Then they should make a serious effort to understand how their ears can fool them. They should absolutely resist making purchase recommendations to other people in a public forum as that just compounds the misunderstanding and helps no-one except the maker of the eqpt.. He becomes richer.
Originally Posted by STHLS5
There are sufficient standard approaches in presenting amplifier power specs, from reputable manufacturers anyway, to prevent ambiguity. There are slight variations between approaches but not so different to cause confusion. You only have to note if the max power is quoted at 1% or 10% THD. Some, (especially for their lower priced AV amps) don’t quote the full 20 Hz to 20 kHz power, but something like 20Hz to 15kHz. So if you do your homework you’ll be allright. I’d avoid the manufacturers who don’t do a sufficient disclosure in any case. The products are probably not sound.
That's the problem. They just can't resist talking about the intoxicating sound of Harbeth and the associated equipments. We all do that when we discover something so wonderful, don’t we?
Originally Posted by <HAL>
Physiologically, having a great home stereo is much more a pride than owing a first class home theater. We have friends who would come over to listen to a particular number but never heard of anyone who would visit a place just to watch a movie again in his HT.
I have been alienated by so called "audiophile" community because I don't subscribe that only X, y or Z brand should be associated with Harbeth or certain cables would bring out the vocals. In fact, there a myth, at least over here, that Harbeth should be associated with a certain tube amplifier. When I told them that reading the designer's posts and listening to him, I doubt he would use a tube amplifier because the degrading nature of a tube over time, which contributes to inconsistency for measurement, but I was ridiculed.
The truth is a large number of HUG are on the other side of the fence. How do we bring them to our side without alienating them? ( Am I going to get admonished for suggesting this? Frankly, I don’t think I passed the HUG acid-test. Keeping my fingers crossed)
What's wrong with insisting that those who espouse such opinions set up a proper test/demonstration to prove their views? On most occasions there will be shouting, squirming, wriggling and indeed ANY excuse to avoid an attempt at proof. Ask yourself why this should be. Obsessive audiophilism has many of the characteristics of a religion or similar belief system. Once you appreciate that fact, many of the strange and unexpected reactions you encounter start to fall into place. It's rather like attempting to argue atheism in a convent.
Originally Posted by STHLS5
In the meantime, I suggest you read this.
p.s. whenever you encounter an unexpected and illogical promotion of a particular piece of equipment, check very carefully for the possibility of stealth commercial interests at work. By the way, I recommend that you only eat Cadbury's chocolate. All other chocolate will adversely affect your enjoyment of music.
Amplifier gain is NOT amplifier power rating. Dont confuse them!
Ah, I see a problem here. A big one. There was discussion of amplifier gain. But the word gain was used assuming that non-engineers knew what that means.
Originally Posted by kittykat
Are you saying something like this: "If I look-up the manufacturers data sheet for two amplifiers and they are stated as being the same POWER output then these two amplifiers (must) have the same gain and so can be directly compared"? For example: are you saying that if amp B is given as "50W" and amp C is stated as "50W" that these two can be reliably compared side by side for sonic quality?
This is an extremely interesting point. Gain should have been explained here. It is very rare to see gain specified in a power amp manufacturer's data sheet. I think the old QUAD specs mentioned gain.
Nope. But at a certain volume/gain level both become indistinguishable. This maybe the reason when one perceives one amplifier is better than another.
Originally Posted by <HAL>
i was responding to STHLS5 second paragraph of post #40 which i should have quoted. Some manufacturers are quoting max power in slightly less than standard ways. This is happening and seems to be associated more with multichannel amps with op-amps and low powered digital amp components inside. Its a buyer aware, of intrinsic rather than volume setting function. cheers, kk
Originally Posted by <HAL>
To return to the original question. yes, I use valves... I have a valve preamp which actually measures very well in all parameters, is hand built by one man and it's this latter aspect which mainly inspires me. For my attached headphone setup I use an updated Quad 33 solid state preamp, which was again hand made and sounds surprisingly good once fettled.
As for driving the speakers (Spendor BC2's), I mainly use a lowish output impedance vintage solid state amp, but in the winter, I bring my re-built Quad II's out for an airing. They help to keep the room warm and their higher output impedance seems to work well with the Spendor crossovers, putting more emphasis on the upper midrange which suits them and me well. I also recently bought a restored Quad 303 and this does exactly the same thing, bless it.
I only mention the above, as it's come to my notice that recent tests on amplifier output impedances have shown that the loudspeaker crossover frequencies and slopes may be modified quite audibly by a high output impedance amplifier and it's this that perhaps makes the audible differences, especially as the mid to tweeter crossover is at a very sensitive frequency range for us humans..
The thing with Harbeth speakers is also that they are a pretty easy load and the crossovers have been designed very carefully. The technical results have then been fine-tuned over many hours of listening to make the speaker as consistant as possible with the widest variety of equipment. The fact that so few Harbeths ever come up second-hand must say something..
