Temperature-compensated resonance ( was Re: [sdiy] RE: [AH]

Tue Feb 23 11:36:13 CET 2010

Hi Scott,

On Tue, Feb 23, 2010 at 02:51, Scott Nordlund <gsn10 at hotmail.com> wrote:
>
> I apologize to everyone for contributing to this trainwreck, feel free to delete without reading.

Same goes for this email :-)

> Before you go piling on all these high-minded philosophical distractions, could you possibly try supporting your original argument?  I believe the initial seed of it was your disagreement with the assumption that temperature compensated Q in a voltage controlled parametric equalizer circuit was superfluous, yes?
>
> And you support this by saying that equalizers used in recording studios are temperature compensated

> (misusing and misunderstanding the term),

Guilty as charged!

> where what you're really saying is that passive equalizer circuits, with their inductors and switches rather than op amp gyrators and potentiometers are built and used specifically for their temperature stability, with the aim of ensuring "repeatability" in a recording environment, yes?

Indeed. I think it is a worthwhile consideration to put your mind to.

> Are you overlooking the fact that a lot of these things were first made, or at least designed, in an era where passive designs were far more practical than active gyrators?  And maybe that recording engineers generally have a boner for anything "vintage", specifically inductors (as well as tubes, which tend to accompany inductors), not due to temperature stability (not that I've ever heard), but because of the saturation characteristics of their core material (I've heard this one many times)?

Definitely not! But I don't think that one excludes the other. You can
have a car that has leather trim (i.e. nice vintage sound) while it is
*also* fast (gets stuff done in a production environment) and *also*
does not suddenly turn in a random direction when you're driving it
(stability)

> Could it not be said, in some fantasy world where equalizer designers of the distant past were considering op amp gyrator based designs, that their design choice to limit the user to discrete switched positions also made assumptions and imposed restrictions?  Is this not the inevitable result of any design decision?

Hmm, yes - it is - but I did not on the other hand mean to say that
discrete settings were 'better' or 'worse'. What I was saying is that
temperature stability is not always useless, and it is also a design
decision - which is just the kind of thought you are presenting; I am
happy we have middle ground here.

> And are you saying that temperature stability and repeatability are an important factor in the domain of analog synthesizers (the general focus of this mailing list), which are infamously unstable and not even repeatable minute to minute?

This comes from bad, bad, bad design which we do not need to mimic. If
you look at more recent designs you will see that this is not always
true of analog designs; they used to be mostly unstable, but it is not
inherent to their nature, and that is a mindset which needs to be
rooted out.

> Can you clarify, or at least state, your actual argument, sans nonsense?

Original argument: temperature stability of the Q setting is a
worthwhile pursuit in the academic sense and it can yield interesting
results useful in the practical approach; it is not good practice to
reject the theoretical considerations for lack of a general trend
towards practical use.

A few points were made later on to facilitate putting this across:

Secondary argument: it is not worth locking yourself into believing
that because something is not general practice it is not going to be
well spent effort.

Ternary argument: you cannot generalize a rule by analyzing a small
number of samples or even a large number of samples; you can only
describe a trend this way.

Quaternary argument: it is not good to hamper theoretical
considerations by showing that the technique being considered is not
used in general practice; the practical and theoretical world are very
separate.

Quinary argument: It is worthwhile to enforce a level of conversation
oscillating rather above, than below, the threshold of logical
fallacy.

Sincerely,
Your local predicate logic policeman ;-)

