Thank you for the explanation, Tom, that's what I got from a second reading, this time a careful one.
It actually shattered some of my previous beliefs in terms of how much capacitance is required for evil loads at large power outputs.
Worse, it made me almost cry when I compared those findings with what actually goes on in the industry. 2x50 WRMS/8 Ohms with just one pair of 6,800 uF caps? Wow, that should sound really powerful.
It also made me understand fully why some designers use very hig supply voltages for relatively low power levels, e.g. +/- 51V for nominally 2x50 WRMS into 8 Ohms, nominal output peak 28,3V, and the supply is just short of TWICE what you need? Oh boy, is that man is expecting some power supply sag, or what?
Lastly, it made me realize that in fact I was not half the capacitor freak I thought I was. Until yesterday, I thought I was a lone pervert for wanting 30,000 uF per supply line, 60,000 uF per channel in a stereo nominally 2x100W RMS into 8 Ohms amp. Then I learn that in fact, I am far too modest.
Oh well, as my late grandma used to say - we live and learn all our lives, yet we still die foolish.
On the plus side, it did confirm my general approach - if you want a really good 100 WRMS/8 Ohm amp, you design a good 150 WRMS/8 Ohms amp and call it a 100 WRMS/8 Ohm amp. Then you get that feeling of limitless power I covet so much, or at least, you have a good shot at it.
dvv,
50W enough? pretty much in the ballpark. I'm a regular guy myself, but what's 6dB between friends?
a.wayne will love this discussion (if you haven't already gone through that, haven't read the last few pages)
50 WPC/8 Ohms should be enough for the vast majority of people, but only assuming:
1. That it is indeed capable of delivering all of the 50 Watts without any compression, and remember, theis translates to 50/100/200 WPC into 8/4/2 Ohms, which is a tall order, and
2. That you live in a European sized living room, listen to your music at home levels and own loudspeakers of reasonable efficiency, meaning at least 89 dB/2.83V/1m, preferably better than that.
I can understand the American point of view. Many of their living rooms are at least twice those in Europe, some of their speakers are not too efficient, and hence they really do need more power for the same effect.
As for the feeling of power, well, the little Naim integrated amp from the early 80ies, sporting 30 WRMS, proved that you do not need oodles of power to get that feeling. But, it was a fully electronically regulated amp, with more components in the regulator than in the audio circuits. If anyone is interested, I have its complete schematics.
Yes, but Wayne, you are THE exception, not the average. You cannot rely on yourself to be the standard.
It's like saying that if it isn't a 42" D cup, it ain't no woman.
There you go, Frank, living proof that there is objective, measurable power and there's the subjective feeling of power.
The two have very little to do with each other.
Ask yourself - how do the people with 2x10 WRMS in tube get away with it? The techie view is that they should start choking about 30 seconds after they switch it on, yet they are happy and listening to this day.
I said it before and I'll say it again - most buy 100+ WRMS amps only to get the first 30 WRMS right, which tells you that it's the engineering that's lacking, in most cases due to economic reasons and "market positioning".
Beat that rap by making a decent 50 WRMS amp, then throw in two 300 VA toroids and install 2 x 22,000 uF caps per channel - see what you get. Watch those commercial 100 WRMS amps struggle where your little guy sails smoothly through.
Spot on, dvv -- my tweaked HT, of very lowly born parentage, has speakers of about that efficiency, 20W chip amps per channel. If I put on some modern compressed rock, say Foo Fighters, at 3/4 volume my ears will start ringing after a couple of tracks at normal listening distance. You only have to work out the very simple maths involved to appreciate that a "minimal" system will do the job, IF working properly ...
Frank
Exactly, Frank.
I assume your comment on your amps, the ears splitting, refers to sheer volume. One of the sure-fire signs of inadequacy in an amp is when its tonal balance changes with increases of volume.
On quality fare, louder simply means more of the same. With such systems, it's easy to err on the side of too loud, the key reason being that other than SPL, NOTHING else changes.
How will you then know you're being too loud? Easy! You'll get an express message via a utensil from the kitchen.
I forgot ...
Frank, NEVER forget that the point of audio is not to have low THD and IM, high slew rates, and so forth, but to make YOU happy.
Thorsten had a good saying, paraphrasing here: you can design for specs, but you should design for the sound.
While I completely agree with this, I realize some of us do this for a living, so naturally they have to cater for market whims, and the world market is - most ufortunately - completely ruled by specs.
