| nina |
...particularly at low volume/level of listening ?
:confused: |
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| tlf9999 |
a couple guesses:
a) distortion tends to be lower at lower output levels;
b) crest factor: even at lower volume you will have high peaks and fast transients that may push a small amp into clipping while a larger one can handle with ease. |
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| darkfenriz |
| quote: | Why hi-power amp produce clearer sound & more details ...
...particularly at low volume/level of listening ?? |
The point is very arguable, most technical issues would prove rather opposite.
Could you give more details about both systems (maybe speakers matter?) you listened to and your impressions.?
regards |
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| janneman |
| quote: | Originally posted by nina
Why hi-power amp produce clearer sound & more details ...
...particularly at low volume/level of listening ??
:confused: |
Does it? I often heard the opposite, that higher power amps sound less clear and detailed, even at low levels. What caused your experience in this?
Jan Didden |
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| thomgun_lc |
:) I'm not sure if Hi-power amp produce more clearer sound.Maybe, Hi power amps poduce more watt/dB, but not always produce high fidelity. Usually Hi power amp use class B, so the signal not purify.So, i think low power amp using single ended in Class A, produce more detail and clearer.
;)
Please describe ur question about"HI"power amp.Is it HI-FI?or Hi-Watt?:smash: |
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| peranders |
| quote: | Originally posted by nina
...particularly at low volume/level of listening ??
:confused: |
What is low level to you?
I'd say the same as Janneman. I find it more likely to make a more performing amp if I don't have to choose high current and high voltage devices.
Is this your own observation? Maybe the low power amps you have been listening to haven't been too good. |
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| DcibeL |
| quote: | Originally posted by nina
...particularly at low volume/level of listening ?
:confused: |
Says who? And what does this have to do with chip amps?
There are many different amp topologies that a general statement like this just cannot be made. There are 1 watt amps that sound just fantastic, and I'm sure there are 1000W amps that sounds pretty slick as well. Power output has little to do with it. In fact, I might even go as far to say that a high powered amp could not outperform the sound quality of a smaller amp built to be the best sounding possible. A smaller amp would have a shorter signal path, and could be less efficient without running into heat problems. |
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| clem_o |
Nina, perhaps you can post / explain the circumstances that brought you to such a question. Maybe you were listening to a series of different amplifiers, etc and you happened to get this particular perception. I'm sure it will be of interest to the others...
Cheers! |
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| Cobra2 |
Maybe it is because you stay within the klass A biasing of the larger (AB)amp, (some are biased to class A from 5 to 20W)
Arne K |
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| Workhorse |
Since the Voltage rails of the high power amp are at much higher potential therefore it directly effects the SlewRate of high power amp...because SR increase with an increase in supply rail voltage...hence the sound "MAYBE" more clearer than with amp having low supply voltage rails....
K a n w a r |
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| destroyer X |
Are operating in class A when operating low volumes.
And class A, clearly reproduces a better sound than AB amplifiers...with exceptions, of course.
Because there are some bad class A designs and wonderfull class AB designs.
But normally, class A quality is much better.
Other effect is result of speaker overdrive.... take one speaker.... everyone that you have near you.... now install a variable voltage small power supply.... go increasing voltage slowly....you will perceive that many speakers reach their movement limits when you connect 5 volts DC into it's terminals.
So...when you have a very powerfull amplifier, say, 100 watts, you may have 30 volts AC entering the voice coil... the speaker already found their movement limit when AC voltage are increasing from zero to plus 30 volts (if sinusoidal).... the result reproduction of this sinusoidal input audio will be a square wave.... acoustic square wave... distortion.
If not fast realise that.... think about some pencil glued into speaker diafragm and a moving papper sketching the diafragm motion.... this way you will see clearly how speakers can be problematic.
regards,
Carlos |
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| planet10 |
Big amps are better?
In this neck of the woods it is held that there is generally a negative correlation between quality & power.
Certainly. once an amp has more than 2 power output devices quality starts decreasing.
dave |
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| destroyer X |
Enormous care and know how are needed to produce speakers.... i think Acoustic is a very hard science, that need deep know how.
Speakers choices must be carefull, and even having expertise, you will face their limitations.
See the image that will try to explain what i mean.
The best of the speakers are the minimum you may desire.
regards,
Carlos |
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| Miles Prower |
crest factor: even at lower volume you will have high peaks and fast transients that may push a small amp into clipping while a larger one can handle with ease.
That'd be my guess. I always "overdesign" the PS. These three watt PC speaker box amps I designed have a PS that could easily do 12W. Even when running at max output, these sound great. Since transistors clip viciously and without warning, I like lots of "headroom". |
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| destroyer X |
Good to have you in this forum.... a relief to me, to see that we have deep experienced guys.
Please, send me your PC Speaker amplifier schematic.
Dinamic Headroom is a must!
nanabrother@yahoo.com
regards,
Carlos |
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| Miles Prower |
Please, send me your PC Speaker amplifier schematic.
I have it Here.
The PS is just a simple +/- supply built from a 24V/2.7A xfmr, with 20000uF filter capacitors and a 100 ohm bleeder resistor per section. That xfmr also is over designed for current, so the DC remains stable with very little residual hum. Even though the actual speakers are nothing special (car stereo replacement "wide range") I can use the sound card graphic equalizer to turn up both the low and high ends. These sound better than expected, and sometimes seem too good, in that I can clearly hear imperfections in carelessly made mp3's and even some early CDs.
