where to attenuate?

[ivo]

I ve got now the HiFace (JKenny MK2 RCA model) and am very satisfied with it.
Wanted to get some clarification about attenuation:

• First, there is XX with its digital volume control - so if I decrease it does it attenuates the signal?
  Next, the HiFace RCA and my DAC's RCA connection - I now I can try those inline attenuators, but....
  Afterwards, my DAC has a volume control potentiometer allowing to control level from -10dBV....+8dBV, so can I attenuate here?
  

What I actually did try is I decreased DAC's volume at about 1/3 and now I feel softer sound, but I need to turn my amp's volume a bit more.
As I understand if my DAC's volume is at 2/3 of max, then my amp receives < +8dBV.

So, just wanted to ask opinions on attenuation strategy: is it better to do in digital domain, in analog or in both???

Ivo

[PeterSt]

Since you have the volume on the DAC, I don't think it can be avoided. Unless there's a switch to shut it off (but the switch will still be in the signal -> ok never mind), or better : when you have separate outputs without Volume Control. That *not* assumed :

Just use the VC on the DAC. The damage is done there anyway, and there's no need to add any "damage" elsewhere.

What I actually did try is I decreased DAC's volume at about 1/3 and now I feel softer sound, but I need to turn my amp's volume a bit more.

I hope this didn't come as a surprise to you.
But it also shows you have *another* volume. Oh boy. Do you ever know (or accept to know) how much better your current sound can be ? I'm sure not many will admit this, but I think I have been working on this subject for too long to know how it already influences measurement results. But merely, the really one second notice on lost dynamics. Dead birds.

Using the digital volume from XXHighEnd does not harm at all, if you're only attenuating less than 48dB for CD material and can output in 24 bits.
On this matter : there was a day that I advised the combination of digital attenuation and analogue attenuation, just because both work differently (in physics). Although this still is the case, the analogue volume is just too lousy. But be careful at "removing" it, because now your DAC will be more audible. If that isn't "100%", the net result may be worse.

As I understand if my DAC's volume is at 2/3 of max, then my amp receives < +8dBV.

Of course. But if you('d only) digitally attenuate, the same happens.

Btw, assuming the +8dBV of the DAC does not worsen the S/N ratio of the DAC (which may not be true at all), using that will make the inherent S/N of your amp *better*. It doesn't has to amplify as much, so it won't amplify its own noise as well.

Peter

[GerardA]

Next, the HiFace RCA and my DAC's RCA connection - I now I can try those inline attenuators, but....

I guess these are the attenuators for the SPDIF-signal which lower the voltage at the output of the hiFace.
They don't change the soundlevel but only take care that the to high signal of the hiFace does not overload your DACs input.
On top of that they can lower the absolute level of reflected signals and in that way lower jitter.
So nothing to do with the soundvolume but worth a try to see if it sounds better.

[ivo]

1) As I understand then keeping DAC's volume control at max is not advisable as it may lower the S/N ratio at its output to amp?

2) Also, it would be even better to combine the SPDIF in line attenuators + lower the level of DAC's volume, right?

BTW, what is the HiFace output voltage and how can I determine if it is overloading my DAC's input? Can I calculate that somehow?

Ivo

[PeterSt]

I'll ket #2 to Gerard.

1) As I understand then keeping DAC's volume control at max is not advisable as it may lower the S/N ratio at its output to amp?

No ...
The other way around.

Suppose the DAC's S/N is 100dB. Lowering its output will normally make it e.g. 80dB (that's worse).
If you amplify the latter, the fed 80dB won't change. So, always wrong to do.

But what I was saying is :
S/N of the amp may be 90dB. But, this is at full output. Lowering the output will make the S/N worse, and maybe can get to 60dB. So, unrelated to what it's fed with, the lower the volume the worse S/N. And thus, the higher the output the better it will be.
Unless ...

Unless your amp has so much noise that the noise is audible as such. Thus, when you do not attenuate, and noise is blasting through the room, better attenuate at the amp. S/N ratio will be worse, but you will attenuate the noise as well.

BTW, what is the HiFace output voltage and how can I determine if it is overloading my DAC's input? Can I calculate that somehow?

Although for Gerard maybe, but just in case he doesn't come up with my smart answer the JKenny mod just already prevented that (and is partly explicitly for that).
Output level of the HiFace just *is* too high; you don't need to measure it (IIRC 2 Volts or so, while it should be 0.6 (??)).

[ivo]

So, my DAC's Dynamic Range is 123 dB from here http://www.audiotrack.net/products/DRDAC2DX/spec/
My amp's S/N at high level is 105 dB from here http://www.marantz.com/new/index.cfm?fuseaction=Products.ArchProd_Specs&cont=eu&bus=hf&prod_id=2599&type=amp&arch=1

So, I guess if I decrease a little the DAC's volume I will move down from 123 dB at its output to amp AND if I increase amp's volume I will be moving up to 105 dB? Maybe I am wrong, just thinking....

Anyway, if I listen music over my headphones (plugged into amp) I hear more 3D, the soundstage is deeper and it is clearer, no harsh at high levels....

I guess all will change when I try those RCA inline attenuators

Thanks you guys for clarifying...

Ivo 

[PeterSt]

Ivo, one more thing : Dynamic Range is unrelated to Noise (hence S/N).

[jkeny]

Ivo,
Glad you're liking the MK2 Hiface. I'm interested in how you find the Rf attenuators.

As I said via email, I believe volume attenuation is best done in the analogue domain. Done in the digital domain you are losing bits & hence resolution!

[PeterSt]

Done in the digital domain you are losing bits & hence resolution!

Not with redbook material, a 24 bit DAC and XX.

[jkeny]

Done in the digital domain you are losing bits & hence resolution!

Not with redbook material, a 24 bit DAC and XX.

Agreed Yes, but Ivo was talking about reducing his DAC vol control to 1/3 at the top of page & I think (but I'm not sure) he is still not operating at DAC max vol ?

Also will he never want to listen to High-res material?

[ivo]

So, I did look for RF attenuators and did not find anything here where I live.
Then I searched in ebay - got only expensive ones, the cheap ones just not shipping to my place, so currently no attenuators.
Will look for them sometimes later again...

Regarding the DAC volume - after various experiments I ended up with my DAC's volume at 15:00, which is around 75% of max in my case.

Ivo

[jkeny]

You're in Latvia, right? Have a look at the international sales reps here http://www.minicircuits.com/pages/irep.html#ge

[GerardA]

Very nice, so we can all order them!
One question, is it better to have one of 20 DB or two of 9 dB at both sides of the cable?

[jkeny]

Very nice, so we can all order them!
One question, is it better to have one of 20 DB or two of 9 dB at both sides of the cable?

Of course, you could always have ordered them - as I said $12 or so + shipping.
I don't know which is better - it seems not to make any difference in practice!

[gonzalito]

I was just about to ask a similar question:

In my case, I have 4 volume controls to manage:

1) Prodigy HD2 driver volume setting
2) Windows 7 volume setting
3) Player (XX o whatever) volume control
4) Amplifier volume control

In which % would you set each volume?

Thanks in advance,

Regards.-