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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 Arpangel » Fri Jun 26, 2020 9:32 am

This article was very interesting, but I’d like to have seen the tests performed using a more revealing source, like the human voice. A choir, and/or small string ensemble. Something more complex tonally than just a piano. I always say that the ultimate test for anything is a full rock band, dynamically, and tonally. I wouldn’t judge, or buy anything purely based on the sound of a piano.
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Re: Preamp comparison in SOS October 2012: the key!

Postby Hugh Robjohns » Fri Jun 26, 2020 9:38 am

Arpangel wrote:I’d like to have seen the tests performed using a more revealing source, like the human voice. A choir, and/or small string ensemble. Something more complex tonally than just a piano.

Argghhh.... If you can come up with a way of making those 'more complex' sources precisely repeatable to make the tests valid then we'll gladly give it a go! But until then.....
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Re: Preamp comparison in SOS October 2012: the key!

Postby Matt Houghton » Fri Jun 26, 2020 9:42 am

Hugh Robjohns wrote:If you can come up with a way of making those 'more complex' sources precisely repeatable to make the tests valid then we'll gladly give it a go! But until then.....

go on then :bouncy:
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Re: Preamp comparison in SOS October 2012: the key!

Postby Arpangel » Fri Jun 26, 2020 9:57 am

Hugh Robjohns wrote:
Arpangel wrote:I’d like to have seen the tests performed using a more revealing source, like the human voice. A choir, and/or small string ensemble. Something more complex tonally than just a piano.

Argghhh.... If you can come up with a way of making those 'more complex' sources precisely repeatable to make the tests valid then we'll gladly give it a go! But until then.....

The test was very interesting, and helpful in a lot of ways, I enjoyed it.
OK OK but...how many pieces of music or takes, are ever the same twice? microphones and preamps have to work in that world, so shouldn’t they be judged in that respect?
The Top Gear test track is a good yardstick for any car, but one long straight road isn’t, that’s what I’m trying to get at with just a piano.
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Re: Preamp comparison in SOS October 2012: the key!

Postby Hugh Robjohns » Fri Jun 26, 2020 10:33 am

:lol: Okay, let me re-phrase... If you can come up with a way of making those 'more complex' sources precisely repeatable to make the tests valid, and in a way that is achievable within production timelines and within SOS resources, then we'll gladly give it a go...

Audio Kitchen have achieved it basically by recording a source once and then replaying that sample through a high quality speaker in an anechoic chamber.

But even if you accept the use of re-amping as a repeatable source for this kind of test -- which I know a large number would object to on principle -- sufficient access to a full anechoic chamber just isn't a practical option (as a freebie), and I don't think potential magazine sales would ever cover the commercial hire of a suitable establishment...

And then there's the expense of hiring things like automated drum-hitting machines, laser alignment systems, and all the rest...

It could potentially be a feasible project in partnership with a university, perhaps, if you could find a suitable academic angle for it, but even then the number of suitable anechoic chambers in the UK is very small and they are generally pretty busy places, which restricts your options even further.

Given the challenges Sam and I went through with the piano-based preamp comparison, the thought of doing that with a string ensemble or full band would be the makings of nightmares! ;-)
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Re: Preamp comparison in SOS October 2012: the key!

Postby Hugh Robjohns » Fri Jun 26, 2020 10:43 am

Arpangel wrote:...how many pieces of music or takes, are ever the same twice?

If the performance is not the same on each take, when you're comparing preamps, or mics or whatever how will you know whether the differences you hear are attributable to the device or the performance?

If you hear more bass in one than another is that because it really has more bass, or did the singer lean in a fraction more and get more proximity effect? if one sounds more 'gritty' than another is that because it has a higher distortion level, or did the violinist add some more rosin to the bow?

The Top Gear test track is a good yardstick for any car...

It's entertaining (for some), maybe, but it's not accurate or even that meaningful. The weather conditions make an enormous difference to the lap times. And although professional drivers can be remarkably consistent lap to lap, that consistency doesn't remain precisely the same week to week and month to month...

If these things were easy it would have been done it years ago, and AudioKitchen wouldn't have gone to the extraordinary and hugely expensive extremes that they have to create a reasonably workable product.
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Re: Preamp comparison in SOS October 2012: the key!

Postby blinddrew » Fri Jun 26, 2020 11:30 am

Matt Houghton wrote:
Hugh Robjohns wrote:If you can come up with a way of making those 'more complex' sources precisely repeatable to make the tests valid then we'll gladly give it a go! But until then.....

go on then :bouncy:
And here was me thinking you were going to link to what should be a very consistent performance: https://www.youtube.com/watch?v=3RBSkq-_St8
;)
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Re: Preamp comparison in SOS October 2012: the key!

Postby Matt Houghton » Fri Jun 26, 2020 11:56 am

I almost did link to exactly that video :beamup:

But the Audio Test Kitchen one does make a slightly different, ore worthwhile point, which Hugh has elaborated on: doing this stuff well is *hard*. Doing it well, and to the satisfaction of every pedant in the world is impossible...
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Re: Preamp comparison in SOS October 2012: the key!

Postby James Perrett » Fri Jun 26, 2020 1:55 pm

One solution would be to feed them with a simulated microphone source rather than a real microphone. This would require the use of transformers with suitable output characteristics to simulate transformer coupled mics or suitable matching networks to simulate directly coupled mics.

