An analogy

[gisgillen]

​A simple analogy referring to amplifiers and their power. If a small engined car was going 100 kilometres an hour and a large one the same, the smaller one would be `flat out´ as it were, whereas the larger one would just be cruising. Presumably the same could be said of amplifiers? I really need to know if improving my amp would make a noticeable difference. I now use a Denon DRA-700AE at 80 watts RMS per channel driving B&W XT 4`s which require power. For example the Cambridge Azur 851a which has 120 watts RMS per channel. I now have the Denon quite high when listening at volume. Any input would be appreciated, but please keep the English simple and not technical!!

 

[davedotco]

Firstly, do not be concerned about the volume setting, it is not an indicator of power being used, so as long as it is loud enough for your needs the setting does not matter.

The effect of increasing output power (other things being equal) effects the ears in an exponential fashion. Ie to make your system sound 'twice as loud' you need 10 times the power so if this is an issue you need to make big increases in power.

The difference in ouput capability between 80 and 120 watts is about 2dB, really not a lot. To give some perspective, using a test tone, the ear can usually detect an increase in level of 1dB as a change in volume but on a music signal you will probably need 2 or even 3dB for the change in level to be clear.

So in reality, the change from 80 to 120watts is not that much. That said, the difference between the 'character' of the amps in question and the way they work in your particular system may make the difference very noticeable, or it might not...*unknw*

 

[lindsayt]

That car analogy does not apply to amplifier power, where both amplifiers are being used at power levels below clipping. With the cars you'd expect to feel a difference in how the cars were driving - even if it were just down to how far down your foot was on the throttle. With the amplifiers any differences in the sound would be down to other factors apart from the max power levels.

A better analogy would be 2 people are going on the same all inclusive holiday. One of them has £10,000 in the bank, the other £10 million. The cost of the holiday is £1000. They both have sufficient money for the holiday.

 

[Samd]

A better analogy would be 2 people are going on the same all inclusive holiday. One of them has £10,000 in the bank, the other £10 million. The cost of the holiday is £1000. They both have sufficient money for the holiday.

Ah but during their hols their banks went bust so A kept his £10k but B only got £75k compensation!

 

[Andrewjvt]

Ja what everyone says. Dont think of it as volume - power that is. Ive heard a 2w anp recently play very loud and clear. My amp turned up just below half way was only using a few watts.

What power and power supplys/transformers/design can give you is greater control and drive hard load speakers. Also the hidden details/base control and clarity is what yous expect to hear with more power.

Sometimes to the untrained ear a low powered amp that is losing control sounds more basey sounding than to one that has grip.

 

[Vector]

Try to think of amp and speakers as a pairing. Some speakers just don't need high power, high current amps because they have reasonably high sensitivity and present an easy load. Something like a pair of big Tannoy or Klipsch will not demand huge power. Others will need loads of power and some just won't go,loud anyway without sounding strained because that's not what they were designed for.

Youve also got to think of your room size, distance from the speakers and also the sort of music you listen to and at what level.

I prefermore sensitive speakers with larger cone size but the best way to find out what works for you is to try as many things as you can.

 

[gisgillen]

Thanks to you all for your replies. I just notice with some CD`s and LP`s I have to really wack the volume up and I have this fear that I`m gonna blow the speakers, although according to the What Hi Fi review they (the XT 4`s)love high volumes. I thought with more power the amp wouldn`t be straining as much? Thanks a lot.

 

[Vector]

I checked out the specs on your speakers and they are lower than average sensitivity at 86 db/w and their impedance also drops to 3.1 ohms minimum. You would certainly get an easier load and need less power with more sensitive speakers but if it's just that you worry about using more volume control travel on lower level recordings, don't worry about it.

 

[lindsayt]

With the CD's that you have to turn the volume right up - I bet if you check them on the DR database, they will have higher DR ratings than the ones where don't.

You could always buy or borrow a calibrated sound meter to give you an idea how much power you're putting into your speakers. I bet it's lower than you think.

Amplifiers are electronic items, not mechanical. They don't strain as long as they're not clipping.

 

[gisgillen]

Thanks again for the replies. I`ve just googled but got a bit lost. What does clipping mean? In very easy terms! I mean, how would I notice if my amplifier was clipping? Great people are so helpful.

 

[lindsayt]

Your XT4's produce 86 dbs for 2.83v (1 nominal watt into 8 ohms, 2 watts into 4 ohms) at 1 metre distance in front of them.

10 watts = 96 dbs at 1 metre

20 watts = 99 dbs

40 watts = 102 dbs

80 watts = 105 dbs at 1 metre.

If you measure peak volumes of 105 dbs or greater, 1 metre in front of your speakers with a calibrated sound meter then your 80 watt Denon amplifier may be clipping.

To keep it on the safe side, avoid volumes in excess of 102 dbs at 1 metre in front of your speakers.

102 dbs at 1 metre will probably be about 95 dbs at your listening position - depending on your room size etc. That's very loud.

I am no expert on what clipping sounds like as I never listen loud enough for it to happen.

Google "amplifier clipping images". It's best explained with graphical images.

 

[gisgillen]

Thank you for your answer, didn`t quite follow to be honest!! I did google what you suggested but....??? Didn`t quite follow also about listening from 1 metre, I lsten from about 5 . But thanks for taking the trouble to find out about my B&W`s. I guess I`m happy as it is, I just have this urge for a bit more power so that I`m not at full blast all the time. Many thanks

 

[lindsayt]

You listen at 5 metres, but measure at 1 metre because that's the standard distance at which speaker efficiency is measured.

What you'd actually do is play some music, as loudly as you'd ever want. Measure at 1 metre to get an indication of how much power you need, then measure at your listening position to see how many dbs quieter it is there. From then on you can measure at your listening position and add on the appropriate number of dbs to get an idea of the power being fed to your speakers.

There's a very high chance that your amplifier is not at full blast all the time. It's much more likely that your ears / neighbours tolerance are at their maximum tolerance. And, with solid state amps, they produce the least amount of THD+N at power levels just below clipping.

What you may be getting is quite audible amounts of distortion from your speakers as you turn the volume up. The answer to that is not to change your amp, but to change your speakers instead.

 

[gisgillen]

Thanks so much for your input. I think I`m gonna stick with what I`ve got, the speakers are new to me, and not only are they beautiful looking, they do sound wonderful. Last night my wife was out so I listened to two whole albums, Wishbone Ash Live Dates on LP then Mahler`s 1st (CD), fabulous. Seems my analogy was a bit off the mark and as for measuring them I wouldn`t have a clue! But I am very grateful for your help, all the very best.