passive crossovers....

[stuman]

on payday this month i will be buying a subwoofer for my bedroom audio, the problem is the small speakers that i use are in full range at the moment and when i put the subwoofer in would like to have a bass pass filter on them at about 50hz where they start to drop off naturally so that when pushed to high SPL's i dont get the port chuffing noises, i could always bung the bassport on the back but not sure weather the response curve would be as good as it is with.

so what im basically asking is are there any good designs out there for a passive 50hz bass filter?

 

[Cal Weldon]

A 50 Hz passive XO will be very expensive. Consider using an active filter. In fact, you can often buy a plate amp with a built in XO for little more than the components needed for a passive 50 Hz.

 

[Lumba Ogir]

Hi,
I would just place a capacitor at the input of the poweramp

 

[planet10]

Hi,
I would just place a capacitor at the input of the poweramp

This is the way to go. Here is a web page that will help you figure out how big the cap needs to be (ise the input impedance of your amp as R2 in the 1st order high pass filter.

http://t-linespeakers.org/tech/filters/passiveHLxo.html

dave

 

[bastek]

I use a 150microF electrolytic in series with the woofer input on the speaker. If your speaker only has 2 posts, you can add a 10microF polypropylene cap in parallel. My 2 way bookself has a 5.25" mid-woofer.

 

[planet10]

I use a 150microF electrolytic in series with the woofer input on the speaker. If your speaker only has 2 posts, you can add a 10microF polypropylene cap in parallel. My 2 way bookself has a 5.25" mid-woofer.

An elco after the amp will not sound anywhere near as good as a poly before the amp... also to get his desired 50 Hz he'd need 400 uF if the speaker was a flat 8 ohms, but a speaker near its cut off is far from flat.

dave

 

[stuman]

sorry, i should have posted some more info.

the sound is going to be sent to my amp which has a dedicated line out for subwoofer which i am planning on using thats all fine however i would like to filter the the speakers on from the standard binding posts and was wandering about decent crossovers? i can spend about £200 for the pair? any ideas?

 

[planet10]

the sound is going to be sent to my amp which has a dedicated line out for subwoofer which i am planning on using thats all fine however i would like to filter the the speakers on from the standard binding posts and was wandering about decent crossovers? i can spend about £200 for the pair? any ideas?

What kind of speaker are your satelittes.

A passive XO on any speaker this low and this close to its cutoff is a nightmare and will likely be a waste of effort. You can't get at the power amp separately?

dave

 

[matthew c]

sorry to take the poster over put i cant post in the main room

 

[phreeky82]

So you just wanna high-pass the satellites using a passive x-over? Wouldn't the amp/system be doing this for you actively? If not (odd), you could just try a cap in series with the satellites but it may not be steep enough depending on the x-over freq.

As stated, a passive x-over at such a low freq is a pain in the a*se (but at least its a high-pass and not a low-pass!!!).

 

[j.michael droke]

Passive hi-pass filter

This is the way to go. Here is a web page that will help you figure out how big the cap needs to be (ise the input impedance of your amp as R2 in the 1st order high pass filter.

Passive High-Level Crossover

dave

Hi there: Would a 12db 2nd order hi-pass filter at 20hz, suggested in Dave's post as mentioned above, be advisable for protecting a TH sub with a low corner of 25hz?