2v or 6v into a tube pre-amp? what would you do (and why?)

[sandyk]

McIntosh Laboratory MC462 power amplifier Specifications ...

www.stereophile.com › content › mcintosh-laboratory-...

Voltage gain: 29dB, 8 ohms. Input sensitivity: 4.2V balanced, 2.1V unbalanced.

 

You will need to greatly attenuate the output unless you use 2.0V out from the DAC, otherwise you will substantially degrade the Signal to Noise ratio. You will most likely already need to use way too much attenuation with an amplifier with 29dB gain.  What is the typical volume control setting on your valve preamp at present ? Is it well left of the middle of it's range ? Valve Preamps do not normally like higher input voltages , and were often designed for more like 1V RMS input signals.

To get most benefit from a higher voltage source signal, you need a Power Amplifier with much lower gain, or having switchable Input voltage settings. 

[sandyk]

12 minutes ago, 992Sam said:

Thanks but I’m not going directly into the MC462... I’m going into a C1100 preamp ... can’t find anything about the input  other than its limited to 20v balanced.   Can you see if you’ve got better luck?

 I was going by this "I'm currently using the Rossini with just an Amp"2

 

C1100

• Total Harmonic Distortion

  High Level: 0.005%
  Phono: 0.05%

• Frequency Response

  +0, -0.5dB from 20Hz to 20kHz
  +0, -3dB from 10Hz to 100kHz

• Maximum Volts Out (Balanced / Unbalanced)

  20V RMS / 10V RMS

• Sensitivity High Level (Balanced / Unbalanced)

  900mV / 450mV

• Sensitivity Phono (Moving Coil)

  0.45mV

• Sensitivity Phono (Moving Magnet)

  4.5mV

• Signal To Noise Ratio (High Level)

  107dB

• Signal To Noise Ratio (Moving Coil)

  79dB

• Signal To Noise Ratio (Moving Magnet)

  77dB

• Voltage Gain (High Level)

  15dB

• Voltage Gain (Moving Coil)

  60db

• Voltage Gain (Moving Magnet)

  40dB

• Input Impedance (Balanced / Unbalanced)

  50K ohms, 25K ohms

 

[sandyk]

On 10/28/2020 at 11:00 AM, 992Sam said:

I guess I will start with .2 and work up from there..

 0.2V suggests that they may have already digitally (most likely) attenuated it already.

[sandyk]

1 hour ago, 992Sam said:

 

Which I would want to avoid, and frankly listening to the system as it stands now with the C1100 not in the mix (it comes next week), and with the Rossini directly into the Amp,  even at 2v it's not remotely loud... at 6v it comes to life..  

 Then unless you like (need?)  a little Tubey artificial warmth along with S/N degradation etc. along the way, why do you need the C1100 unless you have other sources to select ?

[sandyk]

4 hours ago, Bill Brown said:

This is lower than the norm, but it's something I welcome because preamplifiers in general are used to attenuate, not amplify, the levels of source signals" JA in Stereophile measuring an integrated amp

 That's not quite correct. Many people have lower level sources than the 2V RMS from a standard

CD /DVD player . They often include FM Stereo, Phono Preamps, Tape Decks and these days DTV, which often varies dramatically in level between SDTV and HDTV transmissions where different types of Audio were used, including Dolby Surround. In my case, my DIY Class A Preamplifier was designed to have only 3.2 x gain to compensate for those marked differences in level, which in the case of DTV, even when using a STB set to maximum output level into a high quality DAC via Coax SPDIF still needs level adjustment . Even then I need to further attenuate the output from my Oppo 103 when playing CD and other digital sources plugged into it.

 

IIRC, Kal's setup is very different to that of most members because he is a multi channel person.