what cap value for 2 ohm 6x9’s?

Hello, I am new here. I know enough to be dangerous but that's about it. Anyways,...

I have an '01 Pontiac Grand Am with the Monsoon. I have a 12" RF dvc sub & RF punch 400s amp for my subs setup. What I'd like to do is block some of the bass to the stock Monsoon 6x9's They tend to rattle after time as they can't seem to handle lower frequency bass.
Any idea's on what value of capacitor(s) I should use on them?
Any help would be greatly appreciated.

... Sorry, I forgot to ad, incase some of you may not know; the Monsoon 6x9's in question are 2 ohm.
(The Monsoon speaker system is set up as follows; rear 6x9's- 2 ohm / front 4x6's - 2 ohm / rear tweeters - 4 ohm / front tweeters - 6 ohm) I thought that may be of use to someone whom may search this subject

You will need something near 600UF, you will want one that is about 40-50hz at 4 ohms, the frequency will double when you drop it down to 2 ohms.  I couldnt find any at installedge's website, but Im sure there is something out there.

I would first put some hat's on those 6x9's to keep the subs from moving the cones. Next I would add some non-polar mylar caps to the + speaker lead and cut them off around the 150hz mark, perhaps even higher as they are a 6db slope. Nothing wrong with going higher and playing it safe. Here are some values for you, you can see how the scale works with the 3 values I listed, so feel free to go anywhere in between as well.

400hz - 200mf

200hz - 400mf

100hz - 800mf

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Top Secret, I can tell you but then my wife will kill me.

Hey guys, thatnks for the ideas. Looks like I could use one in the range of 525 to 650 uf. Any ideas on where to find one though? Radio Shack jumps from 470 to 1000 uf with nothing in between. :-(

DON'T buy crossover caps at Radio Shack as they are not audio grade.  Try Parts Express or Madisound.

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i have got a 2000watt amp and i my friend is going to sell me two 1.5 caps can u hook them up together or will i have to go buy a 3.0 cap and one other ? i want to walmart and i got the 800watt dub editon speaker is this a good speaker thank you very much

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<33((mike))<33

Mike, that's an entirely different subject.  Start a new topic and follow the forum guidelines when asking your question.  You'll get better help that way.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Everything I have found is geared towards either 8 or 4 ohm. I cannot find a high ebough uf value. Is it possible to run a pair of 250uf capacitors in series to obtain a 500uf value?

(I'd like for my cut off to be at or near 150 hz)

Any suggestions would be greatly appreciated.

Capacitor values are added together by wiring parallel.  Put two caps together and twist the leads together.  Solder.

https://www.carstereo.com/help2/Articles.cfm?id=14 is a crossover calculator.  If you enter 2 ohm for impedance and 150 Hz as the target freq, it tells you to use a 265 uF value.  As you have seen, crossover-quality caps for low freqs get VERY expensive.  I suggest a combination of caps in parallel:  two non-polarized electrolytic and one poly.  100 and 125 uF electrolytics and 40 uF poly.  Bundle them together in parallel to add the values together.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Hehe, I wouldn't suppose it'd be time effective to explain whythe sombo you suggested would be better than this500uf non polar electrolitic?

If it takes to long to explain, I understand.

Ah, I did some research & answered my own question, which leads to another...
If I go with 2 Elect's & 1 poly. will my sound quality suffer at 150hz cutoff? I see it's less of a negative effect on lower frequencies. Will there be a big diff. between this route & going all poly? (I know the all poly route will be expensive but just want to weight the cost versus quality)
Thanks so very much if you could answer this for me. I really do appreciate it. I'm learning way more than I ever thought I would this quickly by joining this forum. This site is just excellence in electronic education!

Glad you're getting benefit from using this forum.  It's a great place.

It's all about prohibitive cost.  You weigh the price with the value it provides.  Most people would install one 250 uF non-pol electrolytic and be done with it.  I would use the bundle of three that I recommended, using the higher quality poly cap as a "bypass cap".  I wouldn't spend the money required for all poly for what you're doing.  And that still might be overkill in this situation because

• you don't know what the actual impedance is at the crossover freq.  It might be much higher than 2 ohms at 150 Hz.  There isn't the supporting test data that you need to have to know what it is.
• using the calc, you can see how the cap value changes according to the impedance at the crossover point.

You'll probably not notice a difference in sound in this application using the different quality caps.  You might have to end up experimenting a bit with cap values because of the question of the impedance.  A non-polarized electrolytic cap is relatively cheap and would be the type you would want to use if you had to switch out the value (had to buy replacement caps).  So, you're best bet is to just put a 250 np cap on each one and see what it sounds like.  If it's not solving the problem, switch to a 150 uF np cap and try that.

OOOPS  I'm going to look this over.  I linked you to a calculator for 2nd order crossovers .

Here's one:  https://www.mhsoft.nl/spk_calc.asp#crossover  First order crossover is indeed over 500 uF at 2 ohms, 265 at 4 ohms.  But I suspect at that freq the impedance is rising rapidly and is well over 2 ohms.  I don't think you would have to be anywhere near 500 uF for your cutoff target.  Try the 250 first because I suspect the impedance is probably closer to 4 ohms at that point.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.