Minimum wattage to play with some buddies

[Akami]

Since your main concern seems to be keeping up with the volume of the rest of the band I'd say right off that speakers are going to be an even bigger consideration than power.

You'll much more easily keep up with 100 watts through a 4x10 than 200 through a 1x12. It'd be nice if you can at least have a two driver cabinet with 300 watts driving it.

 

[fdeck]

It's never too soon to get used to wearing earplugs while playing.

 

[bigboy_78]

350.

 

[monsterthompson]

350.

 

[YourGuitarist]

You need to be concerned with the minimum SPL your require. If you have a target number, you need to consider both usable power power and how efficient your speaker system is.

Most speakers have a Sensitivity rating. Usually it's expressed as the resulting SPL measured at 1 meter from the cab when 1Watt is applied. For example you might see something like:

• Sensitivity = 97dB 1W/1m.

This means when 1W is applied, 97dB is measured at 1 meter.

The SPL goes up 3dB each time you double the power.

Here is the progression, assuming Speaker A sensitivity = 97db 1W/1m:
Speaker A
1W = 97dB
2W = 100dB
4W = 103dB
8W = 106dB
16W = 109dB
32W = 112dB
62W = 115dB
124W = 118dB
256W = 121dB
512W = 124dB

If the sensitivity is 93dB 1W/1m, the progression is
Speaker B
1W = 93dB
2W = 96dB
4W = 99dB
8W = 102dB
16W = 105dB
32W = 108dB
62W = 111dB
124W = 114dB
256W = 117dB
512W = 120dB

So as you see, the resulting SPL is 4dB less at each power level.

If the sensitivity is 100dB 1W/1m, the progression is:
Speaker C
1W = 100dB
2W = 103dB
4W = 106dB
8W = 109dB
16W = 112dB
32W = 115dB
62W = 118dB
124W = 121dB
256W = 124dB
512W = 127dB

My personal standard for playing in a cover band is a rig that is rated for at least 124dB. I can make 118dB work, but it can be frustrating. This is one of those YMMV moments. You may require more than 124dB or you may be entirely content with less than 118dB.

Note that speaker A makes:

• 118dB with 124W
• 124dB with 512W

Note that speaker B makes:

• 118dB with 316W
• 124dB = 1259W **

** 1259W is a lot of freakin power! You need an amp that can deliver the power and you need a speaker system that can handle it.

Note that speaker C makes:

• 118dB with 62W
• 124dB with 256W

You will also want to understand what happens when you add a matching cab. Usually the cab is connected in parallel, so the impedance is cut in half. For example if you have two 8 ohm cabs, the combined impedance in parallel is 8/2 = 4 ohms. An important caveat is to make sure you amp is rated to safely handle 4 ohms or lower. Also, many amps deliver more power at 4 ohms than 8 ohms; so check the amp's specs.

When matching cabs are connected in parallel, the combined power rating is 2X and the two cabs share available power equally. If you have a cab rated for 400W and you add a matching cab, the combined power rating is 400 x 2 = 800W. If your amp can makes 800W at 4 ohms, each 8 ohm cab will get 800/2 = 400W. Make sure the cab's RMS power rating is 400W or more.

Each time you double the number of cabs, the sensitivity rating goes up approximately 3dB. So if you have one cab with a 97dB 1W/1m sensitivity rating, when you add a matching cab the combined sensitivity of both cabs is 97 + 3 = 100dB 1W/1m.

Here is the progression with two cabs rated 97W 1W/1m:

Speaker A x 2
1W = 100dB
2W = 103dB
4W = 106dB
8W = 109dB
16W = 112dB
32W = 115dB
62W = 118dB
124W = 121dB
256W = 124dB
512W = 127dB
Note: This is the same progression as cab C.

If the useable power = 800W, calculated SPL = 129dB

While this may be an intimidating amount of info on first read, understanding it will go very far in practice.

