Sub setup ?'s

It certainly doesn't make sense to have the DT subs and not use them.

Experiment.

What about the roll off created when the DT subs drop out and the SVS sub has to stand by its lonesome?

What about possible compression when the DT's have trouble keeping up with the SVS sub?

Sorry ceh383, wasn't trying to put you on the spot, hence why I posed the question to Bill's quote and maybe he has an answer to my question.

My understanding, when the DT's drop out, the volume will drop in the same said fashion in what I understand to be called roll off. In the same vein, the weaker subs will have to work harder to keep up with the stronger SVS sub and when reaching it's max, will compress and distort, further complicating the marriage of the two dissimilar subwoofers. I'm not discouraging experimentation as to experiment is good in that it extends your personal experiences but I see a conflict and thought it would be helpful if this conflict was addressed.

Maybe you could use some type of dsp to bump the sub level when the speakers roll off. Set at a certain freq.?

I don't know how your above will affect the overall sound quality but if one sets their system up using Audyssey, you're trying to sweep water uphill because everything is based on achieving THX reference sound levels and then when the threshold is reached between the lower capability of the DT's vs that of the SVS sub, you'll still have this roll off problem to deal with.

Another conflict I see, if using a 5.1 system or greater, the DT's are only good for the mains as bass management ports the LFE channel information to the AVR's sub pre-out. My opinion, use the DT's with a crossover of 40Hz and bass manage <40Hz to the subwoofer pre-out to blend with the LFE channel information. Set all speakers to small and set the cross over on the center channel and the surrounds to <60Hz or <80Hz.

BeeMan's advice here is exactly what I suggest you try first: Connect the speakers at speaker level and set 40 to 60 Hz crossovers on them in your receiver's Bass Management. You'll still be using the powered woofers, but you'll be limiting their output to the range they are really designed to carry. The rest of the bass in those channels will be re-directed to the subwoofer, which is the speaker in your system really designed to handle those frequencies.

Craig

Edit: I just looked at the spec's for your speakers. They use a 10" driver mated with a 10" passive radiator. A system like that will be designed with the PR "tuned" to a specific frequency. At the tune frequency frequency, the PR will be producing the vast majority of the output and the driver will be barely moving. The backwave of the driver uses the air air inside the cabinet as a "spring" to drive the PR. The mass of the PR will determine it's "tune" frequency, and the mass of a 10" PR will dictate that the tune will be nowhere near 20 Hz. It will more likely be 35 to 40 Hz. With a PR system, the output drops like a stone, at 24 dB/octave, below the tune point of the PR. Therefore, a 40 to 60 Hz crossover will send the bass that the speakers are not capable of reproducing to the subwoofer, and keep them well above the tune point and keep the system well within it's "wheelhouse" bandwidth. You could even experiment with an 80 Hz crossover.

Bottom line, don't run these speakers "Full Range" the way Def Tech recommends. You are much better off running them with crossovers and sending the deep bass to the subwoofer.
Edited by craig john - 1/24/13 at 9:12am

That depends on their actual capability. You'd see that in an SPL chart. But, of course, there aren't any. The 8060 claims a 20Hz bandwidth, and that's not impossible to realize. I'd run them full range, with the onboard sub amps driven by the LFE output. If they prove unable to keep up with the SVS you'll hear it. If they can keep up the room mode smoothing should be well worth it.

Do you have a "Y" splitter available? If you do, you can play with the LFE input on the 8060ST's and play with your AVR's bass management software while dialing things in using Audyssey or what ever room analyzing program you have at your disposal.

To make things happen the way you want, in the end, I'm sure you're onto this point, you'll need a three way connection setup, two to the 8090ST's and one to the incoming sub so you can avail yourself of the LFE connections on the speakers and the incoming sub. Not sure how this will affect the strength of the subwoofer out signal.

Be aware, with the 8060ST's, the subwoofer in each unit will be used to reproduce the LFE channel information as well as any <40Hz or <60Hz information you (cross over) filter to the sub pre-out. Things are starting to get a bit kinky here. Not saying it's a bad kinky but, just saying, it's starting to look kinky.

Surely you know about the "optimistic" nature of Def Tech's LF extension spec's? They don't provide a -3 dB point, so their FR claims are basically meaningless, (except to their marketing department.) There ain't NFW those speakers will do 20 Hz at any kind of meaningful output level. With a 10" PR, it's much more likely they're tuned in tthe 30's than in the 20s.

