Axiom Home Page Forums General Discussion Technical Questions Distance (delay) has me frustrated...

I posted this at AVSforum with no responses yet, I assume DSP subs are not the norm. I still don't have an understanding on why my 600 is sucking the life out of my 350's, maybe Alan will comment on that thread I started. Brent and Tom's reason that the 600 has more output does not make sense to me.

Anyway,

Curious if anyone has input on what is going on with my distance (delay) setting using my 3 subs. Part of my problem I think is that one is DSP based, and the others are not.
My room is 30 x 31 x 9ft, pretty huge.

Here is what I am using:

Prior to getting my 3808ci the other day, I had a Denon 2805. The distance for my EP600 alone was always like 25-27ft, which I've heard is normal because of the internal delay of a DSP based chipset.

The 350's alone always pretty much measured exactly to their physical distance of about 13ft.

A few months back I started placing my subs "around" the room, trying to follow Welti's white papers at Harman. The 600 was placed up front below the screen, and the 350's were placed to the left/right of the room, centered. I calibrated each sub individually to be at 75dB's, then turned them all on, which increased the dB's by about 6-7db. I also had them placed about 12-13ft from the main seat.

After running Audyssey the first time, it had all the subs about 12ft, which was about right. I was puzzled why Audyssey didn't see the delay of my DSP sub though, like my 2805 found?

It gets better, the other night I moved some things around again. Now I have both my 350's spread out up front next to my mains per Wid's idea of colocating them to help with the other problem I mentioned with gain lost, sucking issue of the 600. I've moved the EP600 sub to the back of the room, still all the subs are about 13ft away from me. Now when I run setup, it is showing 27ft for the distance??

All the subs are daisy chained togethor as well. Is this normal? Anybody else in a similar situation with a DSP controlled sub and other model subs?

Maybe I need to sell the 600 and get something from SVS that is not DSP controlled.

thanks, Randy

Are you seriously considering that, or was it just an off-handed comment based on your current frustration?

I'm kind of interested in seeing what the AS-EQ1 does with the 800s. I haven't spent a ton of time tweaking simply because I've enjoyed what I've heard, but it will be interesting to hear the difference this new EQ makes when I drop it in.

I wish I could help you, and I hope you figure something out that makes you happy.

It has crossed my mind, but most likely won't happen. Back when I was going back/forth on what additional subs to get to go with the 600 I was considering a 500 or the 350's. I think I went with the 350's as I thought by spacing them around the room I could get a more even response.

In talking to Axiom if the conversation would have come up about integrating different types of subs in a room, I might have got another DSP based sub. The internal delay they create makes setting up the environment difficult with regular subs. I guess there is a lot to be said about getting matching subs. Live and learn I guess.

The problem of the 600 sucking the gain from my 350's, and now this issue kinda sucks.

Randy, nothing useful to say about the difference in the distance measurements that you describe now. As to the loss of volume with the 600 connected, the only technical reason that appears is the possibility that even the modified amp(if you actually have it)has an extremely low input impedance and the voltage divider effect which I mentioned in the other thread is causing a loss of preamp voltage output. For that to happen, though, the input impedance would have to be on the order of a few hundred ohms rather than the 10K or more ohms typical for an amplifier, and we don't know if this may be the situation unless Axiom would give the input impedance spec.

Randy, I wonder if there is a possibility the mic is picking up a null from certain placements and simply interpreting the null as the sub being farther away.

I may have missed this in one of your other threads, but how is Audyssey measuring the distance on the 3 subs. Do you hook them up one at a time and run the program?

Is there an easy way to measure the signal strength to your 350s with and without the 600 in the chain? It would seem to me that if you could do this it would at least identify the root cause of one of your problems.

Is there some way to introduce gain back to the 350s to see how that helps? Something like a mic preamp??

If you were able to eliminate one issue for sure, I wonder if it would make tackling the other one a little easier?

And last but not least... Do you still think using Welties method is easier than what Geddes suggests? It seems like integrating multiple subwoofers is complicated either way, at least if you want the 'best' integration.

Well, I made some changes today, and it seems MUCH better. I put the 350's back up front, figuring the combined output may be closer to the 600 in the back of the room. Since my 350's are only 5ft apart now (center of drivers) it is like they are ONE sub. So I calibrated them so when they are both on, they match the SPL dB's of the 600 when it is on by itself.

Before, I calibrated them individually, so when they were both turned on, the SPL was higher than the 600. Anyway, I reran Audyssey and now the distance is 9.5 ft. This seems strange, because this is less than the physical distance of any of the subs. But the Bass is SOOOOOOOOOO Intense now, it is like night and day.

The Darla "tap" and "whale" scenes in Finding Nemo are amazing, better than IMAX.

Fred, Audyssey can't run/calibrate the subs seperataly, as it is only ONE sub preout. I think the highest end Denon, offers independed sub preouts, in that case Audyssey would calibrate each one seperately.

When running Audyssey with this type of setup, they recommend that you keep all subs "in phase", and try to have them the same distance as possible from the first measurement (the one that calculates distance). Also, after calibration, you want to shoot for +-3dB on the receiver trim level. If your near the max or min of the Denon, they suggest adjusting the subs gain, and rerunning.

I just think that when you are dealing with different sub technologies, the internal ciruitry and delay are going to cause problems. DSP chips have a lot more going on inside than a traditional amp sub. It probably would be best to have identical subs.

All I can say is it has never sounded this deep and tight.

I'm glad things sound better.


Thats exactly why I asked. I wasn't sure how the distance dectection applied to a multi sub setup.

If I understand you correctly, Audyssey is recomending to keep the subs equadistant from the measuring point to make the calibration work properly?

Crap! I need boatloads of money so I can play too!!

Your problem is one I also had with the new Marantz receiver I recently purchased that has the " Audyssey" 6 point multi-eq. I have four subs in a room measuring 28 x 12 and the final measurement indicated the subs were 30 ft. away along with turning them down WAY too much. It seems, in the end, with subwoofers, your own experimentation with location in relation to your listening position has a much greater influence on what you hear than what the calibration system does for you. Over the years, that has been my experience. I have subs from three different manufacturers and different price and size levels and doing a proper set-up with volume balance, crossover setting, phase and location did the trick. The design really shouldn't matter.

Dang, I was going to say that I'd take your 600 and you could have my SVS...

Seriously though, I am glad things are getting better!