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Old 25th January 2004, 09:29 PM   #11
sobazz is offline sobazz  Denmark
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My "guess" 10^2 - or 100 times louder. A full scale explanation here: http://www.glenbrook.k12.il.us/gbssc...nd/u11l2b.html
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Old 25th January 2004, 09:39 PM   #12
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Yes...Ed...you mentioned 100Watts? are you rounding that from a tube or tranny amp ?big diff.... The nice rounding-off from tube amp clipping can add more fullness to the sound, although not for Hi Fi users.
So it's a well known fact that many say < a 50Watt tube amp can sound just as loud a 100W tube amp>.
Okay..there's only 3dB power difference for the electronics to fudge up from 50W to 100W.........i.e roughly 14V into 4 ohms v.s 20V into 4 ohms. Looking at a voltmeter or analyser between the two output voltage levels (6dB) doesn't seem much of a change, but it's usually a change in the hardware parts, i.e beeffier PSU and perhaps o/p tranny.

Catch.........3dB differences from LS speaker sensitivities can mean life or deafness for many SE amps. i.e .....it's suicide for many SE amps to liven up low efficency speakers less 87dB or even 90dB 1W/1metre, unless one owns Klipsches.
Don't ignore specs! Do the +/- game; 3dB from amp then add to speaker or vice versa for a relevant power level. So the more speaker (chassis) units there are in a given cabinet the louder and more spacious the sound will be, for a given impedance, amp power & loudness intensity level. That's why I'm an advocate of putting as many speaker units in a cabinet, so long there is still an impedance match with the amp.

In this rough example, comparing two chassis units with same imp;
Profess chassis unit = 99dB and other
Kef B300B = 86dB....(low effic Hi Fi)......an 100W amp would be required for the Kef unit compared to only 25 watts for the same loudness from the first unit with a lower power requiremnt.
<what always happens ??>: the lower sens units risks burn out because someone connects a higher powered amp whereas the higher efficiency unit excels.

Just to recap...

6dB =2xVolts; 10dB=3xVolts; 20dB=10xVolts;30dB=30xVolts:
3dB=2xWatts;10dB=10xWatts, and so on.

rich
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Old 25th January 2004, 09:39 PM   #13
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The above goes to show why an 80 Watt amplifier may not sound much different from an 8 Watt amplifier, but it doesn't address the tube vs SS question.

I think the answer to that lies somewhere in the way that each amplifier clips.
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Old 25th January 2004, 09:47 PM   #14
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Default Interesting question

I think Morse hit it right in his answer.
The question asked about how much "louder", which is perceived by the listener.
Yes, 20db (30 - 10db = 20db) is 100 times more power, but loudness, which is perceived by the listener, would be about 3-4 times.
Think of turning up the "bass" tone control. It may be 15db, but doesn't sound 80 times "louder".


I think the question is flaky, like mixing two different concepts. Wouldn't the correct question be, for 100 to be the answer,
"how much more power is 30db than 10db?"

The lady got the wrong answer, 3, and 100 was given as the right answer.

Cheers.
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Old 25th January 2004, 09:48 PM   #15
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Quote:
but it doesn't address the tube vs SS question.
Yup. My guess is that's much deeper than simple db calcs. I wonder if OTL amps also sound subjectively lowder than SS watts. Could the perception of more power be partly due to the energy stored in the inductance of the OPT?
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Old 25th January 2004, 09:48 PM   #16
Morse is offline Morse  United States
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Hi Positron;

*LOL*!

It's one of those "define your terms" situations. Is the "signal" given in terms of potential (voltage) or power (watts)? Is the definition of "loudness" PERCEIVED loudness or is it a measure of amplitude of output signal with respect to the reference input signal (i.e. a linear measure of V/V0 or P/P0)?

Let's say it's voltage and perceived loudness. Then a 20dB difference represents doubling the volume. Let's say it's voltage and linear amplitude with respect to the reference voltage. Then 20dB represents 10 times the reference voltage. Let's say it's power and perceived loudness. Then 20dB represents 4 times the apparent loudness. Let's say it's power and a linear measure of power with respect to the reference level - then it's 100 times the reference power level.

Now you know why I never wanted to be on a game show!!

All the best,
Morse
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Old 25th January 2004, 10:13 PM   #17
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hmm i've heard of this before. My guitar teacher just got a 250 watt tube amp for his guitar. (i'm jealous... i got his old solid state 150w) He said that when you buy tube amps, multiply the wattage by three to get the wattage it would sound like with solid state. Obviously a watt is a watt, so thru the same speakers it would be just as loud. but with the same cab on this his was ear peircing loud at half volume(course we had ear plugs) and mine well.. wasnt. even though it was turned up all the way.. i dunno
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Old 25th January 2004, 10:18 PM   #18
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Hi,

Quote:
I wonder if OTL amps also sound subjectively lowder than SS watts.
Oh yes, they do.

Quote:
Could the perception of more power be partly due to the energy stored in the inductance of the OPT?
That's got nothing to do with it.

Cheers,
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Old 26th January 2004, 02:27 AM   #19
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All I'm going to add to this soon-to-be-long thread is that 1. tube amps distort softly so maximum power is reached more gracefully. (Unless it's a chunky amp with 30-40dB NFB! ) That means you can run much closer to maximum power output with less average distortion. 2. SS is mainstream, and as such the ratings are embellished, sometimes substantially. PMPO ratings, for example, and silos of pure cow excrement. However, tube amps are typically sold for their mystique, appearance and price tag, with little regard for the power. (Obviously a 300W amp is going to go for a hell of a lot more than a 8W amp, unless it's a WE300B amp. . .so. . .never mind ) 3. A solid state radio may designed so that even with the volume control maxed out, the program material (which due to compression and AVC is going to be a reliable signal strength coming out of the demodulator) will never cause distortion in the output. That is, there purposely isn't enough gain in the system to overdrive the output. Of course, much cheaper radios are just poorly designed throughout and this WILL still happen...

Oh, and 4., all amplifiers tend to have a standard input voltage of say .1, .5, 1 or 2 or 5V of whatever units (RMS, average, peak, peak-to-peak), so between a 5W and a 100W amp, which one will have more gain from input to speaker? So which one will SEEM louder, even though the material may never peak to even 1W?

Tim
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Old 26th January 2004, 03:05 PM   #20
Morse is offline Morse  United States
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Hi Tim;

All true, and point (4) is one that's well worth bearing in mind for DIY'ers.

Most mainstream hifi kit will be at red faced max power out with the volume control around 12 o'clock - and it's designed to be pretty darn' loud at the 9 o'clock position. In other words, it throws away half the adjustability of the volume control to give a false impression of power at a "low" volume setting ("Hey, if it's this loud 1/4 of the way up, how loud is it all the way up" ANS: You'll never be able to use it past "half way up", so it's a silly question...).

Generally I try to design the gain stages in my DIY hifi's so that with the source I'm using I'll make use of the whole volume control. Suit yourself, but I like having the extra adjustability.

Marketing has fouled up the mainstream hifi pretty thoroughly, by introducing un-necessary features and altering designs in fundamental ways that are intended to stand out better on paper and in a crowded showroom for a 5 minute audition rather than sound better or work better over the long haul - which is one reason I went back to DIY.

Save the money, build your own hifi and enjoy better music reproduction....oh well, preaching to the choir!

All the best,
Morse
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