So yes, if you wish to use valves, then fine, but please be aware that an inexpensive "Arcam" style integrated amp will work very well indeed too.. I think it's the inexpensive product that you have little expectation of but which continually delights, that's the winner here.
Last edited by DSRANCE; 15-08-2010 at 01:18 PM.
Reason: minor edits
What is gain? NO relationship to output power
Gain, simply put, is the amplification factor. Well explained here. The important issue about dB, the usual measurement of gain, is that it is not an absolute number but rather a ratio, so it needs to be referred to something to make any sense.
Originally Posted by <HAL>
A gain of 6dB implies that whatever voltage is presented to the input of an amplifier, the output will be double that amount. One of the hardest concepts to grasp is that doubling a voltage is 6dB gain, but a doubling of power is only 3dB gain. This is because the power dissipated in a load is proportional to the square of the voltage. Don't worry if you don't get this. What is important is that 1dB represents a certain change of audio level and it doesn't matter whether you are talking about voltage (Volts) or power (Watts).
Roughly, 1dB is typically the smallest change of level that humans can perceive when switching directly between two conditions, called an A/B comparison. With good equipment in a quiet room, with practice and careful listening you might be able to detect ½dB on some material.
The effects of volume changes when listening to audio equipment can be remarkable. So when comparing two bits of equipment side by side it is vital to make sure that the listening volume is identical i.e. if you are comparing amplifiers, their gain must be equal. It is VERY easy to walk away from an amplifier comparison and mistake the louder unit as having more detail, depth. better imaging, etc. etc. The louder unit need only be 2 or 3dB louder for this to be so - barely noticeable, less so if there are a few seconds or a minute between the two listens. It is a trick beloved of audio salesmen, to ensure that the unit he wants to sell you is played just that tiny bit louder than the other. Now remember, 3dB of extra volume (a just noticeable difference) represents a doubling of power, one reason it is important to run an amplifier well within its rated capabilities.
Back to gain: amplifiers are typically specified to deliver 100 Watts into a 8Ω load, which means that the amplifier delivers about 28 Volts into the load. Do not worry if you don’t understand how I calculated this.
Another part of the specification should tell you that the amplifier has an input sensitivity of 700mV for full output. This means that 700mV at the input is amplified to become 28V at the output, a factor of 40. This factor, or gain, can be expressed as 32dB and once again, don’t be concerned if you don’t know how this was calculated.
So you now see that the gain of an amplifier bears no relationship to its ultimate maximum output. Amplifier makers tend to give their higher powered units more gain than the smaller ones so that the drive requirements remain much the same – the assumption being that you buy the higher powered unit because you require more power! Were the gain of the two identical, you would have to drive the larger unit harder to achieve the greater output of which it is capable.
To summarise – it is unsafe to make any assumptions about the gain of an amplifier unless you have a specific figure from the manufacturer, in dB. Sensitivity figures are notoriously ambiguous because they have to be related to the amplifier’s full output which is, in itself, a rather ambiguous value unless the manufacturer chooses to pin it down. When evaluating amplifiers (or indeed any audio equipment) it is vital that comparisons be conducted at near identical levels. A cheap hand-held sound level meter can be a great aid when it comes to ensuring that, at different places and times, you are listening at similar levels.
This isn't the whole story on the question of level matching. While 1dB is, for most people most of the time, the smallest significant audible change, there is some evidence to support subtle effects of rather smaller changes.
Originally Posted by Pluto
Consider the possibility of changes under ½dB when evaluating audio electronics; it is highly unlikely that such a difference would ever be overtly apparent. For all intents & purposes, the two units would sound as though they were at the same volume. Nonetheless, there is some evidence to support the view that, in the longer term, the louder unit will be perceived as providing greater low level detail and thereby thought of as clearly superior to its competitor.
For a proper, level matched, comparison to take place, the use of a single, standard volume control isn't good enough. The two chains under test must include a variable, pre-set, attenuator to ensure that the overall gain of each chain is identical.
The playing field must be level for the game to count.
I was, I am in love with my Viva Solista.(whic I bought after 10 years off seeking the right one). 22W with 845 tubes. And I was seeking for speakers that could be adequate ( is this the right word?) to Viva and my place (3,4 x 5,4 x 1,9 m). Money wasnt at first place at my investigations.
I had had Avalon NP2, Altec 604, Podium sound 0.5; Avalon ascendant; Living Voice; and at the end I got from our dealer Pear audio for one week SHL 5.
It is a dream combination, and of course thay stays! For ever!
I belive in analog so I listen 90% LPs on Kuzma Stabi with Stogi referenze and Benz Rubby MK II (MC head) and Pear Audio blue with some unknown head ( but it is MM).