There's a thread on TB where ballpark loudness levels in dB SPL are suggested by performance scenario. Someone can probs link to it.

IME 90dB is already louder than you think, I would always suggest trying to play quieter, especially if there's unmic'd vocals.

The other suggestion I have is EQ voicing has a huge impact on perceptibility. The more you rely on your low end heft to be heard, the more power you'll need, the more mids you dial in, the less power needed (often safer for the speakers too). Some amps have baked mid scoops such as fenders and GKs.

 

[Ludwig]

I would just get a Rumble 100. If that is not loud enough, use hearing protection ...

 

[gtirard]

You need to be concerned with the minimum SPL your require. If you have a target number, you need to consider both usable power power and how efficient your speaker system is.

Most speakers have a Sensitivity rating. Usually it's expressed as the resulting SPL measured at 1 meter from the cab when 1Watt is applied. For example you might see something like:

• Sensitivity = 97dB 1W/1m.

This means when 1W is applied, 97dB is measured at 1 meter.

The SPL goes up 3dB each time you double the power.

Here is the progression, assuming Speaker A sensitivity = 97db 1W/1m:
Speaker A
1W = 97dB
2W = 100dB
4W = 103dB
8W = 106dB
16W = 109dB
32W = 112dB
62W = 115dB
124W = 118dB
256W = 121dB
512W = 124dB

If the sensitivity is 93dB 1W/1m, the progression is
Speaker B
1W = 93dB
2W = 96dB
4W = 99dB
8W = 102dB
16W = 105dB
32W = 108dB
62W = 111dB
124W = 114dB
256W = 117dB
512W = 120dB

So as you see, the resulting SPL is 4dB less at each power level.

If the sensitivity is 100dB 1W/1m, the progression is:
Speaker C
1W = 100dB
2W = 103dB
4W = 106dB
8W = 109dB
16W = 112dB
32W = 115dB
62W = 118dB
124W = 121dB
256W = 124dB
512W = 127dB

My personal standard for playing in a cover band is a rig that is rated for at least 124dB. I can make 118dB work, but it can be frustrating. This is one of those YMMV moments. You may require more than 124dB or you may be entirely content with less than 118dB.

Note that speaker A makes:

• 118dB with 124W
• 124dB with 512W

Note that speaker B makes:

• 118dB with 316W
• 124dB = 1259W **

** 1259W is a lot of freakin power! You need an amp that can deliver the power and you need a speaker system that can handle it.

Note that speaker C makes:

• 118dB with 62W
• 124dB with 256W

You will also want to understand what happens when you add a matching cab. Usually the cab is connected in parallel, so the impedance is cut in half. For example if you have two 8 ohm cabs, the combined impedance in parallel is 8/2 = 4 ohms. An important caveat is to make sure you amp is rated to safely handle 4 ohms or lower. Also, many amps deliver more power at 4 ohms than 8 ohms; so check the amp's specs.

When matching cabs are connected in parallel, the combined power rating is 2X and the two cabs share available power equally. If you have a cab rated for 400W and you add a matching cab, the combined power rating is 400 x 2 = 800W. If your amp can makes 800W at 4 ohms, each 8 ohm cab will get 800/2 = 400W. Make sure the cab's RMS power rating is 400W or more.

Each time you double the number of cabs, the sensitivity rating goes up approximately 3dB. So if you have one cab with a 97dB 1W/1m sensitivity rating, when you add a matching cab the combined sensitivity of both cabs is 97 + 3 = 100dB 1W/1m.

Here is the progression with two cabs rated 97W 1W/1m:

Speaker A x 2
1W = 100dB
2W = 103dB
4W = 106dB
8W = 109dB
16W = 112dB
32W = 115dB
62W = 118dB
124W = 121dB
256W = 124dB
512W = 127dB
Note: This is the same progression as cab C.

If the useable power = 800W, calculated SPL = 129dB

Yes, Watt ≠ Decibels.

