XOver still active when front speakers set to large

Posted by: jray

XOver still active when front speakers set to large - 02/12/03 04:48 PM

I have noticed that the crossover settings are still active when I have my front speakers set to "Large" and subwoofer set to
"Off". Changing the crossover settings defintely changes the sound of the bass coming from the front speakers.

Should this be happening? I was under the assumption that when the speakers settings were configured as above that the crossover would have no effect on the signal. My front speakers are towers with each one housing a 300 watt powered subwoofer. It was recommended by the speaker manufacturer (Cambridge Soundworks) to bi-wire the speakers and set the preamp speaker configuration as described above. The idea is to deliver a full-range signal to both the high and low ranges of the speaker and let the speaker's internal crossover figure out what to send to the subwoofer. This is supposedly preferrable to using a line-level connection from the preamps sub-out to the speakers sub-in.

Anyhow, when I contacted Cambridge and ask for a recommendation on crossover settings they were a little perplexed when I told them that the crossovers were still active
even though I configured the preamp's speaker settings per their recommendations.

I read in a different post that somebody else thought they might have the same problem.

Anybody got any ideas on what is going on here? Or am I wrong in my assumptions? My next step is to contact Outlaw.
Posted by: gonk

Re: XOver still active when front speakers set to large - 02/12/03 05:51 PM

I may be wrong here, but here's one possible explanation. With the sub set to off, the towers are also taking care of material from the center and surrounds (assuming they are set to small).

Here's a possible test for you: try a CD with the 950 set in "Stereo" mode (so that the center and surrounds are not active) and see what happens as you change the crossover settings. Then switch to "5 Stereo" and repeat -- the bass going to the mains will likely vary based on crossover points in this scenario, because full-range signals are going to surrounds and center and the crossovers and re-directing bass to the front speakers.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review
Posted by: Scott Griscom

Re: XOver still active when front speakers set to large - 02/12/03 08:39 PM

I had the same problem with the crossover changing the sub output even with the main speakers set to large. I would contact outlaw and troubleshoot with them.

Scott
Posted by: jcmccorm

Re: XOver still active when front speakers set to large - 02/14/03 08:22 AM

Hmmm, I gave my "Pre red dot" unit a shot last night. I had a digital source (music file playing on HTPC, PCM format) and set the 950 to "stereo" with the front speakers set to small. The sub was active. Then I set the front speakers to large - the sub went mute (no cone motion at all). Works as it should. Maybe there's something wrong with your specific unit?

Cary
Posted by: Scott Griscom

Re: XOver still active when front speakers set to large - 02/15/03 03:24 PM

Just tested with my new blue dot and got the following results. In stereo mode switching from large to small on the front speakers passed bass to the sub and then did not pass bass, just as it should. However, in 7 stereo with all speakers set to large, I still get bass from my sub that is affected by the crossover setting of the front speakers. Also, I still experience about a 6 db increase in volume in my rear speakers when switching from small to large. This only happens when the fronts are set to large. Leaving the rears set to large and switching the fronts back to small reduces the volume back down by 6 db in the rear. Actually back to calibration level. I haven't tried this in other modes yet but wanted to see if someone else could test this scenario and see if they can reproduce what I am experiencing. It may be normal functionality, but seems a bit odd to have volume levels change with the speaker size selector. Also, set all speakers to large and see if the sub still plays and if it is affected by the triple crossover.

BTW, my input is from my CD player via the optical 4 input.

Thanks,
Scott
Posted by: Scott Griscom

Re: XOver still active when front speakers set to large - 02/16/03 10:47 AM

Just noticed one thing that should have been obvious. With all speakers set to large and the subwoofer ON, you will still get the .1 LFE channel through the sub. However, the crossover should not affect the sub output level. I still wonder what is happening in 7 Stereo mode, seeing as there is no .1 channel.
Posted by: gonk

Re: XOver still active when front speakers set to large - 02/16/03 01:59 PM

I'm not sure how 7 stereo generates signals to other channels, but I was thinking about something sdurani posted recently regarding how some matrix decoders works -- it is possible that 7 stereo generates a LFE channel and produces non-full range signals for the other channels...