I matched the gain to the sound card output, so that you won't blow the speakers and/or finals. The P(c) rating of the finals is 5.0W, and dissipate 4.9W with constant sine wave input for 3.0W into 8.0 ohms.
Still, haven't blown a final yet despite running them "wide open" for hours at a time. |
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| David Lewis |
It seems (to me) difficult to answer the original question. The problem I have is that I don't believe that amplifiers can be lumped easily into categories like high and low power. For example, if I say to you that your Krell KSA-50 is a low powered amp compared with my 100W Digitor car amplifier you would probably take exception to such an unqualified statement, and you would be correct to do so. Of course, the KSA-50 is quite capable of delivering 200 Watts continous duty and both channels driven into a 2 ohm load, albeit in Class AB. My car amp would self destruct if presented with the same load at full output voltage.
Perhaps we should be exploring the merits or demerits of high current and / or high voltage capable amplifiers. |
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| RetroAudio |
| perhaps it's the parts that each are made of and the way they are used. bias levels often cannot be set as high in a high powered amp or parts quality in any particular line may start deteriorating at a certain point where some cannot be used in a high power amp, but gotten away with in a lower one. these could be just a couple of many reasons i guess. |
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| anatech |
Part of the answer may be that you can get away with murder designing a small amp, that quickly fails at higher voltages / powers. There are some small amps that have very clear crossover distortion that are supposed to be high end. Exposure comes to mind easily for those who need prove of that statement.
So a higher power amplifier forces out many poor practices (but can still leave many).
I agree that the crest factor in music may have a lot to do with it. There is no beating a good design with a good power supply behind it. It is possible that the output impedance around 0V is lower. That may help with out of phase current flow.
-Chris
Edit: spelling probably more ;) |
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| ACD |
| Dynamic (slew rate) / Headroom ;) |
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| sam9 |
| I vote for less prone to clipping as the biggest factor. If the listening level stays below clipping the only reason I can think of for a qualitative difference (other than placebo) is that since you can sell a higher wattage amp for more (were are talking SS not tube, I presume) there is greater return to investing in development and design expense. |
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| destroyer X |
I have line out, but can produce the needed voltage.
I have not amplified power in this unit...using small PC speaker and good headphones.
Your amplifier will be used, thanks.
This thread is running fine...good people cooperating... this is nice.
regards,
Carlos |
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| Miles Prower |
Your amplifier will be used, thanks.
There is one thing that's critically important that can make or break the project. The transistors in the LTPs ( Q(2), Q(3) and Q(5), Q(6) ) Absolutely must be matched for h(fe) and v(BE). What I did was get a couple of packs of NPN and PNP small signal "transistors anonymous" from Radio Shack. Then test every one and select the two with the closest measured values of h(FE) and v(BE).
Yeah, it's boring and a real PITA, but vital to having a low DC offset. With my units, I get DC offsets at the output of around 0.1V. When powering up, there is just a slight movement of the speaker cone that occurs too slowly to be audible, with just a slight "pop" when turning them off. Also, the 1.0uF coupling capacitor should be an AuriCap, not an electrolytic. This makes a big difference in how it sounds.
Finally, I would suggest building each stage and testing for good operation. Make certain that that stage works right before moving onto the next one. Makes trouble shooting a whole lot easier than slapping it together, then going back to see what went wrong. Maybe you can get away with that, but Mr. Murphy likes to slap down such arrogance. |
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| sam9 |
| quote: | | Yeah, it's boring and a real PITA, but vital to having a low DC offset. With my units, I get DC offsets at the output of around 0.1V. |
0.1V = 100mV. I consider anything over 50mV and indicator of something amiss. Do you perhaps mean 10mV (=0.01V)? I generqally get better than 30mV even with not attempt at matching. If I were knocking myself out doing all that matching at still got 100mV offset I would be pounding my head on the wall. Perhaps this is a topology issue? |
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| tlf9999 |
I would agree that 100mv seems to be excessive.
| quote: | Originally posted by sam9
Perhaps this is a topology issue? |
a leaky DC blocking capacitor can cause some large offset. |
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| anatech |
I was wondering as well as I normally get sub 5 mV matching hFE. With a single diff pair I'm getting within 5 mV of my calculated DC offset, normally a couple mV within.
-Chris |
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| anatech |
I'm guessing your design offset is around 55 mV approximately. I guessed at a tail current of 1.3 mA.
-Chris |
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| amplifierguru |
So high power amplifiers sound better? Even at low levels?
Could it be that they often have a much better PS than smaller amps and so lower PSZ commutation inserting through the inherent conventional topology weak point?
Is an oversize PS the answer? Definately not - double the size 6dB improvement! But focussing on topological improvements to increase PSRR can improve/isolate by 20-60dB for much less and represents competent design cf a waste of the planets resources.
But there are plenty that continue to and will happily sell you naive overbuilt design.
So many amplifiers marched out on this forum for contender status are so Hohum they don't warrant comment. An improved topology can solve this very real problem without cost penalty (look away Doug Self).
Cheers,
Greg |
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| Raj1 |
| sometimes high power amps, use lots of feedback, this gives a 'cleaner' sound, but the soundstage is often flatter.. |
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| Greg Erskine |
| quote: | Originally posted by amplifierguru
So many amplifiers marched out on this forum for contender status are so Hohum they don't warrant comment. An improved topology can solve this very real problem without cost penalty (look away Doug Self). |
Hi Greg,
This statement is a little unfair. How can we determine what amps you are referring to? You are probably correct, but for those without your knowledge (i.e. me) your statement casts doubt on every design posted here except yours.
Are you encouraging us to refer to Douglas Self or not?
