Crossover Gain - cut or boost

info@mjpa-hire.co.uk

What are your thoughts on Gain control in the crossover section on the 260, ie. My new bass bins ask for a 10db Boost, do you think I should cut the mid tops by 10db and leave the bass bins at 0db? How will this effect the limiters in the 260? What are the implications of cutting against boosting in this section if any?
cheers.

Dra

What are you basing the \"Bins asking for +10db\" on?


If it is a shear output difference, Gadget usually recommends simply reducing the tops amp(s) level (amp attenuators) to balance the system out.
The main reason is that if you give the sub band a +10 boost, when you do the gain structure, you'll end up attenuating the amp -10 to get back to -0-. The result, same difference. You can boost the x-over levels, but in doing so you will get into the limiter more frequently. You'll gain output, but lose headroom. Make sure that the limiters are set based on unity gain.

If you really need +10 from the subs, try...
putting all subs together,
set next to a wall (or better, in a corner),
more power,
more subs

DRA



DRA

Gadget

For instance if you have one sub and you can achieve 123 db add another right next to it and get a free 3db add another and get an additional 3db of free output.. corner loading adds 6db... a wall 3db... as Dra says there are many ways to do this, as many as there are different amps and speakers...

Consider an amp that has 10db of gain over the amp that runs the tops and you don't need to change anything right? If you stop to consider, if you had the same amps, and needed 10db more you could add 3db @ the crossover to the subs, and decrease the tops output by that much, or leave the DRPA at unity gain and use the amp controls to decrease the volume of the loudest component...

Here we have a lot of \"newbies\" and to simplify the procedure for the masses we proscribe that if you leave the driverack @ unity and do a proper gain structure that will get all the components on the same page. Then we know that all the system will clip at the same point, and that if we then back the gain of the amps down slightly from that point 3-12 db (depending on how much headroom you like) and we are pretty sure that when we reach that point on the mixer where we are approaching clip, that the amps still have headroom, and the rest of the system is near clip and we have no more output left...If we then use this information to set the limiter we can be sure that we have a verifiable, safety factor built in (whatever that is again... depending on how much headroom you want).

Gadget

info@mjpa-hire.co.uk

OK, Understand that, the 10db Boost on xover figure comes from the dsp settings recommended by the speaker manufacture, I didn't know whether to set them at +10 in the 260 or just set a -10db figure for everything else. I haven't had a chance to run them through the system and wanted to get some numbers punched in because I will not have much time to set the system up at the next gig and didn't want to be miles out with the settings if you know what I mean. Cheers.

Dra

Maybe if we knew what we were dealing with here. Can we assume that the speaker manufacturer knows how many subs vs tops you are using and what amps you are using, etc, etc....?

DRA

info@mjpa-hire.co.uk

If +10db produces too much bottom end I can ajust on the fly, I suppose I just really want to know is whether cutting the db value is preferred or perhaps better for the overall set up of the 260 over boosting values or whether it does not make any difference and its give and take on all other effected values. As I mentioned I won't have much time to balance my system at the next venue and needed 'best guess' figures just to get things started and I can fine tune as we go from there.

Dra

Boosting or cutting in the crossover section, since it is digital, should make no difference, except for that you may need to seperate the x-over points a bit, since the increase in gain will cause an over-lap.

Good look.

DRA

Gadget

Look... it's crazy to think that a manufacturer could say that \"In all cases a 10db gain will need to be added to these subs regardless of what speakers and amps you use... \"

As I said if you have a sub amp that has 10db more gain then the problem is solved right there...

What ARE you using for amps... what ARE you using for tops...

Chances are pretty good that what they are saying is that the \"average\" sub is 10db LESS efficient than typical modern tops... that is to say that a typical front loaded sub is ~ 92 db efficient @ 1 watt @ one meter.,..where a typical horn + cone top is 102 db efficient @ one meter @ one watt...

Therefore, if your using a 2000 watt amp for the subs and a 1000 watt amp for the tops the 10db factor of the subs has no meaning... HOWEVER if you had two 2000 watt amps one running each THEN the 10 db becomes
a factor! Add to this confusion a top that is 107 db efficient, or only 96 db efficient and again...the 10 db factor is again moot...

So in conclusion, all this gain/cut banter is pointless without something concrete to factor it against...

This is specifically why one of the FIRST lines in the READ ME FIRST section states:
***When you do post, please provide system information along with your post. Speaker models and quantities,(links would be helpful) Amp models and number of amps, what you foresee them driving...system components and current hookup information if any... IF YOU DON\"T... you will not get help...***

Here we don't even know what subs were talking about.. what amps...what tops...there is NO way to answer this question with the info provided...

Gadget