Fun Amp Wattage reality check - member input requested.

guitar_paul1

Tele-Holic
Joined
May 29, 2003
Posts
875
Location
washington state
Vox AC4 C12 - rated 4 watts output, 45 watts draw.
All my other amps are DIY and I have never attempted to measure their output power or current draw.

I suspect these numbers are not truly equivalent for comparison due to different manufacturers' differing ways of testing their products and calculating these values.
Just as one example, it has always seemed to me that Vox AC15 and AC30 are much louder than one would expect from a 15 or 30 watt amp respectively.


No argument here. There are a lot of factors at play besides simple wattage.
My deal is just that spec inflation leads to abandonment of standards.
 

guitar_paul1

Tele-Holic
Joined
May 29, 2003
Posts
875
Location
washington state
Conclusion: IF you care about wattage when you are looking at an amp,
check the spec to see if it makes sense (i.e. W in greater than W out).
If you don't care about wattage, I apologize for wasting your time in reading this far.

I’m interested (and pleased) that most amps submitted in this thread are labeled sensibly.
Here is a list of the ones we have in this thread that aren’t.
These are all good sounding amps, in my opinion.
They’ve just inflated the output wattage in their specs.


Boss Katana 50 47W in 50W out

Boss Katana 100 77W in 100W out

Crate Powerblock 45 va in 150W out

Roland Blues Cube Artist 68W in 80W out

Vox AV30 27W in 30W out

Vox AV60 30W in 60 W out


I imagine the vast majority of people don’t care about this, but the discussion has been informative to me.
I've also learned a lot about how to write clear questions.
It’s interesting that there are so few examples. When I posted the question, I thought there would be far more.


Thanks to all who contributed.
 

Enricos

TDPRI Member
Joined
Mar 6, 2019
Posts
44
Location
London, UK
Conclusion: IF you care about wattage when you are looking at an amp,
check the spec to see if it makes sense (i.e. W in greater than W out).
If you don't care about wattage, I apologize for wasting your time in reading this far.

I’m interested (and pleased) that most amps submitted in this thread are labeled sensibly.
Here is a list of the ones we have in this thread that aren’t.
These are all good sounding amps, in my opinion.
They’ve just inflated the output wattage in their specs.


Boss Katana 50 47W in 50W out

Boss Katana 100 77W in 100W out

Crate Powerblock 45 va in 150W out

Roland Blues Cube Artist 68W in 80W out

Vox AV30 27W in 30W out

Vox AV60 30W in 60 W out


I imagine the vast majority of people don’t care about this, but the discussion has been informative to me.
I've also learned a lot about how to write clear questions.
It’s interesting that there are so few examples. When I posted the question, I thought there would be far more.


Thanks to all who contributed.


To my astonishment this has proved to be one of the most interesting threads I've read on here in a while.
Thanks everyone.

Now back to watching paint dry :D
 

Enricos

TDPRI Member
Joined
Mar 6, 2019
Posts
44
Location
London, UK
A late contribution – I was so absorbed in reading everyone else's responses that I forgot to add my own.

Of my six amps only four give full information:
Marshall Origin 20 (valve/tube): 100W in, 20W out
Polytone Mini Brute III (solid state): 160W in, 100 out
Aguilar Tone Hammer 500 (solid state class D): 670W in, 500W out
Vox Pathfinder 10 (solid state): 15W in, 10W out

The other two, both English-made boutique amps, are:
Cornell Romany Plus (valve/tube): 50W in, 10W out (power draw stated clearly in owner's manual but not on amp)
JPF Sir Charles 15 (valve/tube): 1.5 amp fuse, 15W out (no power draw given on amp though I could find out from the maker, an honest fellow)

I've no idea what UL certification is. Perhaps it doesn't apply on this Septic Isle . . .
 
Last edited:

guitar_paul1

Tele-Holic
Joined
May 29, 2003
Posts
875
Location
washington state
A late contribution – I was so absorbed in reading everyone else's responses that I forgot to add my own.

