Demo amp

[vprjs]

Hi there. I want to build a sort of "demo amp". I want to use it to try circuits on a breadboard. I found 4 inch regular speaker. And want to put a ruby amp inside. Do I need to add a low pass filter to this circuit to cut "non-guitar" high frequencies?

[mauman]

IMHO, adding a low-pass filter isn't necessary. The Ruby has a pretty flat frequency response on the high end, but your 4-inch speaker will probably have a steep roll-off above 10-12 kHz or so. Here's the Electrosmash Ruby frequency response analysis, and the response of an Eminence Alpha 4-inch speaker for comparison.

Ruby response from Electrosmash

Alpha 4-inch speaker response

[plush]

IMHO, adding a low-pass filter isn't necessary. The Ruby has a pretty flat frequency response on the high end, but your 4-inch speaker will probably have a steep roll-off above 10-12 kHz or so.

It's overall a good design practice. Lowers power draw a little bit and prevents the circuit from possible oscillations and other rf-related issues.

[vprjs]

Alpha 4-inch speaker response

Strange, I thought guitar speakers cut frequencies after 4-6 kHz.

[mauman]

Alpha 4-inch speaker response

Strange, I thought guitar speakers cut frequencies after 4-6 kHz.

Depends on the speaker, you're using a 4 inch speaker rather than the more typical 8, 12 or 15 inch in guitar cabinets so I pulled a 4-inch frequency response. You can compare a lot of different (Jensen) frequency response models at https://www.jensentone.com/frequency-re ... comparison .