Preamp - 18 dB Gain too low?


Being a newbie to audio stuff, I'd like to hear your opinion whether should I replace my preamp. To get to a reasonable loud volume, my preamp has to be at around 1PM to 2PM position for most of CD and music DVD. Should I get another preamp with higher gain? If so how much more? Why don't the manufacturers make higher gain? Probably some sonic compromise with high gain active preamp?

Any suggestions are welcomed.

Preamp: Conrad Johnson PV-10AL, gain 18 dB.
Amp: Shuguang S845MK (tube amp 848)
Speakers: Tekton Lore (Sensitivity 98 dB)
Room: 25 x 17 x 8'
nguyen787
my 845 amp is very high, 200mv. I wonder if I am losing any performance since my volume is at 9pm for normal listening. it sure sounds good though despite the touchy volume control. the manufacturer said I could swap out two resistors to make it less sensitive, which might do.
Being ignorant how you calculate 22 dB more gain with Rogue Apollo? Any websites or references are appreciated.
Nguyen787,
A doubling (2x) in voltage is (almost exactly) 6dB. A 10x in voltage is exactly 20dB. So for example if you have a 20x factor in gain then you could say: 20x = 2x * 10x = 6dB + 20dB = 26dB

Note that dB values are always added together (since dB values are really exponents), while their corresponding multiplication factors are multiplied together.

When comparing power: a 2x in power is approximately 3dB, while 10x is exactly 10dB.

The precise formula for converting Voltage ratios to dB is: dB = 20 * log(V1/V2), where V1 and V2 are two different voltages, and the log function is base-10. Note that if you flip V2/V1, you get the same magnitude dB value but with a different sign. For power ratios, it's: dB = 10 * log(P1/P2), where P1 and P2 are two different powers in the same unit (e.g. Watts).

So in my example with the Apollos, you start out by comparing Voltages:
20 * log(4V/1V) = 12.0412 dB

Thus, the 4V amp will require a 12dB higher input signal to achieve its "full output" (the typical definition of amplifier sensitivity), versus the 1V amp. Next we have to compare the difference in "full output" between the amps:

10 * log(250Watts / 25 Watts) = 10.0 dB

So the amp that puts out 250W will be 10 dB above the 25W amp when both are at full output. Add the two together: 12 + 10 = 22dB difference in amp gain.

--
Mike
An input sensitivity for an amp of 1v is quite normal as nearly every amp I've seen on the market has been .5v to 2v for max rated rated output (to clip/distort).
An input sensitivity of 4v is wrong/bad and I would call the amp broken or seriously badly designed.
You have a problem ask the manufacture to give you a fix to make the amp/s 1 to 2 volt input sensitivity, as the standard is.

Cheers George
Nguyen787
Here is a way out there thought on your problem. You say your running the amp on 115v mains? It is possible that this amp/s are set up for 220-240v mains operation, this could? drop your gain/input sensitivity.

Cheers George