Need help understanding power ratings...

[bassickman]

I always look at heads and cabs but never know what will work with what power wise? And do tubes make a difference?

[Jack]

Meh, it's really not all that important. Tubes do not make a difference other than that they tend to sound awesome when running at full tilt whereas solid state does not so you can get away with a less powerful tube amp.Why are you asking?

Edited May 30, 2012 by Jack

[Lozz196]

Mmmmmm, a can of worms to be opened, methinks.

Everyone has their own opinions, and it`s all down to their needs, and likes. For me, I don`t like single speakers, preferring at least two separate speakers, but preferably a 4x10. Power-wise, I prefer to have a lot of power I know I won`t need, so as to not push the amp. So my ideal is 500 watts and a 410. I`ll never need this, but I just don`t like running amps flat out, and prefer the depth of sound generated by multiple speaker cones.

[GregBass]

OK there are a few rules that make for a good match:

Ideally speakers should have a higher power rating than the amp driving them (check the amp power at the appropriate impedance for the cab)

Always have an amp with plenty of power output. If you drive the amp to its limits, it will clip (the tops and bottoms of the waveforms are flattened, which effectively puts DC across your speakers for a short period)

Check the frequency bandwidth of your cabs - down to 30Hz is what you should be looking for to give deep bass (all decent bass amps do this so you shouldn't need to check the amp).

Valves and transistors produce different harmonics (higher frequency "overtones" of the fundamental frequency). To most people's ears, valves produce a warmer tone.

[JTUK]

A quick generalisation that works for me.

For a loud band needing to produce at times without FOH, then a good 300watts is required.
Any 410 should be able to handle that sort of volume and the better ones, at least twice that

So, the default age old rig would be a TE amp and 410. This is old, tried and tested and bombproof.
A lot of more modern rigs should be able to p** all over this, but the TE is still going after 20 plus years...and that is not to be sneezed at, IMO. and cheap as chips.
Ditto, PV but down a level, IMO.

Current faves are Markbass which is solid. Good quality and SH prices make it worth a look. A bit Marmite-ish tho...maybe.

Mesa and Ampeg get their kudos from their big valve jobs that used to be the main stay of large stage rigs..all valve and oomph.. EQ is ..err...??? ..basic.. .but valve power is THERE.
Step up and plug in and most will love it..they just can't justify lumping it around..EXPENSIVE to own.

Hybrids..they try to get the valve tone witha vlave in the pre amp with a SS power stage.
SWR and Eden did this well and these rigs became the staple rig for pros from the 90's.. bollocking cabs to match and they raised the bar for on stage bass monitoring.

Today..?? the valve is still there and will not go away... but simulation is there as well to get that sound, in the form of pedals and valve pre amps.

Additional current players in the semi pro game are Genz Benz, GK, and Ashdown. there are others, of course, maybe Hartke and the like.
The build of MANY of these amps has moved to the Pacific rim and China...which makes them cheap...but..??

For the benefit of the OP..I've tried to point out a very brief ball park summary of stuff..the type of thing that most bass players have come across in their time.
Not difinitive by any means but you have to have some sort of experience to second guess this.

[chris_b]

You're asking a lot of questions (which is good, don’t stop) and as you can see there is every shade of opinion. A lot overlap, some clash and there is the friction caused by disagreement. So who do you believe? It's not as simple as it seems.

Do you play in a band? Do you gig?

I think at this point you probably need a good second-hand rig that you can play while you formulate your own opinions through your own experience. Upgrade paths will suggest themselves while you are building up your own knowledge.

[xgsjx]

Hahahahahahahaha.

Get what sounds good to you is the best advice to go with. Music shop is a good place to try stuff.

[Mr. Foxen]

[quote name='GregBass' timestamp='1338370850' post='1673315']
OK there are a few rules that make for a good match:

Ideally speakers should have a higher power rating than the amp driving them (check the amp power at the appropriate impedance for the cab)

Always have an amp with plenty of power output. If you drive the amp to its limits, it will clip (the tops and bottoms of the waveforms are flattened, which effectively puts DC across your speakers for a short period).

Check the frequency bandwidth of your cabs - down to 30Hz is what you should be looking for to give deep bass (all decent bass amps do this so you shouldn't need to check the amp).

