speaker setup

[henapen]

Hi

I'm considering using my JBL cabarets with a gigrac 600 which I think will be a good match but I'm concerned about futureproofing the system if I want to add bass bins at some point.

Assuming I use the two 300 watt outputs into the cabarets and then take a line from each into the bass bins (I'll get 8ohms to match the cabarets) I'm assuming this will take the load on the gigrac down to 4ohms and therefore be safe. please shout at me if I'm being incredibly dumb here!!

Yours greenly

hen

[clubman]

You are correct in thinking that the ohm load would drop to 4 ohms per side with two 8 ohm speakers in parellel. But runing subs off of a signal from your tops is not how I would go about doing it. You have full range coming out of the amp and going to your tops (cabarets) and your subs only want to see the lower range. You could put a passive crossover in your sub boxes to dump anything above lets say 100hz but I wouldn't recomend that. THe subs are going to be more power hungry than the tops. I would drive the subs with their own amp and use a active crossover to dump higher freq. If that gigrac has a aux send or line output you could feed that to the xover then to your sub amp and still run the tops full range of the gigrac. Also subs are usealy ran in mono vs stereo. This insures both subs are firing at the same time.

What are you using this rig for? Band, Dj.....?

Hope this helps and is just my .02

[henapen]

Hi clubman - thanks for your help. We are a 5 piece band playing medium to small venues, at the moment I don't really feel we have the need for subs as the bass cab kicks a fair amount out and I low gain mic it into the mix for presence. the main reason for not going for a x-over and additional amp is simplicity really. we are far from sound experts and I really want to be able to control everything from the gigrac. How bad would the loss of power be do you think?

Any way you've got me thinking so, if I were to use the bass amp with some subs how would I wire that in a x-over so that I could control it all from the gigrac? and I guess I would DI the bass into a mic imput?

thanks again!

[clubman]

Not really a loss of power....let my try to describe this the best I know how. If you run a sub box in parellel to a top, they both recieve half of the 4ohm rated output of the amp, (in your case gigrac) considering both the sub and top are 8 ohms. So you ask your self well thats ok isnt it, sure it is. But in most cases you will find that you need more power being sent to your subs than the tops. As it takes more power and greater headroom to produce low freq. Thats where the external sub amp would really help..


Ok so if you go with a sub amp you would do this, run a cable from the Main line out (1/4 inch plug)(not the speaker level) of gigrac into a active crossover, then from there take the low side output and feed it to your amp, then wire your subs to the amp. You would be able to control the crossover point on the xover and the sub level on the xover too.

If you are on a budget and dont have sub cabs yet consider a powered sub cab. They are really easy to hook up and have the amp and xover built in. And if you just play in small to medium size venues it should be fine. Hooks up just the same, go from the line out on gigrac to line in on the sub and ajust the level right on the back of the powered sub. I myself use a powered JBL JRX18 and it works great for weddings and small venues.

The eq on the gigrac will ajust the signal going out of the line-output to the sub as well as the speaker outs to your cabarets. So how ever you eq the rig the sub will be in the mix.

[henapen]

If you are on a budget and dont have sub cabs yet consider a powered sub cab. They are really easy to hook up and have the amp and xover built in. And if you just play in small to medium size venues it should be fine. Hooks up just the same, go from the line out on gigrac to line in on the sub and ajust the level right on the back of the powered sub. I myself use a powered JBL JRX18 and it works great for weddings and small venues.

The eq on the gigrac will ajust the signal going out of the line-output to the sub as well as the speaker outs to your cabarets. So how ever you eq the rig the sub will be in the mix.

Thanks very much clubman - I think this seems to be the ideal solution, certainly easier than playing around with crossovers/amps etc when we have to get subs anyway!