Do amplifiers really sound the same?

[hammeredklavier]

I've had them about 6 months, so too early to tell. However, having got inside the box, they seem well built and run cool so I would expect them to be as reliable as any other similar product. I did short out the output once when running at full power, and the amp just went into protection,with no damage whatsoever.

With Behringer products in general, I now have some 30 units of various products, both personally and at the Radio Station. The ones I use professionally are in use 24/7 and have been for some 3-5 years with no failures to date. Others are used more occasionally, my three A500s, the DEQ2496 and DCX2496 are pretty much used daily.

S.

Thanks Serge. I might get an A500, I wouldn't mind a bit more power.

Alex

 

[spxy]

Whatever. Are you deliberately being obtuse, or does it just come naturally?

S.

I'm looking for answers, you said earlier that your knew amps where transparent not because of the measurements but because of listening tests.

So we need to know whether the listening tests you refer too is a true test of transparency.

You can not prove the transparency of the listening test with the listening test itself.

So the problem is how do we know the test method itself is not reducing the transparency of the entire system?

It is well known in science that the act of testing can effect the measurement. Also anecdotally I have heard on may occasions that plugging extra items into my pre amp has seemed to reduced transparency of the system.

So I just wanted to clear that up.

 

[sergeauckland]

I'm looking for answers, you said earlier that your knew amps where transparent not because of the measurements but because of listening tests.

So we need to know whether the listening tests you refer too is a true test of transparency.

You can not prove the transparency of the listening test with the listening test itself.

So the problem is how do we know the test method itself is not reducing the transparency of the entire system?

It is well known in science that the act of testing can effect the measurement. Also anecdotally I have heard on may occasions that plugging extra items into my pre amp has seemed to reduced transparency of the system.

So I just wanted to clear that up.

Yes you can.

With the switch in Position A, i.e with the PAuT bypassed, this is then the normel everyday listening condition. Using amplifiers which are unquestionably transparent, as evidenced by the measurements , this then is the normal position.

Now, switch to the B path, which introduces the PAut suitably attenuated such that what goes in is the same level as what comes out. Does the sound change? If no, then the PAuT is as transparent as the piece of wire which bypassed it. If yes, then the PAuT isn't transdparent.

A very simple and conclusive test.

Unless:

If one believes that No power amp is ever transparent, then one may doubt the transparency of the main listening amplifier, so the test is invalid.

If one believes that switches affect the sound the test is invalid

If one believes that the piece of wire bypassing the PAuT affects the sound then the test is invalid.

However: These tests were devised by engineers for engineers, not for believers in Fairy Stories, so if one does believe in the fantastic, these tests won't convince.

S.

 

[toprepairman]

Hi Serge.
Which radio station?

 

[sergeauckland]

Hi Serge.
Which radio station?

RWSfm 103.3 Community Radio For Bury St Edmunds

Listen Live at www.rwsfm.co.uk

We have two studios, each with a Sonifex Sovereign desk, feeding the FM transmitter through an Orban 2200D processor. We are allowed 25W ERP vertical and 25 W ERP horizontal according to our license from Ofcom. We cover about 10 miles around Bury, a bit more East-West than North South due to the terrain.

S.

 

[Werner]

Neverthless, it stopped the silliness we get now of £19.99 all-in-ones from Argos being described as HiFi.

Not that it was particularly hard to meet the requirements ...

 

[sergeauckland]

The DIN 45-500 loudspeaker standard is still a difficult one to meet, or at least, it's still not met by a number of quite expensive modern loudspeakers.

Edit: The amplifier standard would exclude a large number of modern valve amplifiers.

S.

 

[hammeredklavier]

3 % distortion between 250 Hz and 1 kHz sound like a bit of a stinker...!

 

[sergeauckland]

3 % distortion between 250 Hz and 1 kHz sound like a bit of a stinker...!

That's a fairly common level of distortion for even high quality Reel-to-reel machines. In fact, the Maximum Output Level was usually set such that the distortion was 3%. It will depend to some degree what the distortion is made up of, 3% 2nd harmonic might actually sound quite nice, 3% third harmonic wouldn't sound as nice.

Modern valve amplifiers often have rather more than 3% distortion at LF and HF at anything more than a few watts.

S.

 

[Barrymagrec]

The DIN 45-500 loudspeaker standard is still a difficult one to meet, or at least, it's still not met by a number of quite expensive modern loudspeakers.

Edit: The amplifier standard would exclude a large number of modern valve amplifiers.
S.

But is significantly inferior to the standards proposed by DTN Williamson in 1947.

 

[sergeauckland]

But is significantly inferior to the standards proposed by DTN Williamson in 1947.

Indeed, but as I understand it, Williamson was proposing a standard for Good, if not state-of-the-art HiFi. DIN 45-500 was a minimum standard that all products had to meet if they were toi be called HiFi.

The DIN standard is still not being met by many of today's loudspeakers, and the amplifier standard pretty much excludes valve amplifiers.

DIN was an attempt to quantify the meaning of HiFi. Today it means whatever one wants it to mean.

S.

