Maplins flogging off 0.5F stiffening caps
11 July 2002, 03:43 PM
#1
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If you want a stiffening cap for £25, hie thee hither to your local maplin electronics where you may be lucky to find the QK81 0.5F capacitor on special offer at £24.99.
(I've just bought the last one in Leeds, so phone your local store to check first...)
(I've just bought the last one in Leeds, so phone your local store to check first...)
11 July 2002, 07:45 PM
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I *think* the recommendation is 1F for 1kW of amplification. I'll see if it makes a difference.
I've never been a fully paid up believer in caps, so this is sorta sticking my toe in the water on the cheap
I've never been a fully paid up believer in caps, so this is sorta sticking my toe in the water on the cheap
11 July 2002, 11:26 PM
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Has saved my speaker magnets from self destructing - as the amps have not clipped with the load.. destroyed 2 sets of Dyn's I think from not having a Farad - but if your not running much bass who knows..
But does'nt stop the lights from dimming.. need a decent battery
But does'nt stop the lights from dimming.. need a decent battery
12 July 2002, 10:15 AM
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Steve....
get a bigger alternator... + something like an Optima Battery.. Im assuming you have decent sized cable 2Awg or similar?? + Uprated the ground on the car??
David
get a bigger alternator... + something like an Optima Battery.. Im assuming you have decent sized cable 2Awg or similar?? + Uprated the ground on the car??
David
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12 July 2002, 12:18 PM
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It's a capacitor.
You need one because it will keep your amplifiers fed with juice better than your battery, apparently.
You charge the capacitor using a resistor (otherwise biiig current draw!) whack the positive terminal onto the battery cable and the positive terminal of your amp using a short cable, and ground the negative terminal.
Also, "RTFM" really does apply here. You *must* use a resistor to initially charge and also to discharge the cap, otherwise you can really do damage. These things have an equivalent series resistance of around 0.001 ohms, which means with a 12V difference in potential it'll draw upwards of 12000 A. This will, if you're sensible and fused correctly, blow the fuse. If you're not fused, I wouldn't like to think what would happen.
You need one because it will keep your amplifiers fed with juice better than your battery, apparently.
You charge the capacitor using a resistor (otherwise biiig current draw!) whack the positive terminal onto the battery cable and the positive terminal of your amp using a short cable, and ground the negative terminal.
Also, "RTFM" really does apply here. You *must* use a resistor to initially charge and also to discharge the cap, otherwise you can really do damage. These things have an equivalent series resistance of around 0.001 ohms, which means with a 12V difference in potential it'll draw upwards of 12000 A. This will, if you're sensible and fused correctly, blow the fuse. If you're not fused, I wouldn't like to think what would happen.
12 July 2002, 01:16 PM
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Similarly on the discharge - its basically a HUGE cattleprod and you really don't want to be touching those nice gold terminals..... (Hint: they will be BLACK afterwards)!
Nick - YHM
Nick - YHM
12 July 2002, 03:51 PM
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Dave
Optima is next on list - I've been told to get the most expensive!
Ground??
Otherwise fine
I have'nt destroyed any speakers lately..... - the previous Dyns - the spider glue came lose - whatever that means - apparently I destroyed the magnet - from Amp clipping... the Genesis amps could'nt hack the current draw....
I only have about 1000 wrms of subs.. I'm gradually getting there..
Martin
Round at Bobs a few weeks ago - as the Farad is situated very close to my rear strut brace and I was removing things in the boot to get at the fuel pump, bob was very, very nervous.......
Optima is next on list - I've been told to get the most expensive!
Ground??
Otherwise fine
I have'nt destroyed any speakers lately..... - the previous Dyns - the spider glue came lose - whatever that means - apparently I destroyed the magnet - from Amp clipping... the Genesis amps could'nt hack the current draw....
I only have about 1000 wrms of subs.. I'm gradually getting there..
Martin
Round at Bobs a few weeks ago - as the Farad is situated very close to my rear strut brace and I was removing things in the boot to get at the fuel pump, bob was very, very nervous.......
12 July 2002, 04:24 PM
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what do you mean by "ground???"
I meant that you need equally big fxuk off cable from alternator to chassis or battery. Battery to Chassis. Dist Block to chassis / or amp to Chassis..
If you have 1kwrms then I would suspect that you have allready done this... Have you had a clamp meter around your cable to see what current you are drawing when in spl mode??
David
I meant that you need equally big fxuk off cable from alternator to chassis or battery. Battery to Chassis. Dist Block to chassis / or amp to Chassis..
If you have 1kwrms then I would suspect that you have allready done this... Have you had a clamp meter around your cable to see what current you are drawing when in spl mode??
David
12 July 2002, 04:25 PM
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nick my only concern is when a garage disconnect the battery for maintainence work..
David
David
15 July 2002, 09:23 AM
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You would possibly still have to recharge the cap when refitting the fuse though.
David
David
15 July 2002, 11:05 AM
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Steve - I bet he was nervous!
As long as the battery isn't disconnected for that long (ie weeks) and you have no problems with the wiring, there's no reason the cap would discharge. Now, if they short something out, there may be a problem.....
As for current draw, I've measured it before on a system with about 1kw RMS and the peak draw was about 175A IIRC. No way a standard alternator can cope with that! Sustained draw was far less, but when the Prodigy CD got going.....
As long as the battery isn't disconnected for that long (ie weeks) and you have no problems with the wiring, there's no reason the cap would discharge. Now, if they short something out, there may be a problem.....
As for current draw, I've measured it before on a system with about 1kw RMS and the peak draw was about 175A IIRC. No way a standard alternator can cope with that! Sustained draw was far less, but when the Prodigy CD got going.....
15 July 2002, 01:36 PM
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most diesel alternators are about @100a I would go for a new alternator and possibly a split charging system... depends on listening would certainly measure current draw and take it from there... also montitor voltage...
David
David
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