Old Watts - vs - New Watts

[alexclaber]

You need the voltage to drive the current flow - you increase voltage and current flows in response, not the other way round. As impedance drops then current has to increase to maintain power output, hence the minimum impedance ratings and how amps don't consistently double max power as you halve impedance.

If you want an absolutely clean sound then valve amps aren't any louder than solidstate amps of equal power. The success of the RH450/750 shows that you can get away with quite a lot of compression and valvelike distortion before many bassists consider the sound to be no longer clean - it doesn't appeal to me for most of my sound(s) and likewise I'm not a fan of valve amps for most of my sounds. Yes, a 200W valve amp can sound loud but you can hear it squashing the transients compared to an 800W solidstate amp when cranked up - whether you like that or not, that's up to you.

Guildbass - have a look here for enlightenment: [url="http://barefacedbass.com/bgm-columns.htm"]http://barefacedbass.com/bgm-columns.htm[/url]

[4 Strings]

[quote name='alexclaber' timestamp='1324382580' post='1473561'] Yes, a 200W valve amp can sound loud but you can hear it squashing the transients compared to an 800W solidstate amp when cranked up - whether you like that or not, that's up to you. Guildbass - have a look here for enlightenment: [url="http://barefacedbass.com/bgm-columns.htm"]http://barefacedbass...bgm-columns.htm[/url] [/quote]

And yet that's the exact opposite of the sounds from the two 30W guitar amps. The valve amp has much higher transients, doesn't sound anywhere near as loud (until you find that you're shouting above it) as it seems to create the sound so effortlessly and without compression. Bit like a good hi-fi vs nasty little one, the 'blaring' sound of the little one makes it appear to be louder.

edit - both on a clean sound.

Edited December 20, 2011 by 4 Strings

[Bill Fitzmaurice]

[quote name='guildbass' timestamp='1324378032' post='1473498']


Now that's what I've SEEN happen out in the world. That's what I've observed happening on a scope,[/quote]What you see on a scope bears no resemblance to an actual musical waveform. In the real world what clipping does is to increase the power density in the harmonics. This greatly increases the voltage swing seen by tweeters, which can toast them. It does not significantly increase the voltage swing seen by a woofer.

[alexclaber]

That's exactly what I'd expect from two 30W guitar amps - the valve one plays louder before it starts sounding dirty because the way it clips is nicer to the ear. When I use the phrase 'absolutely clean' I'm taking about a sound that is miles removed from a typical 'clean' guitar sound.

[4 Strings]

That's not it at all, Alex. The difference isn't before sounding dirty, the valve amp is incomparably louder. I know what you mean about clean, I only mentioned it as I was not comparing dirty/clipped/overdriven sounds. I'd love to know the reason why.

[alexclaber]

I'm not talking about guitar clean, I'm talking about absolutely clean. Different thing entirely. Are you comparing two amps into the same cab? And do either of them meet stringent specs or are both the power ratings 'marketing specs'?

Even if both amps have exactly the same power output at 0.1%THD, the valve one will allow you to push it to maybe many more %THD (maybe 20%) before it starts sounding anything other than clean, whilst the solidstate one could start sounding nasty (not obviously distorted but more edgy and harsh) at 1% THD. That means you can get much greater average power out of the valve amp than the solidstate amp, even if the peak power is basically the same.

[LawrenceH]

[quote name='4 Strings' timestamp='1324394867' post='1473798']
That's not it at all, Alex. The difference isn't before sounding dirty, the valve amp is incomparably louder. I know what you mean about clean, I only mentioned it as I was not comparing dirty/clipped/overdriven sounds. I'd love to know the reason why.
[/quote]

Unless you measure the distortion you can't necessarily tell though, especially on a signal like guitar - a 'clean' sound on a valve amp won't necessarily measure as clean. It could just be the gain structure being different where 1 amp is set up to give more output power at lower settings (similar idea to '11 -it's one louder') but I'm assuming you don't mean that. Voicing has a big impact on perceived loudness.