Valves and transistors produce different harmonics (higher frequency "overtones" of the fundamental frequency). To most people's ears, valves produce a warmer tone.
[/quote]

Dunno if you are trolling on purpose, but pretty much all of this is wrong.

Valve amps totally do make a massive difference, its more to do with the output transformer acting as a high pass than the valves themselves, but it means your power is massively more efficiently used and your cabs are less stressed, so you can get louder without farting out.

Main thing to o is start by being clear in what you want to achieve. Also ignore anyone who says a bunch of stuff from the above quote.

[Balcro]

The power rating for matching amps to cabs is to only recognise "Watts RMS" (I believe this is also similar to AES). There will be specific figures for amplifier output into 4 or 8 Ohms. Amplifier output into 4 ohms will be greater because it's a lower resistance, but in volume terms the difference will be insignificant for bass.

Take no notice, REPEAT, take no notice of "Peak power" or "Program" power.

Balcro.

[GregBass]

[quote name='Mr. Foxen' timestamp='1338376982' post='1673452']
Dunno if you are trolling on purpose, but pretty much all of this is wrong.

Valve amps totally do make a massive difference, its more to do with the output transformer acting as a high pass than the valves themselves, but it means your power is massively more efficiently used and your cabs are less stressed, so you can get louder without farting out.

Main thing to o is start by being clear in what you want to achieve. Also ignore anyone who says a bunch of stuff from the above quote.
[/quote]

Wow, man, you are really aggressive on here aren't you?

So let's get this straight. You reckon it's OK to use a 25W speaker with a 500W amp? Do your speakers last more than a few weeks?

You reckon that driving an amp to saturation doesn't cause clipping? That clipping is not "flattening off: at the peaks of the waveform? That valves don't sound "warmer" to most people?

Congratulations - you have just rewritten the rules of science all on your own. maybe a Nobel prize comes next.

For the OP - if you follow what this man says you will blow your speakers at the very least.

[Mr. Foxen]

[quote name='GregBass' timestamp='1338382198' post='1673580']
Wow, man, you are really aggressive on here aren't you?

So let's get this straight. You reckon it's OK to use a 25W speaker with a 500W amp? Do your speakers last more than a few weeks?

You reckon that driving an amp to saturation doesn't cause clipping? That clipping is not "flattening off: at the peaks of the waveform? That valves don't sound "warmer" to most people?

Congratulations - you have just rewritten the rules of science all on your own. maybe a Nobel prize comes next.

For the OP - if you follow what this man says you will blow your speakers at the very least.
[/quote]

Its ok to use any amp with any speaker if you aren't an idiot about it. I've had one speaker develop a voice coil run in all the time I've been playing really loud bassy detuned music, and that was likely to do with storage conditions.

Clipping doesn't cause DC, and doesn't upset bass drivers. I run my amps in clipping all of the time.

Pretty much no commercial bass cabinets go as low as 30hz, and it isn't a useful frequency for bass guitar anyway.

There are various benefits to valves, and a bunch of them are down to clipping. And a bunch of the others are down to the properties of the output transformer, in particular its ability to filter out extremely low frequencies.

[GregBass]

[quote name='Mr. Foxen' timestamp='1338382649' post='1673591']
Its ok to use any amp with any speaker if you aren't an idiot about it. I've had one speaker develop a voice coil run in all the time I've been playing really loud bassy detuned music, and that was likely to do with storage conditions.

Clipping doesn't cause DC, and doesn't upset bass drivers. I run my amps in clipping all of the time.

Pretty much no commercial bass cabinets go as low as 30hz, and it isn't a useful frequency for bass guitar anyway.

There are various benefits to valves, and a bunch of them are down to clipping. And a bunch of the others are down to the properties of the output transformer, in particular its ability to filter out extremely low frequencies.
[/quote]

So you haven't blown your speakers while not power matching them - good. Just to complete the picture, the power handling of the speakers in my rig is currently double what the amp can kick out at full blast. Guess what - I haven't blown any of the speakers either. Does that actually prove anything? As a general rule, I would say it's a decent idea to make sure your speakers can handle the power you intend to kick out of the amplifier. The simplest way to do this is to look at the power ratings, and make sure that the amp is not going to be chucking out more than the speakers are rated to handle. As a sort of rule of thumb, I hardly think that's contentious.

