Double Bass How much power?

[dar512]

Here's one I haven't seen addressed yet. How much power do you feel is necessary for amplifying your UB or EUB under different conditions?:

- Quiet bar or restaurant
- Noisy bar or restaurant
- Average size hotel ballroom

Assume that there is no PA available.

 

[drurb]

It is not watts or electrical power that matters. What matters is the sound-pressure level achieved.

Check here and follow the links.

In order to radiate the necessary acoustic power fairly evenly into a large room, you will usually need multiple cabs facing in different directions. That's because a single cabinet, that might be fine for a small venue, would usually be far too directional to be sufficient.

Because the sound has to travel farther in a large room, and because the acoustic power will fall of proportional to the square of the distance traveled, a greater sound-pressure level will be required at the source in order for you to be heard properly in the back of a large room (unless, you've placed speakers back there).

Another factor in achieving the necessary acoustic power is the reflective properties of the room.

Large rooms are also typically occupied by more people who will raise the "noise floor," requiring greater sound pressure level in order to be heard above the din. That is, unless those people are sitting quietly in their seats listening to you.

All of this (and more) combines to make it entirely inappropriate to give an answer regarding how many watts are required in any venue. Suppose you say that you'd like to achieve 85 dB SPL fairly uniformly in a room. One would have to consider all of the factors (and more) mentioned above in designing a system that would do that.

Let me take a stab at a rough practical answer. I'd say that if you built a system that could achieve, say 125 dB SPL, one meter from each of two cabinets, you'd have a system that could cope with a very large variety of rooms. How many watts that will require will depend upon the cabinets themselves and could easily vary by a factor of ten or more depending on which cabinets you choose.

 

[Marc Piane]

I love reading the good doctor's answers to these sort of questions. I don't totally understand but they are always very well written. Thanks.

For me I would use my GK MB 150s in all three situations.

In a quiet bar or restaurant I use it alone.

In a noisy bar or restaurant I would use it alone but have my extension cab (a little carvin 1x10 w/horn) in the car in case.

In a big room I'd probably use both for the reasons drurb describes. More air to move.

In the case of this amp, how does the whole watts/spl thing apply?

 

[dar512]

I understand that watts is a less than ideal measure of output. I specifically did not use the term "watts", but used "power" as a sufficiently generic denotation of oomph so that those who chose to answer could use whatever unit of measure they felt comfortable with.

So.. you could specify the SPL you think is required for the above environments. (Edit - oops. went to read the links and forgot to read the rest of the post. Thanks for putting that bit in.)

However, I'm not convinced that knowing the desired SPL for a particular environment would be particularly useful - yet. I just checked the specs on the manufacturers web sites for five combo amps mentioned in a recent thread. Only SWR had a line for SPL on its spec sheets, and the entries for both the WorkingPro 12 and the Natural Blonde were "N/A".

I'll buy that SPL is a better measure of power. But I don't think it's generally supplied yet. As poor a guide as it is, I bet most folks still use watts to guess whether amp x will work in scenario y.

Found your answer interesting in any case.

 

[drurb]

I understand that watts is a less than ideal measure of output. I specifically did not use the term "watts", but used "power" as a sufficiently generic denotation of oomph so that those who chose to answer could use whatever unit of measure they felt comfortable with.

Well, I naturally assumed that you were speaking of amplifier power. Most people don't ask about acoustic power so sorry if I didn't give you the proper credit.

However, I'm not convinced that knowing the desired SPL for a particular environment would be particularly useful - yet.

Perhaps I can persuade you. Actually, it is the only specification that counts with regard to the question you asked.

I just checked the specs on the manufacturers web sites for five combo amps mentioned in a recent thread. Only SWR had a line for SPL on its spec sheets, and the entries for both the WorkingPro 12 and the Natural Blonde were "N/A".

Most cabinet manufacturers will give you a measure of efficiency. That is, they'll tell you what is the expected output in dB SPL measured at 1 meter with a 1-watt input. You can derive the maximum SPL spec by noting what is the maximum power handling of the cabinet. For example, say you have a cabinet that puts out 103 dB SPL at one watt but can handle up to 250 watts. 250 watts is 24 dB above 1 watt. So you just add that to the 103 dB SPL and you get 127 dB SPL at the maximum power that can be handled.