Of my six amps only three give full information:
Marshall Origin 20 (valve/tube): 100W in, 20W out
Polytone Mini Brute III (solid state): 160W in, 100 out
Aguilar Tone Hammer 500 (solid state class D): 670W in, 500W out
Vox Pathfinder 10 (solid state): 15W in, 10W out

The other two, both English-made boutique amps, are:
Cornell Romany Plus (valve/tube): 50W in, 10W out (power draw stated clearly in owner's manual but not on amp)
JPF Sir Charles 15 (valve/tube): 1.5 amp fuse, 15W out (no power draw on given on amp though I could find out from the maker, an honest fellow)

I've no idea what UL certification is. Perhaps it doesn't apply on this Septic Isle . . .
You're right. UL is an American standard.
I think the CE mark is the same sort of thing across the pond.
https://www.cemarkingassociation.co.uk/what-is-ce-marking/
 
Last edited:

Blrfl

Tele-Afflicted
Joined
May 3, 2018
Posts
1,677
Location
Northern Virginia
Some random contributions to the discussion:

Headrush FRFR-108 and FRFR-112: 800W in 2,000W out.

I think the ONLY reason they put the input watts on there is so they cant be sued for you plugging in a high amp draw amplifier into a low amp wiring system isn't it?

It would be a much better world if people could be counted on to be that careful. The safety angle is covered by the design of the plugs and receptacles. An appliance that draws 17 amps would have a NEMA 1-20P or 5-20P plug (see the chart below) on it. Neither of those plugs are physically able to be inserted into a 5-15R receptacle, which can only deliver 15 amps. UL won't list an appliance that draws more current than the plug allows and the electrical code forbids installing outlets capable of delivering more current than the wiring feeding it can deliver. If there's a fire and it's determined that violating either of those rules was the cause, whoever underwrites your insurance will deny a claim.

nema.png



Wattages are listed on appliances so you can figure out what you can operate from a receptacle without blowing the breaker. (E.g., a 15-amp receptacle tops out at 1,875 watts, so you're not plugging in two 1,500-watt hair dryers and running them at the same time.) Secondarily, they give you some idea how much it costs to operate.
 

guitar_paul1

Tele-Holic
Joined
May 29, 2003
Posts
875
Location
washington state
Some random contributions to the discussion:

Headrush FRFR-108 and FRFR-112: 800W in 2,000W out.



It would be a much better world if people could be counted on to be that careful. The safety angle is covered by the design of the plugs and receptacles. An appliance that draws 17 amps would have a NEMA 1-20P or 5-20P plug (see the chart below) on it. Neither of those plugs are physically able to be inserted into a 5-15R receptacle, which can only deliver 15 amps. UL won't list an appliance that draws more current than the plug allows and the electrical code forbids installing outlets capable of delivering more current than the wiring feeding it can deliver. If there's a fire and it's determined that violating either of those rules was the cause, whoever underwrites your insurance will deny a claim.

View attachment 883567


Wattages are listed on appliances so you can figure out what you can operate from a receptacle without blowing the breaker. (E.g., a 15-amp receptacle tops out at 1,875 watts, so you're not plugging in two 1,500-watt hair dryers and running them at the same time.) Secondarily, they give you some idea how much it costs to operate.


Wow. 2000 (peak) w for the price of 800.

Notice they carefully state "peak watts" for the output, not regular "watts".
Everybody has a different definition of "peak watts".

There is a time constant involved and nobody wants to reveal that because the man behind the curtain will be exposed.

It's almost time to start what will be a new ( very contentious) thread about "peak watts" and where they might come from.

Like I said before, lots of opportunity for yelling and algebra. Maybe even a tiny bit of calculus possibly (which is about all the calculus I am capable of).

Thank you for this segue into my next thread, which I won't get to for about a week or so.
Cheers.
 

Asmith

Friend of Leo's
Joined
Nov 27, 2014
Posts
4,207
Location
East Yorkshire, England
Wow. 2000 (peak) w for the price of 800.

Notice they carefully state "peak watts" for the output, not regular "watts".
Everybody has a different definition of "peak watts".

There is a time constant involved and nobody wants to reveal that because the man behind the curtain will be exposed.

It's almost time to start what will be a new ( very contentious) thread about "peak watts" and where they might come from.

Like I said before, lots of opportunity for yelling and algebra. Maybe even a tiny bit of calculus possibly (which is about all the calculus I am capable of).

Thank you for this segue into my next thread, which I won't get to for about a week or so.
Cheers.

