what is the purpose of an amp?

[DRut]

This question may sound rather elementary but I promise you it is not. Other than at home practice when you perform live what is the purpose of the amp.
Im a new player and looking into starting to perform. I originally thought you put your Amp and 8x10 wall of speakers up so the audience could hear you. Ive been doing a lot of reading that says the on stage speakers are monitors so everyone can hear themselves. Then I read to get a di so you can plug straight into the house system.
Then it really gets confusing, I heard to get an amp of at least 100 watts preferably more. But I read about how incredible tube amps are but most of them are like 50 watts some even less.
Now you can see how complicated the question can get. Especially because now im reading that a lot of people are using in ear monitors.
A good friend of mine was saying that a good amp has more affect on your tone than anything else

I currently have a fender Rumble 500 watt and a Genz Benz 15.(that Im looking to get rid of because its to big to lug around)
So is the amp mostly for tone? (couldnt i just get a nice preamp)
Is the amp to hear yourself on stage? (couldnt I just plug in the house through a di)
Is the amp so the audience can hear you?

 

[Aussie Player]

The speakers are the bigger contributor to tone. The amp helps you dial the best from your chosen bass guitar.

 

[Kenan]

When you perform live, are you going to be on a stage at a venue with full sound support and a dedicated sound person/team? If so, then you can certainly get by without an amp because you are relying on the house PA and monitors and/or your in-ears. Good for you! However, if you play small to medium size bar gigs, like I mostly do, then usually your amp is supplying 100% of the bass sound that you, your band, and the audience hears. In that case, you need to have enough rig for the room. No way around it.

 

[J Wilson]

How long have you been playing, and where are you playing: Club jobs, at home, what are you doing, what kind(s) of music?

 

[Wasnex]

As you have discovered, the purpose of an amp depends on the situation and your goals.

If you work with full audio support, then the amp is mostly your personal monitor. You may want to play loud and push the room with your amp, but this will cause it to fight with the PA. It could also cause you to fight with the audio tech and/or club manager. It's often necessary to work out a compromise.

In many other situations, the amp carries the room. But this I mean it serves as your personal monitor and also delivers sound to the other musicians as well as the audience. As you may imagine, one amp is probably not going to deliver optimal sound to everyone. I would prioritize the audience as #1, you as #2, and your bandmates as #3.

Rather than focusing on power, you should focus on SPL. SPL is a function of usable power and your cab's sensitivity.

I like a rig that is rated for at least 124dB continuous.

In order to know how loud a rig plays, you need to know how much power the amp can make at the impedance of your speaker system. You also need to know your speakers 1W/1m sensitivity rating and RMS power rating.

Let's assume you have a 4 ohm cab rated for 400W RMS and it has a 97dB 1W/1m sensitivity rating. Your amp is rated to make 800W at 4 ohms.

In the example, the usable power is 400W.

The sensitivity rating tells you 1 Watt is applied and the resulting SPL measured at a distance of 1 meter is 97dB.

Each time you double the power, the SPL goes up 3dB

So at 2W you get 100dB
4W = 103dB
8W = 106dB
16W = 109dB
etc.

Count the full doublings when you raise the power from 1W to 400W

1,2,4,8,16,32,64,128,256,512

So at 400W the power is doubled 8 times at 256W.

Multiply by 3 to get the decibel change: 8 x 3 = +24dB at 256W

The usable power is more than 256, but less than the next full doublig. Since 400W falls between 256 and 512, you can estimate a number between +1 and +3dB. My guess is it's about +2dB

So to figure out decibel change produced from raising the power from 1W to 400W
24 + 2 = 26dB

Then we add the 1W/1m sensitivity rating
26 + 97 = 123dB)

You could also use a log based formula. If the sensitivity is expressed at 1W we can use a simplified version of the formula

Calculated SPL = [Log(Usable Power) x 10] + Sensitivity

Here is the result:
Calculated SPL = [Log(400) x 10] + 97 = ~123dB

This is 1dB shy of my 124dB personal target. To achieve 124dB you need a cab that can either handle 1dB more power or a 400W cab with at least a 98dB 1W/1m sensitivity rating.

You can use the formula to find the required power at 97dB 1W/1m sensitivity:

Target Power = 10^[(124-97)/10] = ~501.2W.

500W is probably close enough

[Log(500) x 10] + 98 = ~124dB

Here is the math for a 400W cab with a 98dB 1W/1m sensitivity rating.