 

[cooky1257]

Even an art expert would struggle to establish the authenticity of a work of art when viewing it through a dirty window-if in this case the 'window' is the loudspeaker and the work of art the amp then any attempts at claiming an absolute transparency is utter bollocks.

 

[hammeredklavier]

Even an art expert would struggle to establish the authenticity of a work of art when viewing it through a dirty window-if in this case the 'window' is the loudspeaker and the work of art the amp then any attempts at claiming an absolute transparency is utter bollocks.

I suppose it depends whether the distortion introduced by the speakers masks that of the amplifiers you're testing.

 

[Mescalito]

I suppose it depends whether the distortion introduced by the speakers masks that of the amplifiers you're testing.

Just use a pair of decent cans. Much lower distortion levels. If an amp passes a straight wire comparison there, it is truly transparent.

Chris

 

[Werner]

and the amplifier standard pretty much excludes valve amplifiers.

A bit sweeping, not?

Would you care to read through the tens of valve amp measurement reports available on Paul Miller's site and then return to this discussion?



As for the loudspeakers ... if most speakers today don't meet 45500, wouldn't it be safe to assume that even more speakers in the 70s also did not meet this standard? But back then the Germans advertised heavily with Hi-Fi nach DIN45500. They were lying? Or perhaps there was something in the standard or contemporary test methods that allowed them to comply.



Ganz alles Hi-Fi nach DIN45500, aber naturlich nicht unser Lautsprecher!

 

[sergeauckland]

A bit sweeping, not?

Would you care to read through the tens of valve amp measurement reports available on Paul Miller's site and then return to this discussion?



As for the loudspeakers ... if most speakers today don't meet 45500, wouldn't it be safe to assume that even more speakers in the 70s also did not meet this standard? But back then the Germans advertised heavily with Hi-Fi nach DIN45500. They were lying? Or perhaps there was something in the standard or contemporary test methods that allowed them to comply.



Ganz alles Hi-Fi nach DIN45500, aber naturlich nicht unser Lautsprecher!

If you look at the distortion figures on valve amplifiers, they typically rise to a few % at LF and HF. A few don't, but most do. That would take them outside the requirements of DIN 45-500 which at time it was proposed, didn't really need to take valves into account as they had pretty much disappeared by then. It's only in the last 20 years or so that valves have made the resurgence they have.

As to loudspeakers, many today make no attempt at a flat frequency response or accurate pair-matching, and so wouldn't meet DIN 45-500. They seem to sell on style and trying to get people to like their sound rather than going for accuracy. In the 1970s, manufacturers strove for accuracy pretty much above
all else, so meeting DIN 45-500 was relevant.

Many of today's loudspeakers are greatly better than those of the '70s, but many aren't, as clearly their manufacturers don't consider accuracy as in a flat frequency response necessary.

S.

 

[spxy]

Yes you can.

If one believes that No power amp is ever transparent, then one may doubt the transparency of the main listening amplifier, so the test is invalid.

If one believes that switches affect the sound the test is invalid

If one believes that the piece of wire bypassing the PAuT affects the sound then the test is invalid.


S.

but those are the issues we are trying to answer, so this is just circular, and its got nothing to do with fairies.

you said in reply to another poster when asked "how do you measure transparent "? "You don't. Transparency is achieved when an amplifier or other device passes a straight-wire bypass test.. This has allowed the threshold of audibility to be derived for parameters like distortion, frequency response variations, noise levels, etc etc. "

so we could say "how do we know an amp is transparent?, by measuring with an amp we know is transparent".

I do get your point though, if we string enough amps together and the sound isn't much changed they cant be that far off perfect.

 

[sergeauckland]

but those are the issues we are trying to answer, so this is just circular, and its got nothing to do with fairies.

It's only a circular arguement if one doesn't accept the engineering principles it's based on. If one understands those principles and accepts them, then it's a simple and decisive test. If one doesn't accept them, then the test is, for that person, invalid.

Edit: Using an amplifier that is known to be transparent requires acceptance that an amplifier that measures better than a threshold will be transparent. This can be further enhanced by choosing an amplifier that measures, say, 10x better tha the threshold or 100x better, or whathever arbitrary excess one wants to apply. This can then be further checked using headphones, or by doing a subtractive analysis whereby the differences between an amplifier and the straight-wire are measured.

Ultimately, the SWBT is a way of checking for transparency of an unknown amplifier, or for showing that an amplifier that exceeds a threshold will be transparent. If the whole concept of transparency isn't accepted, then no amount of refinement will convince.

S.

 

[Werner]

Serge,

you didn't reply to my questions. You just regurgitated your views.

A valve amplifier designed to normal engineering standards, as opposed to one made to be a retro effects box, has not too much trouble. Ask Johnson, Beard, TdP, ... oh, Williamson, Walker, Leak, ...

As for the speakers: think about the measurement methods available in 1968. How much inherent smoothing would have been going on back then?

 

[hammeredklavier]

A valve amplifier designed to normal engineering standards, as opposed to one made to be a retro effects box, has not too much trouble. Ask Johnson, Beard, TdP, ... oh, Williamson, Walker, Leak, ...

So you're saying it's possible to make a valve amp that works just as well as a solid state one?