Now, combos are different. I agree, they are often spec'ed only in terms of watts. My point is that such information is of little, if any, use! Suppose combo manufacturer A tells you that his combo is 250 watts. Combo manufacturer B tells you that his is 1000 watts. Now suppose that manufacturer B's speaker cabinet is 6-dB less efficient than manufacturer A's. That's not an unlikely difference. Guess what? All other things being equal, both cabinets will produce the same sound-pressure level at maximum output! You are, however, likely to pay far more for manufacturer B's combo and it is also likely to be heavier. If you don't get an SPL spec, you're flying blind.

I'll buy that SPL is a better measure of power. But I don't think it's generally supplied yet. As poor a guide as it is, I bet most folks still use watts to guess whether amp x will work in scenario y.

Yes, I agree that most folks who are buying combos use watts as a guide. Given the above, that's not a sound (pun intended) approach.

 

[dar512]

Well, carp. That's going to make finding an inexpensive combo an inefficient task.

 

[drurb]

Well, carp. That's going to make finding an inexpensive combo an inefficient task.

Then again, you have this community that can give you a wealth of information on combos that work well. There are all sorts of threads on just this topic. If you don't find current information and/or you need more information, just ask away!

 

[Chris Fitzgerald]

Most cabinet manufacturers will give you a measure of efficiency. That is, they'll tell you what is the expected output in dB SPL measured at 1 meter with a 1-watt input. You can derive the maximum SPL spec by noting what is the maximum power handling of the cabinet. For example, say you have a cabinet that puts out 103 dB SPL at one watt but can handle up to 250 watts. 250 watts is 24 dB above 1 watt. So you just add that to the 103 dB SPL and you get 127 dB SPL at the maximum power that can be handled.

Now, combos are different. I agree, they are often spec'ed only in terms of watts. My point is that such information is of little, if any, use! Suppose combo manufacturer A tells you that his combo is 250 watts. Combo manufacturer B tells you that his is 1000 watts. Now suppose that manufacturer B's speaker cabinet is 6-dB less efficient than manufacturer A's. That's not an unlikely difference. Guess what? All other things being equal, both cabinets will produce the same sound-pressure level at maximum output! You are, however, likely to pay far more for manufacturer B's combo and it is also likely to be heavier. If you don't get an SPL spec, you're flying blind.

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[KY resident translation]
Listen to a buncha amps with yer ears, then buy the loudest and best soundin one ye kin afford, y'hear? If'n ye can, try 'er on wunna yer gigs before ye payferit.[/KY]

 

[drurb]

Listen to a buncha amps with yer ears, then buy the loudest and best soundin one ye kin afford, y'hear? If'n ye can, try 'er on wunna yer gigs before ye payferit.[/KY]

Yep, great advice-- just go and try 'em out. Oh, but that picture!

 

[drurb]

...

For me I would use my GK MB 150s in all three situations.
...
In the case of this amp, how does the whole watts/spl thing apply?

I tried to get you an answer but I couldn't find any spec for the GK cabinet in terms of it's efficiency. So, here's an example of what dar512 was saying. The amp is 150 watts. That they tell you.

 

[reedo35]

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AAHHH!! My Eyes! My Eyes!!

 

[drurb]

AAHHH!! My Eyes! My Eyes!!

...and now we have it twice on the same page!

"He is a loathsome, offensive brute --yet I can't look away." (from Seinfeld)

 

[fdeck]

Here's one I haven't seen addressed yet. How much power do you feel is necessary for amplifying your UB or EUB under different conditions?:

- Quiet bar or restaurant
- Noisy bar or restaurant
- Average size hotel ballroom

Assume that there is no PA available.

Here is what I use:

Small rig: GK MB150E combo
Big rig: GK Backline 600 with DIY 1x12 cab

The relative sensitivity of these systems is graphed in the little report at my web page. I can't vouch for the absolute SPL scale, but the big rig can probably get about 6 dB louder than the little one. The price is portability, of course.