Clipping is EXACTLY putting DC in short bursts across the speaker. Think of the theory. Consider a sine wave. When it clips the top of the waveform goes flat - that's basic waveform analysis. A flat waveform is a short burst of DC, that's basic electronics. In fact, the Fane technical department describe it as precisely that when they explain that over pushing the amp is more likely to damage speakers than driving them too hard.

I have a nice little Hartke 4x10 which goes down to 30Hz. My 1x18 EV sub does too. That's two out of two. Not bad considering virtually none do, eh? Maybe I'm just lucky. It's actually very useful for the heavy rock I play, mostly without house PAs to play through.

I didn't mention anything about the benefits of valves, so I fail to understand why you are using that criticise my input to the discussion.

[Mr. Foxen]

[quote name='GregBass' timestamp='1338384355' post='1673631']
So you haven't blown your speakers while not power matching them - good. Just to complete the picture, the power handling of the speakers in my rig is currently double what the amp can kick out at full blast. Guess what - I haven't blown any of the speakers either. Does that actually prove anything? As a general rule, I would say it's a decent idea to make sure your speakers can handle the power you intend to kick out of the amplifier. The simplest way to do this is to look at the power ratings, and make sure that the amp is not going to be chucking out more than the speakers are rated to handle. As a sort of rule of thumb, I hardly think that's contentious.

Clipping is EXACTLY putting DC in short bursts across the speaker. Think of the theory. Consider a sine wave. When it clips the top of the waveform goes flat - that's basic waveform analysis. A flat waveform is a short burst of DC, that's basic electronics. In fact, the Fane technical department describe it as precisely that when they explain that over pushing the amp is more likely to damage speakers than driving them too hard.

I have a nice little Hartke 4x10 which goes down to 30Hz. My 1x18 EV sub does too. That's two out of two. Not bad considering virtually none do, eh? Maybe I'm just lucky. It's actually very useful for the heavy rock I play, mostly without house PAs to play through.

I didn't mention anything about the benefits of valves, so I fail to understand why you are using that criticise my input to the discussion.
[/quote]

You can blow 500w rated speakers with a 200w rated amp, because thermal ratings don['t tell you the power it takes to blow a speaker. This is why watt rating have no meaning and thus should be ignored.

Clipping does not put out short bursts of DC. This is fact. If you scope it, you do not see a constant flat line above or below 0v which is DC, and you only see a flat top into a purely resistive load, an inductive (such as a speaker) load rounds them off, because the impedance varies with frequency. Basic physics is that if its a waveform, it is alternating, otherwise is isn't a wave, its a flow.

Let's see these SPL charts and waterfall plots from the cabs you claim have useable output capacity at 30hz then.

Edited May 30, 2012 by Mr. Foxen

[charic]

This is getting entertaining

FWIW, I agree with Foxen

[xgsjx]

I think Bassickman is gonna consider an electronics degree next just so he can follow this!
Either that or he's gonna take up keys.

[charic]

[quote name='xgsjx' timestamp='1338385759' post='1673660']
I think Bassickman is gonna consider an electronics degree next just so he can follow this!
Either that or he's gonna take up keys.
[/quote]

But then he needs to consider the Power Rating of the PA and/or a keyboard amp

[Bill Fitzmaurice]

[quote name='GregBass' timestamp='1338384355' post='1673631']
Clipping is EXACTLY putting DC in short bursts across the speaker. [/quote]It does not. DC does not alternate between positive and negative. [quote]Think of the theory. Consider a sine wave. When it clips the top of the waveform goes flat - that's basic waveform analysis. [/quote] That's flawed waveform analysis. The difference between a sine wave and square wave is the harmonic content. A sine wave has none, a square wave has all the harmionics of the fundamental occuring at the same voltage swing as the fundamental. [quote] the Fane technical department describe it as precisely that when they explain that over pushing the amp is more likely to damage speakers than driving them too hard.[/quote] If that's the case they're incorrect as well. I doubt Celestion would make such a grievious error, knowing that the tone of a guitar is pretty much predicated on clipping not only the amp but the driver as well.
This document is the source of the myth of underpowering. If readers all paid attention to the key phrase 'high frequency components' the myth might not have arisen. But like all myths it grew with each retelling.

