Common amp myths

[Bob Lee (QSC)]

So, you're saying that setting up an SPL meter, and seeing which one is louder would not be a valid determining method??? That would certainly take the human ear out of the equation... As far as gain structures are concerned - does it really matter, if a bass is plugged directly into an amp, which is then plugged directly into a cab - and both amps are tested in exactly the same method??? I'd say that if both amps have different gain structures within themselves, and that contributes to a volume difference - then the louder amp is still more powerful...

Let's say one happens to be louder than the other. Then you turn up the other amp until it's the louder one. Then turn up the other again.

Is there a point to it?

 

[greenboy]

Gee, and we haven't even addressed cables and power conditioners yet! ; }

 

[Bob Lee (QSC)]

Using the amp's own controls, wouldn't you say that the amp that will create the most volume is most likely more "powerful"??? - atleast as far as any actual usefullness is concerned, that is...

How do you propose to determine which one creates more volume?

 

[georgestrings]

I guess you don't understand the numerous explanations given. LOUDNESS IS NOT A SCIENTIFIC MEASUREMENT!!

You are perceiving something and stating that to be fact. The reason the 200 SS amp can't keep up is because it reaches a certain level of THD beyond which you get distortion, whereas with the tube amp you can keep on pushing well beyond that point and you perceive it as getting louder, when all you are doing is adding distortion and compression to your signal.

You are aware that "loudness" can be scientifically measured, and often is to conform to municipal laws, right??? I'm not talking about perception - I'm talking about something that can actually be measured by a meter...



- georgestrings

 

[shakerattleroll]

So, you're saying that setting up an SPL meter, and seeing which one is louder would not be a valid determining method??? That would certainly take the human ear out of the equation... As far as gain structures are concerned - does it really matter, if a bass is plugged directly into an amp, which is then plugged directly into a cab - and both amps are tested in exactly the same method??? I'd say that if both amps have different gain structures within themselves, and that contributes to a volume difference - then the louder amp is still more powerful...



- georgestrings

I think you should reread my post, wherein it states that a scientific way of measuring this would use an SPL meter, whereas you are using your ears and claiming your perception to be a fact that proves the myth that tubes are louder than ss amps of the same wattage.

You also make it clear that you don't understand the concept of gain structure. For all we know you are cranking the lows on the ss amp so that you are using up a far greater amount of watts in a spectrum that doesn't contribute to perceived loudness and therefore decreases both the available power for other frequencies and makes that amp seem less loud.

 

[greenboy]

Neo speakers all sound thin and handle less power. What's worse they bloom farther away than regular speakers, so you really can't hear them until you cross the state line. But there, damn, they causin' tornados and stuff!

 

[georgestrings]

How do you propose to determine which one creates more volume?

Easy - an SPL meter in the identical same spot, using the same bass and cab - just like one sometimes has to use such a meter to conform to volume codes/laws...



- georgestrings

 

[Rick Auricchio]

Using the amp's own controls, wouldn't you say that the amp that will create the most volume is most likely more "powerful"??? - atleast as far as any actual usefullness is concerned, that is...

No, not more powerful. More effective is the term I used.

Power is measurable: Measure voltage at speaker. Read SPL. Repeat with other amp at same voltage.

Effectiveness is a subjective judgement. We can agree that effectiveness of an amplifier depends on what you want. Volume and tone.

I plan to run SPL tests on a few speaker cabs in a week or two. At that time, I will compare the Eden WTX-260 (which I believe is Class D) and an old Bogen CHB100 all-tube PA amp. I expect both amps to produce the same measured SPL with the same sine-wave source and voltage measured at the cabinet.

 

[Bob Lee (QSC)]

Easy - an SPL meter in the identical same spot, using the same bass and cab - just like one sometimes has to use such a meter to conform to volume codes/laws...

But how do you propose to determine which one can put out more volume?

 

[georgestrings]

Let's say one happens to be louder than the other. Then you turn up the other amp until it's the louder one. Then turn up the other again.

Is there a point to it?

Sure - eventually, their usable volume will reach a max, and more than likely, one will be louder than the other... In my example, I'd make a pretty healthy wager that a B2RE would max out LONG before an SVT would, as measured by an SPL meter...



- georgestrings

 

[Bluesy Soul]

Where you are coming from is using your ears, and trying to tell us that we're wrong. I am sorry, but anytime your ears are involved, that is perception. And yes, you are perceiving the tube amp as being louder. As has been pointed out several times, you perceive tubes as being louder because the distortion isn't awful to your ears, so you can crank and think it is louder, among other factors. If numbers are your thing, let's set up an example.

