watt for watt, is SE louder than PP?

[six_eight]

Is it just me or do the smaller under 10watt single ended amps seem to produce just as many dB as push-pull amps with twice as many watts when you play them through the same speaker?

[Willabe]

I'd say that it could be a few things that might make it sound as loud.

1. It would depend on how clean or distorted each amp is played. More distortion generates more harmonics, even that can fattin and odd that can make the amp crisper and cut through more.

*If you run an amp up to the point that it's output signal wave squares off the amps output doubles, ie, 5 watt to 10 watt.

2. It would also depend on the amount of natural compression the amp generates. Cathode bias verses grid bias and power supply sag from running the amp close to or full up. More compression can give the impression that it's louder. SE class A does not change very much from running at idol to full tilt, except for *. PP class A/B in cathode is high bias current and does not change as much from idol to full tilt compared to a PP class A/B in grid bias.


              Brad        

[Colas LeGrippa]

watt for watt, it is equal. a 10 w SE is as loud as a 10 w PP. The power is function of db. A PP amp will deliver more watts with less power because there is less loss in a PP.

Colas

[Stankfut]

Half the watts does not equal half the volume. Without going into equations that others are probably better qualified to explain, roughly 10% power is probably closer to half volume (I'm sure someone well correct me on this ). For example, I recently was jamming with a guy that has an AC30 reissue. I took along my 5E3. Both are class ab push pull amps, one is half the power of the other. Couldn't hear much of a difference really. Also...speakers can make a big difference as well

[phsyconoodler]

Couldn't hear much of a difference really.

 Please! An AC 30 will drown out a 5E3 easily.A loud drummer will bury a 5E3 in short order too.Hence the need for an AC30 on stage with a loud band.

 Get a band with a bass player who you can actually hear,a drummer who hits the cymbals hard enough and a good monitor mix and your 5E3 will be cranked just to get to hear it.An AC30 on the other hand will easily keep up with that band and have tons left over for solos that will rip off faces.
 Two 12" speakers adds to that loudness in a big way,especially if they are Celestion blues.Freaking loud!

[Willabe]

It's supposed to be that for the human ear to perceive twice the volume you need 10x the power.

So a for a 10 watt amp to be twice as loud to the human ear it would have to be 100 watts.

But when I played out in the blues clubs I had a BF SR (40w) and a lot of the band leaders had BF TR (80 w) and they would absolutely bury me volume wise on stage!      

One guy (Son Seals) I played for would have 3 to 7 horns on stage with us and he could get over them on a solo and I could not.
            

                            Brad        

[thelonious]

Freaking loud!

Especially if you run 'em like:

[PRR]

> It's supposed to be that for the human ear to perceive twice the volume you need 10x the power.

At any reasonable level, 6.02dB (4X power) sounds like "twice".

However guitar is played at HIGH level, where the inner-ear muscle tenses-up to protect your precious ear-nerves. If you persist in LOUDER, yes it may take 10X power to cut-through the self-protection and sound like "twice".

This trend was well-promoted by the early HIGH power hi-fi amp makers to justify their posh prices.

Let us not forget that physical measurements do not agree perfectly with what the ear hears. There's no meter for "soulfulness", "grind", "mojo", "bite", "harshness". I've heard "loud" from low-powered systems which did not really shake the air much, but really excited/irritated the ear.

[jeff]

I never understood what twice as loud meant. I mean, yeah, I can tell if something's louder than something else but what does "twice as loud" mean?
To me that's like saying something is twice as yellow as something else.

[Colas LeGrippa]

the human ear perceives sound on a logarithmic scale , that's why we use log ( audio ) pots for audio and linear ones for other purposes

Colas

[spacelabstudio]

It's probably useful to keep in mind that the relationship between SPL and perceived volume is highly non-linear and probably highly personal as well.  To say that it's logarithmic is also, really, an oversimplification.  The short answer is it's complicated because it's meat and neurons. 

