Hi All,
I'm nearing completion on my first DIY build. I decided to start simple and build a pair of desktop speakers, each containing 4 2" full-range drivers (HiVi BMR-12's).
I also picked up some 200uf non-polarized capacitors to filter out the low frequencies. Trouble is, I can't seem to figure out how to wire the capacitors in? Does each of the 8 drivers need a capacitor, or just each of the two cabinets? I have them wired series/parallel to maintain an 8ohm impedence.
I'm hoping I only need to use 1 capacitor per cabinet and wire it between the positive post on the terminal cup and the positive post on the bottom driver (that would otherwise attach directly to the terminal cup post).
If anyone could help out this noob, it would be greatly appreciated! Here's a pic of the progress so far
I'm nearing completion on my first DIY build. I decided to start simple and build a pair of desktop speakers, each containing 4 2" full-range drivers (HiVi BMR-12's).
I also picked up some 200uf non-polarized capacitors to filter out the low frequencies. Trouble is, I can't seem to figure out how to wire the capacitors in? Does each of the 8 drivers need a capacitor, or just each of the two cabinets? I have them wired series/parallel to maintain an 8ohm impedence.
I'm hoping I only need to use 1 capacitor per cabinet and wire it between the positive post on the terminal cup and the positive post on the bottom driver (that would otherwise attach directly to the terminal cup post).
If anyone could help out this noob, it would be greatly appreciated! Here's a pic of the progress so far
Attachments
It should be good to go with one cap per enclosure as long as it's in series with the signal before the signal gets to the speaker. If you wire it directly off the terminal cup and then wire the speakers off the cap, you should be good.
Mike
Mike
Using 200uF into an 8 ohm load will give you a roll off below 100HZ. You'll be down 3dB at 100, and continuing down from there, so no bass. Personally I'd double those so you can get down to 50HZ.
If you wire the drivers in series-parallel (as you have 4 drivers) the total impedance will be as for a single driver, so you can just use one capacitor.
There is no point, these are 2 inch drivers and have a resonance of 164Hz. Keeping some bass from them may help them actually sound a bit better overall.
These HiWave BNR-12? http://www.parts-express.com/hiwave-bmr12-compact-2-full-range-square-speaker-12w-8-ohm--297-210
With an Fs of 164 Hz, tryig to roll stuff off passively is greatly complicated by the resonance peak (ie in the range of the roll-off the impedance changes dramarically)
dave
Just run them full range and see how it sounds. I do this with 2 in drivers all the time. Limit the power and don't go crazy with high volume levels when listening to HT stuff with low frequency content.
Sorry, yes HiWave, not HiVi.
Forgive my lack of understanding planet10, but are you suggesting I may be doing more harm than good by adding the capacitors in?
Forgive my lack of understanding planet10, but are you suggesting I may be doing more harm than good by adding the capacitors in?
Iam suggesting that the results you get will not be what you expect if you are designing assumming an 8 ohm impedance. At these frequencies, any filters are best before the amplifier.
dave
It would be very easy to try them with the cap in line at the terminal cup to get a "feel" for sensitivity(efficiency) and response then jumper (bypass) the cap and listen again knowing the volume limitations from the previous test.
The resonance on a 2 inch driver is probably around 200HZ. If the impedance of the driver were to go up to 30 ohms due to resonance, where the cap was trying to do its thing, the 200uF cap would then be a 25HZ highpass. So it wouldn't hurt to put the caps in place, but The rolloff frequency will probably be pretty far off of theoretical with 8 ohm nominal. The cap needs to be a bi-polar type if it's an electrolytic.
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