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Preamp comparison in SOS October 2012: the key!

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Re: Preamp comparison in SOS October 2012: the key!

Postby Hugh Robjohns » Fri Jun 26, 2020 5:42 pm

I think James' idea has some legs, and we might look into something along those lines. Although I'm really not sure what genuine benefits it would bring to potential purchasers.

We've already shown very comprehensively that -- when used conservatively within their design limits -- the differences between all preamps, regardless of price and heritage, is virtually inaudible to the critical listener, and completely irrelevant to any end-product consumer!

However, there are audible differences -- often quite significant ones -- if the preamp is pushed towards the edges of its performance envelope through being intentionally over-driven. And it is true that some 'name' recording engineers have achieved the successes they have by following this kind of approach (and not always intentionally... but that's another debate!)

But quite how you could control testing of various degrees of overload adds even further to the mind-boggling challenges.
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Re: Preamp comparison in SOS October 2012: the key!

Postby blinddrew » Fri Jun 26, 2020 5:53 pm

If you could just come up with an agreed, consistent definition of 'good overdrive' as opposed to 'bad distortion' whilst you're at it that would be grand. :D
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Re: Preamp comparison in SOS October 2012: the key!

Postby resistorman » Fri Jun 26, 2020 6:49 pm

@ keithjrichards

RE analogy

:clap: :clap: :clap:
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Re: Preamp comparison in SOS October 2012: the key!

Postby James Perrett » Fri Jun 26, 2020 9:58 pm

Hugh Robjohns wrote:I think James' idea has some legs, and we might look into something along those lines. Although I'm really not sure what genuine benefits it would bring to potential purchasers.

We've already shown very comprehensively that -- when used conservatively within their design limits -- the differences between all preamps, regardless of price and heritage, is virtually inaudible to the critical listener, and completely irrelevant to any end-product consumer!

Hopefully it would show how little effect the preamp has. Although, at the levels I mentioned, it should be possible to compare noise performance (as I'd expect the noise of most preamps to be around 60 or 70dB below the signal level) and the high gain may show up any bandwidth problems with certain designs. Such a test should also be doable with just about any decent audio interface. The only specialist bit if kit would be the input attenuator which would require a bit of design thought but could be built quite easily.

Testing at high levels would require a little more knowledge about what other kit was available as you may well need an A/D convertor capable of handling +24dBu or higher signals from the preamp.

I'm one of those people who remembers the days when hifi magazines thoroughly tested the gear they reviewed. Admittedly back in those days there were a few marginal designs about and the tests were certainly needed, but nowadays we could have the luxury of being able to hear the gear as well as read about it.
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Re: Preamp comparison in SOS October 2012: the key!

Postby ef37a » Fri Jun 26, 2020 11:16 pm

"A piano is arguably more tonally complex than the human voice." I don't think there can be any argument Tom.

The piano obviously has a far wider frequency range than any voice and if the pianists here will excuse my further observations? Much greater harmonic complexity. Each note is 3 strings and no matter how good the tuner they will never quite be dead in tune with each other. Even the MIDI controlled piano was probably not exactly the same from hour to hour as its temperature changed? So, even probably the best attempt to compare pre amps thus far could not eliminate all the variables.

But it does not matter because the SOS 'shootout' (or want of a better word) just proved, pretty well what a lot of technical professionals had been saying for years. "It is relatively easy and cheap to make a microphone amplifier that has a ruler flat response from 5Hz to as high as you like, certainly to 80kHz. Noise will be but a dB or two above that dictated by physics and distortion even at +20dBu out in the third decimal place. Better than most power amplifiers and much better than a loudspeaker at say 90dB SPL, and FAR better of course than any analogue tape machine". Of course, the Golden Ear brigade will tell us, "Ah, but specifications don't tell us everything!" Maybe so but faced with such an exemplary device can they please tell us WHAT of that 'everything' is not being told?

So, this searching for definitive test in the face of shifting parameters is really back with arguments about angels and pinheads!

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Re: Preamp comparison in SOS October 2012: the key!

Postby Tomás Mulcahy » Tue Jun 30, 2020 9:01 am

ef37a wrote:Of course, the Golden Ear brigade will tell us, "Ah, but specifications don't tell us everything!" Maybe so but faced with such an exemplary device can they please tell us WHAT of that 'everything' is not being told?
Well, if you have to ask! ;) ;) ;)

ef37a wrote:So, this searching for definitive test in the face of shifting parameters is really back with arguments about angels and pinheads!

Dave.
Agreed!!
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