When mixing in my studio I tend to find that monitoring a mix loud evens out relative levels of instruments, since the ear tends to compress a bit at high volumes.  Monitoring at lower volumes gives a better feel for relative instrument levels, while monitoring at higher volumes give s a feel for the visceral impact.  The point is the ear hears differently depending on the amount of SPL.  Another lesson from mixing is that perceived instrument balance involves a lot more than just their volume--their relatively frequency spectrums also play a big role.  Two instruments that occupy fairly different frequency spectra can sound distinct from each other at any volume.  If you have a bunch of instruments all piling on 200-400Hz it sounds like a muddy mess and you can't make anything out.  So, it's not just volume, it's EQ too.

Unfortunately, there's no pat answer.  You just gotta try different things until you get a balance that works with a particular line up.

[smackoj]

I may be OTL but isn't there another side to the coin ie, the orig. question: Is a SE amp louder......? Doesn't the efficiency of the speaker contribute a lot to the sound level? A harsh, annoying note may seem louder because it's produced in a freq. range that the ear wants to protect regardless of which type of amp it originates from. And that may be due to a type of spkr that likes that freq. and shoves it out with gusto?

When playing with a group that likes to shake the room, I find that I need some major muscle to make a note stand out in comparison to a thumpin' bass man and a hard hittin' drummer. I can't get there with a SE amp as much as I like their sound.

I love that old B. May photo. Too cool! I used to see Johnny Winter with Rick Derringer and their sound pres. level was deafening x 10. They used stacks of BF TRs and they sucked so much juice outta the venues that the snack bars shut down for lack of lights! no b.s., really.  

[jojokeo]

the human ear perceives sound on a logarithmic scale , that's why we use log ( audio ) pots for audio and linear ones for other purposes

that would also be known as orders of magnitude vs doubling meaning instead of simply multiplying by x2 (times two) it's squaring the number x² or going further the number to x power - this is a major difference as it compounds upwards or downwards. This same theory is also also applicable in sailing (force exerted on a sail) or more appropriately the effects of wind speed forces exerted onto buildings such as hurricane Sandy recently. IIRC for every doubling of wind speed there is four times the force exerted?

example of doubling vs increasing in order of magnitude five times:
5x2=10 x2  =20   x2=40   x2=80    x2=160
5x5=25 x5  =125 x5=625 x5=3125 x5=15625

Is this one of those trick questions like, "what falls faster a pound of featers or a one pound lead weight"???  

W/out hard data or identical operating conditions that even tube data sheets show, my gut feeling is that a BFDR fixed bias is listed at 22watts but if you simply left everything alone, disconnected the neg bias and installed cathode resistors w/ bias caps I'm not sure you'd get the same 22watts output? That said, I have an amp set-up w/ 6V6s which can run either way like this w/ the flip of a switch and I don't think I can "hear" any percieved volume difference when ran one way or the other. But, what I can hear is a difference in harmonic content, break-up level is different, and the amp's feel is slightly different all pointing to maybe that the fixed bias is "slightly" more powerful, tighter, and w/ more headroom. YMMV?

[phsyconoodler]

I guess one would say the harmonics from a single ended amp may be more pleasant to the inner ear and it opens up to let more in?
 My personal experience with single ended vs push pull tells me that the push pull amp is louder watt for watt but i can't quantify it.
 For example,my single ended champ with two parallel 6V6's made 10 watts and my 5E3 made 12 watts with two 6V6's.But...the 5E3 seemed much louder,both used 12" Jensen P12Q's.
  The single ended iron I used was a hammond 125FSE and about the same plate voltage for both amps.
 The champ was easier to warm up stuff with than the 5E3 but both got damn hot.
I would have to say that a single ended amp or one that runs close to class A uses up too much output wattage in heat.Both control panels got pretty hot to the touch.They make great space heaters!

[jojokeo]

My personal experience with single ended vs push pull tells me that the push pull amp...

ooops - I misunderstood the original question and thought it was cathode biased vs fixed bias  my bad!

[PRR]

> what does "twice as loud" mean?