You and I are not. We are the fortunate ones, with perhaps some intelligence thrown in.
Frank, NEVER forget that the point of audio is not to have low THD and IM, high slew rates, and so forth, but to make YOU happy.
Thorsten had a good saying, paraphrasing here: you can design for specs, but you should design for the sound.
While I completely agree with this, I realize some of us do this for a living, so naturally they have to cater for market whims, and the world market is - most ufortunately - completely ruled by specs.
You and I are not. We are the fortunate ones, with perhaps some intelligence thrown in.
I sort of laugh and sigh about this at the same time, that seemingly very few people get it -- that one can get quite excellent sound from relatively ordinary equipment if one goes about it the right way. It's within most people's grasp really, but ego, market pressures as you say, and inertia keep it just beyond their reach, mostly, I'm afraid to say ...
Cheers,
Frank
Cheers,
Frank
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Yes, that just about sums up the capacitor size thread. As it is somewhat counter-intuitive (to those who want ever bigger caps) I assume that many people will continue to use lots of big caps with barely sufficient transformer voltages. Journalists will continue to judge caps and transformers by size alone, when a 50V 500VA transformer might work much better on real music than a 40V 800VA transformer.dvv said:
to me this topic is very interesting.
it's my feeling that the "amp with cojones" subject is surrounded by an aura of myth.
I often hear claims that even a speaker with benign impedance and moderate sensitivity needs a huge amp so it can sing. I've been trying to investigate if such claims can be somehow supported by an ignored phenomena that is measurable and quantifiable, with no success.
it's my feeling that the "amp with cojones" subject is surrounded by an aura of myth.
I often hear claims that even a speaker with benign impedance and moderate sensitivity needs a huge amp so it can sing. I've been trying to investigate if such claims can be somehow supported by an ignored phenomena that is measurable and quantifiable, with no success.
Yes, but Wayne, you are THE exception, not the average. You cannot rely on yourself to be the standard.
It's like saying that if it isn't a 42" D cup, it ain't no woman.
I'm more a 36 "DD cup kinda guy ...
When using SS amps you will always need to use more power than those using tooobs because you cannot listen to an SS to its last watt, unlike tooobs, from experience 33% on the avg , really good ones about 55-60% max before you reach for the volume control , tooobs are much different , far more forgiving , reaching into its full power output at 1%thd and all is well ....
Secondly , i have never heard a speaker that did not benefit from big power, even high efficiency ones ...
Vanity, Frank, vanity. To paraphrase Shakespeare - vanity, thy name is audiophile.
You have to have it bigger than the Joneses across the road. And the industry is quietly feeding this frenty simply because it's for its own benefit, they make more flogginh a 100 WRMS amp tha a 50 WRMS amp.
The writing was on the wall since 1975, when the craze was who's going to make a more powerful receiver? The Day Of Monster Receivers. If memory serves, it had come to point where Sansui had a detachable power section from the tuner/preamp section, and something over 300 WRMS.
That's the bugbear of the consumer society - very soon in the game, all sight is lost of what is truly essential, what it's all about, in favor of gadgets and serving the basic need rather than personal vanity.
Today is even worse, just look at how they sell cars, what is standard, and what is now optional - like (WOW!!!) backside pockets on the front seats. That has become an optional item.
In modern audio, I understand that you don't sell if you haven't got at least 5, and of late 7 separate channels. How many more will they need to add to make it the real deal?
But, I still keep saying - Da Man is the guy who makes a sweet sounding device without any exotic parts, but with off-the-shelf parts. Look at Otala's example non-TIM amp from 1978 or so; mostly off-the-shelf parts, although he did use two rather exotic dual transistors for the day, and still rare and damn expensive even today. But people got around that by buying like 100 equivalent transistors and pairing them manually. As far as I could tell/hear, there was no sound penalty.
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Well, it stands to reason, doesn't it?
What use are mammoth capacitors if they are charged by a teeny weeny transformer?
Ultimately, it all boils down to a good balance.
I believe that's because you would need to be measuring and quantifying vanity, supported by ignorance.
And the audio industry, for reasons of profit. To the best of my knowledge, you cannot buy a say 2x50 W device with what should have been done in the first place, for that you MUST buy the 100 W device. And pay more, of course.
And, to add insult to injury, the moder mastering processes for CDs are all about how to make them sound louder and louder, at the expense of the actual dynamic range, which is decreasing, and thus reducing the need for spare power needed to reproduce them faithfully.
