Re: Bass amp for beginner
How many watts would you recommend?
I assumed if anything you needed less power, as Basses put out a much larger output to start with. I guess that's what I get for assuming. XD
Fender rumble looks good, and I was looking at Peavy and Orange "Crush" amps for the price
TL;DR in bold.
The output of the bass instrument compared to the amp is a rounding error, just as it is for guitar; the peak signal you get from even the hottest bass with onboard preamp is a couple of volts, max, and that's being fed into an amp head with an impedance in the hundreds of thousands of ohms, so the actual current (and therefore power) of the signal loop is in the low milliwatts.
Without getting into an undergraduate lecture on acoustical engineering, bass amps need more power to produce the fundamentals of their instrument because they are working against two fundamental laws of acoustics. First, speakers, even bass-oriented ones, start to "bottom out" and produce lower-pressure sound waves at frequencies less than about 100-150 Hz (depending on even more variables in speaker design and construction), because the speaker cone simply can't push enough air hard enough at the lower frequency to create the needed pressure differential. Second, human perception of volume favors frequencies centered around the 3-4kHz range (the majority of human speech frequencies), and we are less sensitive to frequencies further from that range, to the point that it takes 15dB higher sound pressure level at 100Hz to sound as loud as 1000Hz. All things being equal that's about 40x the pressure of the higher frequency, requiring increased energy on the square of that pressure, using a speaker that gives you diminishing returns. This is why a guitar stack can slick your hair back at 100W while an equal power bass amp will be completely drowned out.
All is not lost, however. That's just the energy required for the fundamental frequency. Bass guitars produce an array of higher harmonics just like guitars do, and these higher frequencies benefit from increased perceived loudness and better response sensitivity from the speakers. These help make up some of the volume difference, so that you don't actually need 100 times more amp than your guitarist to produce a sound of the same perceived volume. In addition, bassists tend to get help from the PA system "earlier" (at smaller venues, lower overall stage volumes) than guitarists.
So, exactly how much rig you need for a gig depends on the genre, the venue, and the band. I generally recommend the following basic formula:
1. Sum the peak power ratings of your guitarists' amps. If your lead player has a 50W and your rhythm player a 30W, that's 80W.
2. Add the RMS power rating of any other stage amps besides the house PA, such as keyboards.
3. If you have a drummer, divide what you have so far by the number of people using amps and add that number into the sum.
So if you have two 30W guitar amps, a 50W keys amp and a drummer on stage with you, you'll end up at about 150W.
You will need at least this much power to hear yourself on stage, and between double and four times this power going out to the audience in a combination of your stage rig and the house PA in order to mix well. So, if the PA is vocals only and the rest of the stage is as I have described, you'll want anything up to a 600W system depending on how hard everyone else is pushing their rig, and you'll want to feed that through as many speaker cabinets as the amp (and your back) will support. God help you if you're competing against two cranked 100W Marshalls with zero PA support. Usually, however, you won't be forced to; guys who've been around the bar circuit more than once and are still getting invited to clubs will be using appropriately-sized and powered amps, lessening the requirements for yours, and anywhere 100W Marshall full stacks are appropriate on stage, you'll have all the help you need from the PA (though you might still be expected to have your own fridge even if it's just for show).
Now, all that said, you're practicing in your bedroom against your computer speakers, a shelf system at best. Even 100W is overkill in this situation. But, bass amps are designed to be run clean; unlike guitarists, you don't have to match your amp power to the actual desired volume level so that when the amp's at the right amount of breakup for your sound, it's also at the right volume. Bass amps are designed to do what they do cleanly at any volume they're capable of (which is why solid state is desirable and even preferred in the power amp stage if not the preamp), and that means you can always turn down the master level and get less of the same sound. So,
as much power as you can afford, turned down to what you actually need in any given situation, is usually the order of the day for bassists.
I would recommend your first amp be somewhere in the 100-150W range. The Rumble 150 is plenty of amp for the bedroom and should also work for garage practices with amplifiers in the 10-30W range. Personally, I like what was being made a generation or two prior to the current Rumble series, such as the silverface Bassman amps, Peavey Combo and BAM series, etc, which are just a little more than your current budget on the used market and worth every penny. My first real gig-worthy bass amp was my Peavey Combo 210TX; 210W by itself, which increases to 300W with the extension cabinet, and by then you're essentially playing through a 4x10 half-stack. I'm currently using something a bit smaller, a Bassman 150 1x12 tiltback, which still has plenty of juice to back the acoustic groups I normally play with now (and it fits the average passenger sedan back seat or trunk without nearly as much fuss as the 210). The Bassman also has a built-in DI with XLR out and a level control independent of the power amp stage, and I plug this into a rudimentary home studio with headphone monitors to get the tone of the preamp at practically zero audible volume (can't beat silent for bedroom practice). You can score either of these amps on the used market for between $200-$300 with a little looking around.
