Common amp myths

[georgestrings]

Why are we using Ampeg's worst head as the measuring stick?

Simple - both made by the same manufacturer, but 2 examples of the different types of heads...



- georgestrings

 

[iamthebassplayr]

Do you work in politics??? - 'cause that sure was a nice spin job...

Let me see if I've got this straight - a tube amp and an SS amp with the same output ratings, but to be "fair" in your world, the SS amp needs to have a compressor, an OD pedal, and be EQ'd to match the tube amp's sound while FLAT???

Yeah, sounds about right - hahaha!!!


- georgestrings

You'd be comparing apples and watermelons otherwise?

 

[bongomania]

I'm sorta a "where the rubber meets the road" type of guy - and don't get as hung up on specs as *some* do...

But what you're consistently failing to understand is that when an engineer states something based on the laws of physics, and uses math or scientific principles to prove it, they are not being "hung up on specs". "Hung up on specs" is the guy who says he has to have 10" speakers because 15's are too slow, or the guy who has to have a cab rated for 3dB down at 30 Hz because they want a really deep bassy tone. Those are people who use specs instead of having factual understanding of how the equipment works.

Play a gig with a LOUD metal/hard rock band, with a typical classic rig: an SVT on top of an 810 - then, play the same gig the following week with with a B2RE instead of an SVT, and compare effectiveness...

You made this argument how many times now? Like six or seven in this thread? And have not listened to anyone who has explained to you what the functional differences are between those two amps. Short version: It has nothing to do with tube versus solid state. Everyone here agrees that the B2RE sucks beans compared to the SVT, and you are not impressing anyone by repeating that fact. It is possible (and even easy, if you know how your equipment works) to make a solid state amp operate with the same loudness, effectiveness, whatever you want to call it as a tube amp of similar wattage. The B2RE does not have adequate features to achieve that on its own, and is therefore a poor example, because it does not prove anything about tube versus solid state- it only proves how badly designed the B2RE is. It does also suggest that the SVT requires less thought or education to make it loud, which is a real benefit.

Again though, repeating your story about the B2RE does not make it a good argument. The fact that you got the results you got just shows you are a plug-n-play guy, not somebody who spends the time to learn how your signal is actually being handled by the amp.

Now, people can throw all the specs, and scientific jargon at this that they want, however - those are cold hard realities that cannot simply be ignored...

If I had a nickel for every time somebody in this forum spat out their chewin' tabaccy and said "well y'all kin argue that ther science talk all day, but I know what I done heard", I'd be rich.

The cold hard facts are that you got the results you got because that's what you knew how to do, not because the tools could do nothing different. You heard what you heard because of how you used the tools, not because "tube watts are louder".[/QUOTE]

 

[georgestrings]

You'd be comparing apples and watermelons otherwise?

Really??? - because I thought I was comparing 2 different types of amps, with all other variables being the same...


- georgestrings

 

[bongomania]

Nope, that's inaccurate.

 

[Bob Lee (QSC)]

You show up for a gig.

Drummers got the biggest set of vistalites you've ever seen, plays with marching band sticks. He's about 7 feet tall, played offensive line for Ohio State in college.

Each of the three guitarists have Marshall stacks, all knobs dimed.

You are presented with an 8x10 cabinet and your choice of an SVT or a B2RE.

If you choose the B2RE you have no real world experience with how these things work.

Watt for watt you can count on tubes providing more usable volume in the real world. Period.

LOL!

 

[georgestrings]

But what you're consistently failing to understand is that when an engineer states something based on the laws of physics, and uses math or scientific principles to prove it, they are not being "hung up on specs". "Hung up on specs" is the guy who says he has to have 10" speakers because 15's are too slow, or the guy who has to have a cab rated for 3dB down at 30 Hz because they want a really deep bassy tone. Those are people who use specs instead of having factual understanding of how the equipment works.


You made this argument how many times now? Like six or seven in this thread? And have not listened to anyone who has explained to you what the functional differences are between those two amps. Short version: It has nothing to do with tube versus solid state. Everyone here agrees that the B2RE sucks beans compared to the SVT, and you are not impressing anyone by repeating that fact. It is possible (and even easy, if you know how your equipment works) to make a solid state amp operate with the same loudness, effectiveness, whatever you want to call it as a tube amp of similar wattage. The B2RE does not have adequate features to achieve that on its own, and is therefore a poor example, because it does not prove anything about tube versus solid state- it only proves how badly designed the B2RE is. It does also suggest that the SVT requires less thought or education to make it loud, which is a real benefit.

Again though, repeating your story about the B2RE does not make it a good argument. The fact that you got the results you got just shows you are a plug-n-play guy, not somebody who spends the time to learn how your signal is actually being handled by the amp.