Thank you so much for providing these great explanations each time Wasnex, you've helped me understand a lot.

But each time a beguinner asks "how many watts do I need to play in a band", I wonder what should we answer, because:

• This explanation is probably too complex for most.
• We never know the sensitivity of the speaker (in fact we never know for a combo, and almost never when it's a separate amp+cab), so it's impossible to make a calculation.

At least, the advantage of combos is that in general, they choose a power section that is coherent with the performances of the speaker.

So at the end of the day, we can say to a beguiner: "it depends on the drummer and guitarist, but in general you need at least 100W".

It's really a pitty that this industry is not capable to define common standards that would be meaningful and relevant. We should be able to read a spec and get an idea of how loud an amp is, and compare several amps. It's incredible. Can we imagine chosing a car without knowing how fast it is?

This content should be a 'sticky' thread, but I think we should add a "TLTR" intro, and/or make a Youtube tutorial "how to choose the right amp to be loud enough for your needs".

 

[Wasnex]

IME 90dB is already louder than you think

This is probably true, but AFAIK the typical rock cover band hits the audience with 100dB or more.

If we assumed the average SPL at the front of the audience is 90dB and they are about 4 meters from your amp, that puts the average SPL at 1m from your amp at about 102db. AFAIK bass has something like a 12dB crest factor, so the peak SPL 1m from your amp is 114dB.

If we are hitting the audience with 100dB, both of these numbers go up 10dB. So the average sound 1m from your amp is 112dB and the peak SPL at 1m is 124dB.

 

[mcrawfordmusic]

A Used Rumble 100 combo is a good starting point.

 

[YourGuitarist]

This is probably true, but AFAIK the typical rock cover band hits the audience with 100dB or more.

If we assumed the average SPL at the front of the audience is 90dB and they are about 4 meters from your amp, that puts the average SPL at 1m from your amp at about 102db. AFAIK bass has something like a 12dB crest factor, so the peak SPL 1m from your amp is 114dB.

If we are hitting the audience with 100dB, both of these numbers go up 10dB. So the average sound 1m from your amp is 112dB and the peak SPL at 1m is 124dB.

I'm referring to practice scenarios. Live is different, I can't speak as confidently for that.

 

[Appogee]

In addition to all the good advice above:

In my experience, as a broad rule of thumb, playing a 5-string with a low B string, you will be better served by a 12" speaker than by a 10". (15" can work too, but can get too boomy. There are a couple of good videos on YouTube that compare 10s, 12s and 15s if you want to validate this.)

Fender Rumble 100 V3 has a 12" speaker and a switchable horn, and will probably meet your needs of playing with a rock band cost effectively.

There are bigger Rumbles with 2x10"s which some will say will also deliver the volume. Personally, I don't think they handle the bassiness of a low B as well as a 12". But at that point it's probably all in the ear of the beholder.

 

[Wasnex]

So at the end of the day, we can say to a beguiner: "it depends on the drummer and guitarist, but in general you need at least 100W".

I have gigged with 85W rigs that were plenty and I have gigged 450W rigs that were barely enough. Don't you think it's useful to understand why an 85W rig may be louder than a 450W rig? I do; so I try to present a technical explanation and the OP can either ignore it or try to learn. I'm okay with either response.

 

[gtirard]

I have gigged with 85W rigs that were plenty and I have gigged 450W rigs that were barely enough. Don't you think it's useful to understand why an 85W rig may be louder than a 450W rig? I do; so I try to present a technical explanation and the OP can either ignore it or try to learn. I'm okay with either response.

Absolutely, you are right.

 

[brianrost]

What’s more important than wattage is the speaker size and number of them.

