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Double Bass How much power do I need from an amp?

droo

droo

Nov 1, 2004
75
0
Oxfordshire, UK
www.milloy.co.uk
#1
I'm in need of a small amp to boost my sound when doing small-ish jazz gigs (in a trio w/piano + vocals).
I just wanted something low-cost which would carry the low end all the way to the other end of the room... just "Sound Reinforcement" really.
I tried out a few with my DB (50s Hybrid with a Shadow piezo pickup) and settled on a Roland Cube 30 - with and without my Fishman preamp... most of the others were too tinny-sounding, even with the preamp.

It was quite pleasingly punchy for such a small amp
Trouble is I'm concerned that 30 watts isn't going to be enough... especially if I start adding a drummer to the equation.

I am from a slab background, where my main rig has a 2x250W head - so 30W sounds very small :)

Anyone have any comments about how much power you need from an amp for a smallish jazz combo?
 
#2
It depends on your playing style, your bandmates, the cab, etc.

In my opinion there's almost no such thing as too much power. The more watts, the deeper, fuller, and more controlled the bass. I use an AI Focu s power amp that puts out 600 watts. But it's very pricey and you pay a lot for light weight. The conventional stereo power amps, like the QSC PLX series, are heavy and bulky but cheaper

I used to do a lot of gigs with an SWR working man's ten--a single ten inch speaker, 90 watts.

But I'd say 200 watts is a good minimum--not because you want to get really loud, but because you want it to be clean and controled
 
#3
I agree with PB+J. A drummer will suck up the 30 watts with the first drumbeat. I use a 150-watt Gallien Krueger MB 150 (which, as I understand it, only puts out 100 watts unless you add an extension speaker). So I've got effectively 100 watts, and it works for quiet-to-medium volume gigs, but is not very useful for a DB in loud gigs like a big band. I don't know the details of your particular situation, but I'd say 100 to 150 watts should be the minimum you should look at.
 
#4
+1 about the MB150. Your understanding is correct. In my locale, I can keep up with most kinds of combo jazz, even with drums, using my MB150 combo. This even extends to big-bands if I don't mind that there will be sections of tunes where the band is temporarily louder than the bass.

When I need more power, it is usually predictable, and I bring a bigger amp. This can be situations like casuals in large rooms without sufficient PA support, or if I happen to know that a "jazz" gig will end up being mostly pop and blues.
 
#5
Cool - this is all good stuff. I hadn't considered big band to be honest but thats a good point - with 10-15 horns blaring as well as a drummer I would have no chance.

I think I'll try and swap it for something that can put out 100W - and fall back on my bigger rig for large gigs (should they start flooding in ;)) - it does sound quite pleasant with the DB, I think the 8" drivers work quite well with it.
 
#6
slight thread hijack, apologies.

Droo how do you manage with the fan noise from the Hartke?
I have one of the older 3500 heads, and while i really like the sound through a homemade single 8inch cab, the noise from the fan drives me mad.

That may be a consideration if you intend to use the Hartke a lot for doublebass.
 
#7
Thomas Stone said:
Droo how do you manage with the fan noise from the Hartke?
I have one of the older 3500 heads, and while i really like the sound through a homemade single 8inch cab, the noise from the fan drives me mad.

That may be a consideration if you intend to use the Hartke a lot for doublebass.
Click to expand...

Hi - I actually rackmounted it in the end, in a 2U rack case. This cuts it down quite a bit.

(I think the way I have it now - if the gig was small enough for the fan noise to be an issue, then I would want to use a smaller amp I think!)
 
#8
the output of the GK 150MB is widely exaggarated here and elsehwere. almost mystically.

the roland cube 100 is louder. the SWR WM 10 is louder.

i believe the cube 30 is in the same league with the GK. havent ABed them yet, though. the 30 vs. 100 watts thing as such is neglegible. with the same speaker it would be just a bit louder.

bang-for-the-buck-wise go for roland.

i am not a friend of using big rigs for DB unless really necessary. deep and powerful bass response is nice for BG but often creates problems with DB.

there is a reason why almost every DB player owns some small combo.


again: 30 or 100 watts says about NOTHING.
 
#10
I did a little a/b testing this weekend while looking for a solution to my own amping needs. I tried the roland cube 100 compared to the new fender bassman 100. I walked away thinking that I'll probably go with the fender. I'm just waiting for the new SWR workingpro 10 to come into the shop so I can compare it to the fender, since I used to have a workingmans 10, and was happy with it (for what it was).

JMO
 
#11
snowdan said:
again: 30 or 100 watts says about NOTHING.
Click to expand...
+1, and thanks for the reminder! A loss of 5 dB in speaker sensitivity would completely eat up the power gain going from 30 to 100 W. According to my crude measurements, the MB150 combo speaker has roughly 93 dB sensitivity in the midrange, a 3 dB hump centered at 100 Hz, and 12 dB/octave rolloff below roughly 85 Hz. According to comments from experts on the EB forum, this hump is associated with "loud bass," so it's not a bad design given the space constraint.

It seems unlikely that the 10" speaker in the Roland Cube has much more sensitivity than the GK. My take on the MB150 combo is that they tackled the job of cramming gig-worthy sound into a cubic foot of space, and their design has stood the test of time. "Obvious" improvements all have their drawbacks. If not by the laws of physics, then probably by the laws of practicality, louder requires bigger.
 
#12
mje said:
The little GK combos give up a lot of efficiency to get low bass out of a 12" speaker in a tiny cabinet. A more modern, efficient cabinet will be a lot louder with less power. Consider that the Ampeg B-15 was only about 40 watts.
Click to expand...

+1 Believe it or not, Ampeg actually it's earlier models at 25 watts. The Portaflex cabinet was a very efficient design. A great pre amp and an efficient cabinet will
go a long way to producing the sound of the DB. It's nice to have lots of available headroom but since you can only amplify an acoustic bass to moderate levels
before it begins feeding back or sounds unnatural the extra wattage may not be completely useful. I actually used to use a Walter Woods MI-100-8 connected to two Ampeg
B-15 Cabinets and it sounded very nice. It wasn't very loud, but it didn't have to be.

Ric
 
#14
fdeck said:
...A loss of 5 dB in speaker sensitivity would completely eat up the power gain going from 30 to 100 W. According to my crude measurements, the MB150 combo speaker has roughly 93 dB sensitivity in the midrange, a 3 dB hump centered at 100 Hz, and 12 dB/octave rolloff below roughly 85 Hz. According to comments from experts on the EB forum, this hump is associated with "loud bass," so it's not a bad design given the space constraint...
Click to expand...
The bump at ~100Hz is a consequence of putting the speaker in a smaller than optimum box. The LF rolloff is more likely 6 dB per octave which is typical of sealed speaker enclosures. I have a GK 112MBX, and there is easily a 10 dB difference in sensitivity between it and my EA Wizzy cab which has a rated sensitivity of 103 dB @ 1W/1M.
 
#15
robgrow said:
The bump at ~100Hz is a consequence of putting the speaker in a smaller than optimum box. The LF rolloff is more likely 6 dB per octave which is typical of sealed speaker enclosures. I have a GK 112MBX, and there is easily a 10 dB difference in sensitivity between it and my EA Wizzy cab which has a rated sensitivity of 103 dB @ 1W/1M.
Click to expand...

From what I've read, a sealed box will have a second order rolloff- 12dB/octave- below the -3dB point.
 

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