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Fitted small J.B.L 5.25 G.T.O's Today as I cant get anything bigger without "Cut and Shut". I remember a artical in some mag about putting these caps in line to cut out sub frequencey's getting to them. About 200 micro farad's if I recal. Got some today from "Maplins".
1. Do they have to be "BI-POLAR"? (these have a - marking one of the "legs"
2. Do you just place it in line with the + speaker cable?
I agree fully. I'm lucky in that my head unit has active high-pass filters on its output, variable from 40Hz to 120Hz.
I currently filter the fronts at 40Hz (believe it or not, they can handle the 40Hz signal and there's an audiable difference between 40Hz and 60Hz settings)
Rears are filtered at 120Hz, and subs have a subsonic filter of 20Hz on them to save unnecessary flapping.
Nick .
What is this head unit you have???
Is it one of the Pioneer DEH series that I want to Buy.
I have a "Soundstream "4. ChannelAmp. 1 x "Punch" 40 Amp. Active" Nakamichi" cross overs.(1 x Mid/High. 1 x Sub)NO THEY ARE NOT FOR SALE !!!!!!! best bit of kit Nakamichi ever made. 1 x "JL" 8 inch duel voice coil Sub and a pair Of "D.L.S" 6.5 with silk tweeters.
ALL SAT IN A BOX. Bollocks cant be asked to fit it all !!!!!!!. Sounds very nice.
This little set will do me for the moment Thought I would try one of these Pioneer units with mosfet amps inside to gige more head room than current Sony 4 x 20(??) head unit.
guys
Where would one acquire caps to do this filtering job??
I was considering buying some sort of x overs to take the lower freqs out of my brothers front speakers in his van as they are very small cones and suffer a lot when he cranks it a bit
Putting capacitors in line sounds like a very easy cheap fix to his problem
Any chance of some more info ??
Thanks
Niall
It's the Kenwood PS970 minidisc unit. Top stuff, love it. I'm almost running the same kit - Soundstream 604, Rockford Punch 200 for subs, bass cube and AudioControl 4XS if I want to go active again...
Used in parallel, it will act as a low pass filter, if I recall correctly.
It needs to be in series, not in parallel. In other words, it needs to be between the speaker wire and the speaker terminal, or cut the positive of the speaker wire and splice the capacitor in.
This page is more use! Note it looks like you need 2000 microfarads to give a 20Hz high pass.
Nick and others
One of the main reasons that I enjoy "SCOOBYNET" so much.Is the fact that since I joined I have found the response to my questions to be amazing .There is such a wealth of information and people taking time to help others.
OK, to start with, in my humble opinion, electrolytics have *NO* place in an audio system bar perhaps the power supply. They are inherently unstable, have massive tolerances, cr*p temperature dependency, the list goes on. Don't do it guys! If you must use this very crude method of filtering then *please* use a *proper* cap, a good high voltage polypropylene will do nicely. But they are BIIIIG and not particularly cheap, that's why most cheapskate audio manufacturers use bipolar electrolytics
As for the position, well you have only *ONE* option, and that is in *series* with the loudspeaker. *DO NOT* put it in parallel, it could blow your amp!! You *only* put it in parallel if you have some means of current limiting; this could be either a resistor or an inductor in series with the speaker, so unless fitment of one of these is planned, fit the cap in series....
What it will do, apart from filtering low bass, is to also add phase distortion to the signal. It will sound different, even beyond the lack of deep bass. Also, it is worth bearing in mind that a series cap relies on its impedance relative to the speaker's. Sadly this is a rather naive assumption, since the impedance characteristics of a loudspeaker are VERY complex, varying from highly capacitive to highly inductive, and also resistive.
That's not to say that it isn't possible to get it right, it just takes time and money messing around with various compenents to get it "right". That explains why high end audio costs so much, these guys have actually taken the time to mess around with stuff until it IS right....
I've maintained for a long time that the best way of driving speakers is direct, no crossover networks, DC coupled, all the filtering done in the pre-stages where things are somewhat more a) predictable and b) controllable. It's not the cheapest option since it will needs loads of amplifier channels but it is invariably the cleanest, given decent quality components.
But as a quick and dirty hack, caps are hard to beat, so you have to make some (again rather naive) assumptions: your speaker impedance will be 4 ohms and will have zero phase angle. Given these assumptions we can work out the correct series capacitor to filter out the unwanted bass....we choose the -3dB point (the knee in the frequency response where we start to filter out frequencies), call this frequency 'f'. We now want the impedance of the capacitor to equal the impedance of the speaker at this point, ie it needs to be 4 ohms. The formula to work out the impedance of a capacitor at a given frequency is one divided by (2*pi*f*c) where c is the capacitance. Set this equal to 4 and you get c equal to one divided by (8 * pi * f), and hey presto you have your value in farads, multiply by one million to get it in microfarads.... BUT remember that the resultant value will only be an approximation because the assumptions made are NOT true.
Capacitors are a quick and dirty, the main reason being phase distortion is introduced into the circuit.
You're also dealing with inductance here, not simple resistance, ... Passive crossovers are a swine to design for this reason, apparently.
BUT! Saying that, it may well be the fix that you're looking for.
The other option is I notice that you are looking for a new head unit. Most kenwood units of the past couple of years have had a filter system called system Es, which allows variable active filtration that applies to both pre-outs and speaker level outputs.
May be that's worth a shot?
If not, try the caps. If you like 'em, keep 'em. If you don't, hoof 'em out. You've probably lost less than a couple of quid from Maplins!
Oh Boy....
You boys are HARDCORE!!!
I thought I had an OK sound setup... until i visited this thread.
Now I think Ive got two plastic cups tied with string
Well, I have a real simple question ...
I want to change my front door speakers (the standard subaru ones are no good.) I have an Impreza 2000. Can you suggest a pair that will not involve me doing any drilling or anything like that...
