Soundweb London Interface Kit Gain control

peter65

Hello,

I have read that a Gain of -10 is 0xFFFE7960. I can agree, it is -100.000. But if I take the Message Tool and try -11 for gain I will get 0xFFFE5909. This is not -110.000 but -108.279. If I take 11 as Gain I get 110000. Can any body tell me whats going on?

Peter

Graham

The gain has a special mapping. From +10 to -10 it is linear. From -10 to -inf (which is at -80dB) it is logarithmic.

Dan Lynch

C:\\Program Files\\Harman Pro\\London Architect\\London DI Kit.pdf

page 22

If the value is equal to or above -10dB:
ValueToSend = dBValue * 10000
If the value is below -10dB, then the formula is:
ValueToSend = ( -Log10( Abs( dBValue / 10 )) * ( 200000 )) – 100000
where Abs takes the absolute value - i.e. it drops the minus sign.


Dan

(DI_SETSVPERCENT ftw)

peter65

Thank you very much!

I got a document with only 15 pages. Must be very old. Now I got one whith 91 pages, much better.

On my pc I must do the calculation with 100001, not 100000, to get the right bytes: -log10( abs( $val / 10 )) * 200000 - 100001

An now there is an other problem. If I set -80 => 0xFFFBB7D6, I get back 0xFFFBB7D7 on subscribe. The same is in message tool. A manually subscription gets D7 not D6. But a second client has subscribed the adr before got spontaneously 0xFFFBB7D6. What game is this now?

Peter

Dan Lynch

I haven't played with it yet, but that's probably the due to the fact that -80 or below is considered -inf. If you use DI_SETSVPERCENT and DI_SUBSCRIBESVPERCENT, none of this will matter.

Dan

peter65

Ok, it doesn't matter. I know gain is an integer. Instead of function \"int\" I use sprintf '%.0f' now. So I get 80 for 79.999. All works fine.

Thank you very much for fast help!

Peter