Watts the deal then?

[AndrewJordan]

With watts that is! Or more precisely, how amp manufacturers rate their heads?

I have three heads now and compared through the same cab (Ampeg 610 4Ohm) they go up in volume in this order.

Ampeg Micro VR 250W @ 4Ohm - Quite loud but not loud enough for my band.

Ampeg SVT 450 450W @ 4Ohm - Plenty loud enough but not tons of headroom left.

GK 800RB 300W @ 4Ohm - Plenty loud enough but can go a hell of a lot louder. (note the very scientific descriptions of perceived volume there).

So the 300W GK beats the 450W Ampeg hands down in the loudness wars.

For quite a while I have had GAS for a vintage valve amp but with a lot of the vintage amps only rated at 100 or so Watts where do they sit in terms of loudness. You regularly see sellers saying that these amps are loud enough for any gig. But are they really?

[JapanAxe]

You could do worse than start [url="http://basschat.co.uk/topic/3730-gain-power-and-volume-a-confusing-menage-a-trois/"]here[/url].

[Twincam]

Valve amps are louder no doubt. I get a bit sick of the science saying there not or are only when pushed into overdrive as its not true even clean power they blow away most transistor based amps.

I have read the science and theories etc and all of them still don't add up to the fact nearly every who tests a valve amp will find its louder than the same wattage of ss transistor based amps clean volume!

My theories are. Valve amps add extra harmonics etc that can be perceived as louder. Many companies bs about there ratings or are bending the truth. And yes valves will be louder into od maybe our ears don't hear valve distortion as quickly as we would with a transitor amp.

And adding class D lack heft! Lol

[AndrewJordan]

[quote name='JapanAxe' timestamp='1464365325' post='3058917']
You could do worse than start [url="http://basschat.co.uk/topic/3730-gain-power-and-volume-a-confusing-menage-a-trois/"]here[/url].
[/quote]

Yeh, I do understand the science(well mostly) I understand the relavence of cab sensitivity and I am not trying to get more volume from any of these specific heads. That was just a direct comparison of three heads into the same cab with the same bass with all the inputs set to just before clipping. The results say to me that either the GK is very conservatively rated or the Ampegs are a bit optimistic with their figures.

If old school valve amps are genuinely louder for a given wattage could it be down to the way the manufacturers arrive at the figures. e.g. old school rating is an honest rating of say 100W @ 40Hz as opposed to moderns inflating the figures by saying 300W but is that 300W @ 1Khz?

[Dad3353]

[quote name='AndrewJordan' timestamp='1464369071' post='3058976']...three heads into the same cab with the same bass with all the inputs set to just before clipping...
[/quote]

The 'heavy guns' will probably weigh in to this, but I'd just like to suggest that, although pretty good, we're far from an accurate assessment of power rating here. The clipping point..? Is that going to be the same on all of these amps..? What level of distortion is being generated..? It's a fair approximation, and better than some, but I wouldn't want to draw definitive conclusions. Does it really matter that much, anyway..? The maker's claims are all very well, but the 'acid test' is whether it performs in [i]your [/i]context, [i]whatever [/i]the figures say. True, it would be nice to have some reference somewhere, and the figures should do this, but that's only a Utopian wish, really. All of this, before releasing the real dogs of war over 'core tone' and such..!

[xgsjx]

I suppose you've just found that watts have little to do with volume.
Just like 200bhp can vary from vehicle to vehicle on how fast it goes.

[4stringslow]

To be honest, there's not much point discussing 'perceived' volumes of different amps based on one listener. Not that I'm questioning the sincerity of the OP, but a different person might well assess the volumes of the amps differently, for all manner of reasons. There is so much psychology involved that such individual assessments are about as worthwhile as those hi-if reviews where the reviewer can allegedly hear the difference between a gold plated fuse in the mains plug and a standard (ugh!) one.

If we really want to have a meaningful discussion then we really need some better data. A double-blind listening test with many people would be a minimum place to start.

Of course, if the OP thinks a particular Amp sounds loudest then that should be good enough for them, but I just think we should keep such findings in perspective and not draw unwarranted wider conclusions

[taunton-hobbit]

I knew someone would get Heft in before me.....I wonder why valve amps [i][b]sound [/b][/i]louder?
I've got a few, and they easily trounce my Crown Class D -
p'raps someone can come up with a credible answer?

[AndrewJordan]

Yes, I realise that my methods are very unscientific. I don't have an osciloscope to tell where the genuine clipping point is. With the Ampegs I adjust the input level until my playing just tickles the clip LEDs. The GK has no such LED but some time ago when I had it with a tech I got him to test it with my bass to find the highest level I could turn the input to before clipping the pre amp. I always set the input to this same level. Again, all very unscientific I know but the best I can do.

