3dB louder sounds like this

[atrapp]

Originally Posted by seanm

Interesting. That spec is full of what we call weasel words in high tech. I always find high grade audiophile specs amusing.

What are the weasel words? Looks pretty straight forward to me.

[Jeff Scott]

Originally Posted by atrapp

You use a Mondial Aragon 2004 as a bass amp? Crazy cool!

I have in the past, but not currently; it is living quite nicely with it's mate, a 24K.

[atrapp]

Originally Posted by Jeff Scott

I have in the past, but not currently; it is living quite nicely with it's mate, a 24K.

I've been looking (halfheartedly) for a 4004 to drive my NHT 3.3's, never considered using an audiophile amp for bass - how did you like it?

[Jeff Scott]

I love the Aragon gear, wonderful sound and it's like having Krell stuff for a much more manageable price. I bought both the 2004 and the 24K together back in '88 from Paris Audio in West Los Angeles (I don't know if they are still around) brand new and they have been champs. I didn't need the power of the 4004 as the 2004 does my Maggies justice quite fine. A Palladium would be a cool amp to have, though.

[seanm]

Originally Posted by atrapp

What are the weasel words? Looks pretty straight forward to me.

Description: Solid-state class-A stereo amplifier. Rated minimum continuous output power: 250Wpc into 8 ohms (24dBW), with no more than 0.1% THD; 500Wpc into 4 ohms (24dBW), with no more than 0.1% THD

The bolded part are the weasel words. The specs are good, I am not arguing that But they do not necessarily show that they can get twice the power at half the impedance.

[Arjank]

Dincz did a good thing in showing how much 3dB (and 6dB) is. IMO the thread should have ended here.

Then there came others who added a few other things to consider (thermal/mechanical compression, loudness level, frequency range, tube vs SS). I can add anotherone myself, bafflestep. Stack two cabinets and the baffle size increase, which in turn lowers the bafflestep frequency and the ear percieves that as a beefier sound....

So, there are a lot of variables why adding a 2e identical cab sounds fuller(thermal/mechanical compression aside):
-doubling cone are +3dB
-8-->4ohms load approx +2dB (with SS amp)
-lower bafflestep frequency due to stacked cabs(works best with cabs in horizontal orientation, or, if you place two big cabs next to eachother)

Also, when stacking cabs, one cab can just stay on the floor which makes a huge difference in the amount of lowend. In most cases people put their (single) cab a bit higher to hear the mids which in turn decreases lowend output.

my 2 cents.

[figuredbass]

I hear a +3 dB volume increase as the difference between an amp on"10" and "11" in "Spinal Tap" terms...

[Arjank]

Originally Posted by figuredbass

I hear a +3 dB volume increase as the difference between an amp on"10" and "11" in "Spinal Tap" terms...

+1
Good description.

[Arjank]

One other way of showing what a 3dB increase does is to record/mix a song with the bass at "normal" level and then make a version with the bass -3dB and a version with the bass +3dB. That will give bassplayers an idea about how these leveldifferences affect the overall bandsound.

[mystic38]

I dont understand what part of
250W min into 8R 0.1% THD max
500W min into 4R 0.1% THD max

are weasel words... ? those specs clearly and specifically state its twice the power into half the impedance.

A high quality amp can provide 2x power into 1/2 impedance. fact.

consider:

a) Running 250W into 8R. P=V2/R ergo this requires a PSU with voltage rails of 45V. P=VI therefore PSU amp supply is ~5.5A

b) Running 500W into 4R. P=V2/R therefore PSU rails required to be 45V. P=VI therefore PSU amp supply needs to be ~11A

Running an amp into 8 Ohms is limited by the PSU voltage, but running into 4 Ohms is limited by PSU current.

Design a solid and capable power supply and you will get 2x power into half the impedance... This is not new, not rocket science, and given even an 8 ohm speaker can have impedance (frequency dependent) varying from 3 to 16 ohms the ability to drive current is a MAJOR factor in a good amp

Originally Posted by seanm

The bolded part are the weasel words. The specs are good, I am not arguing that But they do not necessarily show that they can get twice the power at half the impedance.