While I agree that FR smoothing is a worthwhile goal, IME, the smoothing that is provided by the typical placements of speakers is not usually all that beneficial. If the powered woofers, (let's face it these are not really powered subwoofers, no matter what Def Tech calls them), don't extend as low with as much output as the sub, they will hold the sub back from full performance. That, to me, would be worse than FR anomalies, which can be addressed by other means.

Buy, hey, OP please experiment to your hearts content. You have a myriad of ways to hook this system up. Try 'em all and see what works best.

Craig

Is that an Audyssey thing? I can burp 75dB.
I don't use it myself, I use a DSP and RTA, calibrated at 90dB so that it sounds 'right' at movie levels. If you calibrate at too low a level the lows and highs will be too high when you crank it, due to equal loudness that changes with the playback level. OTOH if you listen to movies at 75dB then that's where you should calibrate it.

Audyssey doesn't use "noise" signals to calibrate. It uses full range sweeps. With the sweeps, it measures FR, levels and distances at up to 8 measurement locations. It uses the measurements to calibrate for levels and distances, and it does it's "fuzzy logic" to integrate the different FR's it measures at different locations to set a global EQ curve for the "area."

The sweeps are at -30 dBFS, so the calibration would be the same as if one used -15 dBFS to set the levels to 90 dB. Audyssey has the "equal loudness" system built into their "Dynamic EQ."

Craig
Edited by craig john - 1/24/13 at 7:18pm

You need to find out the "level" of the test tones. If they are -30 dB test tones, as most receivers are, then you want to use 75 dB. 105 dB = Full Scale, (FS) -30 dBFS = 75 dB. This is what you want if you calibrate to Reference Level. If you don't care about Reference Level, use whatever you want. However, see below:

If you run Audyssey afterwards, it will reset everything so you'll be back at Reference Level anyway. They only consideration there is that you want to be inside the range of the subwoofer trim adjustments of the receiver. If the trims are +/- 10, then you don't want a trim set to either + or - 10. You would be at the end of the range, and there is no telling if you're actually outside the range. If you end up with subwoofer trim settings within the +/- 10 range, you're fine. The easiest way to ensure you're in that trim range is to start out at 75 dB.

Craig

This may help the discussion: some measurements of the 8060ST from S&V.

Hmmm...

The Def Tech website says the there is one (1) 10" driver and one (1) 10" PR. http://www.definitivetech.com/products/bp-8060st

Subwoofer
Quantity 1
Diameter 10" (25.40cm)
Type Active Subwoofer Driver
Bass Radiator
Quantity 1
Diameter 10" (25.40cm)
Type Planar Low Bass Radiator

The review, in the Column of spec's says:

BP-8060ST SuperTower ($1,998/pair)
• (3) 4 1/2-in cone mid/woofers
• (2) 1-in aluminum-dome tweeters
• 10-in active woofer
• (2) 10-in passive radiators
• 300-watt onboard amplifier

In the text of the review, they state: "The BP-8060STs claim overall frequency response down to 20 Hz, a feat engendered, despite their dramatic slimness, by the side-firing placement of the three 12-inch cones (one active subwoofer, two passive radiators) shoehorned into each tower."

So which is it???

Craig

Edit: Here is why I would not run them full range:

The subwoofer section of the BP-8060ST is fairly kicking given the speaker’s compact size. Low bass output (40-63 Hz) averages 110.5 dB and ultra-low bass (20-31.5 Hz) output averages just 103.6 dB — numbers that put some midsize subwoofers to shame. It’s not distortion that limits the useful output in this case but either mechanical noise from the woofer cone or the amplifier’s internal limiter stepping in to protect the driver.
Edited by craig john - 1/24/13 at 8:22pm

Ask about the test tones in the 3313 thread in the Amps, Receivers and Processors Forum. Someone in there will know. Or contact forum member "Batpig." He's the Denon expert. But, yeah, it's almost certainly -30 dBFS.
How close you will be to "0" will depend on the extent of the boosts and cuts Audyssey deploys. What's important is to be within the trim range. I usually like to be a little negative so I have some room to run the subs "hot" if I want to.

Craig

With 2 PR's you double the mass. That allows them to be tuned lower.

Craig

Because then they'd have to post results for all the subs they sell that don't measure the way the specs would suggest (most of them). LOL

Now that Bill and Craig have some measurements to look at, they'll be able to tell you a lot more.