AudioRoundTable.com: Measurement

Home » Audio » Measurement » I' m too cheap

Show: Today's Messages :: Navigator :: Polls
E-mail to friend

I' m too cheap [message #25217]

Tue, 13 December 2005 05:33

Leland Crooks
Messages: 212
Registered: May 2009

Master

to buy a clipcop or a rane gain, I'm going to use my PC for a 440 sine wave into the PA. If you're not familiar with them, they generate a 440hz tone and you plug a pizeo into the output. Turn up gain until it distorts, voila, max gain. They put out at 0dbu, which I understand is 1.23v pro level. Through the di box I don't think my pc will give that much gain. I do now have a meter with a db scale. What's the formula say, if I can give -10db signal, that I can use to mathematically find the 0db level. Then I can adjust my trim knobs and turn down accordingly

I figure I'll only need to do this once, which is why I don't really want to buy one.

Report message to a moderator

Re: I' m too cheap [message #25218 is a reply to message #25217]

Tue, 13 December 2005 08:50

Wayne Parham
Messages: 18791
Registered: January 2001

Illuminati (33rd Degree)

I've heard of folks doing that. You might want to get a scope sometime too, 'cause they aren't that expensive anymore.

Report message to a moderator

Re: I' m too cheap [message #25219 is a reply to message #25218]

Thu, 15 December 2005 12:31

Leland Crooks
Messages: 212
Registered: May 2009

Master

This worked great. All my meters on board, comps, xover and amps all clip at the same time. I figure I gained about 8-10db of headroom. It made big changes to my guess derived settings.

Now on to the rta function.

Report message to a moderator

Re: I' m too cheap [message #25225 is a reply to message #25217]

Mon, 07 August 2006 09:40

telegraph.hill
Messages: 75
Registered: May 2009

Viscount

By pizeo do you mean a piezoelectric crystal?

Report message to a moderator

Re: I' m too cheap [message #25226 is a reply to message #25225]

Mon, 21 August 2006 17:02

Wayne Parham
Messages: 18791
Registered: January 2001

Illuminati (33rd Degree)

Leland is talking about using piezoelectric tweeters. The way he's using them is to listen for HF created by the leading and trailing edge of a clipped signal. If you put a low frequency sine wave into an amplifier, the output signal will also be a low frequency sine wave that can't be heard from a piezo tweeter. But once the amp starts to clip, the sharp edges generated are high frequency so they can be heard with a piezo. That's how Leland plans to use piezos to tell when his amps begin to clip.

Report message to a moderator