Bass amp

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Permalink Reply by Toni on November 3, 2010 at 4:26pm

It can be done either way round, but there's lots of factors that affect how well the amp & speakers will cope.

Generally speaking a guitar should always be fine through bass gear, though it may sound pants. I repaired a friends ancient Laney bass amp a few years back, and trying guitar through it was horrible. Conversely playing guitar through my Hartke HA3500 and a 1X15 cab sounds really surprisingly good, although it's a heavy old pair to lug around.

If you care, there's 2 reasons not to play bass through an *unsuitable* guitar amp:

The output transformers in a valve amp are designed to carry a certain amount of current, and the amount of current a note will cause to be drawn through the OT is related to it's frequency: the lower the note, the more current. This heavy draw is why bass notes often sag, while mid and high frequency notes do not. Many guitar amps use OTs that are deliberately on the limit so that they saturate more easily, providing compression, distortion and warmth when driven near their normal limit. Using a bass with such an OT will try to draw more current than it is designed for, and *may* cause failure, depending on the design of the rest of the amp.

The other reason is speaker excursion. Low frequencies will cause the cone of a speaker to move further than higher frequencies, and playing bass through guitar speakers in an open cabinet will cause the speakers to quickly exceed their maximum travel and damage them. Some 'guitar' speakers can cope with 4 string bass when placed in sealed cabs - the cab provides a cushion effect, preventing the speaker cone travelling too far - and example would be the Celestion G12H. Purpose designed bass speakers normally have a much longer designed travel limit (x-max) to enable them to cope with low frequencies, and require a specific cab design to match each speaker's characteristics. This provides the best tonal response without risk of damage. Speaker cab design is enormously more inmportant for bass than it is for guitar, where you can more-or-less stick whatever speaker in a box, and it will be fine.

Now this is WAY more than you wanted to know.

And your bass amp should be HONOURED to have a nice guitar go through it. ;-)

Permalink Reply by Jon Wolske on November 6, 2010 at 12:17am

Yeah, there is a lot more to it than simple answers can give.

Playing bass through a guitar amp and keeping an eye on the input/output levels and EQ boosts can yield a very pleasing result ( or a naturally distorted tone that may be appropriately pleasing to some) . many times when jamming at home I plug my active bass into the -6dB input on my crate 12" open back guitar combo and turn the boost/cut knobs on the bass to center and play along with new material. It is a solid state combo, so it does the job for low-level playing.

Plugging a guitar into a bass rig makes my spine shake. First-off, the preamp is designed for an instrument that doesn't contain the same amount of high frequencies, so the EQ centers are not generally very good for guitar, and playing an electric through a tweeter is like running your finger nails down a chalkboard... now, if you are playing an acoustic with a built-in EQ (and the amps EQ flat) then I could see that as a reasonable option...

Amps dont blow up from frequencies. Speakers may, if frequencies beyond their design are pushed too hard (bass through a guitar amp with a lot of bass boosted, etc...) but it really comes down to correctly matching the amps output to the speaker. Some guitar amps use low powered speakers to get a bit of speaker break-up in the louder distortion sounds. Bass amps use high-powered speakers that can handle (hopefully) more than what the amp can dish, because most bass players are looking for a nice clean, full sound.

Open back speaker cabs are only so-so for bass if the amp is trying to fill an area larger than a small stage. That same cab can sound great for guitar. Bass cabinets tend to have a bit more design that goes into them as far as the cubic space and port size/placement.

it could get a lot more technical, but this is my two cents. Like anything, in moderation and with the right control, anything could be played through anything...

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