PART 2 - Dual T2 Experiment with Measurements

[Boomzilla]

The original thread with background information is HERE if you want to see it.
Part 3 of this Experiment is shown HERE

The first thing I did with my T2s was to verify phase between the Emotiva PA-1 amps and the Ashly FTX-1200 Series 3 Pro amp. Turns out that one or the other inverts phase. So I fixed that first by reversing speaker terminals on the Ashly speaker set.

Then I level matched the T2s to the Ashly (turns out that -1 click on the Ashly's volume pot give the same output as the PA-1s). Then I reversed the new pair of T2s so that they faced the wall behind the first pair, but were still in phase:

REVERSED BIPOLAR SETUP - EQUAL LEVELS:

This provided a "pseudo omnidirectional" effect. NOTE: All measurement graphics are left speaker - then right."

LISTENING NOTES - REVERSED BIPOLAR SETUP - EQUAL LEVELS:

• Smoother bass than a single pair of T2s
• Slightly lower treble volumes than with a single pair of T2s
• Fuller sound than a single pair of T2s - particularly noticeable on orchestral music
• Slightly more vague images than with a slngle pair of T2s
• Much deeper images, but not much wider

MEASUREMENTS IN THIS CONFIGURATION:

FREQUENCY RESPONSE:

DISTORTION:

RT-60:

WATERFALL:

IMPULSE:

REVERSED BIPOLAR SETUP - REVERSE SPEAKER LEVELS @ -6dB:

After taking the above measurements, I then balanced the T2s with the reversed-facing one set at -6dB from the forward-facing one. Why? Because this is what bipolar-speaker manufacturers do on their bipolar models. The next set of measurements were taken with the speakers placed in the exact same positions as in the first photo in this thread.

MEASUREMENTS IN THIS CONFIGURATION:

FREQUENCY RESPONSE:

DISTORTION:

RT-60:

WATERFALL:

IMPULSE:

Listening notes for the -6dB reversed setup are identical to the notes on listening with the speakers at balanced levels, but with less of the expanded soundstage imaging.

STACKED SETUP - EQUAL LEVELS:

LISTENING NOTES - STACKED CONFIGURATION:

• Images have much better height than the side-by-side or single-speaker-only setups
• The same fullness that sounded so good with the speakers reversed persists with the speakers stacked
• The bass range is much smoother with the speakers stacked
• Bass frequencies do not seem to go as low in the stacked configuration
• Transients are crisp as with a single speaker
• Treble seems slightly sibilant with the speakers stacked

MEASUREMENTS - STACKED SPEAKER SETUP - EQUAL LEVELS:

FREQUENCY RESPONSE:

DISTORTION:

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RT-60:

WATERFALL:

IMPULSE:

Enough for today!

[garbulky]

Looks like stacking them increased FR variations.... hmmm.

[garbulky]

What if you stack them not upside down?

[DYohn]

I am glad you are having fun. You should experiment taking measurements with a better piece of software than REW, such as RealRTA.

[Boomzilla]

What about placing the speakers in an arc around the listening position? Provided all speakers were equidistant from the listening position, their "first arrival" sounds would be synchronized. Further, the room nodes would be unique to each individual speaker, possibly blending, cancelling, and smoothing the room response?

But before I move the speaker stacks, I want to try them with the subs! I'd also like to try KeithL's series wiring.

[DYohn]

Jul 25, 2020 17:05:38 GMT -5 Boomzilla said:

What about placing the speakers in an arc around the listening position? Provided all speakers were equidistant from the listening position, their "first arrival" sounds would be synchronized. Further, the room nodes would be unique to each individual speaker, possibly blending, cancelling, and smoothing the room response?

You'll need a Quadrophonic receiver for that.

[Boomzilla]

Of the variations I've tried so far, I prefer the bipolar / equal-volume setup the best. It provides a huge soundstage without losing too much imaging specificity, and without adding sibilance (as the stacked configuration does). Today, I plan to add the subwoofers to that configuration and after listening, will measure again. I also plan to adjust toe-in / toe-out for the aft-facing speakers to see if I can "tune" the soundstage width some.

Will I ultimately keep the second set of T2 speakers? At the moment, I'm leaning toward a "yes." They definitely add to the listening experience. I think I can get even slightly better performance from the rig once my Schiit Loki 4-band tone-control arrives.

