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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Timothy Jones on August 11, 2014, 01:12:28 pm

Title: QSC Ksub with PRX 615M's
Post by: Timothy Jones on August 11, 2014, 01:12:28 pm
Found a good deal on ksubs. Can I run these with my JBL PRX 615M's? Looking to beef up the low end on the church band.
Title: Re: QSC Ksub with PRX 615M's
Post by: Debbie Dunkley on August 11, 2014, 01:17:19 pm
Found a good deal on ksubs. Can I run these with my JBL PRX 615M's? Looking to beef up the low end on the church band.

Yes…if you use an external crossover in between.
I had this exact same set -up (well, almost the same I have PRX612's) and got fed up having to take a separate crossover with me. QSC have the processing in the tops and JBL in the subs. I finally got a PRX718 and now use the system with the built in crossover in the sub.
It will 'work' without the external crossover but not the way it should.

It was actually not a bad sound and the bass end was tight with the K-subs. Lacking in projection and low end thump though -OK for small venues (or churches) I much prefer the PRX718….
Title: Re: QSC Ksub with PRX 615M's
Post by: g'bye, Dick Rees on August 11, 2014, 01:19:13 pm
Found a good deal on ksubs. Can I run these with my JBL PRX 615M's? Looking to beef up the low end on the church band.

We're not allowed to reply until you change your " handle" to your real, full name.
Title: Re: QSC Ksub with PRX 615M's
Post by: Timothy Jones on August 11, 2014, 01:32:31 pm
We're not allowed to reply until you change your " handle" to your real, full name.

Oh, ok. Done. Thanks.
Title: Re: QSC Ksub with PRX 615M's
Post by: Timothy Jones on August 11, 2014, 01:43:18 pm
Yes…if you use an external crossover in between.
I had this exact same set -up (well, almost the same I have PRX612's) and got fed up having to take a separate crossover with me. QSC have the processing in the tops and JBL in the subs. I finally got a PRX718 and now use the system with the built in crossover in the sub.
It will 'work' without the external crossover but not the way it should.

It was actually not a bad sound and the bass end was tight with the K-subs. Lacking in projection and low end thump though -OK for small venues (or churches) I much prefer the PRX718….

I need compact and light as we move around so I really like these. Only 74 Lbs. with wheels and compact. The PRX 718 is very nice but much heavier and large. I am getting a very good deal on the ksubs but do not want to change my PRX 615's as I just got them. I guess I need to research an external crossover?
Title: Re: QSC Ksub with PRX 615M's
Post by: Timothy Jones on August 11, 2014, 01:45:34 pm
Maybe I keep looking or get a JBL sub

Title: Re: QSC Ksub with PRX 615M's
Post by: Mark Cadwallader on August 11, 2014, 02:44:37 pm
I called around and most people are saying a external crossover is not needed. And this that they should work fine together. As all my speakers are powered.

Yes, they will work without a cross-over. How well is another question.

The -10 dB rating for the K-sub is 44 hz. The -10 dB rating for the prx 615m is 45 hz.

Running them both full range may not get you much more low end than you currently have. YMMV, but if you are asking for the advice of the forum, why are you telling us that "most people" are telling you differently?  Have you listened to the speakers in both configuations?  Mark C.
Title: Re: QSC Ksub with PRX 615M's
Post by: Timothy Jones on August 11, 2014, 03:22:18 pm
Yes, they will work without a cross-over. How well is another question.

The -10 dB rating for the K-sub is 44 hz. The -10 dB rating for the prx 615m is 45 hz.

Running them both full range may not get you much more low end than you currently have. YMMV, but if you are asking for the advice of the forum, why are you telling us that "most people" are telling you differently?  Have you listened to the speakers in both configuations?  Mark C.

After some more research your comment is on par. That is the next step is to hook em up and see if it works out. The most people comment was stupid. I called QSC and they basically said the same thing as you. Mismatching may not be the way to go but my rig can only hold so much gear. A powered JBL 18 is probably the way to go, I think I could fit one in my rig with all my other gear. Thanks for your input. It is much appreciated.
Title: Re: QSC Ksub with PRX 615M's
Post by: Debbie Dunkley on August 11, 2014, 03:57:03 pm
The big plus with the K-subs was they had the best wheels on them so moving them around was a cinch and they were really easy to transport. They looked nice too especially where space was tight and they had a 'smart' appearance to them. …

There is nothing wrong with mismatched brands IF you do it right and a decent external crossover isn't going to break the bank if you are getting the K-subs at a great price. I was using a Samson c/over and it worked fine.  It was the extra cabling and effort that was annoying to me but if you are not moving the system around, it'll make no difference to you. Just remember you won't get the nice meaty thump and low extension that an 18" will give you….Can you set it up and have a listen with your speakers before you buy??
Title: Re: QSC Ksub with PRX 615M's
Post by: Timothy Jones on August 11, 2014, 04:03:46 pm
The big plus with the K-subs was they had the best wheels on them so moving them around was a cinch and they were really easy to transport. They looked nice too especially where space was tight and they had a 'smart' appearance to them. …

There is nothing wrong with mismatched brands IF you do it right and a decent external crossover isn't going to break the bank if you are getting the K-subs at a great price. I was using a Samson c/over and it worked fine.  It was the extra cabling and effort that was annoying to me but if you are not moving the system around, it'll make no difference to you. Just remember you won't get the nice meaty thump and low extension that an 18" will give you….Can you set it up and have a listen with your speakers before you buy??

