Grant's Aussie T39 review

[Grant Bunter]

Subs: 2 x 20" wide BP102 loaded T39's:


Subs stacked so the mouths were on top of each other. V plate not yet made.

Tops: POS 15's and piezo direct radiators. No idea of what they are as can't find any info. Stacked so that cabs were 4' above ground and piezo to piezo. More on that a little later.

CD/MP3 player to Soundcraft Spirit Live 16/2 all run up to just below clip on channel and outputs.
Into a DCX2496. DCX set to -6dB on the limiter on sub output initially. Crossover set to 120Hz. HP 45Hz on subs as per plans.
Out to Jands 920 amplifier, one channel will drive subs, the other tops. Not connected initially.

60Hz sine wave run through system. Peak voltage in the sub side 33.9V. Can't do much better when the target is 35V, so limiter left alone.
Levels dropped on the masters to -10dB
Subs and tops connected.
Music played. Desk Channel EQ tweaked. Multimeter on the subs output unchanged when run up to 0dB briefly.

Oh deary me!
Turned down tops pot on amp from max to 1 o'clock. Better balance.
SWMBO on hand, as she wanted to be...
Back up to 0dB on the masters.
Chest pounding bass, I mean awesome chest pounding bass. This is in the garage, both garage doors open (either end).
She tells me to "turn it off for a tick"
"That's what it was like at AC/DC" says she. Uh huh, we were at the other end of the stadium from the PA at that one.
"Play some real music" (she's into american country) says she. Keith Urban will cover that...
Cranked. Awesome. These are not premium driver 10's? C'mon.
My turn, whack in the reference CD, give that a whirl. Straight to Danny Gatton's 13 women.
OMFG.
Each song after that had different highlights.
Stoked.
Need to check the cabs over after I strap down some speaker wire inside etc,
Build a V plate, try again. So tempted to do 2 more immediately, but tops and monitors beckon first.

Review ended.

Since added a DEQ2496 to the rack.
Will get a reference mike and run rig outdoors with RTA to see where the POS tops fall off the perch on the bottom end to see if I can cross lower, until/when the DR's are done. And system tune with DEQ also.

Community feedback 3 days later (they live half a mile/600m away).
Hey all that music you were playing the other day sounded fantastic, full, warm. Not harsh. Clear as a bell. What were you using?

[Michael Ewald Hansen]

Cool review.. You mentioned leaving the limiter alone because your amp peaks at 33.9volt.. That would be a very bad choice, as most amps are able to produce transients that are at much larger amplitude.. A well built 400w amplifier can easily produce very short bursts of transients at 3-4000w, which means bye bye BP102 in a split second.. Limit your amps at all times

[Gregory East]

I think he meant with the -6dB setting on the dbx that the max voltage to come out over driving everything was ok so he left it as it was.

[Michael Ewald Hansen]

I think he meant with the -6dB setting on the dbx that the max voltage to come out over driving everything was ok so he left it as it was.

Ahh, reread it and it made sense. Only trying to help Thanks Gregory..

Edit: Wait up, did the limiter kick in at -6db or did you set it and then the amp delivered 33.9volt without hitting the limiter? You should try bringing down the limiter until it kicks in so you know exactly where its limited

[Gregory East]

Yeah, all a bit suss there Grant. My old Jansen hits 35V right when the clip light comes on too. I'm not familiar with the dcx but it should show when the limiter has engaged?

[Grant Bunter]

You're both right,
Tickling the limiter on the DCX on sub output, at 33.9V.