If I had a nickel for every time somebody in this forum spat out their chewin' tabaccy and said "well y'all kin argue that ther science talk all day, but I know what I done heard", I'd be rich.

The cold hard facts are that you got the results you got because that's what you knew how to do, not because the tools could do nothing different. You heard what you heard because of how you used the tools, not because "tube watts are louder".

[/QUOTE]


That's a pretty tall load of crap, but thanks for piling it so high - I'll just address the last part:


"The cold hard facts are that you got the results you got because that's what you knew how to do, not because the tools could do nothing different. You heard what you heard because of how you used the tools, not because "tube watts are louder"


No, I got those results because that was all that amp was capable of producing - I can assure you that I know how to make the most out of an amp's gain structure and EQing - I've probably played several thousand gigs in my lifetime - over 75 last year, actually...



- georgestrings

 

[Bob Lee (QSC)]

I'll put my crown MT 1200 against a comparable QSC with a switching power supply...

I would happily pit them against each other, too, but neither one is a tube amp.

 

[iamthebassplayr]

Really??? - because I thought I was comparing 2 different types of amps, with all other variables being the same...


- georgestrings

Well... apples and watermelons are both fruit... all other variables the same.


(yes, watermelons are fruits....not melons, I promise.)

 

[rag]

I notice that you didn't address this:


"A case in point: compare an SVT(300watts) with a B2RE(450watts) - and tell me that the SVT isn't ALOT louder..."


Any answer to that??? After all, there's an example of each type, built and rated by the same manufacturer...



- georgestrings

When you are driving a speaker all Watts are not created equal. An eight Ohm speaker is not the same as a real eight ohm load. The eight Ohm RMS power rating of an amplifier is measured into a real eight Ohm load. A real load means that it is eight Ohms at all frequencies. An eight Ohm speaker on the other hand is only eight Ohms at a few specific frequencies. Over 99% of the audio band the speaker is no where near eight Ohms. A typical eight Ohm speaker will start out at 5 Hz as 6 Ohms. If mounted in a bass reflex cabinet (ported cabinet) it will shoot up to over 50 Ohms at about 30 Hz, then drop down to 8 Ohms at 50 Hz, then shoot back up to 50 Ohms at 80 Hz then drop back down to 8 Ohms at 200 Hz. From 200 Hz through the rest of the audio band (20 kHz) its impedance will increase 6dB per octave (double every time the frequency doubles).
Tube amps have a soft supply that sags with low impedances and returns with high impedances. This means the amp will put out more power into a high impedance than an amp with a hard supply that did not sag. The 8 Ohm real load that the tube amp is rated into causes the supply to sag a lot compared to the supply in a typical solid state amp. So when the tube amp is driving a speaker it can deliver a lot more power to the high impedances it sees than a comparable solid state amp. Of course that assumes the solid state amp has a hard supply as most of them do. But guess what? Some solid state amps have soft supplies.

 

[bongomania]

I can assure you that I know how to make the most out of an amp's gain structure and EQing - I've probably played several thousand gigs in my lifetime - over 75 last year, actually...

And yet you have no idea what makes the tube amp louder, only that it "is" louder. If you knew what makes the tube amp louder, we wouldn't be arguing.

 

[Bob Lee (QSC)]

fdeck are u sure?? we are talkin watts. not current draw from the wall... I know for a fact the QSCs have limit lights that will come on before a crown.... I thin Bob lee knows that too... This is not meant to diss QSCs, just different flavors for different people

You seem to have some of your "facts" mixed up, including that QSC amps don't have limit lights. Do you mean clip LEDs? They'll only light if the amp actually clips.

 

[Bob Lee (QSC)]

Leaving the SS vs Tubes discussion for a while, my favorite myths are:

Loudspeaker ratings are accurate and complete.
I think most speaker manufacturers (as opposed to driver manufacturers) take the sum of the thermal power handling capacity of the drivers in their boxes and call that the rating of the box. However, playing a bass with the lows cranked you're quite likely to send the drivers into over-excursion with ease (depending on how they're tuned.)

Keeping the volume control at 5 uses half the amp power
The correlation between volume control settings and amp power is pretty slim. You can count on an amp getting louder when you turn controls clock-wise, but that's about it. Many instrument amps are designed such that their volume controls have most of the range covered in the first third. That way they'll appear loud in the shop where the potential buyer is expected to think "Wow! If it's this load at 3, just imagine what it'll do at 10!".

Good ones!

 

[Bob Lee (QSC)]

Solid state amps on the other hand are easily built to reproduce DC faithfully, albeit pointlessly.

Most solid state amps have high-pass filtering to block DC. Back in the late 70s, maybe early 80s there was a direct-coupled amp craze, but it eventually fizzled out.

 

[Rune Bivrin]

Most solid state amps have high-pass filtering to block DC. Back in the late 70s, maybe early 80s there was a direct-coupled amp craze, but it eventually fizzled out.