Regarding perceived loudness, all amps were EQd to give roughly the same tone and this testing was done during band practice so it was quite easy for everyone to hear a considerable difference in volume between the three.

Regarding valve amps, I believe it could well be the extra harmonics that make them sound louder especially when driven. I know that if I put a distortion pedal through min ss head while it is DI into the desk there is no increase in level on the desk meters but it certainly sounds louder. Those extra harmonics definately "fill the ears".

Does it matter if in the end the amp does what you need? Not a bit in my opinion. But it would be nice to have that Utopian world where you can shop for an amp without being able to test it and know that it will be loud enough from the wattage ratings.

[AndrewJordan]

[quote name='xgsjx' timestamp='1464369981' post='3058987']
I suppose you've just found that watts have little to do with volume.
Just like 200bhp can vary from vehicle to vehicle on how fast it goes.
[/quote]

Well, I have known for quite some time that watts are only part of the equation when it comes to volume. If you are saying that watts in themselves are not a measurement or indication of volume then I agree entirely.

In other ways watts can have quite a lot to do with volume. I would say that any given signal passed through a circuit with enough gain applied to generate a 200W output into a speaker will be louder than the same signal passed through the same circuit into the same speaker with the gain lowered so that only 100W output is generated. Nowhere near twice as loud, but still louder........................he said, setting himself up to be shot down again

[AustinArto]

Doesn't it take 3x the power to get a 3dB increase in perceived volume - therefore a doubling of perceived volume?

So a 100w amp should go half as loud as a 300w amp, and to refer back to the original poster's gear his 450w amp should go a little less than 1dB louder than his 300w amp.

Maybe the 450w head is broken, or maybe the 300w head is putting out more of the frequencies that the user perceives as loud. Who knows.

[Norris]

There is only one measure really - loud enough

[Guest bassman7755]

[quote name='Twincam' timestamp='1464365765' post='3058934']
Valve amps are louder no doubt. I get a bit sick of the science saying there not or are only when pushed into overdrive as its not true even clean power they blow away most transistor based amps.
[/quote]

Its a measurement problem. Power is usually quoted at a particular THD level often 1% is used for high power instrument/PA amps, a valve amp will usually exhibit measurable THD quite early in its power curve whereas some SS amp stay very low THD until they approach their maximum output. A valve amp can sound "clean" despite being well into single figures % THD hence any power rating based on a THD threshold will tend to penalize a valve amp. That early-onset THD in valve amps will as you say often take the form of harmonics that increase the apparent volume.

[TimR]

Valve amps will distort with odd order harmonics which sound pleasant to the human ear. Transistor amps distort with even order harmonics which aren't.

You can only therefore compare valve-valve and transistor-transistor amps,

And as there's no standard, one amp manufacturer can claim 1000 watts at 10% THD at 1kHz but the amp may not develop any more power than 1000watts. Whilst another manufacturer could claim 500 watts at 1% THD at 1kHz. But the 500watt amp could be louder because it might operate well above 1000 watts.

.

Edited May 30, 2016 by TimR

[luckydog]

I'd be surprised if any of the amps didn't meet their specs....

I think the difference in perceived level at which bass amps sound nasty is partly due to how much sub removal goes on - sub eats power and if the cab can't do it, it's just a waste of amp headroom plus the cab distorts the stuff it can do. Also partly down to built in mid-preshape because low mids seriously affect perception of bass level.

HTH !

LD

Edited May 30, 2016 by luckydog

[Phil Starr]

It's actually very simple and the science explains everything. The op compared the amps through the same speakers, so they aren't the variable.

First thing is that the advertising teams at most companies are lying gits. You are far better off going to the manuals to find power figures you can compare. For clarity I'm only talking about rms or AES measurements. It's the simplest thing to measure amp watts, and completely clear so long as you describe your measuring technique. Two people anywhere in the world using the same technique will come up with the same answer.

The thing to understand is that the sound you hear is made of waves that the speaker driven by the amp is tracking. The power of the amp is only important at the peak of the highest part of the wave in the loudest part of what you are playing. What you perceive as the loudness is to do with the average power in the section of music you are listening to. Your 300W amp flat out is probably only running at 15W if it isn't distorting. It's the behaviour of the amp at these levels which determines part of the difference between amps. Valve amps distort nicely, over driven is a compliment when you talk about a valve amp. This means you can drive a valve amp harder and you might well get a pleasing sound from a 100W valve amp running at 15W average power. To you it is as loud as the 300W transistor amp and to all practical purposes it is just as useful, but it is still a 100W amp, there aren't any extra Magic valve watts. You are just pushing it harder and loving what that sounds like.