Quote:
sdurani said :
I used to think that modern matrix decoders (like Neo:6 and PL II) used to first generate 5 full range channels, which would then be bass managed into a 5.1 speaker set-up. However, it turned out to work a little differently than that. In receivers and processor I've had experience with, the matrix decoders did not generated full range signals for every channel unless they were all set to 'large'. If any of them were set to 'small', they got a derived signal that only contained sounds above the crossover point. It's not like that channel was full-range content that existed discretely on the recording. Since it this derived channel never had full-range content, there's no bass to move around. Each channel gets only what's above the crossover point.


It's a pretty random hypothesis, but I've never really seen specifics on how the 5/7 stereo mode actually works.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review
Posted by: Scott Griscom

Re: XOver still active when front speakers set to large - 02/16/03 02:53 PM

Great thought Gonk. As you said, who knows how the 7 stereo back speakers are being matrixed.

Any idea why my surround backs would have a 6db increase when they and the fronts are set to large and then loose that 6db once the fronts are set back to small?
Posted by: soundhound

Re: XOver still active when front speakers set to large - 02/16/03 03:43 PM

I have noticed that the gain is increased when set to 5 stereo or 7 stereo, but I haven't noticed it being effected by crossover settings.
Posted by: Scott Griscom

Re: XOver still active when front speakers set to large - 02/16/03 04:19 PM

I noticed that gain also, but really noticed it when changing speaker size more than crossover setting.
Posted by: soundhound

Re: XOver still active when front speakers set to large - 02/16/03 04:28 PM

There probably isn't anything wrong with your 950 - but the behavior in those modes is pretty strange!

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The Soundhound Theater
Posted by: Scott Griscom

Re: XOver still active when front speakers set to large - 02/16/03 04:39 PM

Thanks soundhound. That is what I was trying to conclude.
Posted by: sdurani

Re: XOver still active when front speakers set to large - 02/16/03 08:52 PM

Scott,
Quote:
As you said, who knows how the 7 stereo back speakers are being matrixed.
No mystery how the additional channels are generated in the 5/7 stereo modes. The fronts, sides and rears are each treated as stereo pairs: all left side speakers get left channel info (above their crossover points); ditto the right side. The centre channel and subwoofer output each get a simple L+R summed signal (again, defined by their crossover settings).

This has traditionally been how every 5/7 stereo mode (sometimes called "party" mode) has worked. The only variation I've ever seen is where the surround volume is slightly lower compared front channels, in order to keep the energy somewhat foward focused. Otherwise there's no surround processing, such as matrix decoding, taking place.

Best,
Sanjay
Posted by: Scott Griscom

Re: XOver still active when front speakers set to large - 02/17/03 06:38 AM

Then based on sdurani's post, there should not be a volume increase in the large surround back speakers when switching the fronts small to large. Still wonder what is casing that??
Posted by: jray

Re: XOver still active when front speakers set to large - 02/17/03 11:15 AM

I sent an email concerning my issue to Outlaw last week and I am still awaiting a reply.

I did a little testing again over the weekend to make sure I wasn't crazy.

While watching the Con Air DVD, I replayed various scenes that contained a variety of sound-effects. I would play a scene with the front speaker crossover set to 40Hz and then replay the same scene with the crossover set to 150Hz. Definite change in bass/sub bass. Again, the front speakers were set to "Large", subwoofer set to "Off", and the front speakers bi-wired(subwoofers built into each front speaker).

Is it possible that Outlaw didn't take into consideration tower speakers w/built-in subwoofers when developing the crossover configuration settings?

Also-what is the diffence between red-dot and blue-dot 950s?
Posted by: gonk

Re: XOver still active when front speakers set to large - 02/17/03 11:47 AM

The red dot units were the first "hiss fix" units that replaced units shipped prior to August and had a hiss problem. The blue dot revision were replacement units that began shipping in December to replace existing units that still exhibited an objectionable hiss.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review