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Dialing powered sub in a 70v system

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Myles Lemansky:
I have a 4000 sq/ft fitness studio with 25 ft ceilings at peak with the following equipment:

QSC CMX500VA amp
Shure SCM262 mixer
(6) JBL C67 pendant speaker
(2) JBL  C60 subwoofers
(2) Shure Fitness mics

The speakers are tapped for 70V.  I initially did not start with the C60s, but was looking for some thump.  The C60s more or less cleaned up overall sound vs providing any chest pounding thump.   I would not say I am unhappy with the system, but I was looking to gain a little of feel out of the bass.

I found a used  Harbinger V2218s for short and pulled the trigger.  Correct or not, I ran a TRS-XLR from the AUX output on the SCM262.  I just touch the level on the sub and it pumps.  Sounds/feels great to me, but probably not for the masses.  With a wide range of users of the system and clients, I do not want the bass to be offensive.

The Harbinger has a 0 and 180 phase option.  The crossover is a 90 or 120Hz option.  Are there any other options for adjustment or via connections that will allow me to get the most out of the JBL's and sub?

Thank you in advance.


Mike Caldwell:
I think you more or less have it.
I would set the crossover at 90hz.

The phase option may make it sound better at one location and make it worse
at another, take your pick.

You must have plugged into the one of the main output jacks on the 262 mixer as the aux outs are RCA phono jacks, was only one main output jack in use.

You could use the cross over outputs on the sub to feed the QSC amp.

The C60 "subwoofers" were never going to give chest pounding thump but just add a little extra low end at best.

On the QSC amp the filter switch should be on and set to the 50hz position, for the main speakers, in a 70volt system it should be actually higher.

Did you just hook up the C60 speakers in line with the other speakers.

Myles Lemansky:
thank you much for the quick response. 

Yes on the main jack, the line out RCA's are to the amp.

Will double check on the QSC filter switch and the 50hz, will that get more out of 67s?

Yes, I just hooked the C60s in line with other speakers.

The 262 has a bass gain adjustment.  Should I start with that all the way down, dial sub, then go back to the 262 for fine tune?

Mike Caldwell:
The QSC High pass will/should help a little with the JBL67's, if driving then fairly hard they will sound a little cleaner, less transformer saturation and the small woofer is not working as hard.
The JBLC60's have a built in high pass to feed the other speakers in the system, you could put
three on each of the C60's.

I would look at using the crossover outputs on the sub to drive the amp.

At the least leave the bass on the mixer straight up or cut back to some, if you use the
subs crossover outputs then  leave it straight up and adjust the sub level as needed.

Are you running the amp in bridged mono and connecting the speaker lines to the two
red terminals on the amp?

Myles Lemansky:
Sorry for delayed response.  Thank you for recommendations.

Switched the QSC to 50 hz, a definite improvement in clarity.

Feeding the C60s is going to take some time to re-wire. Should I run one wire from amp and split to the C60s. Not to question you, but JBL manual seems to favor 2 or 4 vs 1 or 3, non issue?

I am using crossover on sun to power amp, sun strong and clean. 

Yes, speaker lines in proper place in amp.

Thank you.


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