XMC-2 XLR Output Voltage at LCR?

[thezone]

Hi all,

My apologies if this has been discussed before. I am using a Purifi 3ch amp from Audiophonics for my LCR and in the manual it advises that in order to get maximum power from the amp I need to select an input gain setting to match the output voltage from the XMC-2.

Anyone have any idea what the output voltage of the XMC-2 LCR XLR's is? 

eg 



It also goes on to say that I can disable the input buffer altogether and then overall gain of the Purifi will then be equal to the nominal value of the module, approximately 12.5dB.


An that this configuration is to be used with a powerful preamplifier, capable of driving a 2-4kohm load with 10Vrms. 

[creimes]

I can't be certain but would have to assume it is the same or close to the XMC-1 which is listed as following in the specs from the manual

I would leave it at the value it comes at, the 26db configuration.

Output Impedance (Analog)
Balanced Outputs: 100 Ohms
Unbalanced Outputs: 100 Ohms

Maximum Output Level (Analog)
Balanced Outputs: 11 VRMS
Unbalanced Outputs: 5.5 VRMS

[thezone]

Feb 12, 2024 22:50:07 GMT -5 creimes said:

I can't be certain but would have to assume it is the same or close to the XMC-1 which is listed as following in the specs from the manual

I would leave it at the value it comes at, the 26db configuration.

Output Impedance (Analog)
Balanced Outputs: 100 Ohms
Unbalanced Outputs: 100 Ohms

Maximum Output Level (Analog)
Balanced Outputs: 11 VRMS
Unbalanced Outputs: 5.5 VRMS

Actually, if what you are saying holds true for the XMC-2 and the output is 11VRMS, then I would be looking to disable the buffer stage as per my first post? 

Which, as I've read on another forum, correlates to bypassing the Texas Instruments internal op amp. Which would in turn give the purest signal path no?

[PaulBe]

Feb 13, 2024 2:00:52 GMT -5 thezone said:

Feb 12, 2024 22:50:07 GMT -5 creimes said:

I can't be certain but would have to assume it is the same or close to the XMC-1 which is listed as following in the specs from the manual

I would leave it at the value it comes at, the 26db configuration.

Output Impedance (Analog)
Balanced Outputs: 100 Ohms
Unbalanced Outputs: 100 Ohms

Maximum Output Level (Analog)
Balanced Outputs: 11 VRMS
Unbalanced Outputs: 5.5 VRMS

Actually, if what you are saying holds true for the XMC-2 and the output is 11VRMS, then I would be looking to disable the buffer stage as per my first post? 

Which, as I've read on another forum, correlates to bypassing the Texas Instruments internal op amp. Which would in turn give the purest signal path no?

What really needs to be addressed here is gain structuring. The first thing required is full specs that will help us. Since we don't see these necessary specs for the XMC-2 or the RMC, you'll have to experiment.

1. You need enough gain.

2. The I/O impedance measurements make a difference in drive requirements. Virtually all opamp differential audio outputs will drive a 4K load; or a 2K single ended load. The difference will be mainly in the Very low frequency/phase response which is dependent on output coupling capacitor values.

3. You need enough adjustment range to balance the various speaker outputs.

4. Lower gain settings Might sound better.

5. Higher gain settings may be necessary to achieve output balance from the speakers within adjustment range. Higher gain settings Might not sound as good as lower gain settings - in most systems we are splitting hairs here. I would stay away from the highest gain settings if I could.

6. Try different things till you get the system results you want.

*I set the inputs of my amps for +14dbu = approximately 4V. It's the medium sensitivity input level. My RMC-1L has plenty of drive for this setting, good headroom, and enough independent output level adjustment range.

[KeithL]

At the risk of confusing people...

When you have a choice the ideal setting for gain on an amplifier you're going to connect to one of our processors is either 26 dB or 32 dB.
(If you look you'll see that our current amps are all 29 dB and most amps on the market range from about 28 dB to about 32 dB.)

The reason is something which is rarely actually mentioned specifically... sometimes called "free gain".

Here's the way it works...

The XMC-2 or RMC-1 can indeed put out over 10V and do so without any significant increase in noise or distortion near the top of that range.
Therefore, if you were to set your amplifier so that it delivered its full power with a 10V input signal, everything would theoretically be fine.
With the processor "all the way up", and a 0 dB signal playing, the processor would be putting out 10V, and the amp would be putting out full power.
And, at least in theory, this would "optimize the noise and gain structure of the processor and the amp".

So what's the catch?

Well, with a perfectly optimized gain structure, the amplifier will be putting out full power when the processor is "all the way up" and the incoming signal is at "0 dB".
But what if the producer of the disc decided to "leave a little headroom" and the loudest thing on the disc is at -3 dB?
Well, now, even with the processor all the way up, the amplifier WON'T be making full power...
And, if you're watching a YouTube video, and the loudest thing on it is at -10 dB, even with everything "cranked", the amplifier will only be able to make 10 dB LESS than full power. 

The solution to this is that we normally want to arrange things so that we have "a little extra free gain"....
We chose our settings so that the amplifier is delivering full power when the Volume on the processor is set to "0 dB"...
And we "keep that extra +10 in reserve" ... in case we need it for a source that is a little lower than usual...

And, for that reason, even though the processor can put out 10V, it's still better to set the amp so that it normally hits full power with 1V or 2V input level...