Thanks |
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| peranders |
I think the question is a bit unclear and conditions involved.
Why does an expensive high power amp sounds better than a cheap low power amp? Probably becasue the design is better in most parts.
but...
If I'm going to make a 50 W amp and a 500 W which will be the best if the power need is around 1 watts and I do everything I can to make them good? |
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| amplifierguru |
Hi Greg,
but,but,but... I haven't posted mine! My comment referred to so many of the same old flawed and unremarkable topology simply because they are starting out with a topological handicap - they have little to recommend them. But someone decides they are worth a try...
:D :D
Greg |
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| Greg Erskine |
| quote: | Originally posted by amplifierguru
but,but,but... I haven't posted mine! My comment referred to so many of the same old flawed and unremarkable topology simply because they are starting out with a topological handicap - they have little to recommend them. But someone decides they are worth a try... |
Hey Greg, this may be a case where too much knowledge and experience is spoiling the potential of getting the most fun and enjoyment from DIY amps. What's the quote? "Ignorance is bliss" (Sounds like it might have come out of 1984.)
Anyway, I have built a few DIY amps and have a couple of average commercial amps and to be honest I can't really see a corrolation between complexity. topology and good sounding amps. IMHO it seems a good implementation of any of the topologies seems to work.
Back to the topic: Its a matter of the right amp for the job, not bigger or smaller. |
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| amplifierguru |
Back to topic, indeed. Big amps tend to have a beefier PS and, given a typical topologically handicapped design, will sound better through lower PS impedance and consequent PS commutation artefacts. It is well accepted that adding more PS caps or beefier xformer will positively affect sound - so it's clearly an issue.
Cheers. |
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| planet10 |
| quote: | Originally posted by amplifierguru
It is well accepted that adding more PS caps |
I would question that statement. Look at experiments with gain clones, and what Hugh says about more for the AKSA. More capacitance on a cap only power supply hammers the trafo more and increases the frequency of the RF spike injected into the system by the power supply.
Better power supply design makes a huge difference in general... the same amp with at least CRC or better yet CLC or LC will sound better than C alone.
dave |
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| amplifierguru |
Hi planet 10,
Weak PSRR benefits from more PS C - at least on a typical topology with little regard (or understanding) for PSRR. What RF spike? I can't remember when I last heard an RF spike!
Better amp design makes a world of difference and one can easily have a 150W amp with a 150W x'former and medium C that outperforms the behemoths! Ask the ML or Krell agents in Australia who wouldn't dare put their heath robinsons up against my little block - because they knew they couldn't cut it! And so did the Audiophiles.
:D :D |
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| peranders |
| quote: | Originally posted by planet10
I would question that statement. Look at experiments with gain clones, and what Hugh says about more for the AKSA. More capacitance on a cap only power supply hammers the trafo more and increases the frequency of the RF spike injected into the system by the power supply. |
I'm also the opinion (or the feeling) of that there is a technical limit when adding capacitance doesn't add anything and possible make the oppostite. It's maybe better to feed the driver with stablized voltage instead and then tolerate some ripple for the output stage. |
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| Miles Prower |
| quote: | | 0.1V = 100mV. I consider anything over 50mV and indicator of something amiss. Do you perhaps mean 10mV (=0.01V)? I generqally get better than 30mV even with not attempt at matching. If I were knocking myself out doing all that matching at still got 100mV offset I would be pounding my head on the wall. Perhaps this is a topology issue? |
No, just a typo. Dropped a zero: 0.01V is what it should be. |
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| planet10 |
| quote: | Originally posted by amplifierguru
What RF spike? |
Unless you are using tube rectifiers or Schottky diodes the reverse spike in the rectifier diodes produces RF (with a cap input filter, choke input won't suffer from this). The more C, the shorter the charge time, the bigger the spike. Exotic diodes & snubbers can help but won't get rid of it.
The shorter charge time also stresses the trafo more...
dave |
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| ChocoHolic |
| quote: | Originally posted by Miles Prower
Please, send me your PC Speaker amplifier schematic.
I have it Here.
The PS is just a simple +/- supply built from a 24V/2.7A xfmr, with 20000uF filter capacitors and a 100 ohm bleeder resistor per section. That xfmr also is over designed for current, so the DC remains stable with very little residual hum. Even though the actual speakers are nothing special (car stereo replacement "wide range") I can use the sound card graphic equalizer to turn up both the low and high ends. These sound better than expected, and sometimes seem too good, in that I can clearly hear imperfections in carelessly made mp3's and even some early CDs.
I matched the gain to the sound card output, so that you won't blow the speakers and/or finals. The P(c) rating of the finals is 5.0W, and dissipate 4.9W with constant sine wave input for 3.0W into 8.0 ohms.
Still, haven't blown a final yet despite running them "wide open" for hours at a time. |
I guess Q7 should be NPN instead of PNP. |
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| Miles Prower |
| quote: | | I guess Q7 should be NPN instead of PNP. |
Yeah. I fixed it.
That one got by me somehow. :xeye: |
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| peranders |
Miles, please use the "quote" function, just tick the checkbox and the bottom at each post.
Lightgreen on light blue isn't a hit when it comes to readability. If you do this we do also see whom you are quoting. (was whom right?)
Just a hint..... |
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| janneman |
| quote: | Originally posted by Workhorse
Since the Voltage rails of the high power amp are at much higher potential therefore it directly effects the SlewRate of high power amp...because SR increase with an increase in supply rail voltage...hence the sound "MAYBE" more clearer than with amp having low supply voltage rails....
