Parasound 1200/1500 THX level controls

reberly

I had recently moved and had to setup my system from scratch and noticed all my speakers had a buzz to them when no music was playing. After eliminating any interference I could think of I remembered both amps have a THX level control on the back. The THX level was turned the whole way up and causing the buzz. The parasound manuals say the amps are designed to have the level turned to max and I have to agree that it sounds much better. The other drawback of having the level set very low and no buzz is that you have to crank the volume way up to get decent listening volume.

The buzz can't be heard while anything is playing but could it be harming the speaker at all? What do all of you have this THX level set to and what is advantage/disadvantage to that?

Thanks

dkg999

Isolate your cable/dish coax with a ground loop prevention device. Use a good power conditioner to take any major noise out of your power feed.

reberly

dkg999 wrote: »

Isolate your cable/dish coax with a ground loop prevention device. Use a good power conditioner to take any major noise out of your power feed.

Yeah i do have a panamax 4300 power conditioner and no cable coax connector to my tv or receiver or anywhere near it. This is a buzz directly caused by turning up the THX control knob. I am wondering what other 1200/1500 owners have their level set at and if they notice a buzz

Polkie2009

I've got a 1200,but I believe it's the mk ii model. I bought mine used and didn't get a owner's manual, just figured the pots on back were to adjust input sensitivity(I also have them adjusted all the way up). I have no problem at all with hearing a buzz sound.It's very quiet,great little amp!

reberly

Polkie2009 wrote: »

I've got a 1200,but I believe it's the mk ii model. I bought mine used and didn't get a owner's manual, just figured the pots on back were to adjust input sensitivity(I also have them adjusted all the way up). I have no problem at all with hearing a buzz sound.It's very quiet,great little amp!

Check out parasound website, they have all the old manuals in .pdf format. PM me if you can't find and I'll email to you. Enjoy the parasound its a great amp. Keep it well ventilated it gets very hot

I think something else besides those level controls changed because I swear they were at max before on my lsi15's.

FTGV

reberly wrote: »

This is a buzz directly caused by turning up the THX control knob. I am wondering what other 1200/1500 owners have their level set at and if they notice a buzz

Those THX controls are gain controls.When in the maximum position, gain will be at maximum so any noise/hum will be louder as a result.(The maximum position is the one that adheres to the THX spec for gain). The controls are useful for matching the amp to preamps with higher than normal gains.
It sounds like you may have a ground loop issue.

Polkie2009

Thanks reberly, I looked on the Parasound site before and noticed the manual for a 1200 ,but nothing for a 1200 mk ii. Maybe there really isn't any difference between the two. You are right about keeping it well ventilated,lol,after a couple of hours, mine runs very warm on the top left front side,(nowhere near being too hot to hold my hand on it for considerable time.) but all the other areas of the amp are basically barely warm. The amp is out in the open so it gets plenty of air.

reberly

The buzz in the speakers ended up being a Ground loop as suggested. I had all A/V equipment except the TV plugged into the same power conditioner due to the TV's location. I noticed when I unplugged the TV, the buzz went away so I moved everything so they could use the same wall outlet/power conditioner.

THX controls are back to max where they should be making everything sound great