[Mark Reccord]

Originally Posted by mystic38

I dont understand what part of
250W min into 8R 0.1% THD max
500W min into 4R 0.1% THD max

are weasel words... ? those specs clearly and specifically state its twice the power into half the impedance.

A high quality amp can provide 2x power into 1/2 impedance. fact.

consider:

a) Running 250W into 8R. P=V2/R ergo this requires a PSU with voltage rails of 45V. P=VI therefore PSU amp supply is ~5.5A

b) Running 500W into 4R. P=V2/R therefore PSU rails required to be 45V. P=VI therefore PSU amp supply needs to be ~11A

Running an amp into 8 Ohms is limited by the PSU voltage, but running into 4 Ohms is limited by PSU current.

Design a solid and capable power supply and you will get 2x power into half the impedance... This is not new, not rocket science, and given even an 8 ohm speaker can have impedance (frequency dependent) varying from 3 to 16 ohms the ability to drive current is a MAJOR factor in a good amp

There are always I^2R losses due to the impedance of the power supply with increasing current no matter how overbuilt the power supply is. Clearly overbuilding the power supply mitigates this to some degree but until they come up with a power supply that doesn't have any impedance, it's always going to exist and you will see some sag of the rail voltage between full power at 8 Ohms and full power at 4 (i.e. right at the clip point).

Any amp that is spec'd to deliver 2x power into 4 Ohms vs. 8 is either underrated at 8 Ohms or overrated at 4. I've had some of Krell's amps on the bench and they definitely underrate the 8 Ohm power capability in order to give their specs that symmetry. It's why the spec states "250W min." The ones I tested were underspec'd by about 20% into 8 Ohms and were bang on at 4.

It's also erroneous to assume that an amplifier that isn't spec'd to produce 2x power into 0.5xZ is inferior or poorly designed.

[mystic38]

well if you wish to be pedantic of course there is I2R losses in the PSU but they can easily be minimised and i dont view that as "over building".. simply solid design...does it make a more expensive product? for sure.. but we are not talking huge currents or massive wiring here...its a paltry 10-15A..so an extra 50c of upgraded wiring eliminates those losses.

anyway, fwiw you are arguing the toss of 1% difference whereas my response was to the statement that amps can only provide 1.5x power.

onward.. I guess i dont understand your "over spec" argument at all.. pretty much zero amplifiers produce EXACTLY their rated output..every spec has some tolerance hence amp wattage ratings are a minimum power spec with a max thd spec.. a clearly defined box of parameters.

imo the ability to drive current is more important in an audio amplifier given there is no such thing as a speaker of constant 8 ohm impedance... so the ability of the amp to provide equal power across the impedance/frequency spectrum where the impedance can vary by a 4-5x is a clear indicator of amplifier quality.

So, with all other things being equal, it is most certainly NOT erroneous to assume an amp with higher current driver capability is a better amp.. Those companies dont put huge toroids and cans and heavy wiring in their amps for poops and giggles.

Originally Posted by Mark Reccord

There are always I^2R losses due to the impedance of the power supply with increasing current no matter how overbuilt the power supply is. Clearly overbuilding the power supply mitigates this to some degree but until they come up with a power supply that doesn't have any impedance, it's always going to exist and you will see some sag of the rail voltage between full power at 8 Ohms and full power at 4 (i.e. right at the clip point).

Any amp that is spec'd to deliver 2x power into 4 Ohms vs. 8 is either underrated at 8 Ohms or overrated at 4. I've had some of Krell's amps on the bench and they definitely underrate the 8 Ohm power capability in order to give their specs that symmetry. It's why the spec states "250W min." The ones I tested were underspec'd by about 20% into 8 Ohms and were bang on at 4.

