B1 bandwidth 700kHz -3dB: what's the limiting factor?

[ringing]

In the original Pass B1 document, 2008, it reads that the B1 amp does 700kHz -3dB.

Is this bandwidth limited by the JFETs' bandwidth, or by huge power supply capacitors' bandwidth?

I notice that the original B1 does not have very small bypass caps in the power supply. So I am wondering how bandwidth will extend if very small film and ceramic bypass caps are used in the power supply (physically placed near the JFETs).

Note: My question is NOT about sonic effect (or sonic uselessness) of making bandwidth wider beyond 700kHz.

 

[AndrewT]

The input uses the input R and the capacitance of the jFET to create an RC filter.

 

[ringing]

Toshiba 2SK170 spec: input capacitance 30pF.

30pF, 1kOhm RC low pass filter has -3dB point at 5MHz. Far above 700kHz.

 

[BDP]

I could be wrong, but I think you have to account for the input pot.

 

[knutn]

I could be wrong, but I think you have to account for the input pot.

This is right, so if you uses a 10k pot, you may double the bandwidth.