I'm more a 36 "DD cup kinda guy ...
When using SS amps you will always need to use more power than those using tooobs because you cannot listen to an SS to its last watt, unlike tooobs, from experience 33% on the avg , really good ones about 55-60% max before you reach for the volume control , tooobs are much different , far more forgiving , reaching into its full power output at 1%thd and all is well ....
Secondly , i have never heard a speaker that did not benefit from big power, even high efficiency ones ...
True for SS amps, but a 10W tube job cannot equal a 100W SS job for sheer voltage swing, not to even mention current. And, almost always working against the tubes, is their price plus the price of high quality output transformers.
As for your second comment, that depends what you consider "big power" and what you are comparing it with. I do not believe it's so much the extra power, as it's the extra engineering gone into the more powerful and hence more expensive amp. Manufacturers in general tend to overdo the savings bit for lower powered amps.
The problem is that "big power" is closley knit together with loudspeaker efficiency and the room they need to fill with sound. Remember, 3 dB more speaker effciency means half the power for the same SPL.
Realistically speaking, you yourself do not have speakers, you have short ciruits in drag.
Is that even legal? Kidding aside, Wayne, how efficient are your speakers?
I would say, but it will be a distraction ...
anyway its a linesource so it does get pretty loud regardless of the amp used on the krell i can pretty much go as loud as i could want , since i listen in the 82-84 db din range with peaks in the 94-96 db range , regardless its pretty sad sensitivity wise and switching to neo's would help , but big amplfiers are not an issue to find ...
For reference i very rarely exceed 10amp , except when playing large scale music , opera or choir , the scale and presence is amazing , of course this is when the amps run for cover , always rest them after such a powerful track, well except the Krell , it comes alive down there ....
anyway its a linesource so it does get pretty loud regardless of the amp used on the krell i can pretty much go as loud as i could want , since i listen in the 82-84 db din range with peaks in the 94-96 db range , regardless its pretty sad sensitivity wise and switching to neo's would help , but big amplfiers are not an issue to find ...
For reference i very rarely exceed 10amp , except when playing large scale music , opera or choir , the scale and presence is amazing , of course this is when the amps run for cover , always rest them after such a powerful track, well except the Krell , it comes alive down there ....
One thing I will look at soon is if a series resistance with a tweeter is a good idea . As someone said a few days ago 16 ohms is better load ( why not higher ) . Take for example a very humble power op-amp like TDA 2040 . If driving 4 ohms reactive at 1 watt it will not be the stuff of dreams . Run the TDA 2040 at 8V RMS output into a restive load it will almost look like class A . A potential divider driving the tweeter at a 10 to 1 reduction might offer a bit of zero cost magic . As far as I know no one ever said this ? I tested one of these chips today . I wanted a quick answer to a question before I make a serious time investment , it was that or a L165 in my useful box . It is an industrial application which requires stability and current . I measured the distortion performance by comparison harmonics as I had no high grade signal generator handy ( 6 VRMS 10 kHz 120R load ) . It was a very pleasant surprise . I ran the amp at a gain of 34 potted down to 34 to mimic a buffer ( recommended circuit 680R , 22K g = 33.35 ) . I will try to improve upon that . Remarkable seeing as it has excessive gain that it gives low distortion .
Finding a better window for the tweeter to work at and spend not a penny more . A 20 dB improvement in crossover distortion effects ( doubtless more as the load is much nicer ) . I have haunch this might sound nicer than exulted amps running at sub 1 watt . I base this on how we accept op amps as transparent and accurate . If we don't load them too much they pretend to be class A so well we beleive it . A silk purse out of a sows ear .
Finding a better window for the tweeter to work at and spend not a penny more . A 20 dB improvement in crossover distortion effects ( doubtless more as the load is much nicer ) . I have haunch this might sound nicer than exulted amps running at sub 1 watt . I base this on how we accept op amps as transparent and accurate . If we don't load them too much they pretend to be class A so well we beleive it . A silk purse out of a sows ear .
That's why a divider . If a 8 ohm tweeter is fed from 1 ohm it's not too bad . If used without there might be a slight lack of damping which might be desirable . If the dreaded ferror fluid is used I would imagine that to be possible . As a PA friend said we should not use the amp to damp the speaker . Making the phase angle more resistive by the simplest route is no bad thing . The BBC used auto transformers to tweeters . That is ideal if the quality high enough . Then the damping increases . It can be made from RF materials as no bass required . I imagine a common mode choke core would work .
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