Building a barn. I need a stick twice as big as the one I have. I don't really need a micrometer to find something "twice as big".

At moderate listening levels, I can set a tone to 6dB +/-1dB increments by ear. Not really practice. Do it a couple times, "twice as loud" become clear the same way "twice as big a stick" seems natural now.

> I may be OTL but ......? Doesn't the efficiency of the speaker contribute

QUOTE from six_eight: play them through the same speaker?

If you are going to mix-up the speakers also, say a gennie Fender Champ Six versus an octet of EVM Twelves found with a 300W P-P SVT, then sure the question is too messy to talk about. That's why six_eight specified "same speaker".

[Stankfut]

Phsyconoodler, I think sometimes what I'm trying to say gets a little garbled by the time I say it (don't get my wife started about that ). I was not trying to imply that a 5E3 is as loud as an AC30, of course its not. The AC30 was not twice as loud, though. I'm not sure what speakers he was using, but they are suspect. (I'm trying to talk him into trying Webers). Having said that, with just two guitars, I could still hear myself quite well, although the other amp was 2X the power. I'm sure that with a full band I would either need more power or to mic my amp whereas he would not.

[jojokeo]

I could still hear myself quite well, although the other amp was 2X the power

Maybe it's because most of the time we're standing right in front of our rig where as the other guitarist/band is in front of theirs and more away from you? Naturally you should hear yourself more. I have a hard time hearing my other guitar player on the other side of the stage at times and it's no contest of him being louder than me, quite the opposite but then that's spacing yourself properly too.

[printer2]

Like to give some of my observations on this SE, P-P, loudness question. I built an amp that was P-P running in Class A that I could shut off the signal to one tube making it a SE amp other than the using a P-P transformer. While you do not have the magnetizing current to deal with you still do not get the second harmonic cancellation of a P-P amp.



With one tube you get half the power as with the pair. Sounds like half the power also, no magic with SE over P-P. As close to apples to apples a comparison you can get with the same circuit, same speaker.


A AC30 blows away a 5E3. Well why not? You have a little more than double the wattage, so say a 4dB increase. I will assume that you are using the two speaker combo, using two speakers gives an additional 3dB boost in output for the same wattage in. We had this discussion at tdpri and I thought the output would stay the same given that you only get half the power to each speaker. Convinced myself otherwise by setting up two identical speakers, stereo amp and feeding them a sine wave and measuring the Spl with a meter. Measured with one speaker, two speakers with the same wattage split between them, with double the wattage into one double the wattage into both. So in summary, double the power +3dB, double the speaker area, +3dB. Wish I had four speakers to see if you get an additional 3dB, at some point you should get diminishing returns.



Using two speakers with a 5E3 will get you closer to a AC30, might be plenty with efficient speakers. To make useful comparisons between amps you need to go through the same speaker and make sure that they are the same efficiency. I swapped out one of the speakers I used in my test as it was a couple db down from the other two I had.

[PRR]

> at some point you should get diminishing returns.

A HIGH efficiency speaker must be a half-wavelength big.

Bass waves are bigger, so you check your lowest frequency.

A wave of 82Hz is 164 inches or over 13 feet.

You need a speaker 6.8 feet tall and wide for HIGH efficiency at 82Hz.

Even those mighty 15-inch JBLs are "small" for the job.

What you need is a tight-packed array of 10-inch speakers 8 high and 8 wide. (Or a 5x5 array of your Fifteens.)

Yup, two Full Stacks.

We get-by with far less because amplifier power is relatively cheap. One Watt of acoustic power is a pretty big source. 30 Watts of power is not THAT expensive. Cheap at least compared to the Econoline it takes to transport twin full stacks which would do the job with a couple Watts.

So any "reasonable" speaker will not sum-up to the diminishing returns point.

But there's more. A speaker that big is also directional. If you need to throw to a far bleacher, good. If you need to spread the width of a wide club, bad.

