What am I missing? Pre/power gain and input sensitivity.


I’ve read a few posts about power amps with lower gain needing a pre with additional gain, but no one seems to mention input sensitivity in those conversations. If my source outputs 2V and my power amp input sensitivity is only 1.2V then whether the power amp gain is 16dB or 26dB my pre amp is attenuating the signal and the amount of gain on the pre doesn’t matter at all. With a given set of speakers, to get the same SPL with 2 different amps they should just need to output the same voltage, regardless of how they get there.

Am I missing something?

cat_doorman
My main objection to vinyl is the ticks, pops, and noise.
@cat_doorman A lot of ticks and pops that people react to when playing vinyl are caused by the phono preamp itself (due to high frequency overload) and aren't actually on the LP itself. Its a bit technically complex to describe quickly, but has a lot to do with the fact that the phono cartridge has an inductance and the tonearm cable has a capacitance- together they can create Radio Frequency energy that can overload the phono section's input stage for very brief periods- the ticks and pops. So if the designer didn't take this into account, you get more ticks and pops. And yes, most of the phono sections out there have this problem!
I’m a prime example of what Ralph has stated above. For about 6 years I owned a well thought of phono pre and just thought the tics and pops were part of the vinyl. Couldn’t believe the difference and improvement when changing phono preamp. If playing a clean copy can’t hear anything but the music.
As to the gain/voltage equation, the purchase of an amp with only 18db of gain negated the use of my preamp, which had only 12db of gain. To add to the imbalance, the amp requires 2.5 volt input to reach full power. Purchased a preamp with 20 db gain that definitely pushed the amp to full power. The preamp manufacturer actually mentioned that the amp’s lower gain would be a plus in combo with his preamp. All in all things are matched up very well. And I’m done for the foreseeable future.
Posters like Ralph (AtmaSphere) and Almarg are very valuable to this forum. The technical info they provide can guide you to make sound purchases.

Upnorthsound: Thanks for the link to Steve’s ramblings, I’ve spent a valuable hour perusing his musings. I especially liked his discourse on ‘the weakest link.’

dentdog: +1 on the value of some of the contributors to this space. I have been surprised at how much some of them are willing to give to the community.