sub help

[jonny]

I want to add a sub to my pro-logic system. But my only option is to connect it at speaker level because my amp has no way of telling it a sub is connected to the sub pre out phono output. So presumambly it will still send the same amount of bass to the front pairs as the sub which is what i dont want!
So i was thinking if i connect it at speaker level will it allow me to alter the amount of bass that go to the front pair thru the controls on the amp itself?

Im looking at a PDR 8 sub just incase you need to know

Thanx for any the help, Jon

[Matt F]

In your pro-logic set up there is no specialised low frequency channel as there is with Dolby Digital (i.e. the .1 channel) so the sub out on the back of your amp is just a line out providing a suitable signal that a subwoofer can use.

There is no reason why you shouldn't connect a sub to this line out or you could use a speaker level connection (or even both with the right sub) - it doesn't really matter with your amp (as it sounds as though it doesn't provide any bass management), in fact it may depend more upon what connections the sub you buy can cope with.

There is also nothing wrong with sending a full range signal to your front speakers - they will only go down to a certain frequency. The important thing is that, however you end up connecting the sub, you set the crossover on it so that the sub takes over where your main speakers go down to - so, say your main speakers reach down to 50hz, the sub then needs to go from say 20hz up to 50hz.

Basically, it will take some trial and error to get the crossover set at the right point as it will to get the sub volume set at the right level but once you have got it all set up properly it should sound pretty good.

[jonny]

Thanx alot that makes it all a lot clearer!

[jonny]

One more thing: i chcked the specs for my mordaunt pearl speakers and it says they go from 55khz to 20 khz. so in your reply it doesnt make sense that the sub should go up to 20hz because the speakes already reach this freq? I suppose im getting confused again, so could you explain this final obstacle!!

Thanx again, Jon

[Reiner]

They go from 55Hz to 20kHz and the sub goes down (supposingly) to 20Hz, ie lower than the speakers.

Two choices how to connect via high level:

1. Connect the speaker outs from the amp to the sub speaker in and the speakers to the speaker out terminals at the sub.
This way the sub will cut the low frequencies according to the setting of the knob on the back, as well you can control the subs volume if it's an active sub (which I assume it is?).

2. Connect in parallel, ie speaker out from the amp to the speakers and speaker out from the amp to the sub speaker in, might require some squezzing at the amps end.
This way the bass will be duplicated while the fronts retain their lower frequency response (down to 55Hz).
Again with an active sub you can control the volume of the sub seperately.

I rekon option 1. would be the preferred solution as it reduces the load to the front speakers and hence should result in a better overall sound.

[This message has been edited by Reiner (edited 01-12-2000).]