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More than 25watts realy needed ?
More than 25watts realy needed ?
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Old 21st March 2013, 03:46 PM   #1
Rixsta is offline Rixsta  United Kingdom
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More than 25watts realy needed ?
Default More than 25watts realy needed ?

Hey, Ive heard a lot of amps since i was younger and Iv'e come to the conclusion that most 25w amps are loud enough!

What would you say about that ? i know sometimes its nice to have booming bass but for me i don't need extra.

Iv'e been trying also to figure out how many DB would there be typically from a 25w amp and the average speakers.
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Old 21st March 2013, 03:54 PM   #2
lineup is offline lineup  Sweden
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You are right.
For normal speakers in normal room we can do nicely with 10 to 25 Watt.
100, 200 and 400 Watt is only if you like to play. A bit stupid!
It is not that more is better - many times a 25 Watt amplifier is better.
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Old 21st March 2013, 04:10 PM   #3
suntechnik is offline suntechnik  Russian Federation
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Quote:
Originally Posted by Rixsta View Post
... Iv'e come to the conclusion that most 25w amps are loud enough!
....
Depends on load. Magnepans would not be happy for sure.
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Old 21st March 2013, 04:41 PM   #4
prairieboy is offline prairieboy  Canada
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Soooo many factors for a general statement. What do you listen to for music: high dynamics, or low? Speaker efficiency: high, medium, or low? Size of room: small, large. Proficiency of hearing: young and sharp, older and dull?
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Old 21st March 2013, 04:43 PM   #5
jxdking is offline jxdking  China
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The user's manual of my 100W JBL bookshelf speaker says 2.828Vpp will produce 87dB(1 meter)

2.828Vpp for 87dB, which's pretty loud.

That's only 1/8 watts
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Old 21st March 2013, 04:55 PM   #6
jaycee is offline jaycee  United Kingdom
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I've typically found 30-50W amplifiers are sufficient for domestic listening... and watching films with plenty of rumble from decent floorstanders. I had planned on building a 100W amplifier but now don't see the need for it.
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Old 21st March 2013, 05:03 PM   #7
jcx is online now jcx  United States
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assume 2x speakers, room gain gives ~87 dB/W at the listening spot for those speakers - then 25 W clips at 101 dB SPL

now read up on live music peak values, live concert levels - no you shouldn't listen all day at those levels - but you'll never achieve "realism" without a system capable of reaching live music dynamic peaks

90 - 100 average at live jazz club for a hot set, much higher at a "dance club"

even unamplified classical orchestra's peak way over 101 dB in the audience


while Loudness War compresion now makes anything over 12 dB peak-to-average seem "dynamic" now - really good dynamic recordings can go over 20 dB peak-to-average
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Old 21st March 2013, 05:05 PM   #8
Struth is offline Struth  Canada
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Hi Guys

jxdking, the "1/8 watt" notation is incorrect unless your speakers are about 22-ohms.

The 2v82 standard is supposed to be equal to 1W into 8R.

87db is quite loud. In my own listening room, such an SPL is what I might blast myself with rarely - but usually when this happens I am not in the same room. It is too loud to subject yourself to for any length of time. 70db is much more of a loud TV or movie watching level and requires a lot less power. Frankly, 25W for your whole system is probably quite suitable - and is likely fine for most people.

What works against low-watt systems is mostly fashion, the low cost of solid-state power, marketing, and the low efficency of tiny speakers and woofers.

So-called "subwoofers" are really just woofers in a separate box. There should be two in a stereo system.

My system has two subs that actually go down to 13Hz and two fullrange monitors, biamped with a few watts per output possible to cover peaks. I installed clip LEDs on each of the four speaker outputs. They never light up even for crazy loudness.

Because I measured the SPLs and power used in my room before building a new system, I knew that I only needed a low amount of power. This translates into a low voltage gain given the outputs of most signal sources. With that info, I decided to use Lineup's diamond-feedback buffer for each of the power amps. The active crossovers use discrete opamps and drive the buffers. There is stepped gain ahead of the crossover so that for any listening scenario, the sweep of the volume control can be better utilised for fine control.

There is a fascination with the 120db end of the loudness ranges listed. Modern live music tends to be 100dB+ with no let up. Higher is ridulous and should be criminal. Sound companies should be fined out of business and owners should do jail time for subjecting the public to such SPLs which do serious harm. This is a health factor that cannot be ignored anymore. It is so easy to just turn it down and what do you know?... the music sounds better quieter. You can actually hear everything.

Note that for the most part, designing for lower power does not necessarily mean the PA circuit will be simpler than for higher power. All the same issues of design are still present. However, you have a few more options inasmuch as pure class-A - which can for some designs result in much lower THD - can be utilised with a reasonable heat cost. Paralleling output devices is still beneficial, as is reduced loading on VAS, optimising for neutral distortion spectrum, and so on.

Have fun
Kevin O'Connor
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Old 21st March 2013, 05:17 PM   #9
jxdking is offline jxdking  China
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Oh, you are right 2.83 stands for Vrms. (I thought it's Vpp)
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Old 21st March 2013, 05:32 PM   #10
east electronics is offline east electronics  Greece
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what actually makes the real difference is that you cannot design big amplifiers with astronomical bandwidth, input Z of 500K ,and without real protection such is input limiting or VI limiters .

smaller amplifiers have lower risk and obviously can be designs without all the above so smaller amplifiers have chances to sound better the rest is only load depending...

Kevin... Nice to see you around How are you ??

Kind regards
Sakis
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