EDIT: beaten to it!

Edited December 20, 2011 by LawrenceH

[Bill Fitzmaurice]

[quote name='4 Strings' timestamp='1324394867' post='1473798']
That's not it at all, Alex. The difference isn't before sounding dirty, the valve amp is incomparably louder. I know what you mean about clean, I only mentioned it as I was not comparing dirty/clipped/overdriven sounds. I'd love to know the reason why.
[/quote]Compression, which valve amps do naturally without an outboard device. One can even tell the difference between valve amps that use valve power rectifiers versus SS rectifiers, as there's compression on the DC supply rails with valve.
Keep in mind that honestly rated amps, which is most of them, are measured with a specific voltage into a specific load at a specific distortion percentage. When compression occurs THD goes up, so a tube amp honestly rated for 100w at 0.1% THD will have much more power at 10% THD, and the increased power density that results from compression makes the amp subjectively sound much louder still. With sufficient processing an SS amp can do exactly the same. Tubes just don't need the added processing.
In the case of the TC they rate their amps with processing factored in, therefore at a very high THD. It's equivalent to measuring a car's gas mileage while traveling downhill with a tailwind.

Edited December 25, 2011 by Bill Fitzmaurice

[guildbass]

[quote name='alexclaber' timestamp='1324382580' post='1473561']
You need the voltage to drive the current flow - you increase voltage and current flows in response, not the other way round. As impedance drops then current has to increase to maintain power output, hence the minimum impedance ratings and how amps don't consistently double max power as you halve impedance.

If you want an absolutely clean sound then valve amps aren't any louder than solidstate amps of equal power. The success of the RH450/750 shows that you can get away with quite a lot of compression and valvelike distortion before many bassists consider the sound to be no longer clean - it doesn't appeal to me for most of my sound(s) and likewise I'm not a fan of valve amps for most of my sounds. Yes, a 200W valve amp can sound loud but you can hear it squashing the transients compared to an 800W solidstate amp when cranked up - whether you like that or not, that's up to you.

Guildbass - have a look here for enlightenment: [url="http://barefacedbass.com/bgm-columns.htm"]http://barefacedbass...bgm-columns.htm[/url]
[/quote]

OK...Got that...So what you are saying is that even if the signal goes to a square wave, as illustrated in the 'it goes to 11' article , which is of course effectively DC at rail voltage, albeit switching at high speed between +ve and -ve rail voltage ...That DC voltage plus the current output of the amp won't have any adverse effect on the coil....?

[alexclaber]

If DC alternates then it isn't DC anymore! And then if you do an FFT on that square wave you see that almost all of the increased power density is in the higher frequencies, which the inductance in the woofer's voicecoil blocks - so the amp might try to put out a square wave but a square wave isn't what flows.

[Mr. Foxen]

If DC did break voice coils, most of my cabs would break because I use a 9v battery to check I wired all the speakers in the same polarity.

[discreet]

None of the above is relevant if the rest of your band likes to play too bloody loud!

[Bill Fitzmaurice]

[quote name='Mr. Foxen' timestamp='1324413573' post='1474041']
If DC did break voice coils, most of my cabs would break because I use a 9v battery to check I wired all the speakers in the same polarity.
[/quote]+1. A case of another myth that has its roots in reality. If you blow your amp output devices that can result in a direct connection from the supply rails to the speakers, and that can toast them. Not because it's DC, but because the voltage is more than the drivers can handle. In short, overpowering.
[quote]If DC alternates then it isn't DC anymore! [/quote]+1. Sources that say a square wave is DC should be universally ignored.