Im being told the Ksubs have a built in crossover. The ksub has a 100 HZ low-pass over that cannot be adjusted or bypassed. Im so confused. I have to move a lot thats why I liked these and I have a small truck. lol. Im going to try this set up and see what happens before I buy them. Two ksubs for $800 is a good deal but not if it doesnt work right!
Title: Re: QSC Ksub with PRX 615M's
Post by: Debbie Dunkley on August 11, 2014, 04:13:51 pm
Im being told the Ksubs have a built in crossover. The ksub has a 100 HZ low-pass over that cannot be adjusted or bypassed. Im so confused. I have to move a lot thats why I liked these and I have a small truck. lol. Im going to try this set up and see what happens before I buy them. Two ksubs for $800 is a good deal but not if it doesnt work right!
K-subs DO NOT have a crossover built in - they do have a low pass filter at 100hz but they send full range to the outputs. That is why they marry well to the K series tops. The tops have the high pass built in. Who is telling you this? Call QSC again if you are in doubt. It is clearly stated on the literature provided by QSC.
Title: Re: QSC Ksub with PRX 615M's
Post by: Debbie Dunkley on August 11, 2014, 04:22:34 pm
From the QSC website….
Title: Re: QSC Ksub with PRX 615M's
Post by: Debbie Dunkley on August 11, 2014, 04:37:54 pm
BTW…$800 for 2 is really good !! I sold mine about 6-9  months ago and got $1400 for the 2 (including QSC covers).
Title: Re: QSC Ksub with PRX 615M's
Post by: Steve Garris on August 11, 2014, 06:11:05 pm
After some more research your comment is on par. That is the next step is to hook em up and see if it works out. The most people comment was stupid. I called QSC and they basically said the same thing as you. Mismatching may not be the way to go but my rig can only hold so much gear. A powered JBL 18 is probably the way to go, I think I could fit one in my rig with all my other gear. Thanks for your input. It is much appreciated.

The 615's are phenomenal - and can be run on top of any sub via:
1. Aux fed sub mix
2. Left Right sub mix

I've used option 2, running my 615's over the club's KW181's. The left signal out of the board goes only to the sub's. The right signal, only to the 615's.
I simply pan all vocals and instruments hard right, and run those signals to the 615's.
The kick drum and bass guitar are set at 50/50 pan. This works really well - and I run the 615's in the full-range mode (not monitor mode).

No crossover needed!
Title: Re: QSC Ksub with PRX 615M's
Post by: Debbie Dunkley on August 11, 2014, 08:15:22 pm
The 615's are phenomenal - and can be run on top of any sub via:
1. Aux fed sub mix
2. Left Right sub mix

I've used option 2, running my 615's over the club's KW181's. The left signal out of the board goes only to the sub's. The right signal, only to the 615's.
I simply pan all vocals and instruments hard right, and run those signals to the 615's.
The kick drum and bass guitar are set at 50/50 pan. This works really well - and I run the 615's in the full-range mode (not monitor mode).

No crossover needed!


Good point….I always liked to have the ability to run stereo so I could use panning if necessary and I never had enough auxes to run aux subs - needed them for monitors - so I had no choice but to use a c/over. But good option if OP has the flexibility….
Title: Re: QSC Ksub with PRX 615M's
Post by: Timothy Jones on August 12, 2014, 03:31:20 am
Thanks for all the information which was spot on. Im tried the ksubs with my 615s and they are just pointless. They only send full range as stated and why mess with an external crossover. If we want big sound I really need is the powered 18's, when I hooked the 718's up with my 615s it sounded AWESOME, and a trailer to haul them in.
Title: Re: QSC Ksub with PRX 615M's
Post by: Debbie Dunkley on August 12, 2014, 09:18:01 am
Thanks for all the information which was spot on. Im tried the ksubs with my 615s and they are just pointless. They only send full range as stated and why mess with an external crossover. If we want big sound I really need is the powered 18's, when I hooked the 718's up with my 615s it sounded AWESOME, and a trailer to haul them in.
The first time you use the PRX 615's with 718's live , you'll  realize it was a wise choice !