It's also erroneous to assume that an amplifier that isn't spec'd to produce 2x power into 0.5xZ is inferior or poorly designed.

[Mark Reccord]

Originally Posted by mystic38

well if you wish to be pedantic of course there is I2R losses in the PSU but they can easily be minimised and i dont view that as "over building".. simply solid design...does it make a more expensive product? for sure.. but we are not talking huge currents or massive wiring here...its a paltry 10-15A..so an extra 50c of upgraded wiring eliminates those losses.

anyway, fwiw you are arguing the toss of 1% difference whereas my response was to the statement that amps can only provide 1.5x power.

I'm an engineer, my job is to be pedantic about technical things.

Most of the power supply loss is in the transformer, given a conventional line frequency power supply. The cost increases of over-spec-ing a transformer are highly significant as those tend to be the most expensive individual components in an amplifier. I think you'll find that in even the most robust power amplifiers the transformers/power supplies are not significantly overbuilt compared to the output power and that 4Ohm rated power is not 2x 8Ohm. For example, Lab Gruppen's Fp6000 exhibits 12% loss between 4 and 8 Ohm power specs. Don't think anyone would disparage the quality of that unit.

TB's favourite power amp, the Crest CA9 exhibits 25%(!!) loss between 8 and 4 ohm operation. Rated at 600W into 8 and 900W into 4. So it does exactly 1.5x power into 4 Ohms vs. 8. Another amp that is generally under-spec'd by the manufacturer, BTW.

onward.. I guess i dont understand your "over spec" argument at all.. pretty much zero amplifiers produce EXACTLY their rated output..every spec has some tolerance hence amp wattage ratings are a minimum power spec with a max thd spec.. a clearly defined box of parameters.

Most well-designed and properly spec'd amps come extremely close to doing that when you hold conditions equal to the conditions they were originally tested under (i.e. AC line voltage controlled). Obviously an amp that was tested with a 120VAC line won't produce the same amount of output power if the line sags to 115. The amplifier I referenced in my other post actually produced 300WPC at 0.1% THD into an 8 Ohm load. The specifications said it produced 250W under those conditions. They purposely under-quoted the 8 Ohm output. The amplifier produced 500W into a 4 Ohm load.

imo the ability to drive current is more important in an audio amplifier given there is no such thing as a speaker of constant 8 ohm impedance... so the ability of the amp to provide equal power across the impedance/frequency spectrum where the impedance can vary by a 4-5x is a clear indicator of amplifier quality.

So, with all other things being equal, it is most certainly NOT erroneous to assume an amp with higher current driver capability is a better amp.. Those companies dont put huge toroids and cans and heavy wiring in their amps for poops and giggles.

No argument that ability to source current is important in power amplifiers but you can bet that the power supplies in even the most robust power amplifiers are commensurate with the output power specs. There's a point where increasing current capability by reducing power supply impedance becomes pointless and costly for a particular design.

Once again, there isn't an amplifier on the planet that will actually double its maximum output power at a given THD into a 0.5Z load. Better amps tend to come closer to that goal but it's never actually achievable. I've been around the power amp design track enough times to know this.

[mystic38]

I simply am not seeing that you have any engineering point here...

a) "meeting spec"
not a single amp can meet a hard fixed spec. specs are "minimum" or toleranced for a reason...

b) Supplying 2x power into 0.5x load
If i wish to design an amp that can produce the amp/voltage envelope for 2x power into 0.5x load..i can. period... there is no technical reason why i cannot.

Sure, A by product of that is that the transformer will be bigger with larger windings, the heatsink larger with more devices and the wiring will be upgraded.. but if that is my design objective it can be done.

c) spec fudging
if your argument is that the only way this can be engineered is by over-achieving at one specification simply to support the other spec is a requirement.. you are wrong.

note, I am making an engineering statement here, not a budget one.. the statement "an amp will only produce 1.5x power into 0.5x load" is wrong. period...most do, that i agree but its not a theory limitation, nor a practical one..more budgetary in nature

regards..

oh, p.s. am aged 50, designs to 250A@150V with water cooled heatsinks of 200 transistors, bank voltage regulation, and size of a double wardrobe.. do i qualify for the "around the block award" too?