Two amps, one tube, one ss, both rated at 100 watts, both with .001% THD at 75 watts, .1%THD at 85, and 1%THD at 100.

Even if all those things are equal, you hear "bad" distortion with the SS amp much earlier than with the tube amp.

On top of all that, your "real world" tests are completely unscientific and speculative also. I am going out on a limb, but can you prove to us that the gain structure in both amplifiers was set up exactly the same?

Anyways, to do this scientifically you would use a sine wave from a signal generator, and the gain structure of both amps would be set up identically, and you would use the sine wave at differing levels of output and record the SPL at the speakers. You would then see that both amps would be equal, watt for watt.

Check any electrical engineering book and get back to me on where it states that there is such thing as one type of watt being more powerful than another. It simply is not true.

That all seems perfectly logical to me and, based on technical measurements, I'm sure one solid-state watt is equal to one tube watt. That doesn't mean, of course,--and I think you have acknowledged as much--that greater perceived loudness isn't also greater effective loudness. Until my bandmates and audience members become signal processors and oscilliscopes, however, I'll play to human perceptions. (See Rick Auricchio's comments above.) When you demo and compare new amps or new cabs, do you hook up the EE devices or do you perform A/B comparisons to determine what your ears perceive.?

The notion that perception constitutes a form of reality applies to many phemonena that are measured by the senses. For example, the moon appears to become smaller as it rises higher in the sky (measure it sometime).

Bluesy Soul

 

[shakerattleroll]

You are aware that "loudness" can be scientifically measured, and often is to conform to municipal laws, right??? I'm not talking about perception - I'm talking about something that can actually be measured by a meter...



- georgestrings

You are talking perception. Loudness and SPL, at least how you are using them, are two different things.

Unless you're telling us your ears are SPL meters, when you refer to the SVT being louder, that is the perception of volume that your ears and brain is creating.

IF, we measured the output of both to have the same watts, let's say we turned the amps up to 100 watts at their output, we might even then perceive them differently based on the gain structure of the eq in both.

 

[fdeck]

I would say that a more relevant test than using an O-scope would be using an SPL meter to record volumes between amp types with the same ratings - with all other variables being the same... After all, people *usually* listen to what an amp puts out more than they care how it's output shows up on an O-scope... - a "real world" test, if you will...

That's certainly a valid point. One problem is that an SPL meter does not measure volume as we perceive it. However, perhaps a combined measurement is possible. These days, an "oscilloscope" for the purpose of audio measurements is software that uses the audio input of a PC. Also, a SPL meter works simply by measuring the output of a microphone and displaying the results on a meter.

The PC could do both jobs. It could measure the output of the amplifier (through a suitable attenuator to avoid destroying the PC -- don't do this unless you know how to do it safely), and the output of a microphone, simultaneously. The recorded waveforms could be analyzed to provide relative measurements of SPL, but also other sorts of analyses as well.

To calibrate the PC's SPL scale, one could compare the PC measurement to a SPL meter using a sinewave input.

 

[georgestrings]

I think you should reread my post, wherein it states that a scientific way of measuring this would use an SPL meter, whereas you are using your ears and claiming your perception to be a fact that proves the myth that tubes are louder than ss amps of the same wattage.

You also make it clear that you don't understand the concept of gain structure. For all we know you are cranking the lows on the ss amp so that you are using up a far greater amount of watts in a spectrum that doesn't contribute to perceived loudness and therefore decreases both the available power for other frequencies and makes that amp seem less loud.

Actually, I said that my ears have told me this, and that I was pretty sure than an SPL meter would verify it as so - BUT, no one here has ever actually done such a test, or if they have, they haven't submitted the levels of their findings... We've just been expected to accept it as fact - without anyone actually measuring volume differences between the two... Now, if my ears tell me something, but I'm expected to believe something to the contrary without any actual test results - then of course I'm going to be a bit apprehensive of buying into it...



- georgestrings

 

[shakerattleroll]

That all seems perfectly logical to me and, based on technical measurements, I'm sure one solid-state watt is equal to one tube watt. That doesn't mean, of course,--and I think you have acknowledged as much--that greater perceived loudness isn't also greater effective loudness. Until my bandmates and audience members become signal processors and oscilliscopes, however, I'll play to human perceptions. (See Rick Auricchio's comments above.) When you demo and compare new amps or new cabs, do you hook up the EE devices or do you perform A/B comparisons to determine what your ears perceive.?

