Separate preamp/power amp question. I want more volume...

[Chienmortbb]

4 hours ago, Downunderwonder said:

How do you get output without gain? Must be a definition problem.

You could have a unity gain amplifier. 

[Downunderwonder]

2 hours ago, Chienmortbb said:

You could have a unity gain amplifier. 

Aka EQ unit?

[Jack]

14 hours ago, agedhorse said:

It's NOT gain that's the issue, it's the maximum output level which is an entirely different parameter. 

Ok, I'll take one for the team. I would assume that those specs are somewhat linked, with the amount of gain on tap allowing you essentially a better chance of reaching the required output level. Obviously, this depends on the input. Can you elaborate a little more please?

[bremen]

Gain/max level: 

 

Here's a pedal with 40dB gain . (amplifies the signal voltage x100)and a 9V battery. So put 10mV in, get 1V out. Happy days.

But put 100mV in you won't get 10V out - the 9V battery is inadequate.

Simillarly, increase the gain to 60dB and put 10mV in - still can't gey 10V out.

 

Now if that pedal has an output impedance of 10k (the equivalent of a 10k resistor in series) and the following power amp an input impedance of 10k, those two resistors form a potential divider which halves the signal, taking us even further from sonic satisfaction.

 

 

[Jack]

Ok, that's pretty much as I understood it then, they are linked but there's a limit.

[agedhorse]

On 03/04/2025 at 13:37, Downunderwonder said:

How do you get output without gain? Must be a definition problem.

(Voltage) Gain is output level divided by input level. 
 

Maximum output level it the voltage that an output can deliver without clipping. 
 

You can have high gain but all it does is clip because there’s not enough output level to reproduce the unclipped signal, that’s the basis for distortion pedals. 
 

The two parameters are relatively unrelated, you can look this up on a good engineering website. 

Edited April 4 by agedhorse

[agedhorse]

16 hours ago, Jack said:

Ok, I'll take one for the team. I would assume that those specs are somewhat linked, with the amount of gain on tap allowing you essentially a better chance of reaching the required output level. Obviously, this depends on the input. Can you elaborate a little more please?

Maximum output level depends on the capability of the output stage, it has to have enough voltage swing capability to reproduce whatever input level x gain requires for undistorted or unclipped output.

[Obrienp]

Reading through this I have gained the impression that you won’t get full power out of most power amps using pedal preamps, because their (preamps’) output is insufficient. However, there are some power amps on the market specifically aimed at pedals, modellers and preamps for guitarists/bassists. Examples being the GRBass Pure, Seymour Duncan Power Stage series, Harley Benton GPA-100, Fryette Power Station, etc. Are these not designed to match the output levels of typical pedal preamps? If not, their marketing promises are very misleading.

 

Personal experience of using the (cheap as chips) Harley Benton GPA-100, is that I seem to be getting the full oomph out of it driven by my Bass Flyrig II into an LFSys Monza. The Monza does seem to have great sensitivity, which may explain some of the apparent volume I get from it. It works fine as a combo for rehearsals and coffee shop/bistro type gigs (our drummer uses an electronic kit, so can be turned down). This positive experience had encouraged me to consider a more powerful (and expensive) preamp like the Palmer Macht 402, or even the GRBass Pure. Reading this thread has made me question whether I might be very disappointed with the resulting output. Any thoughts?

[agedhorse]

9 minutes ago, Obrienp said:

Reading through this I have gained the impression that you won’t get full power out of most power amps using pedal preamps, because their (preamps’) output is insufficient. However, there are some power amps on the market specifically aimed at pedals, modellers and preamps for guitarists/bassists. Examples being the GRBass Pure, Seymour Duncan Power Stage series, Harley Benton GPA-100, Fryette Power Station, etc. Are these not designed to match the output levels of typical pedal preamps? If not, their marketing promises are very misleading.

 

Personal experience of using the (cheap as chips) Harley Benton GPA-100, is that I seem to be getting the full oomph out of it driven by my Bass Flyrig II into an LFSys Monza. The Monza does seem to have great sensitivity, which may explain some of the apparent volume I get from it. It works fine as a combo for rehearsals and coffee shop/bistro type gigs (our drummer uses an electronic kit, so can be turned down). This positive experience had encouraged me to consider a more powerful (and expensive) preamp like the Palmer Macht 402, or even the GRBass Pure. Reading this thread has made me question whether I might be very disappointed with the resulting output. Any thoughts?

Depends entirely on the particular pedal, some can and some can't. If all pedal manufacturers included the necessary information in their specifications, specifically the maximum output level, it would be a LOT easier to determine this.