Dear Brian
I was interested to read your comments because I have heard (in a blind trial hearing) the sound from equipment soldered with SnPb and two different Pb-free alloys. It certainly seemed to me that there was a very obvious difference between all three - although which is 'better' is of course subjective. Perhaps I was just imagining it?!
regards
Kay
-----Original Message-----
From: Brian Ellis [mailto:[log in to unmask]]
Sent: 07 September 2003 08:19
To: [log in to unmask]
Subject: Re: [LF] resistance od solder joints
Thanks for this info, Keith. Firstly, the resistivity figures I gave
were for a homogeneous mixture of the metals, without taking into
account the presence of intermetallic crystals, which is beyond my
knowledge. This would explain the different values, compared with
empirically measured values. The actual values are not material; it is
the principle I was referring to.
With all due respect, having worked as an engineer and director, from
1964 to 1974 for a company right at the very cutting edge of
professional sound technology, Kudelski SA, I am aware that there is so
much twaddle talked in the sound industry that a subjective judgement is
ismpossible. For example, the proponents of valve (tube) amplifiers just
do not have a clue as the "better sound" they produce is a result of
considerable harmonic distortion, much lower with good semiconductor
amplifiers (which are a rare beast, anyway). Double-blind tests with
trained musicians with fine ears reveal no difference, for example,
between monocrystalline silver speaker cables and a common two-conductor
mains cable used for the same purpose, although the former cost 30 times
more (and are worth perhaps the double).
Your subjective tests of "cleaner" sound imply lower distortion. This
means less generation of harmonics, so it actually contradicts "richer
harmonics", which are produced by non-linear components. A solder joint
is not non-linear but perfectly linear at any given temperature (the
current flowing is directly proportional to the applied electromotive
force). It cannot, therefore, generate harmonics, richer or poorer,
until death does it part. In any case, harmonics are easily measurable
by spectrum analysis, so the difference would be easily measurable if
there were a difference due to the solder composition and it would not
be necessary to resort to the ear, trained or otherwise. I would not
mind betting that these subjective tests were not double-blind, but the
guys were told beforehand to expect to hear better results with the
latest version.
I'm sorry, interesting though it be, your report cannot bear scientific
scrutiny, although this may be a different kettle of fish if, for
example, the THD or crossover distortion of 50 amplifiers, half of which
were soldered one way and the other half the other way, were *measured*
so that the mean values were significantly better with one or the other,
although I don't believe this would happen. If I'm right, and all 50
amplis were given the subjective test, but double-blindly, there will be
no correlation between the two types and "cleaner" sound or "richer
harmonics".
Sorry to shoot you down, but I know too much about the audio industry
and the myths that are perpetrated in the name of separating consumers
from their money!
Best regards,
Brian
[log in to unmask] wrote:
> Brian,
>
> We have reports from several of the well known Japanese manufacturers of
> hi-fi equipment that systems made with lead-free solder (in this case
> the Nihon Superior Ni-stabilised Sn-0.7Cu which has a resistivity of
> 0.13microOhm.m at 25C compared with 0.17 for 63/37) have sound better
> than those made with 63/37. The tests are, however, subjective in that
> they just rely on the opinion of a trained ear to tell the difference.
> They talk of a "cleaner" sound and "richer harmonics" but I do not know
> whether such things can be quantified.
>
> There have been reports of better sound from a UK manufacturer of hi-fi
> equipment but that test was not really an "apples and apples" comparison
> because the lead-free board was hand soldered compared with a wave
> soldered/reflowed tin-lead board. We were told that you can improve
> the sound quality of a board machine soldered with 63/37 just by going
> through and resoldering all the joints by hand. That is probably just
> because joints made by a skilled hand solderer are going to be generally
> better than mass soldered joints.
>
> By the way we measure the electrical conductivity of a Sn-3.8Ag-1.0Cu
> solder as 0.15microOhm.m (using the four terminal method).
>
> Best wishes
> Keith Sweatman
> Nihon Superior Co
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