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Farmer Ted
05-26-2007, 06:47 PM
Is it better to run two sets of speakers in Series or Parallel?

Speakers are Polk Audio DB 651
Amp is an old (15+ years) JVC 100 + 100 but it still works great

After reading this.....
http://www.termpro.com/articles/spkrz.html

is it better to go Parallel?

projectely4
05-26-2007, 07:07 PM
depends. you are going to want to keep your ohm load as low as possible but keeping it high enough so the amp doesn't overheat

Farmer Ted
05-26-2007, 07:20 PM
depends. you are going to want to keep your ohm load as low as possible but keeping it high enough so the amp doesn't overheat

Like I said, I got this Amp about 15 years ago in Japan, I can't find the manual and this is what I got off Google,

JVC KS-A202
2x100w ou 200W mono. 30khz avec moins de 0.04% de dht. Tolerance 4 et 8 homs 20hz-40khz(+-3db). 90db avec gain control et fusible de protection

So if I understand the Series/Parallel thing correctly, I should run them in Series since they are 4 Ohm speakers, two in Series = 8 Ohms and the Amp is rated 4 to 8 Ohms

Correct?

JimN
05-26-2007, 08:15 PM
How loud will you run them? Do they really need to have full range going to them or do you want to limit the low end so they don't puke? If you put a capacitor in series with them, you can run them in parallel. The reason the impedance needs to be 4 ohms or more is that the DC resistance is important, but only at clipping. Extreme clipping is basically short bursts of DC voltage and at high frequencies, it looks like only DC, not at all like AC. If you put a cap in series, there's no way to pass DC, therefore, it's easier on the amp.

Farmer Ted
05-26-2007, 08:28 PM
How loud will you run them? Do they really need to have full range going to them or do you want to limit the low end so they don't puke? If you put a capacitor in series with them, you can run them in parallel. The reason the impedance needs to be 4 ohms or more is that the DC resistance is important, but only at clipping. Extreme clipping is basically short bursts of DC voltage and at high frequencies, it looks like only DC, not at all like AC. If you put a cap in series, there's no way to pass DC, therefore, it's easier on the amp.


I was hoping you'd chime in Jim!!!

I'm not looking to entertain the lake or the rider, just looking for some decent sound without frying my amp or ruining the speakers by hooking them up incorrectly.
There will be 4 speakers on the tower and 4 in the boat (on seperate amps)

The speakers look like they have a capacitor soldered on them already,
one has heat shrink on it and all I can make out is -H TUBE (connected to both terminals)

the other one has 0.35 mH (connected to the + terminal, and ground)

jclose8
05-26-2007, 09:07 PM
Put it this way.... If you wire them in series, you are definitely safe. You won't fry your amp.

If you wire them in parallel, the speakers will play louder and clearer, as long as your amp can handle it. 4 ohm speakers wired parallel will present the amp with a 2 ohm load. Today, nearly any amp can do that. A 15 year old amp... maybe, maybe not.

JimN
05-26-2007, 09:33 PM
Farmer Ted- If the caps are 3.3 μF or close to that, they're for the tweeters only. If you want to select the crossover frequency, the formula is C=1/2ΠfR and the decimal for the capacitor's value will be at the sixth place to the right of the decimal in the result e.g., f=120 Hz and R=4 ohms, it'll be 1/2Π(120)(4) = 1/3014.4 = .00033174, so you would use a 330 μF cap (a common value) to block the bass at 120Hz. It's not a brick wall filter- it rolls off at 6db/octave and 120 HZ is the -3db point, which means that at 240 HZ, there's virtually no change but at 60 HZ, it's 12 db down and 18 db down at 30 Hz, which is close enough for jazz. If you want to be safe and aren't going to try to peel paint, wiring them in series will give you the same volume as one speaker but because the impedance is higher, you won't get the extra output of having a second driver. If you wire them parallel, you'll add 6db, which is the same as quadrupling your power output. This can also mean that you won't need to turn the volume up as high and may keep the amp from clipping.

jclose- they'll be louder at any volume setting but won't be any more clear. There's no reason for them to be. The cap will, as I said, block DC and DC resistance becomes a non-factor because of that.

Farmer Ted
05-26-2007, 10:01 PM
Thanks guys!

JimN
05-26-2007, 10:41 PM
Clear as mud?