Scale signal in EQs to reduce quantization?

[tor]

Dont remember if i asked this once before. Sorry if i did. But, SM uses floating point... Is there any point in scaling the signal going into a biquad filter in a SM design considered the use of floating point precision? As I understandit is will not make any difference. But am I wrong here?
See this article: http://www.bores.com/courses/intro/iir/5_scale.htm
I guess the case in the article is a fixed system.

[MichaelBenjamin]

they are talking about integers - with floating point i would guess its still preferrable to stay in -1/1 since float resolution is not equally spaced. you could try to add dc of say 500 000 and hear if it makes a difference.

[trogluddite]

add dc of say 500 000 and hear if it makes a difference.

Adding a large fixed number will reduce the resolution, as you would be confining the original +1/-1 to fewer bits in the mantissa of the float number. The bigger the number you add, the lower the resolution of the smaller part that you are interested in.
As a simple analogy, imagine I have a calculator that can only show 8 digits. The decimal point can be shown at any place across the screen - so it is a sinple form of 'floating point' maths.

so..
4.5 +
3.0002
=7.5002
No problem, the decimal place moved further left, and we can still see the whole result.
But...
10000000 +
3.0002
=10000003
Or
0.0000001 /
10
=
0.0000000

Something is lost with these examples because there are no more digits left or the decimal point couldn't move any further.
Float numbers work very much like this - there are 23 bits representing the 'digits' (matissa) and 8 bits representing the 'position of the decimal point' (exponent), plus a sign bit for +/-.

Scaling (multiplying) your input wouldn't alter the precision (same number of digits), but might allow a feedback loop to go on longer before the numbers got too small (run out of decimal places). But in practice those numbers are so small, that a soundcard could never represent them anyway.

The Wiki article about IEEE754 has a few useful explanations and tables about the limitations of float numbers.

[tor]

Thank you for the nice refreshing explanation and examples Trog. Some times i just start to doubt what i earlier have learned. You have the abilty to explain things so even my mother could understand. Are you or have you concidered becoming a teacher?

[trogluddite]

explain things so even my mother could understand.

He he, I do provide a kind of '24hr telephone tech. support' for my mother, she decided to become a 'silver surfer' when she retired.
Thanks for the compliment doing the little examples often reminds me of things that I had forgotten.