Caps to help an inexpensive powered sub

[drjjpdc]

I have a integrated amp (Music Hall a15.2) with an inexpensive powered sub on a second system. I want to use the Hi pass speaker wire connections. The sub's crossover obviously isn't the tops in quality. Is there any way I could get some good quality caps and use them on my bookshelf speakers or on the powered sub to get some better sound? I would like to not use the bookshelf spk full range if possible. Thanks.

John

[Dr.EM]

By the sounds of it you are hooking up the subwoofer to the speaker level outputs of the amplifier, which unfortunately rules out the potential to use an active line level crossover as this would remove bass before it reaches the subwoofer.

You're right to not want to run the bookshelfs full-range since you have the subwoofer, they should perform better with the bass filtered off of them.

Using caps at speaker level to filter bass from the bookshelfs isn't likely to work well, firstly the required value will be large (assuming around 80Hz cut-off and 8-ohm speaker load it's 250uF), in electrolytic territory really. The main problem is that this forms a 1-pole filter with only 6dB/octave roll-off which isn't really sufficient but you could try it. Perhaps bypass the large electrolytic with a quality polypropylene cap.

Ideally though an active crossover is used, which means the subwoofer needs to be fed at line level, the issue is obviously that the volume control on your amp now only works to control the bookshelfs. A seperate pre-amplifier solves this, some amps even have a pre-out which would facilitate hookup with the volume control in circuit. Have a look if you have one, and what tape loops you have available.

[drjjpdc]

Well this is the powered subwoofer that I have.

Dayton Audio SA70 70W Subwoofer Amplifier 300-784

My integrated amp has a line out but it is really a tape out, there is no volume control on it. I was told to use the speaker outputs because that way the speaker/subwoof combo would "see" the integrated better. I have no problem using the low pass RCA's if that would work. Thanks.

[Josephjcole]

Originally Posted by drjjpdc

I want to use the Hi pass speaker wire connections.

John

I'm not entirely sure what you mean by this... does your amp have a built in hi-pass crossover to be used with subs? If not an active crossover is your only real option. I would recomend something like this: MiniDSP. Fairly cheap, and powerful... This may be more complexity than you want though. Really though a capacitor will not help you to any noticable degree.

[drjjpdc]

Originally Posted by Josephjcole

I'm not entirely sure what you mean by this... does your amp have a built in hi-pass crossover to be used with subs? If not an active crossover is your only real option. I would recomend something like this: MiniDSP. Fairly cheap, and powerful... This may be more complexity than you want though. Really though a capacitor will not help you to any noticable degree.

I think it is just the speaker wire i/o as opposed to using RCA plugs. My powered sub is shown with a link in post #3. I think it has hi pass and lo pass circuitry.