Impulse responses

I think everyone who tried to record rock guitar these days are familiar with the impulses, used to simulate cabinets, reverbs, and stuff. Now here is a fun idea: if you can record impulse response of a guitar cabinet to catch its signature sound, why not to do it with an old computer? We can easily record sound of Spectrum's internal speaker, and get a very similar frequency response in a DAW, and potentially in a emulator too.

I did this with various lo-fi devices just recently, but I don't have an original ZX to try. So maybe someone could do it? All that is needed is just to record one singular click (like, OUT (254),16 with reasonable quality (better-than-karaoke mic, 44100, 24-bit, minimized ambient noise).