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Blown Speakers? [message #7426]

Mon, 04 September 2006 12:27

twsnell1984
Messages: 8
Registered: September 2006

Junior Member

Hey, this has kinda been addressed 4 million times before but all the info is confusing to put together so i here i go again for my specific situation...

i have a k200 b-1 with what appears to be the original cabinet and speakers (although the speakers are labeled that they are 8 ohms a piece which is not consistent with what i've read on the boards). anyways with the bass guitar volume all the way up and the amp volume at about half way the speakers crackle quite unpleasantly on loud and/or low notes. i've read that this is normal in another post but it sure sounds an awful lot like blown speakers to my ears.

so here are my questions

1. how can i tell the difference between "normal" and blown speakers?

2. if they are blown what is the best replacement without breaking the bank? and is there any way i can up acoustic wattage or volume while doing this? 4 ohm speakers? something else that i'm not aware of? i was looking at jensen mod-15s cause they are cheap but i read on the board that those are bad news. why is that?

3. if this is normal is there any way to get around it? - cause most of the time i really need to be at this volume and it kinda sounds like crapola.

4. also, if "cone sag" is a possible culprit, how long after flipping those babies back over does it correct itself. would it be weeks (or months?) before they corrected themselves? or if it's already damaged are they even correctable at all?

[Updated on: Mon, 04 September 2006 12:30]

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Re: Blown Speakers? [message #7427 is a reply to message #7426]

Tue, 05 September 2006 07:28

stevem
Messages: 4739
Registered: June 2004
Location: NY

Senior Member

Hi,Here hopefully are some cures for you.
1) K200s heads are quite happy with a 4 ohm load, so if your two 8 ohm drivers are now wired in parallel your set.A k200 will output about 35 watts RMS more with a 4 ohm compared to a 8 ohm load which will produce a 1 DB gain in SPL level and is easly heard.
Of course if you are using the cabinet for bass I hope you have at least the CTS standard bass driver and not the jensen c15p guitar drivers.

2) A speaker that is still working, but has a fuzzy sound to it at the ringing end of a note played at low volume is not blown, but for what could be a number of reasons has the voice coil out of alingment and is rubbing in the voice coil gap.
If your drivers surrounds and spiders are well worn than you may be driving the cone to the limits of its travel and getting a crakling sound.
Also a k200s output stage at a half up volume setting is into producing clipping distortion depending on you playing style.
If the amps pilot lamp is dimming pretty well at the volume level you are hearing this problem at than the amp is ok, and if you can see your speaker cones move when you play, and they do not extend out more than 1/2 inch then they should be ok also.

3) As far as replacement drivers go that will not break the bank, The eminence legend model 1518 is about 75 bucks from parts express and is rated for a higher SPL level than the original CTS driver.
If you have about twice that amount to spend than their model Kappa 15 will give almost twice as much clean head room before the amp clips as before.
in stalling 2 12,000 MFD power supply filters to replace the amps stock 4500 MFD caps will tighten up the bottom end more and give the amp a little more range before cipping.
Other than these things the only way to get more volume is to run the RCA jack output on the back of the head to higher wattage power amp( the head can run with out a load fine) OR! drag around another 2-15 cabinet for a true doubling of the sound pressure level(the seperate power amp would have to be 1000 watter to get the same times 2 SPL increase, so a additional 6 to 12 DB gain from better drivers would be my first choise.
Hope this helps you out!

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Re: Blown Speakers? [message #7432 is a reply to message #7427]

Tue, 05 September 2006 08:52

twsnell1984
Messages: 8
Registered: September 2006

Junior Member

my speakers don't appear to be labeled in any way really, is there somehow i could tell if they are the CTS's or not?

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Re: Blown Speakers? [message #7437 is a reply to message #7426]

Tue, 05 September 2006 12:45

stevem
Messages: 4739
Registered: June 2004
Location: NY

Senior Member

The cabinets speaker jack mounting plate will say on it what the cab came loaded with if you can still make it out, or if you open up the cab, a CTS speaker will be marked in a white ink stamping with a 137 and then 3 or 4 other digets.
A jensen driver will have on the mounting frame lip 220 and 3 other digets.
Latter cabs that came with eminence drivers will have in black on the magnets the numbers 038.
Altec lansing drivers, should you be so lucky will have a white cast frame, and have the numbers 391 on the mounting lip.

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Re: Blown Speakers? [message #7440 is a reply to message #7437]

Tue, 05 September 2006 20:46

twsnell1984
Messages: 8
Registered: September 2006

Junior Member

it looks like they might be jensens, i can't find those numbers anywhere on the speakers but the plate on the outside says 'jensen'....maybe they are not the originals.

also i looked at the eminence 1518s, they are definitely more like my price range. are they meant for bass though? do you know anything about the basslite series?

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Re: Blown Speakers? [message #7443 is a reply to message #7426]

Wed, 06 September 2006 07:14

stevem
Messages: 4739
Registered: June 2004
Location: NY

Senior Member

Well all I can tell you is that the original jensen and cts 15s look almost alike, they both have square magents that are bigger than the frame of the driver they mount to, as do the early eminence drivers but the eminence driver have a little bump on the back of the magnet that the others do not.
I have never seen a jensen speaker that did not have the 220 code on the lip unless the frame was very worn or rusted.
Cts driver that I have seen have also been stamped in black ink and when the black oxide coating fades off the back of the magnet, so does the 137 stamping.

Yes the eminence driver is for bass and this model is used stock in tons of other amps. If you have ever played the reissue 300 watt tube sunn amp, this is the driver they use.

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Re: Blown Speakers? [message #7445 is a reply to message #7443]

Wed, 06 September 2006 09:49

twsnell1984
Messages: 8
Registered: September 2006

Junior Member

awesome, thanks for all your help man.

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