[Log(400 x 10] + 98 = ~124dB

 

[drpepper]

The purpose of an amp depends on context. In most basic terms, the answer to your questions

...is the amp mostly for tone? (couldnt i just get a nice preamp)
Is the amp to hear yourself on stage? (couldnt I just plug in the house through a di)
Is the amp so the audience can hear you?

are all yes

or no

depending on the context

With live music being played for an audience where a PA is being used, there is stage sound (amps, monitors and drums) for the band members and the sound from the PA for the audience (called front of house sound (foh)). Every situation is not the same. Where the audience size and lower overall volume of the band make it appropriate for only vocals to be running through the PA, the stage sound and foh sound are the same (coming from amps and drums) except for the vocals...the amp is both for being be heard on stage and by the audience. At the other end of the spectrum, where the audience is large, volume is high and/or the PA has the capability to carry everything at the full volume the audience is hearing and IEMs are being used, an amp isn't needed for either stage or foh.

Then there are kinds of situations (audience size and how loud the band is) in between where some combination applies. Bass may be in both an amp and PA and the sound of both is being mixed as part of foh sound as well as being for stage sound. There are situations where a band is playing to bigger audiences and the PA is carrying everything but IEMs aren't being used by some or at all and the at certain level an amp is really only being heard on stage. Here, an amp may not be needed strictly speaking for stage sound or foh and is being used because that's what someone is used to, prefers over either type of monitoring, likes the appearance of, or feels that the physical sensation added is preferable.

 

[bucephylus]

This question may sound rather elementary but I promise you it is not. Other than at home practice when you perform live what is the purpose of the amp.
Im a new player and looking into starting to perform. I originally thought you put your Amp and 8x10 wall of speakers up so the audience could hear you. Ive been doing a lot of reading that says the on stage speakers are monitors so everyone can hear themselves. Then I read to get a di so you can plug straight into the house system.
Then it really gets confusing, I heard to get an amp of at least 100 watts preferably more. But I read about how incredible tube amps are but most of them are like 50 watts some even less.
Now you can see how complicated the question can get. Especially because now im reading that a lot of people are using in ear monitors.
A good friend of mine was saying that a good amp has more affect on your tone than anything else

I currently have a fender Rumble 500 watt and a Genz Benz 15.(that Im looking to get rid of because its to big to lug around)
So is the amp mostly for tone? (couldnt i just get a nice preamp)
Is the amp to hear yourself on stage? (couldnt I just plug in the house through a di)
Is the amp so the audience can hear you?

First, it seems somewhat confusing that you are a "new player;" yet your signature shows you became a TB member 11 years ago. Could you please clarify?

Electric instruments don't generally make enough sound for entertaining purposes without some kind of amplification and projection system.

Individual players will usually have their own dedicated amplification / projection system, referred to as an "amp." But, modern PA systems have become sufficiently sophisticated that they are able to perform amplification and projection for the entire band. So, there are a variety of amplification systems in use. Your needs will depend on the specific ensemble / gig in which you are performing. No single answer.

A little further research in the Amplification and Live Sound forums should educate. GL

 

[hennessybass]

For me, the amp is part of the instrument. It's my rig (strings to speakers).
It's a huge part of my tone, and a HUGE part of my performance.

Small stage or big stage - I am playing and listening to my amp. I try to focus on my little part of the stage, and how it sounds where I am. The amp is for me.
When my corner of the stage sounds good, I feel good, and I play good. That translates to the audience - even if they are listening to the PA and can't hear the amp.

For me, that means having an amp and cab that works with my bass to allow me to make the sounds I want. I've found a good size / volume that works for me in terms of schlep, volume, tone, etc.

Even for at home practice - I still play an amp.

 

[DRut]

I keep posting this every time I post a new thread.i joined however many years ago. After joining I got married went to school finished my masters degree bought a house then got a doctorate degree discovered I had cancer had surgery and had another kid. Suffice it to say I took some time off. Before my bass time took off.

Like I said I understand what an amp does but what is its purpose, tone stage monitor or sound system for the crowd

 

[DRut]

How long have you been playing, and where are you playing: Club jobs, at home, what are you doing, what kind(s) of music?

Playing blues looking to gig probably starting in bars.

context of the original question. There is a common theme that bigger is better with amp sizes but it seems that isn't always the case.

 

[hennessybass]

what is its purpose, tone stage monitor or sound system for the crowd

Yes to all, and probably in that order.
1. tone machine
2. stage monitor
3. for the crowd - depending on the size of the venue. At some point the venue gets big, and the PA starts to handle this.

 

[ahc]

If you're not gigging, the purpose of an amp is to annoy the neighbors.

 

[J Wilson]

So you:re working towards playing out in bars.

I look at bass guitar as I would any instrument: I need to hear it. When it comes to bass you need to look at like this:

Bass + amp(effects if any) = Your Instrument

.... from the standpoint that an electric bass unplugged makes no sound, and an amp with nothing plugged into it is also silent.

