Bass Amps / Cabs (or) Combos and their frequency response

jaymenon

On a bass guitar the low open E is 41.2Hz and open B string is 31Hz.

Reading up on the specs of various bass amps. many with reasonable size drivers (eg. 2 x 10" and 2 x 12") quote a range of 40 - 18,000Hz (with a tweeter obviously). One 1 x 15" enclosure quoted 35-18,000Hz.

And yet some smaller amps quote a frequency response of 30-18,000Hz.

What's happening here? Do these smaller amps really reproduce (faithfully) the open B string?

fretmeister

Some do.

My ancient Roland bass cube is excellent at low b.

but do be aware that the human brain fills in a lot of information that might actually be missing. 

ICBM

The classic example of this is the original Ampeg 8x10" cab from the early 70s - in those days the typical 15" and 18" speakers could theoretically handle the lowest frequencies better, but because they, the cabinets and the amps themselves had low damping factors, the result was a farty mess with no definition which absorbed a lot of power but did nothing very useful - or worse, had a sudden cut-off below the speaker's resonant frequency where the notes simply disappeared. The SVT cab was designed specifically to have a much higher damping factor - all eight speakers are in parallel, they had to use special 32-ohm drivers to achieve that - and in four sealed 2x10" boxes inside the 'refrigerator'. The result is that it rolls off the lowest fundamentals, but smoothly and retaining much better definition even below the resonant frequency, so the result is tight, loud, and punchy - and the human brain fills in the missing bottom frequencies so it actually sounds like it has *more* low-end power than the old-fashioned cabs.

Speaker and cab technology has come on a long way since then too - you can now get even smaller speakers than 10" which have very serious low-end response, because the cone travel has been increased far beyond what would have been possible in the 70s. Even though the frequency response may be listed as cutting off at say 40Hz, that's simply where it goes to -3dB compared to the average - that's still half the power output, and if it's done smoothly you will barely notice. Many modern cabs are also tuned-ported, which means the cut-off frequency is even lower - although there is then a more sudden drop below that it doesn't matter since it's then outside the useful range.

Funkfingers

jaymenon said:

On a bass guitar, the ... B string 

The what?

jaymenon

Unfortunately with my limited vocal range I need to take songs in lower keys than these famous Alto singers :-)

The B string then comes in handy...!

ICBM

You can always tune a 4-string BEAD, you don’t really need the tinny little high notes on the G string anyway .

(I did briefly try a 5-string, by the way... it’s now up for sale as it contravenes the Lord’s commandment for bass .)