loud thump when i turn on TV

[sgtbyls]

i just a got a new Harman Kardon AVR 235 and a Infinity beta250 center speaker. It sounds great! But when i turn on my TV before the reciever, i get a loud thump sound coming from all the speakers. Is there something i can do to eliminate this? Im gonna try to set up a macro so the tv comes on first, but the directions are a little hard to follow. Any suggestions will be much appreciated.

 

[emason17]

Same problem, open to new solutions (other than turning on tv first.

 

[MDS]

That kind of thing usually happens when you turn on an amp and there isn't yet a signal for it to amplify, so it amplifies the noise floor of the amp. That's why amps are usually turned on last after the other components are up and sending a signal.

How is the tv connected to the receiver - straight from audio out on the tv to an H/K audio input?

Most TVs take a few seconds to start up and in that time they do not accept IR commands or start transmitting the audio or video. You could try adding a delay to the macro if the HK remote allows that so that it isn't turned on until the tv is ready.

 

[sjdgpt]

But when i turn on my TV before the reciever, i get a loud thump sound coming from all the speakers. ....... Im gonna try to set up so the tv comes on first

Is the receiver powered up before the TV? Or are you hearing the noise from the speakers BEFORE the receiver is turned on?

 

[sgtbyls]

That kind of thing usually happens when you turn on an amp and there isn't yet a signal for it to amplify, so it amplifies the noise floor of the amp. That's why amps are usually turned on last after the other components are up and sending a signal.

How is the tv connected to the receiver - straight from audio out on the tv to an H/K audio input?

Most TVs take a few seconds to start up and in that time they do not accept IR commands or start transmitting the audio or video. You could try adding a delay to the macro if the HK remote allows that so that it isn't turned on until the tv is ready.

Thats exactly how its hooked up. I'll have to look into a delay. Im still trying to learn how to get the macro to work.

 

[sgtbyls]

Is the receiver powered up before the TV? Or are you hearing the noise from the speakers BEFORE the receiver is turned on?

I hear the noise when i turn on the amp first, then the tv. I guess im just trying to find out if its a somewhat normal thing, or if i have done something wrong.

 

[sjdgpt]

I hear the noise when i turn on the amp first, then the tv. I guess im just trying to find out if its a somewhat normal thing, or if i have done something wrong.

The amp is trying to amplify anything present. aka Noise floor, or just a spurious signal from the TV.

In this case, there is a small signal (garbage signal) from the TV upon startup. Most likely the noise is from the switching system for the TV, or the startup juice needed for the TV display. Remember, most TV's, especially big CRT's, have a pretty significant initial power consumption, so some noise is possible.

Is it normal. Normal would not be the word that I would use, but it is common.

Is it desirable. No.

To avoid the problem, sequence your equipment so that the TV comes on first.

My separates recommended a specific sequence of preamp, CD, amp etc to avoid similar problems.