The notion that perception constitutes a form of reality applies to many phemonena that are measured by the senses. For example, the moon appears to become smaller as it rises higher in the sky (measure it sometime).

Bluesy Soul

Right, but to say that tube watts are louder than ss watts, well...

A correct phrasing would be "I perceive my tube amp to be louder" or something along those lines.

 

[JansenW]

And we have a winner for the thread.

I just discovered another myth which came out from this thread...

People can agree about amp myths...

 

[shakerattleroll]

That's certainly a valid point. One problem is that an SPL meter does not measure volume as we perceive it. However, perhaps a combined measurement is possible. These days, an "oscilloscope" for the purpose of audio measurements is software that uses the audio input of a PC. Also, a SPL meter works simply by measuring the output of a microphone and displaying the results on a meter.

The PC could do both jobs. It could measure the output of the amplifier (through a suitable attenuator to avoid destroying the PC -- don't do this unless you know how to do it safely), and the output of a microphone, simultaneously. The recorded waveforms could be analyzed to provide relative measurements of SPL, but also other sorts of analyses as well.

To calibrate the PC's SPL scale, one could compare the PC measurement to a SPL meter using a sinewave input.

This might get us close to measuring our perception but the fact remains, tube watts are no louder than ss watts. We just perceive a difference based on audition, otherwise known as the perception of sound.

Side note to George. It isn't my job to do the research for you. Look into scholarly works on this, or read an electrical engineering book. Simply because you don't believe it does not mean it's not true.

 

[Rick Auricchio]

I also expect my SPL charts to have differences within the frequency spectrum, attributable to the coloration of the amplifiers. And that's just with straight sine waves. I'm not considering dynamic response, which is what we call upon when plucking strings.

I'll test and post. But it won't be for a couple weeks.

 

[shakerattleroll]

from geofex.com

"Are Tube Amps louder than solid state amps of the same power?
Yes and no. If you put a power meter on the output of a tube amplifier and a solid state amplifier that have been matched for total output power, then the meter will read almost exactly the same power for equivalent drive conditions - so in this sense, the answer is no, they are not louder. However, if you LISTEN to the two amps, you'll find that the tube amp does indeed sound louder to your ears, in opposition to what the meter is telling you. Why?
It's tied up in the sensing instrument - that is, your ear. The way the human ear works is that it is very sensitive to the harmonic content of a sound. A tube amp is less linear (that is, has more distortion) at signal levels below clipping than a solid state amplifier. The distortion will increase slowly, and then more rapidly as the amp starts to clip. In fact, the distortion increases so gradually and is of such a benign nature that the onset of audible distortion has no easily defined threshold. The solid state amplifier on the other hand has no such gradualism. It is almost perfectly non-distorting right up to the point that it clips, and then it clips HARD. It's easy to hear the threshold.
This sudden onset of distortion is also composed of relatively harsh sounding distortion, not like the subtle second and third harmonics of the tube amp. The human ear hears the sudden harsh distortion as clipping and harshness. It interprets the low order distortion of the tube amp as a louder sound, not as distortion. In effect, the tube amp fools the ear into thinking that its early distortion is more loudness. They therefore sound louder or more powerful than the actual measurements show are really there."

Again, the variable here is your perception. A watt is a watt. Your ears just perceive the amps differently, not the actual power of the amps.

 

[alexgeddy]

First..me thinks you deliberartely tried to start a flame war.....watts are watts till they are usable....Ampeg specs their amps at 1200 wats at 5 % THD plus no IMOD specs so for the casual bass player this results in less usable power.....therefore so many post about why ampeg sounds so underpowered,..... For your edification, go read a Crown power rating.... it's called usable watts......crown has a 5 db headroom..most bass amps have 2 or 3 at the most...My eden has 3 at best. i do agree when a SS power amo distorts it's ugly. Tubes handle the 3 db compression points better. but then you lose power...assuming you know that

Whatever you were talking about with headphones....go ask the phone company how they get deep voices through the phone. it's a trick to fool the ear into hearing deep tones..same as headphones.......


so i guess my main question is why did u post that? when you are full of it.

And yes bass frequencies take time to develop. Go spend some time in an anechoic chamber.... or a pro recording studio.... longer wavelengths = time to proprogate..a law of physics.....dispute that ...listen to an upright real close up...it sounds like crap....move about 10 fet away and it sounds great....duhhhh


feel free to pm me

Bill