Converting RMS watts to peak watts is pretty easy. Peak watts is 2.82*RMS watts, 2*sqrt(2)=2.82, you can also use 3 for a rough calculation.
 

guitar_paul1

Tele-Holic
Joined
May 29, 2003
Posts
875
Location
washington state
Converting RMS watts to peak watts is pretty easy. Peak watts is 2.82*RMS watts, 2*sqrt(2)=2.82, you can also use 3 for a rough calculation.
This is for another thread?
There is no formal math definition of "rms watts". Watts themselves are defined be rms volts x rms amps. I have written the sequence of logical steps down, but I think that's another thread. Applying rms to anything other than sine waves is invoking the integration function from calculus.

Likewise "peak" has no real world meaning unless it is accompanied be a time constant. A peak of a million watts lasting for a microsecond can average to 1 watt if it occurs every second.

Or I guess we could let this thread wander there. I'd much rather start a new thread with a more descriptive title. I'm away from my computer for a few more days, so it will be next week.
 

bettyseldest

Friend of Leo's
Joined
Nov 13, 2011
Posts
3,163
Location
UK
So what is going on here? Looks to me like 30 watts in provides 200 or 130 watts out depending upon the speaker ohms. If I can convert the output sound energy back into something more useful at even 50% efficiency I could be onto something. This is what we Brits can do when we work with the US and Chinese, without being held back all the time by those lazy europeans with all their red tape and bureaucracy.

upload_2021-8-1_19-16-21.png
 

Asmith

Friend of Leo's
Joined
Nov 27, 2014
Posts
4,207
Location
East Yorkshire, England
This is for another thread?
There is no formal math definition of "rms watts". Watts themselves are defined be rms volts x rms amps. I have written the sequence of logical steps down, but I think that's another thread. Applying rms to anything other than sine waves is invoking the integration function from calculus.

Likewise "peak" has no real world meaning unless it is accompanied be a time constant. A peak of a million watts lasting for a microsecond can average to 1 watt if it occurs every second.

Or I guess we could let this thread wander there. I'd much rather start a new thread with a more descriptive title. I'm away from my computer for a few more days, so it will be next week.

My 2sqrt(2) is indeed wrong, I did over simplify something and also somehow forgot negative watts don't exist so there is no peak to peak watts just peak watts.

Assuming they're using any kind of standards they would be calculating the power (or peak power) using a sine wave input, probably around 1kHz. I did calculate (using integration) the average power of a sine wave voltage through a fixed load and it is just 1/2 of the peak power. So you certainly seen to be on to something.

Either the manufacturers are inflating the wattages artificially or the amps are using giant capacitors which have enough energy stored to provide short bursts of large peak power. Either way it's definitely misleading.
 

PhredE

Tele-Afflicted
Joined
Sep 25, 2017
Posts
1,779
Location
Suburban PDX, OR
So what is going on here? Looks to me like 30 watts in provides 200 or 130 watts out depending upon the speaker ohms. If I can convert the output sound energy back into something more useful at even 50% efficiency I could be onto something. This is what we Brits can do when we work with the US and Chinese, without being held back all the time by those lazy europeans with all their red tape and bureaucracy.

View attachment 884362

The TC Electronic BAM 200 is very similar to the Trace Elliott ELF. Almost identical features, tone stack, power, XLR Out, and footprint even. I bought one recently and was going to post the info from it in this thread, but.. I couldn't find any listed power consumption specs/notes anywhere.

Anyway, these are cool little units if a player gets his/her 'tone' from pedals, floor rig or the like. Powerful, small and can connect out to speaker and DI out to a PA if needed. Sounds good and not expensive either.

Edit: Here's a link to the TC Electronic BAM200 manual:
https://mediadl.musictribe.com/media/PLM/data/docs/P0DI5/TC Electronic_BAM200 P0DI5_Product Information Document.pdf
I see output listed a lot, but consumption??? I don't see it. Maybe someone else will (?)
 
Last edited:

guitar_paul1

Tele-Holic
Joined
May 29, 2003
Posts
875
Location
washington state
So what is going on here? Looks to me like 30 watts in provides 200 or 130 watts out depending upon the speaker ohms. If I can convert the output sound energy back into something more useful at even 50% efficiency I could be onto something. This is what we Brits can do when we work with the US and Chinese, without being held back all the time by those lazy europeans with all their red tape and bureaucracy.

View attachment 884362
This is what I was talking about, right?
Thanks for sharing this.
 




Top