Volume control in the middle of the chain.

[modusmongo]

Hi,

 

Boring history starts here. Skip down to *** for the real question!

 

For over a year now I have been enjoying great audio at home. I bought a pair of BC Acoustique Gange towers, pulled out the crossovers between the lows and mids, and substituted a mini-DSP active crossover. I'm currently powering 350Hz and below with a Linn LK-85 and everything above that goes through a Rotel RB-971. The low end is EQ corrected slightly according to readings I did with REW5. I created a sweet spot listening area with bass traps and anti-reflection panels. I like it!

 

I play mostly flac files in Foobar via DirectKS ASIO to an Audio-GD NFB 2.32 DAC which then goes RCA direct to the mini-DSP. No preamp!

 

So, recently I broke my crappy headphones by standing on the cable as I got out of my chair. Cool! I can buy some good cans ;-)

 

I'm waiting on a pair of Shure SRH940s and after some research and thinking, I have ordered an NFB6 preamp/headphone amp from Audio-GD. I like the idea of connecting the preamp to the DAC in ACSS, and the reviews were (mostly) very good. Now I will have a proper preamp in the chain!

 

*** I have been controlling volume with a potentiometer soldered to the board of the mini-DSP - post crossover. This is the last point in the chain before the amplifiers. For those of you unfamiliar with the mini-DSP, there is a voltage control port on the board expressly for this, I'm not running the audio signal through a pot :-)

 

Now with the new preamp, I will have a volume control BEFORE the active crossover. So my question is this:

 

Should I run the preamp at 0dB and continue to use the mini-DSP volume knob, or should I remove the volume pot and change volume on the preamp?

 

I imagine there will be some people who think I should run everything full out and use analog pots. I'd like to hear all opinions.

 

FYI, I like it loud! I almost never have the volume at less than 1 o'clock...

 

Best,

Peter

[4est]

To answer I think I need to understand what this really is. If it is variable gain, then keep your pre at full and adjust this.

Hi,

 

Boring history starts here. Skip down to *** for the real question!

 

For over a year now I have been enjoying great audio at home. I bought a pair of BC Acoustique Gange towers, pulled out the crossovers between the lows and mids, and substituted a mini-DSP active crossover. I'm currently powering 350Hz and below with a Linn LK-85 and everything above that goes through a Rotel RB-971. The low end is EQ corrected slightly according to readings I did with REW5. I created a sweet spot listening area with bass traps and anti-reflection panels. I like it!

 

I play mostly flac files in Foobar via DirectKS ASIO to an Audio-GD NFB 2.32 DAC which then goes RCA direct to the mini-DSP. No preamp!

 

So, recently I broke my crappy headphones by standing on the cable as I got out of my chair. Cool! I can buy some good cans ;-)

 

I'm waiting on a pair of Shure SRH940s and after some research and thinking, I have ordered an NFB6 preamp/headphone amp from Audio-GD. I like the idea of connecting the preamp to the DAC in ACSS, and the reviews were (mostly) very good. Now I will have a proper preamp in the chain!

 

*** I have been controlling volume with a potentiometer soldered to the board of the mini-DSP - post crossover. This is the last point in the chain before the amplifiers. For those of you unfamiliar with the mini-DSP, there is a voltage control port on the board expressly for this, I'm not running the audio signal through a pot :-)

 

Now with the new preamp, I will have a volume control BEFORE the active crossover. So my question is this:

 

Should I run the preamp at 0dB and continue to use the mini-DSP volume knob, or should I remove the volume pot and change volume on the preamp?

 

I imagine there will be some people who think I should run everything full out and use analog pots. I'd like to hear all opinions.

 

FYI, I like it loud! I almost never have the volume at less than 1 o'clock...

 

Best,

Peter

[modusmongo]

Hi Forrest. Thanks for answering.

 

Yes the miniDSP crossover has a voltage-controlled output volume, AND it is the last thing in the chain before the power amps. So if I understand, you're saying I should put the NFB6 preamp at max, and continue to use the miniDSP volume control. Right?

[4est]

Not so quick...

 

Voltage controlled and variable gain are not the same thing. What does the voltage control- digital attenuation or adjustable signal gain? I do not know the answer, but it would be in your interest to look into this and how the pre works. It might be best with a little of both. A pre amp set to full may clip or over drive.

[beanbag]

The minidsp has jumpers for .9V or 2V inputs. Be sure to set the preamp level so it does not exceed this. You should run the preamp volume so that it is near the max input voltage of the minidsp in order to use the full range of the ADCs. Then use the pot on the minidsp to control volume.

[modusmongo]

The minidsp has jumpers for .9V or 2V inputs. Be sure to set the preamp level so it does not exceed this. You should run the preamp volume so that it is near the max input voltage of the minidsp in order to use the full range of the ADCs. Then use the pot on the minidsp to control volume.

 

Thanks Beanbag,

 

According to the specs, the RCA output of the NFB-6 at max volume is 10V. I have sent an email to Audio-GD asking if they can suggest a volume level suitable for the 2V max input of the miniDSP.

 

Is there a way I can measure the NFB-6 output?

[beanbag]

Thanks Beanbag,

 

According to the specs, the RCA output of the NFB-6 at max volume is 10V. I have sent an email to Audio-GD asking if they can suggest a volume level suitable for the 2V max input of the miniDSP.

 

Is there a way I can measure the NFB-6 output?

 

yes, you can play a full amplitude sine wave thru your preamp, and look at the input level monitors on the minidsp.

[modusmongo]

yes, you can play a full amplitude sine wave thru your preamp, and look at the input level monitors on the minidsp.

 

My miniDSP doesn't have input level monitors. Could I just do a group of readings and apply RMS calculation? I have a digital volt meter.

[beanbag]

The plug-in to run your minidsp doesn't have input level meters?

[modusmongo]

Hey! Yes it does! Okay, I can use these to test the strength of the signal coming into the miniDSP and go from there.

 

FWIW, I had an email from Kingwa saying that, given the 2V max input of the miniDSP, the "NFB6 should turn the volume not over 40 steps on high gain."

 

At any rate, I'll be able to monitor it in the software. Thanks so much; this makes it much easier.

 

Peter