> ----------------------------------------
>> Date: Mon, 22 Feb 2010 22:22:07 +0100
>> Subject: Re: Temperature-compensated resonance ( was Re: [sdiy] RE: [AH]
>> From: cheater00 at gmail.com
>> CC: synth-diy at dropmix.xs4all.nl
>>
>> People have hardwired the first computers in order to avoid the tabs
>> vs spaces debate.
>>
>>
>> On Mon, Feb 22, 2010 at 21:40, David G. Dixon  wrote:
>>> Cheater, do you have a specific point to make, or are you simply arguing for
>>> the sake of arguing?
>>
>> There are several points I hoped to have made here; ones that are very
>> close to my heart and I find them quite important.
>>
>> One of them is what Olav brings up: that it is often very worthwhile
>> to challenge 'no one will ever want to', instead of locking yourself
>> in a box in which you cannot grow. I couldn't have said that better
>> than Olav.
>>
>> The second point I was hoping to bring up is that the conversations
>> here are of different nature than when people are trying to come up
>> with a production-ripe product they can sell to real-life clients. It
>> is worth to ask questions about what the perfect filter, vco, eq,
>> exponential converter, ... would be like.
>>
>> Another point is that simply rebuking someone's thesis based on your
>> personal 'twist' on the truth is not the way to lead a conversation
>> about technology and solutions thereto. Ages past, logic used to be
>> taught to children as part of 'trivium' from which the word 'trivial',
>> meaning basic, comes. Logic was so basic. It is not taught in schools
>> anymore and it is quite apparent that it is lacking. As long as we
>> have this sort of deficiencies in basic thinking (don't take me wrong,
>> I'm not calling anyone stupid, but this is really basic) - then I will
>> feel compelled to get back to basics and point out the things
>> essential to effective communication and exchange of ideas between
>> people who are after all thinkers and should be valuing quality of
>> thought.
>>
>>> I've been following this thread, trying to glean
>>> something useful out of it which might help me build better synthesizers,
>>> but so far I'm coming up empty.
>>
>> Imagine someone would come in here saying that resistors are a special
>> type of capacitor ... you would probably feel compelled to straighten
>> them up. This would not make for a conversation especially informative
>> to most of us; it would not let most of us know how it might help us
>> build better synthesizers. But it would be important.
>>
>>> Yes, we're all fairly certain that Cary has
>>> not taken the time to finish that double-blind statistical study on the
>>> preferences of audio recording engineers to temperature-compensated Q (for
>>> shame, Cary, for shame!).
>>
>> Then if he did not - why make statements that require this sort of
>> knowledge? One side to the quality of knowledge contained in a
>> bulletin, publication, forum or mailing list is what is said. It is
>> very helpful when true, informative points are made. Another side is
>> what is *not* said. If an opinion, which is not true (and here I am
>> abstracting from Cary or anyone else) is stated on a forum of
>> discussion, and nobody even mentions it might be wrong, then it is
>> customarily accepted as not untrue; which is detrimental to the
>> quality of conversation. Without 'straigtening out' problems we see in
>> our partners of conversation, we allow ourselves to be victims of
>> indifference, and allow the quality of conversation to drift down
>> rather than rise. It is below certain standards to accept certain
>> kinds of argumentation; it is important to make this point; I'm sure
>> you keep the same kind of discipline in your lecture hall when someone
>> comes up with bogus statements about material sciences.
>>
>>> Why are we supposed to care again?
>>
>> Because without this sort of discipline we are, for one thing, losing
>> the spirit of diy, which is to try new things, rather than getting
>> packed into the bag of 'it doesn't matter'. If you are happy with 'it
>> doesn't matter', then why did you pursue your exponential converter
>> questions? After all, the exponential converter 'doesn't matter'.. :-)
>>
>> D.
>>
>>
>> On Mon, Feb 22, 2010 at 21:13, Olav Martin Kvern  wrote:
>>> Colleagues--
>>>
>>> This is the sort of question that quickly turns into a "religious"
>>> argument--like most engineering design questions. I've seen mature,
>>> intelligent people become physically violent over differing opinions on
>>> correct code indentation--let's try to avoid that!
>>>
>>> In software engineering over the last thirty+ years, I've run into a lot of
>>> limiting design decisions based on questions that start with "Why would
>>> anyone want to ?" Why would anyone want to use this
>>> program after the year 1999? Use more than 8 bits to define a character? Use
>>> a color space other than RGB? Open multiple documents at once?
>>>
>>> You get the idea. Whenever you hear "No one will ever want to..." or "Why
>>> would anyone...", it's a good idea to question the assumption.
>>>
>>> At the same time, making *no* assumptions about the way a product will be
>>> used can lead to a big problem: the product never ships.
>>>
>>> You all already know this, but: The point is to reach a reasonable
>>> balance--neither making overly-limiting assumptions (like the ones listed
>>> above), nor spending forever trying to create a design that accounts for
>>> every possibility. In addition, the issues that tip the balance one way or
>>> another depends on the audience and the intended use (defined as broadly as
>>> possible) of the product.
>>>
>>> Mr. Wiltshire has already created some of the most interesting DIY projects
>>> around--I look forward to seeing how he solves the design dilemma.:-)
>>>
>>> Thanks,
>>>
>>> Ole
>>>
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at dropmix.xs4all.nl
>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>>
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>
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