It would probably be more difficult to design in the first place and may not satisfy certain "purists" but it would make the test process much easier.
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Re: Preamp comparison in SOS October 2012: the key!

Postby blinddrew » Fri Jun 26, 2020 1:57 pm

Yeah, I wish I could get their app to load on my machines. :(
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Re: Preamp comparison in SOS October 2012: the key!

Postby Arpangel » Fri Jun 26, 2020 2:07 pm

Ears, rooms, monitors, it just goes on and on.

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

Postby Matt Houghton » Fri Jun 26, 2020 2:35 pm

James Perrett wrote:One solution would ... not satisfy certain "purists"

Pardon the questionable abridging... but it sums up the problem nicely!

I've thought of a few different possible ways to test/demonstrate this sort of thing. But they're all hugely time-consuming to set up, and different "purists" would object to all of them...
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Re: Preamp comparison in SOS October 2012: the key!

Postby keithjrichards » Fri Jun 26, 2020 2:47 pm

So just pondering with a possibly meaningful analog - had some time on my hands locked up in isolation here ...

I make some money as a photographer (or did until a few months ago) , I take photos with a moderately priced Canon 90d circa £1K . I also have a Canon 1D X circa £5.4K . I sell photos fotos for the same price from both cameras, made far more cash from the cheaper Canon.

Light is slightly higher in frequency than sound Ill give yer that, but same sort of animal so bear with - who says there's no less emotion in a recorded image than in a recorded voice ? You'll get where Im going with this ...

I take a shot with both cameras - analogue to digital conversion takes place and I load my 20Mb photos in to the pc using Photoshop e.g. Tracking & DAW (I use Reaper, its cheap does the job) .

The cheaper Canon a produces the same image "more or less" - given the same lens is used (lens=mic) - generally speaking there will be tiny minor differences if scrutinised to the enth degree , such as noise pattern, moire, colour accuracy blah blah - same mior differences with your pre

I then manipulate the hell out of what I orginally recorded as a RAW image file (post processing) . Darker skys , bluer sea, air brush teeth whiter, delete spots and wrinkles (I do weddings too) - this of course is your eq , compression, double tracking, reverb , autotune (?!) etc . This process goes about pretty much changing everything you had orginally.

I appreciate there are some who record classical and will be spitting feathers at the above . This is an analogy, there are exceptions - that said a crap triangle player will still sound crap on the worlds best mic / pre combo.

Back to the anal ogy.

I do whatever i think is necessary to my original photo to get maximum cold hard cash / payback . What I produce is not that original image - nothing like. The creative changes I lay down are much more extreme forms of distortion and discoloration than those introduced by camera performance differences alone.

So point is hopefully obvious , which equally applies to audio. I understand that rubbsh in= rubbish out , granted, but as long as you have a moderate, professional level of capture which I guess starts at something like an ART Pro MPA II @ £350 (see original 2012 results), it is far more important to have your scene nicely lit (room accoustics) and have a happy, smiling bride (performance) than a £5K pre that typically has miniscule differences to a far cheaper viable option. Spend the cash saved on fit backing singers I say.

Valve saturation, 3rd harmonics from a St Ives tranny ? Lets be honest - sat in your Opel Ascona listening to Thriller cranked up to 12 on the Apline (back in the day). Put your hand on your heart and ask yourself if you could tell if Jacko recorded his vocal with an SM7 or a 47 let alone which pre - of course you bloody couldnt - not even the hifi bods with a stack of of Krells and Martin Logans could tell any difference push come to shove - performance end of..

Luckily for the marketing guys, ego (perhaps?) and obsession will ensure we buy the expensive eye candy though, mysel included..
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Re: Preamp comparison in SOS October 2012: the key!

Postby James Perrett » Fri Jun 26, 2020 2:57 pm

Matt Houghton wrote:
James Perrett wrote:One solution would ... not satisfy certain "purists"

Pardon the questionable abridging... but it sums up the problem nicely!

I've thought of a few different possible ways to test/demonstrate this sort of thing. But they're all hugely time-consuming to set up, and different "purists" would object to all of them...

So possibly the easiest thing to do is to adopt a standard practice and subject every unit to the same tests. I'd suggest just using a known piece of music with silence at the start and end, feeding the preamp via a resistor network so that it peaks at say -60dBu, then adding 50dB of gain via the mic preamp, recording the result and putting it up on the website for everyone to hear. You'd need to make up an attenuation network for every reviewer and give them instructions on how to use it but the only other thing needed would be a decent audio interface.

You'll still end up with people saying that it isn't a real world test but, for anyone with a bit of sense, it would really help them to make meaningful comparisons.
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Re: Preamp comparison in SOS October 2012: the key!

Postby Tomás Mulcahy » Fri Jun 26, 2020 3:02 pm

Arpangel wrote:Something more complex tonally than just a piano.
A piano is arguably more tonally complex than the human voice. The bigger issue I think is that (a) we are all much more intimately familiar with voices than pianos and (b) there is an emotional connection to the voice that is instinctive because it's on of the first sounds we ever hear.

I think you are practically trolling here with your suggestion :lol: But seriously, within the bounds of the test, the point is very very well made. Pre amps make a much much smaller difference than people on other forums want to believe! Imagining a better test to find the negligible differences is a total waste of time. Instead, get a Prism Sound D SCope and you'll be able to measure things no human can hear.
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