[alanbass1]

Because of this thread I paid a quick visit to the TC Electronic website where they have a paper on how they rate their output:

[url="http://www.tcelectronic.com/media/tc-electronic-power-rating-and-active-power-management.pdf"]http://www.tcelectronic.com/media/tc-electronic-power-rating-and-active-power-management.pdf[/url]

Trouble is that I'm more confused than ever when reading the table at the end of the paper. Is it actually saying that the RH750 delivers 236 RMS at 4ohms (the same as the RH450) and only 11 watts more at 8 ohms. Whereas the 'burst' ratings show the RH750 to deliver 450 watts at 4 ohm (which is significantly higher than the RH450 which is rated at 264 watts at 4 ohm in the burst rating column). What does this actually mean when driving speakers - should I take the RMS as the safe load for my Bergs (should I get excited and turn them all the way up ).

[Bill Fitzmaurice]

[quote name='alanbass1' timestamp='1324757114' post='1477691']
should I take the RMS as the safe load for my Bergs (should I get excited and turn them all the way up ).
[/quote]99% of speaker thermal ratings are worthless as the drivers will run out of excursion at no more than half that amount of power anyway. That includes Bergs. If it distorts turn it down.

[chris_b]

[quote name='alanbass1' timestamp='1324757114' post='1477691']
....What does this actually mean when driving speakers....
[/quote]
[size=4][color=#222222][font=Arial][color=#222222][font=Arial] [/font][/color][/font][/color][/size]
[size=4][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial]As I said last time, it means that the RH450, Classic and Staccato are rated at 450 watts and the RH750 at 750 watts[i][font=Arial].[/font][/i] These are the numbers, the [i][font=Arial]only[/font][/i] numbers, you use when matching cabs.[/font][/color][color=#222222][font=Arial][size=1][/size][/font][/color][/font][/color][/font][/color][/font][/color][/size]
[size=4][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial] [/font][/color][color=#222222][font=Arial][size=1][/size][/font][/color][/font][/color][/font][/color][/font][/color][/size]
[size=4][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial]I played my Staccato through 2 300 watt cabs and my RH750 goes through 2 400 watt cabs. I'd be surprised if you really think that your RH450 is actually only putting out 236 watts!![/font][/color][color=#222222][font=Arial][size=1][/size][/font][/color][/font][/color][/font][/color][/font][/color][/size]
[size=4][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial][font=Arial] [/font][size=2][font=Arial][/font][/size][font=Arial][size=2][/size][/font][/font][/color][/font][/color][/font][/color][/size]

[ficelles]

[quote name='Mr. Foxen' timestamp='1324413573' post='1474041']
If DC did break voice coils, most of my cabs would break because I use a 9v battery to check I wired all the speakers in the same polarity.
[/quote]

It kind of depends on the amount of DC, as DC can of course refer to any amount of current or voltage. But then you all knew that as you all know electronics. 9VDC at some milliamperage won't hurt a speaker and is fine for testing. 30VDC+ at 3 or 4 amps will fry the coil and bend the cone as it will make it stand out like, well, a standy-out thing.

ficelles

[ficelles]

[quote name='alexclaber' timestamp='1324411598' post='1474011']
If DC alternates then it isn't DC anymore!
[/quote]

+1000. If anyone doesn't understand this, then please unplug your amplifer from the mains (that's what comes out of the square white plastic thing on the wall) and book in to your local college for an "electric appliances for beginners" course.

DC can't alternate. If it does, it's AC.

There's a clue in them there abbreviations:

DC = Direct Current
AC - Alternating Current

Wiggly volts (even square wave) are always AC. DC is a straight line.

ficelles

[Musky]

[quote name='chris_b' timestamp='1324777619' post='1477840']

[size=4][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial]As I said last time, it means that the RH450, Classic and Staccato are rated at 450 watts and the RH750 at 750 watts[i][font=Arial].[/font][/i] These are the numbers, the [i][font=Arial]only[/font][/i] numbers, you use when matching cabs.[/font][/color][/font][/color][/font][/color][/font][/color][/size]

[size=4][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial][color=#222222][font=Arial]I played my Staccato through 2 300 watt cabs and my RH750 goes through 2 400 watt cabs. I'd be surprised if you really think that your RH450 is actually only putting out 236 watts!![/font][/color][/font][/color][/font][/color][/font][/color][/size]

[/quote]
The TC document does state that the RH450 puts out 236w RMS long term, which is how other amps are usually measured. Whether other manufacturers figures are accurate is another matter though.

