Bass Management

[RogueAngel]

I have had a JVC A/V receiver for about three years. In the process of getting frequency response measurements on my recently completed DIY speakers I heard a strange clicking sound. It seems that even with the receiver's internal crosover set to 100 Hz and all speakers set to small, a strong enough signal below 35 Hz was getting through to the rear speakers to make it sound like the rear's were bottoming out. :cry: I'm very worried now that there is a very real danger that there will sooner or later be permanent damage to my speakers. If it's bleeding through to the rears, it must be getting to the other three also. This was with a peak reading from the subs of 91 db. A setting well within my normal listening range for movies. Sounds like a new receiver is in order. Have any of you run across something like this before? I don't want to get a new unit without being fairly confident that the filter I am counting on to protect the speakers is actually doing that. Should I consider putting a high pass filter at 80 hz on the input to the speakers? Any help or advice is surely appreciated.

[Lex]

Well, if you could get access to a test tones CD, you could determine for sure whether lfe below a certain level is getting to them. You don't have LFE set to off do you for your sub out? In which case, it would be re-directed to the mains I think. But you said it was to the rears, so that is likely out.

Test Tones CD is the sure fire way to check it, then determine if your crossover settings are working as advertised.

Goodluck!
Lex

[RogueAngel]

I was doing 1/6 octave test tones from a CD i burned on the computer. Tones covered from 160 Hz to 16 Hz. The subs did great , but........ a clicking noise coming from behind you is not a good thing in my mind.

[Lex]

I assume these speakers have internal crossovers that you bought as a kit and installed, right? If so, I think this topic is heading to DIY, where you can get the help that you need, I hope.

Lex

[Markj]

Don’t know if this will help, but the JVC rear amp section could be clipping. In older receivers the rear channels got less power. Try turning the volume down and check if the clicking is still happening. There are others on this forum that know a lot about amps so they should be more definitive.

[RogueAngel]

I've had a chance to do a little more checking. I've tried all three crossover frequencies (80/100/120) with the test tones again. Here's what happens....... from 160 Hz down to the 25 hz tone, nothing noticeably wrong. At 22 hz and down to 16 hz, with all speakers set to small and at all three crossover settings, there is an audible clicking coming from the L, center, R, and rears all the way down to a reading of 49 on the volume control. Normal listening is a setting of from 52 to 68 which results in a maximum avg SPL of 85 db. Either all the amps are clipping with a very low level setting, the pre/pro section can't handle these low frequencies or the filter slope levels off at some point. This is bad. BTW the unit is a JVC RX 778V purchased Jun 99 for $350. Do any you have any idea if this unit is defective or if this a design flaw?

[Markj]

I think you are hearing clipping. Run the test again but not at 85 db try 60dbs or lower and check if you still hear the clicking. If you don’t then the amp or pre/amp is clipping. When I had a receiver I had clipping too. I was getting clipping after I added external amps. It was the pre/amp section in the receiver that was doing it.

[RogueAngel]

Indeed, I had clipping in the pre-amp section.

The sloution?....just put a deposit on the new Rotel 1055 receiver. I should have it by the end of next week.