Has anybody else experienced strange results with their Auto Setup AVR's in respect to the Sub distance(delay) setting? In regards to the dB levels my Denon 2805 is pretty accurate, I've only had to make some minor adjustments using the SPL meter. Also, the distance setting from the Auto Setup is pretty accurate, except for the Sub. Everytime I run the setup, the sub is like 20-25ft when I go back to check the results. In reality it is only 12-15ft. So what gives?

Randy, you may have noticed that a few times when I've commented on auto-calibration that I've said that it may be more accurate than a manual calibration, especially for the sub. Your experience probably illustrates this, the reason being that there's a delay in the circuitry of the sub which causes the sound to arrive later than would be expected from a simple measurement of the physical distance.The delay may only be a few milliseconds, but each millisecond makes about a 1.1' difference. In other words, trust your receiver, not your tape measure. I didn't recheck, but I think that the Denon manual is one of those that makes a brief reference to this somewhere in the auto-calibration section.

Took a look at the manual , Randy; see the note at p.24.

The Denon manual does state that speakers with a built in filter such as a sub might be set with a value that differs from the physical distance because of the internal electrical delay. Mine sets my sub about 7 ft farther than the actual physical distance.

One of the problems with the auto-setup is that they rarely give you enough information to understand what is going on. If the measurements seem "strange" you really have no way of actually knowing if an error has been made or if it is accurate.

If it sounds good to you, I'd leave it alone. If it doesn't try a manual setting and see what it sounds like. However, I'd suspect with most folks "ears," you won't hear any difference.

If you try it both ways, I'd like to know if you hear any difference.

Can it be that the mic picks up a strong reflected sound? That can double the delay. May be to try to point the sub at different directions, turning it aroung?

Ten feet difference is about 10 millisecond delay. If my memory is not wrong even a simple filter would give a delay about 1/(3fc). So if it's set at fc=80Hz, then the delay would be only 4ms. Does your sub has an option of bypassing crossover? Might try that too.

Regards,
Gena

I guess my question would be, so what? If the delay in the circuitry of the sub means the receiver thinks it's farther away than it really is, isn't that what we're trying to find out? That is, won't the receiver compensate for the physical distance PLUS this 'virtual distance'? I would think that's what we want it to do...

Am I missing something?

-Brian

I see at least two problems:

1. As ratpack has mentioned it is not clear how the receiver makes its choice.

2. If it does compensate for some filter delay then this delay is frequency dependant, so some frequencies would be compensated correctly and some not. If, on the other hand, it's reflection then the delay does not depend on the frequency.

But, of course, it's just that, speculations. Besides, the difference, I suspect, is not that noticeable.

I don't know how and why the reveiver makes these choices technically, I just know it seems to work, and sounds great.

Thanks John, Michael, and others. Now that you mention that John, I do remember reading the Note: in the manual months ago. It just seemed odd to me it was coming back with 25ft+ distance settings. Anyway, it does sound awesome and most likely I'll just leave everything as is for now...

By the way, I have my basement finally done, hope to start a new thread soon with new pics.

Mine came back with 25ft when it was really 12ft. I set mine to 12ft and used a meter and have been rockin since.

Jimmie, as mentioned by other above, and in the Denon manual, it is normal for the delay distance to be longer for the sub, because of the internal circuitry. I've left mine at the auto setup distance and it still rocks the house. Your mileage may vary.

I have the same experience. My Denon 3805 thinks the sub is 25ft away. It is actually 10ft away. But the EP600 works flawlessly, so I don't change the distance setting for the sub on the AVR.