firmware version 33.
This doesn't really make any sense, since (in theory) at '40' you're just passing the unadulterated digital signal. This would be the same as the signal from any other digital source without volume attenution, such as most CD players and transports.

pfarrell
2006-03-11, 14:57
JJZolx wrote:
> Mike Anderson Wrote:
>
>>Thus I have to turn the SB volume down to 35-37 to avoid clipping. Is
>>it true that I'm losing sound quality by using the SB at volume 35 as
>>compared with 40? It tends to sound better at 40 (at least when
>>there's no clipping) but I can't tell if it's just because it's
>>louder.
>>
>>BTW, I'm using the SB2 with optical digical output, Slimserver 6.2.2
>>6245 - Windows XP - EN - cp1252 and firmware version 33.
>
> This doesn't really make any sense, since (in theory) at '40' you're
> just passing the unadulterated digital signal. This would be the same
> as the signal from any other digital source without volume attenution,
> such as most CD players and transports.

That is weird for optical output.
The SB's analog output is pretty hot, and can overdrive
some downstream stuff, and the default output of
my Benchmark DAC-1 is too hot for my preamp, but
the Benchmark has attenuation settings to make
joy and happiness.


--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

Mike Anderson
2006-03-11, 15:40
Perhaps its the analog stages after DA conversion that are "too hot" and clip the signal...

As far as I know, the Behringer isn't (at least I hope it isn't) doing any conversion to analog. I'm taking the digital signal in, EQ'ing it, and taking a digital signal out. I bought it specifically because I wanted to keep the signal processing in the digital domain and convert it to analog later.

The "clipping" is the volume meter on the Behringer going into the red. I think it's clipping audibly, but I can't tell if it's the Behringer or something down the line.

But of course, if it doesn't make any difference whether the SB2 is on 35 or 40, then I wouldn't have to worry about where it's clipping -- which is why I asked.

radish
2006-03-11, 15:52
Ahh I see - I didn't realise what the device was, I thought it was a DAC. If you're at full input range and you EQ it up, it'll clip. To verify that it's not the SB doing something weird hook up a regular CDP and play the same track, should be exactly the same.

Mike Anderson
2006-03-11, 15:57
Ahh I see - I didn't realise what the device was, I thought it was a DAC. If you're at full input range and you EQ it up, it'll clip. To verify that it's not the SB doing something weird hook up a regular CDP and play the same track, should be exactly the same.

According to the Behringer's manual, the meter measures the level of the input signal, not the post-processed signal.

PS -- I've set the gain offset on the Behringer to -5db, so that should prevent the post-processed signal from clipping down the line. But that doesn't affect the signal inputted to the Behringer, and I still get red on the meter.

Mike Anderson
2006-03-11, 22:53
OK, I see the problem now. It's not the input signal. Even though the meter measures the input signal, it also hits red if the output signal clips.

So setting the gain offset to take off about -7db definitely solves the problem.

Mike Anderson
2006-03-12, 10:17
^^^ Alright, I take that back again!

It's possible to isolate the input signal, and according to the Behringer, it IS in fact clipping.

I don't think I can hear it clipping audibly (as long as I take a few dbs off the output signal); but that that's what it says.

Any more insight in this?

Thanks.

dwc
2006-03-12, 16:39
I ignore it when the DEQ shows digital input into the red. I cannot hear any actual distortion or degredation in the sound, so I don't worry about it any more. I used to pad the input with the gain offset, but I've brought it back up to zero since then. Any digital sample at 0db is going to register a clip on the meter, but I do not think that necessarily means the (digital) output is going to be distorted as a result.

I do avoid boosting any frequencies with the EQ though. Cut only.

-Dan

Mike Anderson
2006-03-12, 19:02
^^^ Yeah, that's sort of where I am with it too. I can't hear any clipping, so I guess I'll forget about it.

You can definitely hear it if the output is clipping though.

seanadams
2006-03-12, 19:13
There is something wrong with the behringer if it's clipping on a full-scale digital input. A PCM signal, by definition, has a fixed range of output values - you can't make it arbitrarily "hot", like you can for an analog output.

Try the built-in sine wave test (hold power to reset, then press "3" on the splash screen. This is a 100% full swing signal and if there's any clipping you'll hear it and hopefully be able to track it down.

Mike Anderson
2006-03-12, 19:19
Thanks -- Yes, I've inputted test signals at exactly 0db, and it says it's clipping, but it sounds OK as nearly as I can tell.

joncourage
2006-03-12, 20:46
I'm having what seems to be a similar issue with a Clari-T amp.

Analog out to the amp without any Pre-amp Volume attenuation in the SB3 results in significant audible clipping and popping and distortion with the amp's volume above 1/4 of the dial.

Digital out to a DAC and then to the amp, with the SB digital on fixed volume results in the same nasty behavior.

About 13 db of attenuation in the SB analog out is required to eliminate the weirdness, and nothing above 8 on the digital out volume.

So, it's controllable, but I don't understand why that happens. I have another T-based amp that doesn't exhibit this behavior at all....

verbatone
2006-03-13, 12:10
This probably has more to do with the clip detection than much else. I have an old sony pre-amp (home theater) switcher which I run the digital optical out to and don't see any clip indicator while playing normal music at either vol. 40 or fixed out level (should be the same thing). Certain devices detect clipping differently. A Yamaha EQ that I've used before would show clipping whenever a singular 0dBFS (full scale) value sample occured. So it would show clipping on the test tone from the SB. Programs like Sound Forge will only show clipping when two or more consecutive 0dBFS samples occur. Minor clipping isn't that big of a deal (my opinion), lots of mastered music has pushed into digital clipping, but it is really only audible after pushing it a bit too hard. The problem might also be your source material having been mastered too hot. Someone suggested playing the same file back on a CD player digitally, this is a good comparison point.

My suggestion would be to make the EQ flat on the Behringer and then see if clipping with the test tone still exists on the output. If it does, lower the output level by 1 or 2dB, if it still exists, you have gain that's not accounted for.