A large source made with multiple small sources (like an 8X8 array of 10-inchers) has additional problems. Off-axis (99% of your fans are at least a little off-axis) the highs combine in-and-out-of-phase. Comb filter. This is not the worst problem on the planet, and maybe not as bad for single guitar music production as for speech/music RE-production, but arrays sure do sound different.

All of which has little to do with the Single-Ended versus Push-Pull question, except that in the sizes we need to cover a paying audience, SE watts are more expensive than P-P Watts.

[printer2]

> at some point you should get diminishing returns.

A HIGH efficiency speaker must be a half-wavelength big.

Bass waves are bigger, so you check your lowest frequency.

A wave of 82Hz is 164 inches or over 13 feet.

You need a speaker 6.8 feet tall and wide for HIGH efficiency at 82Hz.

Even those mighty 15-inch JBLs are "small" for the job.

What you need is a tight-packed array of 10-inch speakers 8 high and 8 wide. (Or a 5x5 array of your Fifteens.)

Yup, two Full Stacks.

We get-by with far less because amplifier power is relatively cheap. One Watt of acoustic power is a pretty big source. 30 Watts of power is not THAT expensive. Cheap at least compared to the Econoline it takes to transport twin full stacks which would do the job with a couple Watts.

So any "reasonable" speaker will not sum-up to the diminishing returns point.

But there's more. A speaker that big is also directional. If you need to throw to a far bleacher, good. If you need to spread the width of a wide club, bad.

A large source made with multiple small sources (like an 8X8 array of 10-inchers) has additional problems. Off-axis (99% of your fans are at least a little off-axis) the highs combine in-and-out-of-phase. Comb filter. This is not the worst problem on the planet, and maybe not as bad for single guitar music production as for speech/music RE-production, but arrays sure do sound different.

All of which has little to do with the Single-Ended versus Push-Pull question, except that in the sizes we need to cover a paying audience, SE watts are more expensive than P-P Watts.

Electovoice Mr smartypants. 

[six_eight]

I guess one would say the harmonics from a single ended amp may be more pleasant to the inner ear and it opens up to let more in?

This is more of what I was getting at in my original post.  Throw all the wattage to dB conversion out the window.  Is there some phenomenon that causes the human ear to perceive SE and/or class A output as being louder than PP and/or AB output of equivalent wattage?

[printer2]

I guess one would say the harmonics from a single ended amp may be more pleasant to the inner ear and it opens up to let more in?

This is more of what I was getting at in my original post.  Throw all the wattage to dB conversion out the window.  Is there some phenomenon that causes the human ear to perceive SE and/or class A output as being louder than PP and/or AB output of equivalent wattage?

Nope. If anything P-P should sound louder as you have less second harmonic to pass and you can push more higher harmonics.

[HotBluePlates]

Is there some phenomenon that causes the human ear to perceive SE and/or class A output as being louder than PP and/or AB output of equivalent wattage?

I don't hear it as being louder.

Google "psychoacoustics". Read for weeks. 

Your particular case may have variables particular to your case. That's not clever word-smithing, but simple truth.

The presence of distortion, how much, presence of compression, nature of your source sound, how you had EQ set, etc. could all factor in. There are some sonic effects that can give the perception of loudness with being truly louder as measured by an SPL meter.

The whole discussion is somewhat like, "are tube watts louder than transistor watts? Then why do transistor amps need so many of 'em?"

However, I'll also confess to not playing any SE amp bigger than a Champ/Princeton.

[PRR]

> confess to not playing any SE amp bigger than a Champ

Dammit, someone's gotta put together a 40-Watt 813 or HK257 SE amp and try it against real amps.

[phsyconoodler]

When I fist started building amps I built a Blackface Champ with a Celestion vintage 30.It was plenty loud and sounded awesome in every respect.Then I built a 5E3 in the same cabinet and when I turned it on the first time I was blown out of my seat with how much louder it was.HUGE difference.
  I thought nothing could be that loud.(long time ago :) )
Then I played an AC30 for the first time.My ears hurt big time after that experience!

