Interesting thread Mooly 
I'm not exactly sure how much power i stuff into my speakers each evening, i haven't really measured it I think i'll have to get the scope out & take a look though it'll be interesting as the bass drivers are driven straight from the power amp. Upper bass/mid, mid & treble are driven through a crossover from the second channel of the same power amp.
One thing no-one has mentioned is that active speakers will go a lot louder than standard speakers with passive crossovers driven from the same wattage of power amplifier. I reckon just going two way active can increase absolute volume level by about 6Db before clipping. A 3 or 4 way system might make an extra 10Db.
As PMA & tinitus mentioned though there is no substitute for having a massive power supply even if the amplifier is much lower powered than the PSU would suggest. It's all about having that power there instantaneously available to cope with any difficulties. I always tend to think of it like an engine, i'd rather have a more powerful engine than i'm ever likely to need (Ferrari) than expect a Ford Fiesta to get me out of trouble.
A massive PSU just makes things easy & this will certainly be evident in the reproduced sound
I'm not exactly sure how much power i stuff into my speakers each evening, i haven't really measured it
I think i'll have to get the scope out & take a look though it'll be interesting as the bass drivers are driven straight from the power amp. Upper bass/mid, mid & treble are driven through a crossover from the second channel of the same power amp.One thing no-one has mentioned is that active speakers will go a lot louder than standard speakers with passive crossovers driven from the same wattage of power amplifier. I reckon just going two way active can increase absolute volume level by about 6Db before clipping. A 3 or 4 way system might make an extra 10Db.
As PMA & tinitus mentioned though there is no substitute for having a massive power supply even if the amplifier is much lower powered than the PSU would suggest. It's all about having that power there instantaneously available to cope with any difficulties. I always tend to think of it like an engine, i'd rather have a more powerful engine than i'm ever likely to need (Ferrari) than expect a Ford Fiesta to get me out of trouble.
A massive PSU just makes things easy & this will certainly be evident in the reproduced sound
That figure was based on the RMS output of the amp when fed with a "0db" test CD, the volume control having first been set by listening at the very loudest I would ever normally do. I can't see why that's not valid.
A valid point... however almost all my listening is classical of one form or another, and the dynamic range of many recordings is (IMO) excellent.
Something like this on CD, which is a particular favourite.
http://www.youtube.com/watch?v=DRgh6yozmR0
I know what you mean about poor quality MP3's etc, and many pop/rock recordings seem to be mastered to just give a constant loudness with no real sense of dynamic.
I find I just don't need it particularly loud to be enjoyable... maybe that's just me.
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What you say applies perhaps to "commercial" amps where we might expect a 20watt amp to have very limited "real world" driving ability.
As DIYer's we can do better than that, designing a smaller amp, but keeping the ability to drive difficult loads... 20watts into 8 ohm, 40 into 4, even going down to 3 ohm capability or less if needed.
Good point..
My 2 x 5W + 10W can drive loads as low as 1 ohm...
Easy when using two pairs of 150W/10A Sanken devices , as the low output
(and thus supply) voltage allow operation at high currents while being
largely in the SOA...
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So within it's performance "envelope" it should sound just as good as a 100 or 500 watt amp
40 volts pk/pk into (say 4 ohms) is quite do able with -/+30volt supplies... but I agree "easier" with more certain results by increasing to -/+60volts.
So we compromise, you don't have to double the supply... raise it a little to say -/+ 35 or 40 volts if that's what the topology needs to deliver into low impedance loads. That maintains the philosophy of a "lower powered" design.
I used a classical symetrical differential.
Left and right channels are supplied with +-15V rails,
and +-20V for the basses channel..
I used the schematic below, with slightly modded components
values to match he lower supply voltages.
Also, i used Sanken s fast darlingtons for the output,
thus getting rid of the double emitter follower arrangement.
http://www.diyaudio.com/forums/solid-state/155993-awb50-simple-power-amp.html
I must be going deaf. My basement system uses biamped amplifiers, 100 watts for bass and 35 watts for treble for my 40 year old Voice of the Theatre Speakers. The bass led vu shows that the bass amp clips quite often. I live in a quite rural area and I can only play music at this level when no one is home. Yes it's kinda loud, ok very loud, well actually really F'n loud, music can be classical, big band jazz, Hendrix or LED Zeplin. Many times I say to myself, wow what a sound, I need MORE POWER!!!