I did look into the Real-RTA software, but it is a Windows product only, and my listening room system is running a Mac Mini. I could install VM-Ware Fusion or Parallels Desktop (or else just use Apple's "Boot Camp"), but it's not worth the trouble to me. I'm still learning about REW and have a LONG way to go before mastering all its capabilities.

So "part 3" of this series will be dual T2 speakers with the subwoofers.

Cheers - Boomzilla

[jackfish]

Now it begs the question of three pairs?

[robs]

Damn that is one badass setup.  I liked how the stacked setup looks.

Are you using auxillary DSP?

[klinemj]

From a measurement POV, in the original 2 speaker system, I noted the openings in your room speaker right were sucking a lot of energy out. The reverse bipolar seem to have less of an issue with that, but the stacked don't help that at all. It might be interesting to play with both pairs facing forward but not stack, as well as reverse bipolar with with the reversed ones at an angle inward toward your rack vs. outward away from the rack. You definitely have a major room effect still going on thanks to those openings to the speaker right.

Mark

[Boomzilla]

Jul 26, 2020 10:17:34 GMT -5 jackfish said:

Now it begs the question of three pairs?

You're a bad man, jackfish - a bad, BAD man! You should just hope my wife doesn't catch up with you! LOL

[Boomzilla]

Jul 26, 2020 13:36:02 GMT -5 robs said:

Damn that is one badass setup.  I liked how the stacked setup looks.

Are you using auxillary DSP?

No DSP. Dual towers only.

[Boomzilla]

Jul 27, 2020 7:32:50 GMT -5 klinemj said:

From a measurement POV, in the original 2 speaker system, I noted the openings in your room speaker right were sucking a lot of energy out. The reverse bipolar seem to have less of an issue with that, but the stacked don't help that at all. It might be interesting to play with both pairs facing forward but not stack, as well as reverse bipolar with with the reversed ones at an angle inward toward your rack vs. outward away from the rack. You definitely have a major room effect still going on thanks to those openings to the speaker right.

Mark

As Cajun Humorist, Justin Wilson once said, "great mines, dey tink alike!"

Since taking the stacked measurements, I've since put the second set back on the floor, and arranged the primary pair widely with the drivers pointed directly at the listening position. The second set was placed behind the first set with the driver mounting board parallel to the wall. Result = yawn.

So I tried angling in the rear-facing set at a 45-degree angle to the wall. Result = better but no cigar.

So I then tried angling the rear-facing set at a 90-degree angle to the primary speakers, still pointed inward at the center of the wall behind them. Result = Oh yes! Excellent imaging & much crisper transient response.

I then put the two subs back in the mix, and things got better yet. I'll measure this setup today & see what we've got.

Then I read your post! LOL

[klinemj]

Jul 27, 2020 8:48:51 GMT -5 Boomzilla said:

Jul 26, 2020 10:17:34 GMT -5 jackfish said:

Now it begs the question of three pairs?

You're a bad man, jackfish - a bad, BAD man! You should just hope my wife doesn't catch up with you! LOL

This reminds me of an Onion article (title hidden for obvious reasons, but enjoy anyway): -->CLICK HERE FOR ONION ARTICLE<--

Those of us at P&G had a good laugh at this...Gillette is owned by P&G.

And, looking forward to your next REW update.

Mark

[Boomzilla]

Jul 27, 2020 9:10:25 GMT -5 klinemj said:

Jul 27, 2020 8:48:51 GMT -5 Boomzilla said:

You're a bad man, jackfish - a bad, BAD man! You should just hope my wife doesn't catch up with you! LOL

This reminds me of an Onion article (title hidden for obvious reasons, but enjoy anyway): -->CLICK HERE FOR ONION ARTICLE<--

Absolutely awesome! LOL

[jackfish]

Then there is the wall of sound approach.

[Boomzilla]

Jul 27, 2020 13:51:47 GMT -5 jackfish said:

Then there is the wall of sound approach.

Grateful Dead, HERE WE COME!

[novisnick]

Jul 27, 2020 13:54:14 GMT -5 Boomzilla said:

Jul 27, 2020 13:51:47 GMT -5 jackfish said:

Then there is the wall of sound approach.

Grateful Dead, HERE WE COME!

You know what comes with “The Wall of Sound”?
This! 🤣

[Boomzilla]

Looks just like what I've currently GOT! LOL