And, yes, you can add some extra gain using the channel level trims...
But, to be quite blunt, modern amplifiers are really quiet...
So you don't actually NEED to "perfectly optimize the gain structure to squeeze the last dB of performance out of it"...
And not all modern source material is perfectly balanced so that its maximum output level peaks at just 0 dB...
So usually you're better off setting the amp to reach full power at 1V or 2V input level and "leaving a little free gain"...

[PaulBe]

Feb 13, 2024 11:25:09 GMT -5 KeithL said:

At the risk of confusing people...

When you have a choice the ideal setting for gain on an amplifier you're going to connect to one of our processors is either 26 dB or 32 dB.
(If you look you'll see that our current amps are all 29 dB and most amps on the market range from about 28 dB to about 32 dB.)

The reason is something which is rarely actually mentioned specifically... sometimes called "free gain".

Here's the way it works...

The XMC-2 or RMC-1 can indeed put out over 10V and do so without any significant increase in noise or distortion near the top of that range.
Therefore, if you were to set your amplifier so that it delivered its full power with a 10V input signal, everything would theoretically be fine.
With the processor "all the way up", and a 0 dB signal playing, the processor would be putting out 10V, and the amp would be putting out full power.
And, at least in theory, this would "optimize the noise and gain structure of the processor and the amp".

So what's the catch?

Well, with a perfectly optimized gain structure, the amplifier will be putting out full power when the processor is "all the way up" and the incoming signal is at "0 dB".
But what if the producer of the disc decided to "leave a little headroom" and the loudest thing on the disc is at -3 dB?
Well, now, even with the processor all the way up, the amplifier WON'T be making full power...
And, if you're watching a YouTube video, and the loudest thing on it is at -10 dB, even with everything "cranked", the amplifier will only be able to make 10 dB LESS than full power. 

The solution to this is that we normally want to arrange things so that we have "a little extra free gain"....
We chose our settings so that the amplifier is delivering full power when the Volume on the processor is set to "0 dB"...
And we "keep that extra +10 in reserve" ... in case we need it for a source that is a little lower than usual...

And, for that reason, even though the processor can put out 10V, it's still better to set the amp so that it normally hits full power with 1V or 2V input level...

And, yes, you can add some extra gain using the channel level trims...
But, to be quite blunt, modern amplifiers are really quiet...
So you don't actually NEED to "perfectly optimize the gain structure to squeeze the last dB of performance out of it"...
And not all modern source material is perfectly balanced so that its maximum output level peaks at just 0 dB...
So usually you're better off setting the amp to reach full power at 1V or 2V input level and "leaving a little free gain"...

At the risk of being argumentative...

An optimized analog path Has free gain/headroom designed into the system. Optimized analog gain structuring always has fiddle room, and professional opinions about 'how much is best' is variable, with different applied standards, in different locations around the world.

Thanks for stating Emotiva's standards and for disclosing the XMC/RMC available output levels. This is all I ever wanted from Emotiva on this subject. Perhaps a FAQ page at your site would be useful.

At my current system gain optimization, I run my RMC-1L volume at about -10 to 0 for best sound, good headroom, and max usable playback levels with variable sources.  Plenty of output and plenty of wiggle room...

You did add confirmation to what I thought I knew.

[thezone]

Feb 13, 2024 11:25:09 GMT -5 KeithL said:

At the risk of confusing people...

When you have a choice the ideal setting for gain on an amplifier you're going to connect to one of our processors is either 26 dB or 32 dB.
(If you look you'll see that our current amps are all 29 dB and most amps on the market range from about 28 dB to about 32 dB.)

The reason is something which is rarely actually mentioned specifically... sometimes called "free gain".

Here's the way it works...

The XMC-2 or RMC-1 can indeed put out over 10V and do so without any significant increase in noise or distortion near the top of that range.
Therefore, if you were to set your amplifier so that it delivered its full power with a 10V input signal, everything would theoretically be fine.
With the processor "all the way up", and a 0 dB signal playing, the processor would be putting out 10V, and the amp would be putting out full power.
And, at least in theory, this would "optimize the noise and gain structure of the processor and the amp".

So what's the catch?

Well, with a perfectly optimized gain structure, the amplifier will be putting out full power when the processor is "all the way up" and the incoming signal is at "0 dB".
But what if the producer of the disc decided to "leave a little headroom" and the loudest thing on the disc is at -3 dB?
Well, now, even with the processor all the way up, the amplifier WON'T be making full power...
And, if you're watching a YouTube video, and the loudest thing on it is at -10 dB, even with everything "cranked", the amplifier will only be able to make 10 dB LESS than full power. 

The solution to this is that we normally want to arrange things so that we have "a little extra free gain"....
We chose our settings so that the amplifier is delivering full power when the Volume on the processor is set to "0 dB"...
And we "keep that extra +10 in reserve" ... in case we need it for a source that is a little lower than usual...

And, for that reason, even though the processor can put out 10V, it's still better to set the amp so that it normally hits full power with 1V or 2V input level...

And, yes, you can add some extra gain using the channel level trims...
But, to be quite blunt, modern amplifiers are really quiet...
So you don't actually NEED to "perfectly optimize the gain structure to squeeze the last dB of performance out of it"...
And not all modern source material is perfectly balanced so that its maximum output level peaks at just 0 dB...
So usually you're better off setting the amp to reach full power at 1V or 2V input level and "leaving a little free gain"...

Thanks Keith, I will leave it at the default setting it came from the factory at 26db!