Class D amp settings

[PWRmx24]

Getting ready to set up my Class D Buckeye Purifi amp. There's low, med, high gain settings on the back. Any thoughts on how to determine best gain setting?

 

[PWRmx24]

My Rotel RSP-1570 pre-amp manual says: s/n ratio (IHF A-weighted) 95 db (analog bypass) 92 db (Dolby Digital, dts) 0dBFs; input sensitivity/impedence: Line Level 200 mV/100k ohms; Pre-amp Output Level/Output Impedence: 1.0V/1k ohms; Contour (LF/HF) +- 6 dB at 50 Hz/15kHz. The amp spec says s/n 137dB; 4 ohm 25dB/2.2Vrms (high), 20dB/3.9Vms (med), 15dB/6.9Vrms (low). Is it better to let the amp or the pre-amp do the "gaining"? I guess it depends if the s/n gets worse as you turn the knob on the pre-amp???

 

[Steve81]

Hello there. The goal is mostly to find the balance between the preamps clean output capability and system noise while achieving full output from your amp. I’d start with high gain, and move down to medium and see how noise levels compare. If no appreciable difference, don’t sweat it.

 

[Golfx]

Hello there. The goal is mostly to find the balance between the preamps clean output capability and system noise while achieving full output from your amp. I’d start with high gain, and move down to medium and see how noise levels compare. If no appreciable difference, don’t sweat it.

I agree with this.
Theoretically, high gain “may” let you hear hiss from your speakers (from the preamp’s electronics). If so, try the lower setting until you hear less or no hiss.
I use high gain as I can not hear any hiss.

 

[CherylJChristman]

My Rotel RSP-1570 pre-amp manual says: s/n ratio (IHF A-weighted ultimate tic tac toe ) 95 db (analog bypass) 92 db (Dolby Digital, dts) 0dBFs; input sensitivity/impedence: Line Level 200 mV/100k ohms; Pre-amp Output Level/Output Impedence: 1.0V/1k ohms; Contour (LF/HF) +- 6 dB at 50 Hz/15kHz. The amp spec says s/n 137dB; 4 ohm 25dB/2.2Vrms (high), 20dB/3.9Vms (med), 15dB/6.9Vrms (low). Is it better to let the amp or the pre-amp do the "gaining"? I guess it depends if the s/n gets worse as you turn the knob on the pre-amp???

Great!The information is of excellent quality.

 

[PENG]

My Rotel RSP-1570 pre-amp manual says: s/n ratio (IHF A-weighted) 95 db (analog bypass) 92 db (Dolby Digital, dts) 0dBFs; input sensitivity/impedence: Line Level 200 mV/100k ohms; Pre-amp Output Level/Output Impedence: 1.0V/1k ohms; Contour (LF/HF) +- 6 dB at 50 Hz/15kHz. The amp spec says s/n 137dB; 4 ohm 25dB/2.2Vrms (high), 20dB/3.9Vms (med), 15dB/6.9Vrms (low). Is it better to let the amp or the pre-amp do the "gaining"? I guess it depends if the s/n gets worse as you turn the knob on the pre-amp???

It depends on your speaker's sensitivity, and your listening habit, that is, distance, max spl you need at your mlp.

Based on the RSP-1570 pre out spec alone, you most likely need to set the buckeyeamp's gain to high. Even then, you may not be able to get to its max rated output. "may", or may not, because we don't know what is the maximum rated output of the RSP-1570, spec says 1.0 V but that likely is not the maximum.

1 V from the Rotel will only get you about 80 W into 4 ohms or 40 W into 8 ohms. That is likely enough for real world music listening depending on things mentioned above but is not even close to the buckamp Purifi based amps rated output.