Oh, absolutely! But as a consequence of the potential ability, they'll easily be straight down to 3Hz, just to not introduce phase shifts at 30 Hz. And in the worst case faithfully reproduce the movement of the E-string as your anchored thumb pushes it back and forth. Given, of course, that all the components in the signal chain are equally lenient.

 

[derrenleepoole]

This is a great thread, and I've learnt some interesting things - so thanks. Maybe though, someone could explain something to me. Apologies though if it's been covered already in this topic, or if it's not strictly relevant to this thread, but I'm sure many people like myself get confused and baffled by frequency response of cabs and amps and what it truly means....

Say for example you take two different amplifier brands and one lists it's lowest frequency response as 40hz and the other as 60hz. In realistic, laymans terms, how do these two figures differ in the way that the lowest frequencies are produced/perceived? If the resonate frequency of the low E string is 41hz, how does a cab frequency response of 60hz affect the note reproduction? I'm I right in thinking that the lower the frequency response of the cab, the more accurately it can reproduce the colour/timbre of the note? Is for example the difference between 40hz and say 100hz noticeable to the ear? Is 100hz still bassy by comparison? I hope this makes sense and someone gets what I'm trying to say?

 

[fireincairo]

No one has mentioned the myth that you can't gig with a low wattage amp.

 

[BadB]

When you are driving a speaker all Watts are not created equal. An eight Ohm speaker is not the same as a real eight ohm load. The eight Ohm RMS power rating of an amplifier is measured into a real eight Ohm load. A real load means that it is eight Ohms at all frequencies. An eight Ohm speaker on the other hand is only eight Ohms at a few specific frequencies. Over 99% of the audio band the speaker is no where near eight Ohms. A typical eight Ohm speaker will start out at 5 Hz as 6 Ohms. If mounted in a bass reflex cabinet (ported cabinet) it will shoot up to over 50 Ohms at about 30 Hz, then drop down to 8 Ohms at 50 Hz, then shoot back up to 50 Ohms at 80 Hz then drop back down to 8 Ohms at 200 Hz. From 200 Hz through the rest of the audio band (20 kHz) its impedance will increase 6dB per octave (double every time the frequency doubles).
Tube amps have a soft supply that sags with low impedances and returns with high impedances. This means the amp will put out more power into a high impedance than an amp with a hard supply that did not sag. The 8 Ohm real load that the tube amp is rated into causes the supply to sag a lot compared to the supply in a typical solid state amp. So when the tube amp is driving a speaker it can deliver a lot more power to the high impedances it sees than a comparable solid state amp. Of course that assumes the solid state amp has a hard supply as most of them do. But guess what? Some solid state amps have soft supplies.

What he said!

 

[JFace]

This is a great thread, and I've learnt some interesting things - so thanks. Maybe though, someone could explain something to me. Apologies though if it's been covered already in this topic, or if it's not strictly relevant to this thread, but I'm sure many people like myself get confused and baffled by frequency response of cabs and amps and what it truly means....

Say for example you take two different amplifier brands and one lists it's lowest frequency response as 40hz and the other as 60hz. In realistic, laymans terms, how do these two figures differ in the way that the lowest frequencies are produced/perceived? If the resonate frequency of the low E string is 41hz, how does a cab frequency response of 60hz affect the note reproduction? I'm I right in thinking that the lower the frequency response of the cab, the more accurately it can reproduce the colour/timbre of the note? Is for example the difference between 40hz and say 100hz noticeable to the ear? Is 100hz still bassy by comparison? I hope this makes sense and someone gets what I'm trying to say?

Those numbers are the lowest frequency that the manufacturer considers "usable". The problem with that is everyone considers usable to be a different thing. Some companies use a -6dB rating, some -10dB. That is, if you are looking at a frequency response graph, what frequency crosses the -6dB line.

Cabs with a 41Hz response might actually have the same response as one that has 60Hz. Of course, many factors play into the equation, such as ported/sealed, speaker size, cab volume, rigidity of the baffle. I'm not saying the numbers are useless, but it is difficult to gauge the true response of a cab. It's equivalent to guessing how loud it is by reading the power rating. Not very effective.

These frequencies are very noticable. 3dB of difference is double the volume. If the low usable frequency is -10dB, that's practically inaudible compared to the other notes at unity.

Another thing to consider is the harmonics produced by the low notes. Often times, the cab produces more harmonics than the fundamental, especially in the lower registers. So a cab doesn't necessarily have to be tuned to 30Hz to amplify a low B.

There's a ton of science at hand here, and if one were to study this too much, you can go in circles figuring out the "best cab". It's best to let your ear decide.

 

[mitb]

this thread is awesome!
i really learned alot from it!