Co-axials need to be x'd-over, but at what frequency and internal or external x-over to be used?
To walk someone though this who hasn't done it before, or not very often, what do you guys recommend?
Should a person use their amp's internal x-over set to hi-pass at 80/85/100/120/etc. or go with a decent external x-over? Should they use both? What are your experiences and recommendations?
Thanks
UB
* If these last two posts of mine are too simplistic, repetitive, not informative, etc. please let me know and I'll stop doing them. I just remember starting out and wished that I could find he information as easily as someone can reading through this board.
posted
I personally try to use the internal xovers when ever possible. I prefer the ones that can be adjusted, even like the RF X-cards that must be modified to change frequency. In most installs for everyday listening the internal crossovers do a good enough job to high pass a set of coaxes and lowpass a sub. In the other post I explained how I set the crossover frequency and it really depends on the speaker being used but around 80 for a 6", 100 for a 5", and 120 or higher for a 4" is where I start. Personally I like a lower crossover point for my sub than what is available in an amp so the frequency I use for my components has to be adjusted to avoid a huge response dip.
UB - I think posts like this are a great idea for people new to car audio. I know when I first came to WW I was somewhat afraid to ask the simple questions, so maybe this will help get the new members interested and involved.
In most general (non hardcore competition) applications, a bassblocker capacitor will serve to cross over coaxials just fine for most people.
If the power applied is VERY high, then a 6db slope isn't quite fast enough and they still get a little too much low end, and then is when the higher slope amplifier crossover is important.
Also, using a passive crossover (bassblocker) protects the speaker from defects in the active crossover which might cause it to send killer signals to the speaker (such as power supply failure or some such stuff) and many audiophiles wire capacitors in series with their speakers EVEN if using active filters.
ShadowStar
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Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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posted
I agree with everybody here. Depending on the size of the speaker, your crossover frequency should be between 80 and 150 hz. If they are only 4", try and keep it as high as possible. is they are larger, like 6x9's then you can probably run them to 80 hz. While an active crossover is best, a simple capacitor wired in series with the speaker will work fine, something in the range of 400 uf.
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Posts: 138 | From: London Ontario Canada | Registered: Feb 2000
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posted
ShadowStar, I totally agree! I think that too many people are running active x-overs with no DC protection for they're speakers. What really needs to be done is, in active systems, after the amplifier, but before the speaker, series in a cap of approx. 1/2 of the x-over freq. This will serve several purposes, mostly, to help protect from DC should a catastrophic failure occur in the amplifier. This is especially important for tweeters! It also helps the x-over slope indirectly, making the "knee" tighter. Note, this is not as issue with most subwoofers, they generally tend to take a LOT more abuse then the fragile mids/tweets in use today!
------------------ Sometimes the majority only means that all the fools are on the same side.
Use your ears to judge components, NOT your wallet! K.I.S.S.
posted
I have some Polk DB 4x6 plate speakers in my dash. The amp feeding them is set at 120hz @ 24db/octave high pass.
They came with a small cap to x-voer the tweeter, but I took that out. I bought some DB crossovers that come with Polk's 4" component set. The signal from the amp gets split from the x-over to the mid and the tweeter. Sounds a lot cleaner and it can handle a lot more power.
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