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Passive tops with active sub
Old 31st October 2019
  #1
Here for the gear
 

Passive tops with active sub

Hi,

I'm currently looking to add a sub to dynacord 600 with 2 ev sx300's. I was recently advised by a sales rep at an fbt dealer to run the tops passively full range and to run an fbt subline 115sa active. I'm seriously considering taking his word for it and buying the subline, he was pretty convincing! What do you guys think? Is this good advice?

Thanks, Paul
Old 31st October 2019
  #2
Lives for gear
 
Pro Sound Guy's Avatar
 

I would use a HPF on the passive tops.
Sounds like the rep just wants you to buy his subwoofer without a HPF resolution for your tops.
His sales pitch is just run your tops as is and buy my subwoofer.
Old 31st October 2019
  #3
Gear Maniac
 
Mike M's Avatar
definitely a sales pitch...

...like going to a Toyota dealership and saying to a salesman: "Can you choose a car a me?". (oh, btw, that salesman drives a Honda...)

It has been my experience that most pro audio salesmen know little more than the written material that can be found online by anyone.

What I have found: Running a hi/mid cab full range and adding a sub without a crossover/HPF/LPF inline mucks-up the sound....

I am sure that others will chime in..
Old 31st October 2019
  #4
Lives for gear
 

This particular subwoofer does have a HPF (with outputs) built-in, so it would be at least theoretically possible and possibly satisfactory to run the tops off of that output. You'd have to connect your existing amplifier to these outputs from the subwoofer rather than directly to your mixer or whatever, which may or may not be a cabling challenge. I have no idea how well or poorly the built-in crossover compares to dedicated external crossovers.
Old 1st November 2019
  #5
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Quote:
Originally Posted by pjowsky View Post
Hi,

I'm currently looking to add a sub to dynacord 600 with 2 ev sx300's. I was recently advised by a sales rep at an fbt dealer to run the tops passively full range and to run an fbt subline 115sa active. I'm seriously considering taking his word for it and buying the subline, he was pretty convincing! What do you guys think? Is this good advice?

Thanks, Paul
quite common to do so: full range tops will give you a bit more output but puts higher stress on tops.
with tops nearby a boundary, you may want to use a hpf.
Old 1st November 2019
  #6
Here for the gear
 

Damn he really sold it to me as if it was better to run the tops full range and he knew my desk doesn't have hpf. I guess he is just looking for a sale.
That being said I don't know if I have any other option at this time. I need a sub for upcoming gigs and I can't afford a new desk or new tops atm. Perhaps DrewE's suggestion of figuring out cabling to run the tops off the sub with it's hpf is the answer. I called the fbt dealer and mentioned this to him and he is still trying to convince me that running the speakers full range with no hpf is better! He says the vocals will suffer from lack of bass. Thanks a lot for the input guys. I guess at least if I buy the sub I have the option to try running them full range or through the sub.
Old 2nd November 2019
  #7
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Pro Sound Guy's Avatar
 

This guy you are dealing with is way off the mark.
First of all there is really not much if at all below 100hz on a male vocal and female vocal is much higher like 200hz.
You actually do not want vocals in the sub.
How about running your sub off of an AUX send and then roll off the tops through the mains with the main EQ on your powered mixer?
It will work.
Old 2nd November 2019
  #8
Lives for gear
How much $ is he asking for the fbt 115a? If that's your entire budget, maybe you could consider looking at some other options.
Old 4th November 2019
  #9
Here for the gear
 

I'm gonna first try running two jacks from l/r main ouputs to male xlr's into the left and right on the sub and run the tops passive with the speakon desk outs and roll off lows on graphic equalizer.
Old 4th November 2019
  #10
Here for the gear
 

Main eq will effect main xlr outs as wel as powered outs ...






Quote:
Originally Posted by pjowsky View Post
I'm gonna first try running two jacks from l/r main ouputs to male xlr's into the left and right on the sub and run the tops passive with the speakon desk outs and roll off lows on graphic equalizer.
Old 4th November 2019
  #11
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Pro Sound Guy's Avatar
 

Quote:
Originally Posted by pjowsky View Post
I'm gonna first try running two jacks from l/r main ouputs to male xlr's into the left and right on the sub and run the tops passive with the speakon desk outs and roll off lows on graphic equalizer.
You have to run the sub from the AUX output because the main EQ will
effect the tops and sub if you hook the system up as described in your post.
Run the tops out of the speakon out L/R on main.
Run the sub out of AUX 2 out and then add bass guitar and kick drum
on AUX 2 mix. Leave everything else out of the sub.
Roll low frequency off on the main EQ out for the tops.
Old 4th November 2019
  #12
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Quote:
Originally Posted by Pro Sound Guy View Post
(...) the main EQ will effect the tops and sub if you hook the system up as described in your post (...)
it better does: eq similarly affecting sub and tops is a feature, not a bug!!
Old 5th November 2019
  #13
Gear Maniac
 

Quote:
Originally Posted by deedeeyeah View Post
it better does: eq similarly affecting sub and tops is a feature, not a bug!!
It's a bug if he's going to roll off the lows with the main EQ (as he says he is planning to do).

Geoff
Old 5th November 2019
  #14
Lives for gear
 

Quote:
Originally Posted by cbc6403 View Post
It's a bug if he's going to roll off the lows with the main EQ (as he says he is planning to do).

Geoff
guess you haven't been aligning sub(s) to tops much? using the same eq on all outputs is not a bug: it's mandatory actually for phase coherence! and rolling off lows on tops specifically with a geq is neither very sensible nor needed in general (as mentioned previously)...
Old 5th November 2019
  #15
Here for the gear
 

Damn, I usually use the aux output to run a stage monitor for vocals. That fbt dealer guy told me I could use the main l/r jack outputs for the sub!!!
Old 6th November 2019
  #16
Lives for gear
 

If you have the newer version of the Dynacord 600 with power amp input jacks, run the main mixer L/R to the sub, and the sub's L/R outputs (with HPF enabled) to the power amp in jacks on the powered mixer, and then run the tops from the amp there. The aux can then be used for your monitor.

If your Dynacord 600 doesn't have the power amp in jacks, you're kind of stuck, I guess, without either replacing it or getting an external power amplifier or giving up the monitor mix.
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