Originally Posted by Mark Reccord

. I've been around the power amp design track enough times to know this.

[HolmeBass]

I thought adding a second of the same cabinet was a ~+6 db increase- +3 for twice the radiating surface, +3 for twice (more or less) the power coming out of the amp.

+3 db is the difference in going from a 8 ohm to a 4 ohm version of the same cabinet, or for doubling the output on a watt-stable amp like a tube amp. Jazz Ad also has a really valid point- for a cranking loud rig a 3 db increase is going to be perceived as more of a jump than for a quiet rig, or computer speakers. Still worthy to frame this for people to see the difference between an 8 ohm and 4 ohm cabinet is not a whole lot- but sometimes it can be just enough.

[Jim Nazium]

Originally Posted by figuredbass

I hear a +3 dB volume increase as the difference between an amp on"10" and "11" in "Spinal Tap" terms...

You see, most blokes, you know, will be playing at ten. You're on ten here, all the way up, all the way up, all the way up, you're on ten on your guitar. Where can you go from there? Where? Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do? We go up 3db.

[Bassamatic]

This was a good intention, but not a good demonstration of doubling amp power.
You only get such a +3dB in SPL by doubling the number of speakers AND lowering the impedance (all other things being equal).

+3dB (double) of AMP power gives less than 1 dB of acoustic power gain - most people can not even hear this.
The reason is that amp power is in 2D. Acoustics is in 3D. It takes a lot more power to create a difference.

I you had a voltmeter on the speakers during that demo you would see that it takes TEN times the amp power to create DOUBLE the acoustic SPL. Blame the laws of physics and acoustics for this.

[Downunderwonder]

Why insist on making it more complicated than it already is? 9999 times out 10000 all else isn't equal and the doubled up driver count is half the impedance.

3dB is 3dB all week and all year. To increase the SPL by 3dB I need to double the power from the amp. All the reasons it isn't quite that simple have already been rehashed.

[Foz]

IMO the first step for someone looking to address the challenge of loud lows equivalent in scale in the mid-band - as represented in the original material - and yet not highly distorted [muddy] = embrace the point made by the OP.

This aint a teddy bear's picnic, per the OP's track, 3 dB is just enough to notice a difference - and further, a 3 dB increase is no more than a first small step toward the goal.

To me, the bottomline is:

Playing louder is much more of a challenge for the low frequency end of the band [a pun!] than the guitardist end of the band. And if you want to accurately reproduce the original material - then playing louder lows than traditional bass rigs can provide is necessary.

You're bucking:

1) the equal loudness curve [-20 dB difference from 60 Hz to 1k Hz for a 75 dB composite signal]

2) the 1/f distribution typical to music [generally - each octave lower you go requires 3 dB MORE loudness to accurately emulate the original material]

3) The electro-mechanical non-triviality of getting drivers and boxes to stand the weather when making sub 100 Hz sound [low frequency production is hard on the horses].

TB is always telling folks that if you need to be louder: you don't need a bigger amp / turn off the bass, play mids / get another cab just like the one that aint cutting it now.

And that's alright - if you are willing to stop playing bass and settle for playing mids - because getting louder in the lows is a BFD. But with modern drivers and cab designs you can do it without hiring a road crew or mortgaging the farm, or making a muddy mess of the low end. Drivers can be had that have enormously improved from a weight to spl ratio and amp watts have become cheap both in dollars and pounds [OMG another pun!]. But if you are gonna really make a difference you have to accept that one must quit f*cking around and make some big changes from the traditional methods and means.

[BogeyBass]

Cool, well the next time the sound man says that it just absolutely
ridiculous to have 2 810's for stage volume.

I will just say....dude dont trip it is only 3dB louder
your ears cant really tell the difference.