K a n w a r |
Sorry Kanwar, but SR has NOTHING to do with supply levels. SR has to do with the change of output level in volts per microsecond, and is a function of the used devices, topology, compensation and a lot of other interrelated issues.
A +/- 20V amp can have a SR of 50V/uS and a +/- 100V amp can have a SR of 10V/uS. Go read your books.
Jan Didden |
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| janneman |
| quote: | Originally posted by sam9
I vote for less prone to clipping as the biggest factor. If the listening level stays below clipping the only reason I can think of for a qualitative difference (other than placebo) is that since you can sell a higher wattage amp for more (were are talking SS not tube, I presume) there is greater return to investing in development and design expense. |
Dynamic headroom is a relative number saying how much the amp can deliver in peaks above the average output. You can have both high and low power amps with the same headroom.
Higher power amps can handle bigger signal levels of course, but the original question states "low listening levels" so that would take this particular advantage away from the high power amp.
This can only be answered if you know the speaker efficiency, listening levels, biasing of the two amps (A, AB, B) etc. I can probably come up with two amps and a speaker that proves just the opposite.
Jan Didden |
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| peranders |
| quote: | Originally posted by janneman
Sorry Kanwar, but SR has NOTHING to do with supply levels. SR has to do with the change of output level in volts per microsecond, and is a function of the used devices, topology, compensation and a lot of other interrelated issues.
A +/- 20V amp can have a SR of 50V/uS and a +/- 100V amp can have a SR of 10V/uS. Go read your books. |
Kanwar is right sort of but SR is related to output power and is given by:
Which bandwidth and which power, so if you know the desired max power and specified load and also wanted bandwidth you also know the required SR but SR is neither a separate thing nor a quality mark as you want to emphasize, Kanwar.:att'n: |
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| amplifierguru |
I'll stick with my original theory that it's the better power supply of a larger amp. It's reasonably to expect a designer to allocate sufficient power supply capacitance to keep ripple low (say 1V) at maximum power, so a high power amplifier will have a higher C by 2 or maybe 3 times AND a lower Z transformer (150VA typ 10% regulation, 500VA typ 3%). Given the commutation artefacts
due to class AB - spray of harmonics AND the emphasis of these at 6 dB /octave by the typical declining PSRR of a conventional miller compensated design, I'd say I'm right on target.
See attached typical miller comp PSRR HF emphasis.
Cheers,
Greg |
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| planet10 |
| quote: | Originally posted by amplifierguru
I'll stick with my original theory that it's the better power supply of a larger amp. |
Big amp does not imply a better power supply.
Big has nothing to do with quality. It is certainly easier to build a better supply for a low power amp than for a big amp. A LCRC (all Cs poly) power supply in a 5 W amp is (likely) better than any caps only power supply regardless of amp size (or cost). And within its power limitations is a fantastic amp.
dave |
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| amplifierguru |
| quote: | Originally posted by planet10
Big amp does not imply a better power supply.
Big has nothing to do with quality. It is certainly easier to build a better supply for a low power amp than for a big amp. |
You cherry picked - I explained why! Again - It's reasonably to expect a designer to allocate sufficient power supply capacitance to keep ripple low (say 1V) at maximum power, so a high power amplifier will have a higher C by 2 or maybe 3 times AND a lower Z transformer (150VA typ 10% regulation, 500VA typ 3%).
The miller comp lets through this, going up at 6dB/octave - |
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| carlosfm |
I agree that in some cases it's very noticeable when an amp is not driving a pair of speakers properly, and that is evident even at low listening levels.
Untight bass is there.
But in my oppinion (and in my experience) it is not directly related to the power of the amp.
Several things may make an amp become unstable, and a weak PSU doesn't help either.
Complex crossovers, very capacitive cables, etc. can make even a high power amplifier to sound like a mad cow.
:D
In the end, it's all a matter of sinergy, but even then, some low(er) power amps can drive some difficult speakers beyond believe, while others just throw away the towel. |
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| Ultima Thule |
Hi Dave,
are you aware that this: (with emphaze on the underlined in the quoted text)
| quote: | Originally posted by planet10
Unless you are using tube rectifiers or Schottky diodes the reverse spike in the rectifier diodes produces RF (with a cap input filter, choke input won't suffer from this). |
...and this...
| quote: | Originally posted by planet10
The more C, the shorter the charge time, the bigger the spike. Exotic diodes & snubbers can help but won't get rid of it.
The shorter charge time also stresses the trafo more...
dave |
...is not the same thing?
Appologize me if there's some misunderstandings, but it seems to me to be two diffrent issues you are mixing up here.
Cheers Michael |
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| anatech |
Hi Greg,
I agree with you that a poor power supply will cripple an otherwise good amp. I view the power supply as a subtractive thing as it's quality goes down.
All things considered equal, just changing the voltage, the layout and amplifier design is more important. Some amplifier designs are just better than others. Some of these are higher power.
-Chris |
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| planet10 |
| quote: | Originally posted by Ultima Thule
...is not the same thing? |
But aren't they related?
dave |
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| darkfenriz |
well
just thinking of the thread starter.
He (she?) hasn't taken part in this discussion from the very beginning.
Also I am a bit suspicious about the topic, actually opposite to this hypothesis is believed, most like low power amps for better and clearer sound.
Isn't it a kind of provocation?
Or test thread to tell wisemen from wiseguys?
Looks like searching for proofs to prove wrong theory....
just thoughts |
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| amplifierguru |
Hi anatech,
Agree wholeheartedly. My argument was based on the weakness of miller C/Vas topology causing sensitivity to PS.