Until the 1970s, amps over 100 watt were rare. Most “beginner” amps had a 12” or 15” speaker. My very first (and terrible) amp was a bottom of the line Univox that put only 20 watts into a 15” speaker. Today’s 10 watts into an 8” speaker simply didn't exist. Nowadays until you hit 100 watts it’s rare to see a speaker larger than 10” in a combo amp. When you needed to be louder, you added more speakers either with an extension cab or a head/cab rig with 2-15”, 2-12”, 4-10”, etc. instead of a combo. If you needed to be even louder, you ran multiple amps which is why you see walls of amps on stages in the late 60s and early 70s.

In the 1980s I gigged in a top 40 band using an amp that was only 75 watts into a 15” speaker. This was loud enough to work without PA support alongside drums, guitar and keyboards. I did eventually move to a higher wattage rig but that was only because there were times I wanted more dynamics without the amp starting to break up or worse the speaker farting out (a warning it was running at it’s limit).

Unless you need a lighter amp, a used combo amp from the 80s or later with 100-200 watts and a 15” speaker will do the job. They are dirt cheap these days, $100-300 will get you something that’s gig-ready but it may be heavy, 60 pounds or more. That’s why many amps came with casters back then so the only time you needed to lift it was when you encountered stairs and curbs or loading the amp in and out of your vehicle. You’ll also find speaker cabs that were once very popular like Hartke 4-10 cabs for under $200, then you can drive it with a featherweight modern class D head (some sell used for under $200) or a heavier head which might only cost you $100.

 

[Ritter667]

I would say 100W is the minimum for playing with a drummer, I would personally get a 200W amp, just to be certain.

That said I have gigged with a 60W tube amp in a hard rocking band (not hardrock) and a hard hitting drummer without any issues whatsoever.
And I have never needed more than 200W at rehearsal even in loud heavy bands.

And yes, if you don't mind it weighting about a ton, get a used old Trace Elliot combo amp, they are freaking loud compared to their rated wattage, and they sound amazing.

 

[Clark Westfield]

I say 1200 watts.

OK for real, I would get something 300/500 watts (8/4 ohms) to grow into and not need to revisit punching another amp.

 

[BAG]

So, OP still hasn't responded on what style of music he's playing (or wants to play) and what gear the others use (if he knows) but there's already two pages of responses many of which will turn out to be irrelevant. ........ TB makes me laugh even when it's not trying to.

 

[hieronymous]

Hey, at least most of the people seemed to be trying to answer the actual question rather than not read the first post and reply with a complete misunderstanding of the topic as seen in the subject line...

 

[Killing Floor]

I'd think more about decibels than Watts.

 

[Ray Ng]

So, OP still hasn't responded on what style of music he's playing (or wants to play) and what gear the others use (if he knows) but there's already two pages of responses many of which will turn out to be irrelevant. ........ TB makes me laugh even when it's not trying to.

Sorry about that, I was waiting to get an answer from my friend about his gear before I answered everybody. I didn't realize I was accidentally ignoring people. That was rude, my bad. Thanks for the call out.

What kind of music would you be playing and what kind of equipment do your friends have?

I haven't gotten word about my friends' gear yet, but IIRC they like to play rock a lot.

Are you after a combo or a separate head and speaker cab ?
If you are after a cab and a head then make sure the cab can handle the amp, the speaker must be able to handle more watts then the amp can put out.
If you get an amp that can put out 500 watts at 4 ohm and 250 watts at 8 ohms then you can get one 8 ohm 250 watt speaker now, you can always get a second speaker cab later so you end up with 2 8 ohm in parallel to get the 500 watts at 4 ohm.
There are so many possibilities that its best if you let us know if you find something so we can advice you on the best setup.
Like my teacher told me when I was an apprentice electrician, stupid questions can be embarrassing but stupid mistakes can be deadly, so just ask away.

PS. Where are you located ??

I'm in Arizona.


If I understand correctly, speaker size is going to matter more than wattage? I'll check out amps at stores with this in mind next time. Maybe a better question would've been to just to ask for amp reccomendations instead of wattage or stuff.
I'm still not sure about this Ohm and SPL stuff, though. Googling it isn't much help either, it's a little too confusing for my puny brain.