Charles1dad 12-30-2017
I believe most if not all BAT power amplifiers have input impedances of 100K ohms.
Right you are, Charles, as usual!
Repeter, as Charles indicated the input impedance of your amplifier is spec’d at 100K (much higher than the input impedances of the majority of solid state amps). And the input impedances of many and perhaps most JL subs are spec’d at 50K unbalanced/10K balanced. So provided that you are using balanced connections between the preamp and power amp and unbalanced connections to the subs impedance compatibility is probably not the **major** contributor to the issue. Although it nevertheless is probably contributing significantly to the bass issue you described, given the **extremely** high 14K balanced output impedance of the preamp at 20 Hz (assuming the Six-Pak option is not installed), and given that the 100K and 50K loads together constitute a load of 33K. 33K/14K is a ratio of about 2.4, far short of the generally accepted rule of thumb guideline of a minimum ratio of 10 at all audible frequencies. With the consequences of that shortfall being particularly compounded by the wide variation of the preamp’s output impedance over the frequency range.
Also, it is still quite possible that if the cables to the subs are particularly long and/or if they have high capacitance per unit length their capacitance could be affecting the upper treble content of the signals received by the BAT power amp.
Regarding ...
Repeter 12-30-2017
Cabling from pre to power amp would be Nordost. Could these long (2 meter) flat silver (Ag) play into flat/dull performance at low volume? FYI, I used them to drive my Sophia 3s and Geoff Poor (BAT) recommended the massively improved Audioquest CV-8s. So.. Could driving my power amp with these be a weakness?
... I’m not sure I follow this. I thought the CV-8 is a speaker cable. And what specific model are the Nordost interconnects?
Regards,
-- Al