Hi darkfenriz,
Have we all been suckered? No matter, the whole thread is so general there's plenty of room to move.
:D :D
cheers,
greg |
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| tlf9999 |
| quote: | Originally posted by peranders
Kanwar is right sort of but SR is related to output power and is given by: |
i agree with peranders here. My explanation is simpler: higher output means higher voltage swings which in turns means higher SR. so a (compotent) high power amp will have higher SR than a low power equivalent, everythign else being equal.
| quote: | Originally posted by amplifierguru
I'll stick with my original theory that it's the better power supply of a larger amp. |
that is true in general but as we are talking about sound quality at low output levels I doubt power supplies make that big of a difference.
| quote: | Originally posted by planet10
Big amp does not imply a better power supply. |
a big amp is likely to have beefier power supply as it needs to have the capability to deliver more to the load. "Better" or not is subjective. But i would say that statistically bigger amps have beefier and more capable power supplies. |
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| bogicp |
| quote: | Originally posted by darkfenriz
well
just thinking of the thread starter.
He (she?) hasn't taken part in this discussion from the very beginning.
Also I am a bit suspicious about the topic, actually opposite to this hypothesis is believed, most like low power amps for better and clearer sound.
Isn't it a kind of provocation?
Or test thread to tell wisemen from wiseguys?
Looks like searching for proofs to prove wrong theory....
just thoughts |
I agree with you
Probably it will be better to start voting, not the discussion about this question.
Best regards,
-boggy |
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| Ultima Thule |
| quote: | Originally posted by planet10
But aren't they related?
dave |
Hi Dave,
the first issue, the reverse spike thing occurs only during the stage when the voltage over the diode is altering, eg. going below Vf.
The diode take some time to stop conduct in the reverse direction when the voltage is altering over the diode, but with rectified 50/60 Hz this is a none issue when considering a fast diode Trr can be around 20nS or so, during this tiny time the 50/60 Hz sine voltage doesn't change much at all, especially near the peak sine voltage where the reversing is mostly occuring. The event is so slow so there's not much RF energy occuring here.
A small note on snubbers, the above explained effect is where to use the snubber for.
In SMPS it's MUCH more important with low Trr time of the diode because there's slew rates of the switched voltage up to severeal thousands of volts per uS, this is what really causes RF enrgy even up to GHz regions.
The other issue when we talk about the peak current when charging cap's occurs only in the forward conduction mode of the diode and has nothing to do really with the reverse current spike due to Trr of the diode, they are quite different things. Under the forward conduction mode the current peak occuring is quite a slow event too, as the change is quite slow due to the very low mains frequency it's in order of mS(compared to Trr in nS), however harmonics can occur but is certainly not in the RF region but rather more in the audio region I would say, but nevertheless can be of course harmfull.
Hope this explains.
Cheers Michael :) |
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| planet10 |
| quote: | Originally posted by tlf9999
a big amp is likely to have beefier power supply as it needs to have the capability to deliver more to the load. "Better" or not is subjective. But i would say that statistically bigger amps have beefier and more capable power supplies. |
Maybe in commercial-ampLand, but i'd say there is no correlation in diy-ampLand (which is where i assume we are)
dave |
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| tlf9999 |
| quote: | Originally posted by planet10
Maybe in commercial-ampLand, but i'd say there is no correlation in diy-ampLand (which is where i assume we are)
dave |
the opposite is true. |
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| mastertech |
"Why hi-power amp produce clearer sound & more details...particularly at low volume/level of listening ?"
i guess that holds true for a hi-power amp that is bad too
you see guys, if you compare a hi-power amp to a low power one
you mostly compare power levels
cheers |
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| amplifierguru |
It just dawned on me..
Could it be that the often higher gain of high power amplifiers results in more power so impresses the listener more? For a fixed input level.
There's a desperate explanation.
Cheers,
greg |
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| mastertech |
99,9% spot on i would guess my friend
cheers |
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| Tony |
| quote: | Originally posted by amplifierguru
It just dawned on me..
Could it be that the often higher gain of high power amplifiers results in more power so impresses the listener more? For a fixed input level.
There's a desperate explanation.
Cheers,
greg |
the problem is how to interpret someones' experience in listening in such a way we are sure we know what he really meant! |
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| janneman |
| quote: | Originally posted by amplifierguru
It just dawned on me..
Could it be that the often higher gain of high power amplifiers results in more power so impresses the listener more? For a fixed input level.
There's a desperate explanation.
Cheers,
greg |
Yeah, it's pretty desperate ;) . Its the gain that determines the loudness level at a given input level (assuming same speakers of course). So, same gain, same loudness. What would be different with a high power amp is that it will clip at higher input levels. But, since the question was "at low levels" that doesn't appear to be a point.
Jan Didden |
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| janneman |
| quote: | Originally posted by amplifierguru
I'll stick with my original theory that it's the better power supply of a larger amp. It's reasonably to expect a designer to allocate sufficient power supply capacitance to keep ripple low (say 1V) at maximum power, so a high power amplifier will have a higher C by 2 or maybe 3 times AND a lower Z transformer (150VA typ 10% regulation, 500VA typ 3%). Given the commutation artefacts
due to class AB - spray of harmonics AND the emphasis of these at 6 dB /octave by the typical declining PSRR of a conventional miller compensated design, I'd say I'm right on target.
See attached typical miller comp PSRR HF emphasis.
Cheers,
Greg |
I agree that higher power amps would normally have higher C values. But, how does that jive with all those reports that we are bombarded with, that lower C gives better sound???
