Let's talk about amp power

[Tom_C76]

Perhaps in part because a transistor has a hard cut at its maximum theoretical output (clipping) but a valve saturates beyond it?

[dojo]

scrubchub said:

h is actually too much for most venues. The 'tvp' stands for ' true valve power' so it is supposed to be as loud as the equivalent valve amp. I'm not sure it is but its close.

Which begs another question - why are valve amps so much louder than solid state?

I think thats because Solid State amps are usually equipped with cheaper speakers that aren't as efficient. If you get a well made SS it will be as loud as a tube amp.

[davidd]

My little V30 (30watt) has 3 modes, high and low power on the main switch and then another small switch that allows me to turn off one of the output valves. It is still really loud though, even just using the 1x12.

In most gig situations I run both output valves but the main switch is set to low. We do run our amps through the PA as well but that is mainly just to even the mix a little. It is plenty for a room with a couple of hundred people in it.

Great amps if anyone is looking for a small (lunchbox) head.

I meant to add, much, much louder than my bandmates Line 6 which is rated at 50w and also my blackstar ht40.. Make of that what you will.

Edited by davidd on Wednesday 13th May 11:04

[bennyboysvuk]

scrubchub said:

Wattage rarely seems a good indicator of actual volume. I gigged for years with a Peavey Bandit 112 - classic first gigging amp. Had to crank it almost to 11 to be heard over the drummer and sometimes still couldn't be heard (fecking drummers). It was 85 watt.

Now I use a Blackstar id 60 tvp which is 60 watts and I'm yet to need to take it past 6, which is actually too much for most venues. The 'tvp' stands for ' true valve power' so it is supposed to be as loud as the equivalent valve amp. I'm not sure it is but its close.

Which begs another question - why are valve amps so much louder than solid state?

My first gigging amp was a Peavey Renown 400, a 210 watts rms 2x12 combo, which sounds like a lot, but it struggled against 50w valve amps. That was back when I was playing metal at really very high volumes.

[Mave]

Tom_C76 said:

Perhaps in part because a transistor has a hard cut at its maximum theoretical output (clipping) but a valve saturates beyond it?

I'd go with this. 5v is 5v when a transistor is switched on. Valve amps are rated more on thermal output, if you look at the voltage trace it can transiently go way higher than the nominal rated output with the initial attack when you hit the strings.

[Crackie]

dojo said:

Now on reading other bits and bobs it suggests that to create twice the volume you need 10x the wattage... So to get an amp twice as loud as your 50w you would need a 500w amp...

If someone could help me understand I would be very appreciative!

The max sound pressure level that a speaker & amp can produce can be found using dbw. Simply add the dbw power rating of the amp to the sensitivity of the speaker and that is the max SPL produced 1 meter from the speaker. If there is a pair of speakers then add three dB.

Example. A speaker with 95dB 1w @ 1m sensitivity is driven with a 100Watt amp. 100watts can be expressed as 20dbw so max output in dB is 95dB + 20dBw. I.e. 115dB max for a single speaker and 118 for a pair at 1 meter.

SPL reduces by 6dB for each time you double the distance from the speaker. For the example above; a pair would produce 112db at 2 meters and 106dB at 4 meters.

25w = 14dBw
50w = 17dBw
100w = 20dbw
200w = 23dBw
400w = 26dBw
800w = 29dBw

Using a 6dB more sensitive pair of speakers is equivalent to quadrupling the power of your amp.

Edited by Crackie on Friday 15th May 00:35

[Oakey]

HarryFlatters said:

Here's mine, 1982 or 83, I can't quite remember. It's been modified before I owned it with an additional preamp valve and an effects loop.



It's utterly pointless me owning it as I'm not in a band at the moment. It's too loud to use in a rehearsal room, never mind at home

I still won't part with it though

My dad had one just like that, he sold it to the local Cash Convertors when he and my mum got divorced and he needed the money.

To say he was wounded would be an understatement!

He's got a Jim Kelley FACS these days, every cloud and all that.

[HarryFlatters]

Oakey said:

My dad had one just like that, he sold it to the local Cash Converters when he and my mum got divorced and he needed the money.

To say he was wounded would be an understatement!

Painful

[Oakey]

Oops, forgot the pertinent point.... he sold it them for £100!