 Two Celestion Blues are VERY loud.Webers? No way!

[Willabe]

Dammit, someone's gotta put together a 40-Watt 813 or HK257 SE amp and try it against real amps.

A 40w SE OT is gonna be huge, heavy and cost big time.     

(You've brought this up many times PRR. )


                   Brad     

[six_eight]

When I fist started building amps I built a Blackface Champ with a Celestion vintage 30.It was plenty loud and sounded awesome in every respect.Then I built a 5E3 in the same cabinet and when I turned it on the first time I was blown out of my seat with how much louder it was.HUGE difference.
  I thought nothing could be that loud.(long time ago :) )
Then I played an AC30 for the first time.My ears hurt big time after that experience!

 Two Celestion Blues are VERY loud.Webers? No way!

The 5E3 doesn't have a NFB and just has a high cut tone knob.   The BF champ has a tone stack and NFB loop.  I think those things create a bigger dB difference than one 6v6 in SE vs. two 6v6 in PP.  I think the tone stack alone cuts 6dB overall.  I have a SF champ that I added switches to add/remove the tone stack and NFB, and the difference in volume without those features is really impressive.

[Ritchie200]

Speakers certainly make a BIG difference.  I've played my Major through a single 4x12 on 9 and it pales in comparison to 4 - 4x12's on the same setting.  Or even one 12" compared to 2x12 or 4x12.  Speaker and cabinet efficiencies.  Way way back...  I plugged my little Radio Shack am/fm pocket radio into our Altec Lansing Voice of the Theatre PA speaker and it sounded like a home stereo and just about as loud.

I also think UL sound louder.  Maybe due to more complete reproduction before falling of?

Now, lets talk about solid state wattage compared to tube wattage and the SIGNIFICANT differences in sound levels for the same wattage!

Jim

[printer2]

Speakers certainly make a BIG difference.  I've played my Major through a single 4x12 on 9 and it pales in comparison to 4 - 4x12's on the same setting.  Or even one 12" compared to 2x12 or 4x12.  Speaker and cabinet efficiencies.  Way way back...  I plugged my little Radio Shack am/fm pocket radio into our Altec Lansing Voice of the Theatre PA speaker and it sounded like a home stereo and just about as loud.

I also think UL sound louder.  Maybe due to more complete reproduction before falling of?

Now, lets talk about solid state wattage compared to tube wattage and the SIGNIFICANT differences in sound levels for the same wattage!

Jim

Different sound level between SS and tube because tube sounds better distorted. As far as loudness measured by a meter, same Spl.

[HotBluePlates]

Dammit, someone's gotta put together a 40-Watt 813 or HK257 SE amp and try it against real amps.

A 40w SE OT is gonna be huge, heavy and cost big time.     

(You've brought this up many times PRR. )

I think he's giving me a hard time, cause he knows I've got a silly transmitting pentode. But it's an 803 not an 813.

125w plate dissipation, I guess I could make a 40w or so SE amp. I just don't really want to make a space heater...  50w just to light the tube up.

But it would be fun, since this type is supposed to run mildly red-plated.

[PRR]

> giving me a hard time

803 needs big grid current (or insane plate voltage) to make any decent power. Not a good choice for audio. Build a radio transmitter or Tesla coil.

[rzenc]

> confess to not playing any SE amp bigger than a Champ

Dammit, someone's gotta put together a 40-Watt 813 or HK257 SE amp and try it against real amps

803 needs big grid current (or insane plate voltage) to make any decent power. Not a good choice for audio. Build a radio transmitter or Tesla coil.


6550 data sheet specs 20W single tube class A. How about using a   parallel quad for ~80W?? If it doesn't sound right, it sure will be a deluxe boat anchor!

Best Regards
R.

PS. I think someone built a single ended class A pair of KT88 sometime ago and stated the thing was as loud as hell... sounds like a nice project...

[HotBluePlates]

... and whats wrong about building a class b amp?

That's a whole thread of its own...