Sensitivity Ratings on Preamplifiers or Integrateds vs. Amplifiers


Ok, so I am interested in a better understanding of gain issues. As I understand it sensitivity values for an amplifier provide the voltage needed to achieve rated output. I am not sure about the sensitivity rating for preamps, thinking it serves as the minimum required to drive the preamp. In the case of an integrated I have seen this spec provided for the included preamp and amplifier stages.  However for many it is not.

Specifically for my Line Magnetic 211ai it is specified as 200mV and I assume this is for the preamp stage.  This seems low and may be why, when driven by my DAC having 2V output, I need not turn the volume past 10 o'clock for sufficient loudness. I understand the volume position is no measure of the wattage one is asking the amplifier stage to deliver. 

I am seeking clarification /correction on my thinking. Thanks in advance!
mesch

Showing 3 responses by mesch

George,  thanks for your response. I usually get around to looking inside a piece of equipment I own to see what I purchased. Never in a hurry to do so with something new (to me). My LM211 is just past the broken in stage. I will play with the volume control, maybe using the SYS to allow more full sweep, to try and discover whether it is linear or log. 

Regarding the sensitivity spec, I believe 0.2V is way over sensitive for full power from an amplifier. I believe 0.5V is also. Of course high sensitivity often drives one towards a passive pre. That was what drove my question.

Is the 200mV spec for the preamp or the amp stage in this integrated?

If for the amp, is the preamp passive and the small signal tubes only input and driver tubes for the amp? It seems that no gain would be required from the preamp stage.
@yogiboy  Thanks for your response. I do own a SYS. I am really not overly concerned with the volume position as I am wondering how much power I am reaching at the position. I don't feel I would accomplish much adding another potentiometer and pair of cables between DAC and amplifier.

 I am going to play with my SPL meter measuring at different levels. My Tannoy Sterlings have a sensitivity of 91dB and don't drop below 5 ohms impedance. If I take that at face value, knowing the distance between the SPL meter and the speaker I might be able to get a rough guess of what power I am using. I am not interested in pushing the amp to the point of distortion. 

I have had integrated amplifiers that exhaust the amplifier stage at 12 o'clock volume. It seems the preamps in these integrateds have gain to accommodate low phonostage outputs. Often too much gain for digital sources. These days 2V from a DAC is the minimum. So many preamps have far more gain than needed for digital sources. 

As an aside to this, My Aric Audio Tube preamp has variable gain, 0-20dB. I find this a useful feature. Of course not in use with the LM 211ai.  
Thanks, George. I wasn't aware of the 12AY7 tube. I believe there is another tube, having a 4 digit designation,  that can replace the 12AX7 for lower gain. Maybe the same tube with different designations?

I am currently not in the mood to get overly concerned about the gain issue specific to this amp to the point of modifying or even tube rolling it. I purchased it slightly used at a reasonable price to use as an educational tool to better understand the power requirements of my speakers, and to play with all tube amplification. It is serving me well for that. will likely move on from it. 

Currently using the Aric Audio pre into a SS amplifier. Should I purchase a all tube integrated I believe I would look into those having a active tube preamp stage. Otherwise a tube amplifier to rotate with a SS one using my preamp.

One thing about the LM 211ai, I believe it to be better suited to a vinyl system where the sensitivity could be an asset with lower gain cartridge and phonostage.  Either way, vinyl or digital it sounds very good with my Sterlings. I will have a better feel for how it compares with my preamp/amp combo one I reincorporate it into my system. Still getting familiar with the LM.