[JohnFitzgerald]

FFS Lads !

(With the exception of all you techy dudes who do all this stuff for a living.)

Please don't tell my old 150W Trace head that it's only 150W or I'm screwed.

For as long as it doesn't know that it's 0nly 150W, it gets on fine.

Maybe the fact that I don't wind shed loads of subsonic rumble and smiley faces onto the graphic helps, I don't know...

My sonic space, right above the bass drum, below the guitars helps.
They've also had all the bottom tweaked out fo their sound too.

There I am, 150W, Above the bass drum, below the guitars, in my space. 150 watts, plenty.


I must be doing it all wrong.

[Muzz]

This ^. Except with a RH450.

[chris_b]

[quote name='Musky' timestamp='1324801690' post='1477866']
....The TC document does state that the RH450 puts out 236w RMS long term, which is how other amps are usually measured. Whether other manufacturers figures are accurate is another matter though....
[/quote]
[size=4][color=#222222][font=Arial]....then they boost this number two and three fold to reach the volume which comes out of the speaker outputs, which is the number that is amps are rated at and the number that musicians need to know when they buy their cabs.[/font][/color][/size][color=#222222][font=Arial][size=1][/size][/font][/color]
[size=4][color=#222222][font=Arial] [/font][/color][/size][color=#222222][font=Arial][size=1][/size][/font][/color]
[size=4][color=#222222][font=Arial]Good grief!!! No wonder TC had an issue with how to market their amps to the average musician so that they wouldn't blow the speakers!! [/font][/color][/size][color=#222222][font=Arial][size=1][/size][/font][/color]
[size=4][font=Arial] [/font][/size][font=Arial][size=2][/size][/font]

[alanbass1]

[quote name='Musky' timestamp='1324801690' post='1477866']
The TC document does state that the RH450 puts out 236w RMS long term, which is how other amps are usually measured. Whether other manufacturers figures are accurate is another matter though.
[/quote]

Yep, and Bergantino quote that their speakers will take 300 watts continuous power and peaks over twice that figure....which is why I ask. Is the RH750 putting out 236 watts continuous power at both 4 ohm and 8 ohm, as their chart suggest?

[icastle]

[quote name='chris_b' timestamp='1324813931' post='1477919']
[size=4][color=#222222][font=Arial]....then they boost this number two and three fold to reach the volume which comes out of the speaker outputs, which is the number that is amps are rated at and the number that musicians need to know when they buy their cabs.[/font][/color][/size]

[size=4][color=#222222][font=Arial]Good grief!!! No wonder TC had an issue with how to market their amps to the average musician so that they wouldn't blow the speakers!! [/font][/color][/size]

[/quote]

Good job there are no cynics amongst us or one could come to the conclusion that TC were using this confusion as a marketing tool for their own brand speaker cabinets...

[Musky]

[quote name='chris_b' timestamp='1324813931' post='1477919']
[size=4][color=#222222][font=Arial]....then they boost this number two and three fold to reach the volume which comes out of the speaker outputs, which is the number that is amps are rated at and the number that musicians need to know when they buy their cabs.[/font][/color][/size]

[size=4][color=#222222][font=Arial]Good grief!!! No wonder TC had an issue with how to market their amps to the average musician so that they wouldn't blow the speakers!! [/font][/color][/size]

[/quote]
I'm the below average musician.

You'll have to explain this to me in terms I'll understand. I realise TC are boosting the output figures to something they feel is more consonant with the perceived volume. I'm just not sure why, when cabs are usually rated in Watts RMS, we should ignore the manufacturers RMS output figures and go along with "quasi watts" to determine if the cabs are man enough for the job.