Jan Didden |
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| amplifierguru |
Hi jannerman,
Yes I said it was desperate - because I was assuming a very naive listener would use a fixed input level not knowing the higher gain of the big amp - and being impressed!
By the extra power.
Cheers,
Greg:D |
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| janneman |
| quote: | Originally posted by anatech
Hi Greg,
I agree with you that a poor power supply will cripple an otherwise good amp. I view the power supply as a subtractive thing as it's quality goes down.
All things considered equal, just changing the voltage, the layout and amplifier design is more important. Some amplifier designs are just better than others. Some of these are higher power.
-Chris |
Amen!
Jan Didden |
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| janneman |
| quote: | Originally posted by tlf9999
quote:
Originally posted by peranders
Kanwar is right sort of but SR is related to output power and is given by:
i agree with peranders here. My explanation is simpler: higher output means higher voltage swings which in turns means higher SR. so a (compotent) high power amp will have higher SR than a low power equivalent, everythign else being equal. |
This is simply not true. SR is DEFINED as the rate of change of output voltage per unit of time, like in Volts/uSec. That is determined by the amp topology, the compensation, the used devices etc.
A higher power amp would REQUIRE a higher SR if it has to reproduce 20kHz at full power, and a lower power amp can get away with lower SR to reproduce those 20kHz at lower power. After all, it need to swing less output voltage in the same time (the 20kHz period). BUT, most amps have SR that is waaaay beyond what is required. And also, you can easily have a low power amp with 50V/uS SR, and a high power amp with 20V/uS slew rate.
In fact, because the higher power devices used in a high power amp are generally slower than low power devices, I would EXPECT that a high power amp has LESS slew rate than a low power amp.
You CANNOT say that a high power amp by definition has higher SR, because it is not true.
Of course, you can say a COMPETENTLY designed high power amp has higher SR. That is technically true, but it ONLY means that it has the SR to give undistorted output at full power. But that low power amp also gives undistorted with its lower SR. So, the sound would not be different because of the different SR.
It all says one thing: saying that a high power amp sounds better because of higher SR is nonsense.
Jan Didden |
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| amplifierguru |
As I said -
"I'll stick with my original theory that it's the better power supply of a larger amp. It's reasonably to expect a designer to allocate sufficient power supply capacitance to keep ripple low (say 1V) at maximum power, so a high power amplifier will have a higher C by 2 or maybe 3 times AND a lower Z transformer (150VA typ 10% regulation, 500VA typ 3%). Given the commutation artefacts
due to class AB - spray of harmonics AND the emphasis of these at 6 dB /octave by the typical declining PSRR of a conventional miller compensated design, I'd say I'm right on target."
If that wasn't topology related I don't know how to say it in words of one syllable.
R.I.P. |
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| anatech |
Hi Greg,
Soooo, if we take an iffy amp and put a really good power supply on it, it will sound great? I have some Nikko's to improve!
I'm not trying to be silly, but I think I'm missing your point entirely. My belief is that you can destroy a good amp with a bad power supply, not the reverse.
-Chris |
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| janneman |
| quote: | Originally posted by amplifierguru
Hi jannerman,
Yes I said it was desperate - because I was assuming a very naive listener would use a fixed input level not knowing the higher gain of the big amp - and being impressed!
By the extra power.
Cheers,
Greg:D |
Quite right. The original poster is conspicuously absent, as has been noted. He must be leaning back enjoying the show. :D
Jan Didden |
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| amplifierguru |
Absolutely!!
The jokes on us - we bit, on a topic that was so vague and subjective to be laughable.
Cheers,
Greg |
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| janneman |
| quote: | Originally posted by amplifierguru
Absolutely!!
The jokes on us - we bit, on a topic that was so vague and subjective to be laughable.
Cheers,
Greg |
The interesting thing is that people come up with complete bonkers explanations in their eagerness to give an explanation. Engaging the keyboard before the brains.
Jan Didden |
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| anatech |
| quote: | | The interesting thing is that people come up with complete bonkers explanations in their eagerness to give an explanation. Engaging the keyboard before the brains. |
That can be said of any thread. Joke or not, it looks like an honest question from a lay person. There are some unbelievable things posted here, and they are fun to watch.
Okay, where is nina? It's been about 3 days.
-Chris |
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| RetroAudio |
| Ok, here's a twist. I just purchased an amp off a guy that said it sounded better at low volume than his more powerful amp. I'm just confused..:whazzat: |
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| tlf9999 |
| quote: | Originally posted by janneman
This is simply not true. SR is DEFINED as the rate of change of output voltage per unit of time, like in Volts/uSec. |
so to output more power, don't need to output more voltage (higher voltage swing). Doesn't that give higher SR in a given period of time?
| quote: | Originally posted by janneman
Of course, you can say a COMPETENTLY designed high power amp has higher SR. |
if we aren't considering competently designed amps, we will run into tons of weird possibilities then the whole discussion is meaningless.
| quote: | Originally posted by janneman
That is technically true, but it ONLY means that it has the SR to give undistorted output at full power. But that low power amp also gives undistorted with its lower SR. |
the lower powered amp will do so only at lower output levels. In otherwords, at the same output levels, the higher powered amp is capable of following faster signals -> better bandwidth if you will. |
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| planet10 |
| quote: | Originally posted by anatech
Soooo, if we take an iffy amp and put a really good power supply on it, it will sound great? |
Not necessarily great, but better. We did a fair amount of that with NAD 3020s & Haflers back in the day when they were new.
