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Modifing some monitor cabs.
Modifing some monitor cabs.
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Old 4th August 2014, 05:10 PM   #1
DangerAZillionVoltz is offline DangerAZillionVoltz  United Kingdom
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Default Modifing some monitor cabs.

Basically they are the mid/tops from a Kam compact vocal 300 active system that I bought cheap, just missing the active sub.
The mid/tops are nicely paint finished mdf cabs.

Already tried them out taking the speakon plate off the back and connecting the bare wire to other wires via a wago connection block.
Surprised the 6.5 inch mid drivers give out pretty good bass and they have large vented magnets with a rubber surround. But are 4 ohms.

The tweeters are mismatched so either will need to change both or add a ceramic wirewound resistor of the right value on the compact bullet tweeter which is much louder and harsher than the soft dome tweeter on the other.

Both cabs are rated at only 50w rms, so might be fine for home dj use, but the occassional house party they might not survive or should I replace the everything including the crossover?
I got 2x Fane Sovereign 6-100 (100w rms) drivers sitting here I could use that go from 60hz-7khz, so what crossover and tweeters could go with them?, cutout hole for the tweeter is about 2 inch.
I'm thinking some not too expensive but nice sounding Monacor or Vifa soft dome tweeters.

I plan to run them off either a Behringer A500 or Samson Servo amp like the 120A. Which ever sounds better for the home dj and occasional house party use. Don't fancy noisy fan/s on a standard pa amp when mixing at lower volumes or poor sound quality.

Last but not least as the cab is a sealed cab I want to turn it into a rear ported cab, what size port would I need and how would I work this out?

I know CPC sell 2 inch ports that are adjustable in length by the user.
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Old 8th August 2014, 12:41 PM   #2
Xoc1 is offline Xoc1  United Kingdom
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The Eminence APT80 is a decent HF unit for not much money. The mount flange is 87mm square so might fit.
Eminence also do a decent passive crossover I would think the Eminence PXB2-3K5 Two Way Crossover @ 3.5 Khz would work OK
Thing is I have already spent 100 of your cash with those 2 items! Have the speakers not got crossovers in them already?
You might need to add some resistors to pad down the HF.

To port the speakers you would really need to calculate the internal volume of the speakers and have the data for the drivers so that you could run a sim in Winisd, Hornresp or another speaker sim program.
If you port the speakers you may gain some lower mid - these cabs are not going to give much bottom end output anyway. Unless you protect the speakers with a hi-pass filter you might reduce the power handing by porting the cabs.
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Old 8th August 2014, 11:34 PM   #3
chris661 is offline chris661  United Kingdom
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IMHO, the best thing you can do here is add a subwoofer, and replace the tweeter to original spec.
A pair of 6.5"s is never going to hold up for party levels, but a decent 12" should.

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Old 8th August 2014, 11:46 PM   #4
sreten is offline sreten  United Kingdom
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KAM Compact Vocal 300 Active Speaker System


IMO ditch the bullet, and find the correct replacement dome
tweeter, or fit two new domes. Don't convert to vented.
Don't replace all drivers and fit new x/o's.

Do understand they really need the active x/o to work well.

rgds, sreten.
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Old 21st August 2014, 08:07 PM   #5
DangerAZillionVoltz is offline DangerAZillionVoltz  United Kingdom
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After thinking again and looking everything I came up with a solution, I would get this active sub:

the box pro Achat 108 Sub A - Thomann UK

Which gives 2x 60w for the sats and sub amp is 100w, which I presume is rms.
Although only an 8 inch sub driver but they say it goes to 40hz to 125hz.

Will only be using it at home for dj monitoring and house parties and for the very occassional small discos which don't play bass heavy music.

As for the tops, I've decided to keep the original 6.5" drivers in them, especially as they are 4 ohms and the internal crossover is 4 ohm,s also I presume.
Strange the tweeters are rated 8 ohms though.

What I need help with is finding the xover point, so I can get some replacement tweeters.
How can that be done?, will a basic multimeter help me find the xover point of the unmarked random crossover?
And it's not the most accurate multimeter either, just an Amprobe AM220.

The crossover features two air cored inductors,one yellow polyproplene capacitor and one cheapy non polarised electrolytic capacitor.

But will take the actual crossover board out later and see if I can find any component values on it.

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Old 24th August 2014, 06:12 PM   #6
DangerAZillionVoltz is offline DangerAZillionVoltz  United Kingdom
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Think I'll just replace everything, crossover I just took out today has no markings whatsoever on it.
And the cheeky company has gone as far as scratched off the markings on the components, so the only way to test the individual components is with a multimeter.
Was just going to do that until I releasised once of the 6.5 inch midrange drivers makes a rubbing sound when pushed evenly.
Either a overheated voice coil or shifted magnet.
And even WORSE the main drivers are held in with screws NOT t-nuts.

Least I got 3x new old stock Eminence alpha 6a that I can use in there. And to t-nut the holes.

Just need the replacement xovers and tweeters now.

Not much room to work in the cab which means only a very tiny xover board can be fitted.
Either I custom build one on a scrap piece of 9mm ply, or I use a compact off shelf one, or the cheap and cheerful approach would be use just a coil on the Eminence alpha 6a and buy a genuine Motorola piezo(I know a seller on ebay that does them but at a price) and suitable resistor for it.
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