[url="http://www.jblpro.com/pub/technote/lowpower.pdf"]http://www.jblpro.co...te/lowpower.pdf[/url]

And as to why cliiping has no effect whatsoever on woofers, not only does the added harmonic content of a clipped signal not increase the maximum voltage swing, the majority of the added harmonic content is filtered out by the inductlve and capacitive reactance of the voice coil.

Edited May 30, 2012 by Bill Fitzmaurice

[Mr. Foxen]

[quote name='Bill Fitzmaurice' timestamp='1338385955' post='1673665']
If readers all paid attention to the key phrase 'high frequency components' the myth might not have arisen. But like all myths it grew with each retelling.
[/quote]

This aprt is why it needs correcting every time someone decides to start retelling it.

[GregBass]

[quote name='Bill Fitzmaurice' timestamp='1338385955' post='1673665']
It does not. DC does not alternate between positive and negative. That's flawed waveform analysis. The difference between a sine wave and square wave is the harmonic content. A sine wave has none, a square wave has all the harmionics of the fundamental occuring at the same voltage swing as the fundamental. If that's the case they're incorrect as well. I doubt Celestion would make such a grievious error, knowing that the tone of a guitar is pretty much predicated on clipping not only the amp but the driver as well.
This document is the source of the myth of underpowering. If readers all paid attention to the key phrase 'high frequency components' the myth might not have arisen. But like all myths it grew with each retelling.

[url="http://www.jblpro.com/pub/technote/lowpower.pdf"]http://www.jblpro.co...te/lowpower.pdf[/url]

And as to why cliiping has no effect whatsoever on woofers, not only does the added harmonic content of a clipped signal not increase the maximum voltage swing, the majority of the added harmonic content is filtered out by the inductlve and capacitive reactance of the voice coil.
[/quote]

Bill - what does happen to a sine wave when it clips then? Lets say an amplifier with +/- 10V supplies and an amplification of 10 is fed with an input sine wave of +/- 2V, what will the output be (let's neglect losses etc to make it simple)?

[GregBass]

[quote name='Mr. Foxen' timestamp='1338386163' post='1673668']
This aprt is why it needs correcting every time someone decides to start retelling it.
[/quote]

Indeed. Maybe you should start with the standard curriculum of most electronics and electrical engineering degree courses )

[GregBass]

Try taking a look at the waveform shown on the scope here:

http://en.wikipedia.org/wiki/Clipping_%28audio%29

The tops and bottom of each excursion is flat. Now I could find you an authoritative link to direct voltages, but are you prepared to accept that they are basically voltages of a constant value (that would be flat when shown on a scope)? If so, then surely for that small period when the peak is cut off during clipping, the output is DC?

[charic]

[quote name='GregBass' timestamp='1338386350' post='1673675']
Indeed. Maybe you should start with the standard curriculum of most electronics and electrical engineering degree courses )
[/quote]

I did electronics as part of my course and it never lined up with what you've said. You're basically coming across as comparing apples and pears, ok it's not apples and oranges but you should stick to apples

[GregBass]

[quote name='charic' timestamp='1338387286' post='1673701']
I did electronics as part of my course and it never lined up with what you've said. You're basically coming across as comparing apples and pears, ok it's not apples and oranges but you should stick to apples
[/quote]

See my post immediately above yours - doesn't that show clearly that clipping is flattening of the peak of the wave? And isn't a flat voltage waveform actually a direct voltage?

[bassickman]

I'm totally new to the in depth world of bass. I've played for years but I want to step up in my knowledge. I fortunately can just afford some good gear. So I want to get it right. I'm on tour with a London Community Gospel Choir. I have 5k to spend on gear. hense the questions so I can get it right.

[chris_b]

If you're playing Gospel, get a 5 string bass, a 410 or 212 cab, a 500 watt amp with a good DI and some flight cases.

I think your brain would be better off full of bass lessons than this other stuff!