In modern day, the chip-amp is a good example. Bigger, better regulated trafos, better rectifier diodes, higher quality smoothing caps, & regulation all make a big difference in amp quality.
dave |
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| anatech |
Hi Dave,
Just making a point. See my earlier posts on the subject.
| quote: | Hi Greg,
I agree with you that a poor power supply will cripple an otherwise good amp. I view the power supply as a subtractive thing as it's quality goes down.
All things considered equal, just changing the voltage, the layout and amplifier design is more important. Some amplifier designs are just better than others. Some of these are higher power.
-Chris
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-Chris |
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| amplifierguru |
Hi Planet 10,
"Bigger, better regulated trafos, better rectifier diodes, higher quality smoothing caps, & regulation all make a big difference in amp quality."
- that's a flag of poor amp topology throwing the onus for performance onto the power supply!
Cheers,
Greg |
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| planet10 |
| quote: | Originally posted by amplifierguru
- that's a flag of poor amp topology throwing the onus for performance onto the power supply!
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I disagree. The power supply is at least half the amplifier. The amp is simply a valve that controls how much of the power supply gets to the speaker.
dave |
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| amplifierguru |
When an amplifier performs as badly as in this example , quite typical of the diff'l -Vas - EF configuration, it is indeed a poor valve and should be replaced with a competent one.
30dB - 50dB PSR means you're listening to the vagaries of the power supply! And it comes as no surprise that overbuilding will have a very audible effect.
It's a Poor Design that needs more of the world's resources to achieve a goal that can be achieved much more elegantly with less and better design of the amp proper.
Cheers,
Greg |
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| planet10 |
| quote: | Originally posted by amplifierguru
It's a Poor Design that needs more of the world's resources to achieve a goal that can be achieved much more elegantly with less and better design of the amp proper. |
This is untrue. Some of the world's best sounding amplifiers are very simple and have low PSRR and the designer realizes that the power supply is an integral part of the amplifier and takes care to execute its design properly.
The amplifier below is simple, sounds excellent, and, even thou Class A, because it is low power, uses little power.
dave
PS: since this map was drawn it has been converted to RH style (pentode with plate to grid feedback) to more than double the output power without an increase in draw (and better sound to boot) |
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| amplifierguru |
Ha, very good planet 10 - it's a tube amp running low current! Solid state amps are generally direct coupled and draw load current directly from the supply. This is the big difference between the two that has rarely been fully acknowledged by designers and largely responsible for the 'solid state' or 'transistor' sound.
trouble with your little tube amp is it's in decline from day1, microphonic, and unreliable. Make a great sub or car amp?
Todays solid state feedback amps of conventional topology are seriously lacking in PSRR so your listening to the vagaries of the power supply! Due to flaws in the topology that needn't be.
Cheers,
Greg |
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| planet10 |
| quote: | Originally posted by amplifierguru
rouble with your little tube amp is it's in decline from day1, microphonic, and unreliable. |
Not really. I have used 50 year old EL84s that test as new (ie they are extremely long lived if run conservatively), the amp is quiet, doesn't give a lick of problem, and makes music better than any SS amp we've had thru (and have no lack of those to try out).
dave |
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| amplifierguru |
That's nice planet 10,
For many tube amps have a high running cost and are well serviced by 'specialist' shops with markups akin to those on printer cartridges. The feeling of being 'got at' prevails.
But seriously, you've tried many SS amps but perhaps you need
to look past the hype for the better topology - one where you're not listening to PS artefacts!
To quote from my last review - ".. down near the threshold of audibility, notes seemed to crystallise out of silence, stay for as long as necessary, then disappear back into a perfect grainless silence. The stereo image was magnificant. Not only were instruments precisely and correctly positioned in terms of width, it was also possible to precisely locate their position in 3 dimensional space....."
My amps sell themselves.
Cheers,
greg:D |
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| planet10 |
| quote: | Originally posted by amplifierguru
or many tube amps have a high running cost and are well serviced by 'specialist' shops with markups akin to those on printer cartridges. The feeling of being 'got at' prevails. |
Not this amp... less than a $100 invested so far
| quote: | you've tried many SS amps but perhaps you need
to look past the hype for the better topology |
Long ago i learned to ignore the hype. I haven't heard your amplifier*, but i've certainly heard a number that have had similar flowery phrases written about them.
*(i followed the thread where you talked about your topology and thot it would be an interesting amp to listen to)
dave |
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| amplifierguru |
Yeah, don't you love those flowery phrases!
I would sell them by trial - the audiophiles would call me and say "is it as good as xyz.." , I'd say "I don't know, is that what you have" , "Yes", Why don't you try it for 2 weeks. OK.
When two weeks was up they'd ring "I have to keep it - my ears won't let me go back!"
All the time.
Cheers,
Greg |
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| janneman |
| quote: | Originally posted by amplifierguru
Ha, very good planet 10 - it's a tube amp running low current! Solid state amps are generally direct coupled and draw load current directly from the supply. This is the big difference between the two that has rarely been fully acknowledged by designers and largely responsible for the 'solid state' or 'transistor' sound.
[snip] |
What nonsense is this?? That tube amp has the "supply vageries" directly coupled to the load through the output transformer. If PSRR is responsible for the sound difference, that tube amp *should* sound horrible. Could the reason that your view has rarely been acknowledged by designers be that your view is simply wrong?