I have been bringing the bigger rig to "noisy bar" gigs. One other factor to consider is regional. Judging from many threads about amp power, I conclude that jazz gets played loud out here in the Midwest. I wear plugs for a lot of gigs.

Despite technological improvements discussed in other threads, the big rig is still powerful enough to go way beyond the threshold of feedback with my particular bass. Thus I depend on a magnetic pickup for the loudest gigs. For instance I have backed up loud big-bands, and also, I end up at a lot of wedding and corporate that turn to pop music after the first set. But my point is that more than enough power is simply wasted if you can't use it because of feedback.

And also for the same problem of feedback, there are cases where you might end up with more useable acoustic power if you have a smaller speaker, so you can benefit from creative positioning of the cab to combat feedback.

 

[dar512]

Then again, you have this community that can give you a wealth of information on combos that work well. There are all sorts of threads on just this topic. If you don't find current information and/or you need more information, just ask away!

The problem with searching through the threads for recommendations is that most posters here seem to be pros or at least buy like they're pros. I'm an amateur. I've got a large mortgage, two kids headed off to college in a couple of years, and our retirement to consider.

I have a head and cab that works for me, but I'm considering a combo to save me some manual labor setting up and tearing down. The head is a 300W Behringer. I've never had it even halfway turned up, so power-wise it's overkill for me.

If I can find something inexpensive (read incredibly cheap) that sounds as good as what I've got now, I might decide it was worth the money to save myself some effort.

So the question is, how cheap can I get and still get decent power and sound?

BTW, I know Behringer stuff is sneered at in some quarters, but I've found this head to be reliable and transparent sounding - when all the rock garbage is turned off.

 

[drurb]

Okay, fair enough. If we're talking budget, then despite all the sneering, I have had good results from a little Behringer combo. Their new ones represent even more bang for the buck. Again, despite all of the ill-will against Behringer, some of which is well-founded, the performance to price ratio they represent is rather large. I am not going to go near the ethical issues. Their BXL 1800A can be had for all of $250. No, it isn't going to sound like an AI, and EA, or a GK but I figure you know that.

 

[dar512]

I am not going to go near the ethical issues.

I'm not familiar with this. And it might move me in another direction. Can you expound or point me to more detail?

No, it isn't going to sound like an AI, and EA, or a GK but I figure you know that.

Probably not. I'm not always convinced that more expensive is better. But even if these are better, are they $500-$700 dollars better? I guess if you make your living from playing they might be.

In my situation, I'm not sure I want my ears to know. I once made the mistake of listening to a very high end stereo system...

 

[drurb]

I'm not familiar with this. And it might move me in another direction. Can you expound or point me to more detail?

Oh, just do a search here. PM me if that doesn't work.

Probably not. I'm not always convinced that more expensive is better. But even if these are better, are they $500-$700 dollars better? I guess if you make your living from playing they might be.

In my situation, I'm not sure I want my ears to know. I once made the mistake of listening to a very high end stereo system...

I agree that there are diminishing returns. My current EA rig costs over 5x what my little Behringer did. Is it better? You bet! Is it five times the sonic value? I don't think so. The same holds true in high-end stereo (and some extremely high-priced gear borders on fraudulent, IMO). Then again, my stereo system speakers went for more than some people pay for a car.

 

[dar512]

Supposing I want to avoid the Behringer stuff. Some folks have spoken positively about the GK Backline 110 and 112. Any opinion on those, drurb?

 

[drurb]

Supposing I want to avoid the Behringer stuff. Some folks have spoken positively about the GK Backline 110 and 112. Any opinion on those, drurb?

No first-hand experience but see post #13.

 

[Greg Clinkingbeard]

Supposing I want to avoid the Behringer stuff. Some folks have spoken positively about the GK Backline 110 and 112. Any opinion on those, drurb?

I tried both of these once at the local Guitar Center and thought they were total crap. A used SWR WM10 would be a better choice.