I sometimes listen to my "12 Vegas at over 150 w and even I have tried over 300 and have reached 350w peaks... maybe last time I fried some caps in the crossover...
My Goldwoods "18 in H-frame are tested to about 180w mean level continuous, but I was afraid to continue.
Most of the time I listen at under 1 w though.
But with 18 or 75w amps and 90 db/w speakers the fun ends just before it begins... It might be once a month or even more seldom, but you'll want to listen at realistic and convincing levels and with 18w it just won't happen as it won't with 35w or 75w... (even the worst neighbors will take half an hour decibel torture every now and then)
A 85w amplifier will clip before it makes a 89 db/w speaker go really loud and convincing - it is theoretically capable of 108 db, but that means that he mean level must not surpass 10-15 w
And 108db in low frequencies is somewhere between 70 and 90 Phon (subjective perception of loudness compared to the same loudness in the 1-3 kHz area)
But if the mean level is 10w then you'd be listening at 99 db mean SPL and again 2/3rds will be in the sub 100 hz region which means that you'l get low frequencies roughly at under 70 phon...
Those problems are not very obvious as most recording engineers compress and limit the signal and the dynamics of the recordings are greatly reduced.
There are some partially true, but reliable superstitions that a SS amp sounds best when driven between 10 and 50% of it's power. I feel best between 15 and 75 watts mean level on 96 db/w speakers at 4-5 m (16 ft) distance in a big room.
Many manuals state that with big and powerful amp you can safely go beyond the power rating of a speaker for short periods with no penalty. And the same manuals state that a small overdriven amp can damage speakers 10 mimes higher rated than it...
p.s. nevertheless I do the 300w+ "tectonic weapon" tests at our summer house...
p.s.2. At over 150-200 w you could get the impression that your ribs and chest are hollow, even though we all know they are not... why spare yourself this experience? - it comes with a big amp and big speakers... and you only pay once and after that you can experiment all the time till you burn something...
My Goldwoods "18 in H-frame are tested to about 180w mean level continuous, but I was afraid to continue.
Most of the time I listen at under 1 w though.
But with 18 or 75w amps and 90 db/w speakers the fun ends just before it begins... It might be once a month or even more seldom, but you'll want to listen at realistic and convincing levels and with 18w it just won't happen as it won't with 35w or 75w... (even the worst neighbors will take half an hour decibel torture every now and then)
A 85w amplifier will clip before it makes a 89 db/w speaker go really loud and convincing - it is theoretically capable of 108 db, but that means that he mean level must not surpass 10-15 w
And 108db in low frequencies is somewhere between 70 and 90 Phon (subjective perception of loudness compared to the same loudness in the 1-3 kHz area)
But if the mean level is 10w then you'd be listening at 99 db mean SPL and again 2/3rds will be in the sub 100 hz region which means that you'l get low frequencies roughly at under 70 phon...
Those problems are not very obvious as most recording engineers compress and limit the signal and the dynamics of the recordings are greatly reduced.
There are some partially true, but reliable superstitions that a SS amp sounds best when driven between 10 and 50% of it's power. I feel best between 15 and 75 watts mean level on 96 db/w speakers at 4-5 m (16 ft) distance in a big room.
Many manuals state that with big and powerful amp you can safely go beyond the power rating of a speaker for short periods with no penalty. And the same manuals state that a small overdriven amp can damage speakers 10 mimes higher rated than it...
p.s. nevertheless I do the 300w+ "tectonic weapon" tests at our summer house...
p.s.2. At over 150-200 w you could get the impression that your ribs and chest are hollow, even though we all know they are not... why spare yourself this experience? - it comes with a big amp and big speakers... and you only pay once and after that you can experiment all the time till you burn something...