Jan Didden |
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| janneman |
| quote: | Originally posted by RetroAudio
Ok, here's a twist. I just purchased an amp off a guy that said it sounded better at low volume than his more powerful amp. I'm just confused..:whazzat: |
Do you have any reason to believe his statement is correct? Is he the Worlds Best Audio Designer? If it helps you, I'm willing to state the opposite ;) ...
Jan Didden |
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| janneman |
| quote: | Originally posted by tlf9999
so to output more power, don't need to output more voltage (higher voltage swing). Doesn't that give higher SR in a given period of time?[snip] |
Yes, it would need higher slew rate to give undistorted output compared to a low power amp. For double the power, you need 40% more output voltage, so for the SAME quality you need 40% more SR. But that only means that, with the higher slew rate, the high power amp has the same sound quality than the low power amp, just louder. It is NO basis to say that because it has higher SR it sounds better. That is a faulty thinking.
Jan Didden |
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| janneman |
| quote: | Originally posted by tlf9999
[snip]the lower powered amp will do so only at lower output levels. In otherwords, at the same output levels, the higher powered amp is capable of following faster signals -> better bandwidth if you will. |
If we compare same quality amps, the high power one must be capable of higher SR to have full undistorted output power, while the low power amp can reach full undistorted power with a lower SR. But both have undistorted full power. The high power amp only goes louder if we crank up the level. But if we use both amps below clipping, the SR has no effect on quality.
Jan Didden |
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| tlf9999 |
| quote: | Originally posted by janneman
If we compare same quality amps, the high power one must be capable of higher SR to have full undistorted output power, while the low power amp can reach full undistorted power with a lower SR. But both have undistorted full power. The high power amp only goes louder if we crank up the level. But if we use both amps below clipping, the SR has no effect on quality.
Jan Didden |
But we are not comparing them at their full output power: the original poster said that both amps are driving at low listening volume -> same output power for both amps. That will give the SR advantage to the higher powered one. |
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| tlf9999 |
| quote: | Originally posted by janneman
Yes, it would need higher slew rate to give undistorted output compared to a low power amp. For double the power, you need 40% more output voltage, so for the SAME quality you need 40% more SR. But that only means that, with the higher slew rate, the high power amp has the same sound quality than the low power amp, just louder. It is NO basis to say that because it has higher SR it sounds better. That is a faulty thinking.
Jan Didden |
they do give the same quality at their respective full output ratings. However, the higher SR of the high power amp at the same output levels allow for the possibility of higher quality sound - that's Kanwar's argument and I don't know how that could be faulty.
You keep comparing t heir performance at full power, which isn't the essence of this particular discussion. We are discussing performance differeence at the same output power. |
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| janneman |
| quote: | Originally posted by tlf9999
But we are not comparing them at their full output power: the original poster said that both amps are driving at low listening volume -> same output power for both amps. That will give the SR advantage to the higher powered one. |
Am I writing English or what? At low levels, both amps deliver undistorted (from SR) sound. Why should they sound different?
Let us put some realistic examples up. Lets say, the low power amp has 20V/uS to be able to deliver full power. The high power amp has SR of 50V/uS to be able deliver full power.
At low levels, say you need a SR of 5V/uS (I am being VERY generous here) to deliver 5 Watts. Why should the amps sound different at 5W because of SR??
Jan Didden |
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| tlf9999 |
| quote: | Originally posted by janneman
At low levels, say you need a SR of 5V/uS (I am being VERY generous here) to deliver 5 Watts. Why should the amps sound different at 5W because of SR??
Jan Didden |
because the higher powered amp at this point will be able to go above 20khz or have smaller phase shift, and to the extent that such a response could be audioable (we don't know for sure), it will be a positive impact on that sound.
That is why I think Kanwar used the word "may" in his post. |
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| janneman |
Wishfull thinking my friend. Both amps deliver undistorted audio at low levels. It is PRECISELY because we look at the low level response that there is no diffrence.
And it may well be that both amps go out to 50kHz. And audio goes to 20kHz. We have no clue. Trying to pin this to SR looks nice, until you really start to think about it.
And it might well be that the low power amp has higher SR than the high power one. Saying that by definition a higher power amp has higher SR is in direct contradiction to reality. There are 20W amps with 100V/uS SR, and there are 100W amps with 40V/uS slew rate. And all sound OK, or at least all sell.
And I am not even sure (or you?) that that hi power one sounds better, in a general sense. Therer are so many factors, the question itself is nonsense.
Jan Didden |
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| carlosfm |
| quote: | Originally posted by planet10
I disagree. The power supply is at least half the amplifier. |
Amen. :angel: |
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| tlf9999 |
| quote: | Originally posted by janneman
And it may well be that both amps go out to 50kHz. And audio goes to 20kHz. We have no clue. Trying to pin this to SR looks nice, until you really start to think about it. |
it may or may not. The point is that the higher powered one extends further out.
| quote: | Originally posted by janneman
And I am not even sure (or you?) that that hi power one sounds better, in a general sense. |
But that's irrelevant as the premise of this discussion is that the higher powered one sounds better and the original poster was asking why that's the case. S/he didn't ask if that's the case. |
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| janneman |
| quote: | Originally posted by tlf9999
it may or may not. The point is that the higher powered one extends further out.[snip] |
Some do, some do not. Some goes less far out than a low power amp. That's the point.
Jan Didden |
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| janneman |
| quote: | Originally posted by tlf9999
[snip]But that's irrelevant as the premise of this discussion is that the higher powered one sounds better and the original poster was asking why that's the case. S/he didn't ask if that's the case. |
I can better that. Question: Why is it that everybody on this forum is smarter than you?:D
Jan Diden |
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