When you start playing out, you may run the nto venues or bands that run effective In Ear Monitors, but you can not depend that will always be the case, just as you will run into a range of PA from wonderful to dreadful. And no IEM or wedge monitor system approaches the tone and feeling of a great amp working the stage and the room.

I have to HEAR my bass, and it has to sound good to me, so it starts with me, then a bass I like, and an amp to make it sound right so I want to play and play well.

Because of the low frequencies, bass requires far more power to keep up with a band, to still sound good and under control in all volume ranges. 100 watt bass amps are great for around the house, but almost useless in even moderately loud situations, and running out of steam fast if your guitarist is running a Marshall or Twin Reverb. A 50-100w guitar amp is WAY louder than a 100w bass amp: He's pushing far smaller high frequencies alongside of the huge low frequencies you're working with.

I'd figure a minimum of 400w, and 800 would be better yet. You're not playing as loud as those figures would suggest, but amps these size can run with power in headroom and control at the volumes you'll be working at. A 100w amp would be out of headroom and control trying to keep up in that situation. You'd likely hear it distort, you,'re getting buried, and what you can hear of yourself ain't pretty.
And don't let the numbers scare you: 800w is only 8-10db louder than 100w, but the headroom and control you gain is enormous.

Simply calling an amp a monitor completely ignores tone, tone is everything, and small amps are only good for very intimate acoustic guitar gigs. Or door stops.

Think of it this way: An amp is a big part of your sound, and a bigger amp can always be turned down to suit, but most usually a small amp gets ugly and out of breath trying to keep up when it's just not enough.

 

[prndltech]

What are amps? I've heard about them… kinda like dinosaurs.


I haven't needed one in a long time. In ear monitors and silent stages are where it's at! Yes, I do miss the feel of air moving… but not enough to want to carry an amp/cab again. The quad cortex and 64 audio N8's are wayyy lighter!

 

[DRut]

So you:re working towards playing out in bars.

I look at bass guitar as I would any instrument: I need to hear it. When it comes to bass you need to look at like this:

Bass + amp(effects if any) = Your Instrument

.... from the standpoint that an electric bass unplugged makes no sound, and an amp with nothing plugged into it is also silent.

When you start playing out, you may run the nto venues or bands that run effective In Ear Monitors, but you can not depend that will always be the case, just as you will run into a range of PA from wonderful to dreadful.

I have to HEAR my bass, and it has to sound good to me, so it starts with me, then a bass I like, and an amp to make it sound right so I want to play and play well.

Because of the low frequencies, bass requires far more power to keep up with a band, to still sound good and under control in all volume ranges. 100 watt bass amps are great for around the house, but almost useless in even moderately loud situations, and running out of steam fast if your guitarist is running a Marshall or Twin Reverb. A 50-100w guitar amp is WAY louder than a 100w bass amp: He's pushing far smaller high frequencies alongside of the huge low frequencies you're working with.

I'd figure a minimum of 400w, and 800 would be better yet. You're not playing as loud as those figures would suggest, but amps these size can run with power in headroom and control at the volumes you'll be working at. A 100w amp would be out of headroom and control trying to keep up in that situation. You'd likely hear it distort, you,'re getting buried, and what you can hear of yourself ain't pretty.

Simply calling an amp a monitor completely ignored tone and small amps are only good for very intimate acoustic guitar gigs

Think of it this way: An amp is a big part of your sound, and a bigger amp can always be turned down to suit, but most usually a small amp gets ugly and out of breath trying to keep up when it's just not enough.

So what is the deal with tube amps that people played in the past are those obsolete. Jameson 30 watts B 15?

 

[J Wilson]

Personally I have no use for tubes, but there are many who swear by them.

I look at a 300w SVT with all those tubes and the maintenance they can require from time to time, and it weighs close to 90 pounds. These days, there are any number of Class D amps that average five pounds and require no maintenance and sound great to me.

That is a no-brainer choice for me.

 

[DRut]

So what is the deal with tube amps that people played in the past are those obsolete. Jameson 30 watts B 15?

Exactly thats king of my point, other than at home practicing it seems like they are starting to wain

 

[Topkat13]

Put the bong down and slowly step away.

 

[DRut]

Personally I have no use for tubes, but there are many who swear by them.

I look at a 300w SVT with all those tubes and the maintenance they can require from time to time, and it weighs close to 90 pounds. These days, there are any number of Class D amps that average five pounds and require no maintenance and sound great to me.

That is a no-brainer choice for me.

See like you said some people swear by them as the best thing since porn. I would tend to agreen that they add a special sauce to tone. However i agree with you they are heavy and fragile, and it seems they are really underpowered for todays venues

 

[DRut]

Put the bong down and slowly step away.

NO, why would I do that, put the bong down?