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back in my tube days, I had a 96dB efficient pair of Adire 10" monitors. With a (regulated) 300B amp, I could hear clipping with AC/DC at mid-moderate+ levels.
With my current Magnepan 1.6QRs, ~20Ws of SE EL156 tube power was a joke. I mean it makes just barely makes music. The Maggies really sound much better with a Threshold S/500. The same set of amplifiers on a pair of UREI 813As - very little difference.
So yeah - max power needed depends on the speakers, room, listening levels and type of music...
With my current Magnepan 1.6QRs, ~20Ws of SE EL156 tube power was a joke. I mean it makes just barely makes music. The Maggies really sound much better with a Threshold S/500. The same set of amplifiers on a pair of UREI 813As - very little difference.
So yeah - max power needed depends on the speakers, room, listening levels and type of music...
average SPL : transient peak SPL
Hi,
depends on the type of music you listen too.
10times is probably adequate if you listen to streamed modern music.
100times might be required for very dynamic music from sources that have preserved the wide dynamic range that exists in natural audio sources.
That equates to averages of 100mW to 1W for normal to loud listening and requires a 100W+100W amplifier driving >=90dB/W @1m speakers with a listening distance of about 2.5m.
If your target is 110dBpk SPL at listening position then the speakers will need to be ~95dB/W @ 1m after allowing for power compression.
Hi,
depends on the type of music you listen too.
10times is probably adequate if you listen to streamed modern music.
100times might be required for very dynamic music from sources that have preserved the wide dynamic range that exists in natural audio sources.
That equates to averages of 100mW to 1W for normal to loud listening and requires a 100W+100W amplifier driving >=90dB/W @1m speakers with a listening distance of about 2.5m.
If your target is 110dBpk SPL at listening position then the speakers will need to be ~95dB/W @ 1m after allowing for power compression.
My new used speakers have sensitivity of 101 db@1W@1m , impedance of 8 ohm (minimum 5 at crossover) and I listen in a room of 15'Wx12'Hx28'L with carpet and sofas. I typically see 1.5 V PP on the scope at the output of my amp. I got the 280W/channel@8ohm amp with the speakers that I really wanted, not thinking I really needed that much but it was a bargain. (1.5^2)/8= 1/4 watt, so 100 x that is 40 W/channel. On Beethoven sonatas, which really go soft to hard piano hits, or on 1812 overture, which goes as loud as anything with cannon shots. my ST120 (with NTE181 O.T. and DJoffe bias board) and the CS800S sound exactly the same, except the ST120 has more gain and is "louder" requiring lower preamp setting. Both can deliver your 40W, so I think I have enough. For calibration and level setting I use the Steinway, which is not as loud as a concert grand, but I sit much closer and the sound is focussed at the player, not to the side. Am tuning up the tube ST70 to see how it sounds on these new to me speakers.
I tried putting one speaker in the front door and doing 1812 last fourth of July pointed at the factory across the road, but my volume was limited by the feedback of the other speaker into the turntable. Next year I need to hire my yardman to help me move the speakers (98 lb on poles) & prove something.
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The lowest power amp that I ever had was a Marantz 2238B receiver (vintage) that was 38 watts per channel, I found it really powerful for a 38 watts.it was plenty of power for sure. I think for a domestic listening 50 watts RMS per channel is enough,I have one here that is 60 watts RMS per channel (Bryston) and I am sure I do not need more power than this. But again depending in the speakers too (efficiency).
I feel that my current system is just about enough for my house (and my neighbors)
Adco Gfa 5400 200 wpc at 4 ohms running 2vifa 5.5" drivers in each Ariel
Bk st140 runs the tweeters which are 6 ohm
Haffler dh200 runs the 16" cv's I use as subs
What's that? About 400 wpc with efficient speakers...yes almost enough....
Adco Gfa 5400 200 wpc at 4 ohms running 2vifa 5.5" drivers in each Ariel
Bk st140 runs the tweeters which are 6 ohm
Haffler dh200 runs the 16" cv's I use as subs
What's that? About 400 wpc with efficient speakers...yes almost enough....
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