The other factor in the box you call your amp is the power supply. You might all have the same class D output module but different manufacturers use differently rated power supplies. The amp might be 300W but the power supply might only be able to provide enough current for half that. If you only reach that peak once every few seconds then the power supply will be fine but if you start to get too demanding of current the voltage in the power supply will drop and it won't be a 300W amp any more. Beefy power supplies cost more than weedy ones so manufacturers wont normally provide you with a full spec power supply unless you pay a lot more for your amp than you would be happy to pay. And to be fair most of the time you wouldn't notice anyway, few of us run our amps flat out at gigs, just when we are messing around at home to see what they can do.

The last factor in loudness that isn't to do with watts is tone. Bass amps aren't usually neutral sounding. I'd bet the the tone of the OPs three amps are different. If the peaks in output are at the bottom end then they demand more power and the amp will demand more power. But, if the peak is in the midrange then our ears are really sensitive in that area and the amp will sound louder for the same power. If I designed an amp to sound loud in the demo room I'd design in a mid boost. That's how your transistor radio sems louder than its one or two watts would suggest. I also know that a 'smiley face'frequency response sounds nicer to most people, so cynically I might design that in to an amp. If the OP had used a graphic to dial in a similar frequency response I suspect the two solid state amps would have been similar. The difference between 300 and 450W is only just over 1db so barely noticeable.

[AndrewJordan]

Well explained Phil! My personal suspicions on this are that the GK head is a very well engineered bit of kit that has been designed to deliver 300W cleanly at the freqs that matter. I've been inside it a few years ago and remember seeing a lot of very beefy caps in there and I think I remember a fairly HEFTy (see what I did there) tranny inside as well. So, to my untrained eye it looks to be capable of delivering a lot of juice. I suspect that the Ampeg figures may have been influenced by the marketing department. I haven't been inside it but if you ignore the big wooden(fake svt look) box then the actual amp casing doesn't look big enough to have huge caps or a proper tranny in it.

Don't get me wrong, I am not slagging the Ampeg. It's a great sounding and performing amp. Just doesn't have the same balls as the GK. I gigged with the Ampeg on sat night and really enjoyed it. We shared a stage with another band and the bass player who also plays in a very loud metal band used my rig and was blown away by it, commenting on how nice it was to play through a really meaty amp.

The GK is actually a bi-amp head so there is another 100W power section in there also and a tuneable crossover(it can be switched out so that either or both amps can be used full range). For a laugh once in the practice room I set up a stack of two 18" PA subs with 15" + comp PA top all driven by the GK with the crosover set to around 100Hz. WOW............that rig could knock you on your back. In drop C the whole concrete building was shaking not to mention my bowels.........Oh, and a lady who was in the room had a very interesting smile on her face!

[KevB]

There's watts and then there's trace elliot watts. They seem to get them from a different supplier....

Edited May 31, 2016 by KevB

[tauzero]

[quote name='TimR' timestamp='1464636922' post='3061063']
Valve amps will distort with odd order harmonics which sound pleasant to the human ear. Transistor amps distort with even order harmonics which aren't.
[/quote]

That's the exact opposite of the truth. Valve amps contribute even-order harmonics which sound good (as they're octaves), transistor amps produce odd-order harmonics as they go into clipping - a square wave is the product of an odd-order series f + 3f/3 + 5f/5 + 7f/7... (the multiplier is the frequency, the divisor is the volume, hence 3f/3 is a third the volume and three times the frequency) which is why the odd-order harmonics are produced.

[taunton-hobbit]

Cor - there's teknikal....I'll stick with my KT120s & let everyone else fight............

[TimR]

[quote name='tauzero' timestamp='1464980064' post='3064433']


That's the exact opposite of the truth. Valve amps contribute even-order harmonics which sound good (as they're octaves), transistor amps produce odd-order harmonics as they go into clipping - a square wave is the product of an odd-order series f + 3f/3 + 5f/5 + 7f/7... (the multiplier is the frequency, the divisor is the volume, hence 3f/3 is a third the volume and three times the frequency) which is why the odd-order harmonics are produced.
[/quote]

Ah thanks. I knew it was one way round.

Seems we both may be wrong. It's the A vs AB amplifier design that causes the difference. The push-pull cancels the unpleasant harmonics.

Anyway. You can push one further into distortion than the other and it will not sound harsh.

[grandad]

Due to the perculiarities of our auditory system, we tend to interpret the gradual distortion produced in valve amplifiers as a pleasant and louder signal.

When SS amplifiers distort we hear sudden harsh distortion and dislike it.

So it's largely about how they move into distortion as the input levels increase aswell as the harmonic content of each.