[daba]

On my Dynamight I have the choice of two unbalanced pairs of RCA inputs and one XLR input. However, the music is noticably louder when using RCA than XLR. Is this normal? I thought XLR had twice the gain of RCA.

I do notice that there is less "noise" in the background with XLR, but that might just be because there is less signal output from it.

Maybe I need to tweak the Benchmark DAC1's output?

 

[jbloudg20]

Quote:

Originally Posted by daba I thought XLR had twice the gain of RCA.

Incorrect, the amplifier is where the gain stage it... not in the source. 'Gain' and 'balanced' are completely unrelated.

 

[ghiberti]

as I know, it's louder when we use balanced input.
it may be related with the strength of signal.

 

[Solude]

Unless SFT has inline attenuators on the XLR inputs XLR should be louder.

That said the DAC1 may still be set internally to -30, -20 or -10dB instead of 0dB.

 

[ken36]

Only to your ears.

 

[daba]

Quote:

Originally Posted by jbloudg20 Incorrect, the amplifier is where the gain stage it... not in the source. 'Gain' and 'balanced' are completely unrelated.

Hmm, could you explain in more detail, or provide a reference/book I can read on this?

Wikipedia states: http://en.wikipedia.org/wiki/Balanced_line

Quote:

As an example: a microphone connected to a mixer. A typical professional microphone has 3 pins on the XLR connector: "hot", "cold", and shield. If the hot wire has the signal from the microphone S, the cold wire has the opposite (inverted) signal −S. (This is usually achieved with a transformer inside the microphone). The 2 wires are twisted together very closely, so any noise N induced on the cable affects each of the 2 wires equally. (So we would have S+N on the hot wire, and −S+N on the cold wire.) On the receiving end (often a mixing console) there is an operational amplifier which subtracts cold from hot: (S+N) − (−S+N) = 2S. So at the end, you have 2S gain (twice the signal, or 6 dB), and the noise has been canceled out.

I suppose it depends on the opamp at the end of the cable, and what it does to the signal, but that makes sense for balanced cables having no external noise if created properly. So that claims you have double the gain due to the XLR cables (amplifier).

 

[daba]

Quote:

Originally Posted by ken36 Only to your ears.

No, according to the ears of several people who have heard it as well.

 

[Solude]

Did you open the DAC1 as instructed to see what setting you have?

On 0dB the XLR should be 6dB louder. But if set to -10dB then well -4dB, -20 gives -14dB and so on. Crack it open and look.

 

[jbloudg20]

Quote:

Originally Posted by daba Hmm, could you explain in more detail, or provide a reference/book I can read on this?

GAIN is calculated by the equation: Code:

[left]voltage(out)/voltage(in)[/left]

It has nothing to do with the type of signal. I think you meant to say that XLR has twice the potential. That statement would be true.

 

[daba]

Re: Solude, sure I'll crack it open when I get the chance. Although, it is stated here that the calibrated and variable settings are "identical" according to a Benchmark engineer: http://www6.head-fi.org/forums/showthread.php?t=166115

Re: jbloudg20, so that means if I have twice the potential gain with balanced than that of unbalanced; how would you explain the lower volumes using the balanced cables versus the unbalanced cables?

 

[dip16amp]

The DAC1 XLR outputs have internal attenuation jumpers that used to be set for default at 0 dB (Rev C to Rev G). Units starting at Rev H are set for default at -20 dB.

 

[jbloudg20]

Quote:

Originally Posted by daba Re: jbloudg20, so that means if I have twice the potential gain with balanced than that of unbalanced; how would you explain the lower volumes using the balanced cables versus the unbalanced cables?

Its not potential gain... the gain has NOTHING to do with the source.
The potential I was referring to is electronic potential, also known as voltage.

It seems dip16amp may have an explanation.

 

[Solude]

Quote:

Originally Posted by dip16amp Units starting at Rev H are set for default at -20 dB.

Side question, what S/N range starts Rev H? It bugs me when companies do this, I want to buy one but now I need to worry about getting the right DAC1 oye

 

[dip16amp]

Quote:

Originally Posted by Solude Side question, what S/N range starts Rev H? It bugs me when companies do this, I want to buy one but now I need to worry about getting the right DAC1 oye

The "(Rev C to Rev G)" that I mentioned is actually for the manual which is PCB Rev C. The manual Rev H starts at PCB Rev F. Most of the changes between the two seem to be at serial number 39260.

 

[Solude]

Ouch Benchmark sure has shipped a lot of these