Question about setting the gain structure and the xover gain

smurray

I have a quick question. I've been going through the \"read me first\" post in order to set up the gain structure of our system, and am a little confused about one thing. I ran the wizard first per the instructions, and the wizard sets up the xover of the system w/ a -9db gain for the lows. Should I raise this back up to unity when I setup my gain structure? If so, do I lower it back down afterwards, or does setting up the gain structure accomplish the same goals?

Thanks

Gadget

Without a full idea of your system it's difficult to determine whats happening here but I'd guess :
1. It's a JBL setup..
2. You may have a big amp for the subs?
3. Somewhere the efficiency of a componentis in question...

The Gain structure as posted here is a simplified one... the deal is, if you calculate your amp power and your speaker compliment and they are close, as in:
1. you have subs with a an efficiency of 92-96 db and are under powered (less than double the RMS value of the speaker and up to rated \"peak\" watts) you will perhaps need to use the gains in the xover, or turn the other amp down...

I guess I'd look at that spec with a little skepticism...but then again I don't have all the facts either... but if you change the gain point in the gain structure...leave it there...
G

smurray

We have two Yamaha CW115V subs, driven by a QSC RMX1450 in bridged mono mode. Both the amp and the subs were listed as choices in the wizard, so that's what I chose. I wasn't able to specify that we're running two subs off the amp, could that have something to do with it? All I know is that when the wizard set up the xover it set the gain for the mains at 0db, and the gain for the subs at -9. I honestly don't have much of a clue what this all means, so if you think I should raise the gain close to unity please let me know. I'm kind of learning as I go with all of this.

Thanks,

Sean

Dra

Wizard is not all knowing. For example, what if you had 2) 200w main speakers on 1) 200w amp. The wizard thinks that is what you have. It now asks you what sub and amp you have (again assuming 2 and 1). But you have 12 subs and 6 amps of what you input. The wizard is going to recommend the wrong x-over gains (which are suspect anyway).

If you feel really insecure about doing a manual gain structure and system tuning, then the easy way out will be the wizard (if you have match component numbers (1 top speaker on 1 amp channel and 1 sub on 1 amp channel, or 4,4,4,4, etc)). But the wizard cannot do what a human can do with a little effort.

DRA

Gadget

Well, you STILL didn't say what tops you have... but ...Id raise the gain to at least unity and probably 4 to 6 db added. The subs are MORE power hungry, and LESS efficient...
G

smurray

Sorry, didn't realize what the tops were affected the xover gains for the subs. I'm currently running a pair of Bose 802 Series II's (yes I know they suck). The xover gain for the highs was at 0db. I've raised the xover gain from the subs up to 0db, are you suggesting I raise it even higher, or that I should raise the gain for the highs above 0db, or both?

Gadget

There's part of the problem... the inefficiency of the bose ... Ok IF you find you have to have much more gain on one amp... say the one driving the subs...you can turn up the xover gain even more...

G

smurray

I setup the gain structure again, and the gain on the amp for my mains ended up being at 14 (about 9 o'clock on the dial), while the sub amp ended up being at 24 (around 2 o'clock). Should my goal be to have both the amps have the same gain? If so, I would accomplish that by raising the xover gain for the lows in the driverack?

Gadget

Not necessarily... it all fits well into the \"way things are\"... as I said the subs need more power and are less efficient...I would set the mains @ 0 and the sub xover gain @ +4 to +6 then use the amp gains to finish...

BTW the request for all info for each system in order to get ANY answers is the first line in the READ ME FIRST BEFORE POSTING section...

G

smurray

Sorry about that, I'm still getting used to how things are done here. In case it still might help at this point, our mains are a set of Bose 802 Series II. Our subs are two Yamaha CW115V's. The mains are powered by a QSC RMX1450, and the subs are both powered by another QSC RMX1450 in bridged mono mode. Our mixer is a Mackie cfx16.mkII.

Dennis

smurray

After every gain structure change you made, when you ran full range music through the system, did it sound better or worse? did the balance between sub and mid/high speaker improve or not so much?

Dennis

Gadget

wow I just looked up specs...

which bose is notorious for NOT providing...and ...

I had no Idea they were that pathetic...91 db @ 1 meter 1 watt...and 114 db max! Wow...my 6 1/2 \" 2 way studio monitors will BLOW THEM OFF THE PLANET!

Wow... well thats all for this day... sorry about the post but I can't abide by
\"Better sound through marketing\"!

Hey GADGIT... come get some...
G

smurray

Gadget wrote:

wow I just looked up specs...

which bose is notorious for NOT providing...and ...

I had no Idea they were that pathetic...91 db @ 1 meter 1 watt...and 114 db max! Wow...my 6 1/2 " 2 way studio monitors will BLOW THEM OFF THE PLANET!

Wow... well thats all for this day... sorry about the post but I can't abide by
"Better sound through marketing"!

Hey GADGIT... come get some...
G

I don't know enough about sound to really know what all that means, but I do agree that the Bose speakers sound awful. We also have a set of Peavey 112TLS speakers that I've been storing in my garage, I found some specs on them listed online and it says they're 98db at 1 meter 1 watt. Still not sure what that means, but I'm assuming 98 is better than 91. I'm going to set those up next Sunday and compare them to the Bose. Maybe they'll sound better and we won't have to mess with the Bose anymore. I agree that they suck, and we're in the process of buying some new powered speakers (I'm pushing for a pair of QSC HPR122i), but I'm just trying to make due in the mean time.

Gadget

Bose are meant to be good midranges.. and they are fair at that... the Peaveys are bright and could increase your feedback issues...Do you have the measurement mic? If so you might be able to get those sounding better in the meantime...

What I was indicating is that yes... the bose are In-efficient... that number is a level of volume measured @ 1 meter @ 1 watt of power sent to them...

G

Dra

Just to put into perspective...
Your Bose at 91db 1w 1m
compared to my Yorkie's at 102db 1w 1m...
your Bose on one side of the amp and the Yorkie on the other side...
The Yorkie will be twice as loud no matter how much (equal) watt you put into them. Yorkville is known for high effieciencies, but most pro level cabs are usually in the high 90's at least.

I do like Bose for their lack of feedback.

I wonder how the Bose and the Peaveys would sound as a tandum. Typically the chaos caused by dissimilar speakers is a no no, but all things considered :? ... Maybe the Bose would smooth out the Peavey and the Peavey would add some crispness. All it can do is suck or get better, right?

DRA

DRA