Now I can spend all the diference beetwen other speakers and SHL 5 for LPs. And enyoj in manj new records!
At my 60 I am exited as I was many years ago when I got my first car. That is wonderfull feeling!!
Why some amplifiers perceived to be different ?
Thanks for the detailed explanation.
Originally Posted by Pluto
If I may add, my concern is, why some people find amplifiers can sound different? My humble opinion is no one really uses SPL reader or any equipment to evaluate amplifiers. They just turn it on and listen at their preferred volume level and come to conclusion that certain amplifiers are better than another.
I wouldn't say their observations are flawed. They are correct to perceive the differences. While engineers can prove after level matching and under DBT two amplifiers are indistinguishable but in reality that's not the way normal listeners judge their amplifiers.
Speaking form experience with my preamplifier with 6 stage of gain to the amplifier and 3 stage of gain at the input stage. What should be the correct setting was left to the user's preference as it depends on his equipment and sonic preference. The designer advised to use the highest gain in the input stage but he also says that technically the lowest setting (input) is correct but not necessarily musically the best setting.
After many months trying with different combinations I realised there is no such thing as one setting suits all. In fact, at my normal listening level around 75 dB I prefer the high gain but when listening really loud I preferred the low gain position.
So let's say the high gain position is Amp A and the low gain position is Amp B and their gain is not adjustable I would prefer Amp A and to those who listens really loud would prefer Amp B depending on how loud they play.
Just thinking out loud.
This is going back a bit in the discussion, to the general question of "why can a lower powered amplifier sound better than a more powerful one".
Now what's interesting is that this can be true even within the same product range, same designer, and even the same amplifier topology. I would hazard a guess that this is because the need for a high power output is another contraint on the design. High power output means higher voltages and currents, and this limits the choice of components that go into the amplifier - it may also affect the way that the amplifier is configured (bias levels, etc.). Those design choices affect the sound quality even when the amplifier is not called on to supply a lot of power.
The other thing to consider is that most of the time domestic music reproduction requires very little power - I tried a friend's "Son of Ampzilla" with the P3ESRs and even on Mr. Beethoven's finest the old amp's VU meters were reading about 0.5W on average and 2.5W during the noisy bits. That's in a room 3.5 x 4.5m, about 2.5m high ceiling, speakers 83.5dB/1W/1m. The VU meters are damped (and it would have been handy to use an SPL meter to cross-check) - so some brief peaks will almost certainly have been higher.
So given the difference in sensitivity between P3ESR and M40.1 it is quite conceivable that the latter will work well with a genuine 30W of amplification in a domestic setting. In terms of dB, a 30W amplifier is capable of "just a little less" than the recommended 50W.
Subjectively, when it comes to valves vs. transistors one can't really generalise... well designed amplifiers tend to occupy a sonic middle ground regardless of technology or topology. But one can probably generalise to say that when an amplifier falls short of the ideal (and they all do in one way or another), the audible effect of this will depend on the type of device and the amplifier topology. And that is where taste comes in.
Maybe, amplifiers frequency response changes at different level of output? I am just speculating.
There's no reason why a power amplifier should do that (unless it's being driven too hard and the heat is affecting some of the components)... however some characteristics (noise floor, crossover distortion) are important at low volume levels and others (linearity, power supply stiffness) more important when supplying a lot of power. A lot depends on where the designer has chosen to spend his budget...
Originally Posted by STHLS5
One more thing... the frequency response of your *ears* changes with SPL (see the equal loudness contours that Mr. Shaw posted a while back... if they've survived the site transfer).
Guess again: if anything, the converse is true. In general, a well designed high power amplifier which is "coasting" will perform better than a lower power unit running closer to its design limits.
Originally Posted by honmanm
It all depends how close to the design limits... if borderline, obviously the lower-powered amp is going to run into trouble.
However if we are talking about an average power output requirement of, say, 1W, the difference between 20W and 50W is *almost* academic... on another thread there are several happy Harbeth customers (and a similarly happy dealer) talking about how well the Sugden A21 goes with P3ESRs.
One of the problems with low-powered amplifiers is the tendency of the manufacturer to skimp on the power supply, in which case yes, the sound quality falls apart when operating close to its limits. However if we take two amplifiers with the same power supply, is there any reason why the sound quality of the lower-powered one should degrade before the onset of clipping?
I suspect one of the reasons for the consistent performance of class A amplifiers is simply that they are operating at full power all the time, so (a) the power supply simply cannot be under-specified and (b) loud passages in the music do not place any additional demands on the supply.
A specific example was a comparison between Sumo's Polaris and Nine amplifiers coupled to very revealing 4 ohm speakers at a dealer's premises. Neither of the amplifiers could really cope with the speakers, while the Polaris could deliver 195W into this load it sounded rather harsh at all volume levels. The 80W-into-4-ohms Nine was sweet up to a point, beyond which it simply sounded dull.