samsagaz said:
It sounds like you're for a full mono class d type system, and I can recommend UCD wholeheartedly.
You can easily build yourself an amp that will last a lifetime, but I'd recommend you start slowly to gain some experience in implementing them before going all out. This will also give you an intro to their sound and you'll know what to expect from them.
Even if it takes two years to learn all the tricks and get it done right, when they're done they're done and will last a loooong time.
The other upside to doing it this way makes it easier to reconfigure your system or add this or that at anytime down the line which you can never really do with commercial junk.
I'd seriously consider the DIY way 🙂
BWRX said:
Unless you listen really loud your estimate is probably an order of magnitude high.
dave
planet10 said:
1-2W with 89dB at 1W/1m speakers while sitting about 2 meters away produces good listening levels in an 11' x 12' (approximately) room. Listening at lower levels is nice for some things but I like it a bit louder when listening critically or just really feeling the music
samsagaz said:
I would consider that to be a medium sized room.
i will be seated at like 3, 3.5 mts and for movies and some music (like salsa) i really like louder 😀
I rarely ever see speaker efficiency measure across the frequency spectrum. It's usually 1khz. You need more power at say 40hz to make it sound even at low volumes where your ears are more sensitive to midrange.
Come on folks, take out your scopes and meters and do some real world measurements.
Come on folks, take out your scopes and meters and do some real world measurements.
fokker said:
As an engineer, you may think along the above lines (that Class D "must" be worse), however, if you listen to recent Class D amps you will probably be quickly convinced that we are talking high-end and I find them better than expensive AB amps. Have you listened to any recent Class D amps?
Gertjan
ghemink said:
I do not believe I said anywhere that Class D must be worse. I said that Class D was historically ultra-low-end. I don't believe that is without fact.
fokker said:
Only in practice, in theory they've always been superior, well, since the theory came to be.
You can't seriously shame the technology as a whole simply because the components of the day weren't up to snuff to properly realize the theory.
How many thousands of years did the wheel exist before a decent racing tire came along?
Quite often we're given new technology to contend with that promises to be the next best thing, all the early adopters dive right in and I think more often than not regret it. Sometimes that technology is even pushed out the door with the next greatest thing before it even became optimal..... laser disc for instance.
High end class D has been here for a good five years now and it's only going to get better from here. Just ask Bryston 🙂
Although, it may take another decade or two before the class d you see appearing in commercial scrap is up to par with mid fi A/B standards.. you can't build a race car by nickle and diming everything either right.
Just read what I wrote! Max. 100 mW.
Of course not. On figure6 you can see definitely less then 50% efficiency at 1W output, so wasted power must be higher then 1W. On figure5 you can see ~2W loss at 0W output power, while loss of ClassB (red curve) reaches near zero! Don't guestimate, when you have relevant data!
I have measured the voltage on my speakers at a comfortable volume: ~20 mV. Yes, that's true! Little more than 100 uW/speaker.
Just think! 1W on a 86dB sensitivity speaker means 86dB volume (assuming 1 meter distance)! Volume of human speaking is ~50 dB, 1/4000th power of the above mentioned!
My relatives would immediately shout at me, if I listened this high (86 dB) volume! My student has just left. He asked me to turn off that 400 uW music, because it disturbed him!!!
Human hearing, and logarithmic scale are very strange things...
fokker said:
OK, you did not say that, I thought you implied it. Anyway, my question whether you ever have heard a recent Class D amp still stands. If you have heard one, what was your impression? My opinion is that they easily beat high-end Class AB amps. Would be interested what your experience is.
I have to admit that I had not expected that Class D would sound that good. I have an Accuphase E407 amp (I guess everyone knows that by now🙂) and for experimental purposes I bought a cheapo 4 channel Marantz Tripath based amp about 2 years ago. When I had a brief listen to that amp in an audio shop I was already a bit surprised about how good that cheapo amp sound was. Then at home hooked it up and immediately knew that this was different, very clean sound, can play very loud without sounding loud (I guess a sign of low distortion at high power levels), very good imaging etc, all the good stuff you often hear people say about Class D. From that moment on I was hooked to Class D. I`m now using UcD based amps as these are very good problemfree modules. They are extremely low noise (much lower noise than the Tripath based Marantz) and are therefore very good in an active setup (3 amps per speaker). I have the tweeters directly connected to the amps (UcD180) and have in that 2 year that I have them never blown a tweeter.
That`s enough from my side, would like to know your personal experience with class D, not from an electronics point of view but from a sound point of view.
Best regards
Gertjan
Pafi said:
My point was that there's no need to be concerned with efficiency at 100mW or less with a power amplifier. Class d is less than 50% efficient at 1W but class ab is even worse.
In the attachment is a portion of the efficiency vs power output graph from my previous link. The visible tick mark on the x axis is 2.5W output, the next line I added is about 1.125W output, and the next is about 0.5625W output. At 1.125W the class d amp is about 25% efficient while the class ab is around 7% efficient. Around 0.5626W both amps are clearly under 5% efficient and the power dissipation mainly depends on idle losses in the amplifier.
Pafi said:
I have measured about a couple volts rms at the output of my amps at more realistic listening levels. I told you I sit about a couple meters away so you obviously more power to get louder. Surely you've been to concerts where the level is a lot higher than 86dB? 86dB is fine for low level listening but I know I like to blast it once in a while - who doesn't, right? 🙂 Regardless, class d is more efficient than class ab where it counts. The fact that the good class d amps sound really good is certainly nice as well.
Attachments
Then don't say untrue things about an amp, only say that you just can't hear the sound what is the highest room volume for me!
86 dB=low level? 😱 Then consult with your doctor about your ears! More then 80 dB can cause health problems if you are exposed to this for a long time!
Check this out:
http://www.nonoise.org/library/levels74/levels74.htm
This tells e.g.: "Stereo music: 50-70 dB" (Page 15, table2.)
"PREPARED BY
THE U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF NOISE ABATEMENT AND CONTROL"
When I measure 3-4 V, then I start to feel bass, not only hear. I sit less then 1 m from speakers, but they are absolutely not efficient (~82 dB).
Sometimes I like storm-like bass for fun also! When I drived 6 pcs of Eminence Kappa pro 18s in band-pass boxes, in a 6*8 meter closed room with my bridged, +/-63V supplied amp module (~ 10 kW peak power), then sound pressure rumpled my hair in a point of the room, but this is not listening to music at all!
Yes, I have some, but you seems to have been too many times!
Pafi said:
What did I say that was untrue???
I can certainly hear low level sounds and like to listen to background music below 50dB SPL, but when I want to really listen I like to have more realistic sound levels. 90dB or more is not uncommon there.
Pafi said:
I overstated myself there 🙂 You are right that 86dB is not low level. The most I listen at higher levels is for the majority of the tracks on a CD. So probably about 30 to 60 mins.
Pafi said:
My upper hearing limit is 17kHz so chances are I have damaged my hearing a bit but I really haven't been to too many really loud concerts. I never go in really loud night clubs either. I can't stand it when you can't talk to the person right next to you and everything reeks of smoke
This: "The most power that will be wasted below 1W output will clearly be less than a watt."
I think we just talk about different things. What you talk about is more similar to a concert, when you want to hear _only_ the music. I meant music as background, while I can do other things in same time (exept talking). I think this is more typical.
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