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Pop sounds with a k-250 when switching off? Plus a bit of hiss at all times... [message #15942] Sun, 10 July 2011 20:32 Go to next message
trembling_blender is currently offline  trembling_blender
Messages: 5
Registered: July 2011
Location: Glasgow, Scotland
Junior Member
Hey folks,

A total newbie here so firstly want to say hey!! Came across a really nice, all be it slightly roadworn, k-250-2 with matching 4x12 cab on ebay last week, hence i bought it! I saw Mike Campbell (of the heartbreakers) play one back in '99 and after all this time i finally found one over here in the UK.

So, all in, its looking like a great amp...a bit unusual in that it has a red voltage regulator (a rare export model perhaps?) but i was so lucky to find this with the matching cab. Just a few questions...

1. Every time i switch it off, it makes a really loud pop. Is this a fault? It'll just be a major issue when gigging..i'll know to unplug the speaker, but i'm thinking the sound man or other band members won't hehe!

2. The top right speaker magnet is cracked all the way through, and the top left is ever so slightly loose by 1mm or 2mm...being as its a 4x12, one speaker being completely useless is not an issue, however could this be causing the problem?

3. At all times, there is a very slight 'hiss'...not a fuzz, not a distortion, but a 'hiss'. It's in no way over powering, but having not gigged with it yet, i'm thinking it might be amplified through the PA. Is this another issue?

4. Sadly, it came with no wheels...having already order the standard fender amp casters before realising how heaving the whole rig was, i'm reluctant to invest in another 4 heavy(er) duty casters. When they arrive, will the standard fender casters hold the load OK?

Sorry for the questions, but i'm really excited about getting this on the road...hopefully you can help!

Thanks,

Ross

[Updated on: Sun, 10 July 2011 20:35]

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Re: Pop sounds with a k-250 when switching off? Plus a bit of hiss at all times... [message #15943 is a reply to message #15942] Mon, 11 July 2011 07:25 Go to previous messageGo to next message
cassent5150 is currently offline  cassent5150
Messages: 341
Registered: August 2009
Senior Member
Warm Welcome to the place. Congrats on the find, I know you'll enjoy it!!! Popping at power up and power down is common. Maybe not not so much in the extreme loud, but common. Could be an imballance in the power filter caps, they could have drifted apart in value over the years. It shouldn't be a problem for the speakers to handle. The hiss is also a common thing in most all Kustom amps and many owners have gone to great lenghths to eliminate it, but for the most part its normal. The rollers really should be mounted to a steel plate the whole width of the cabinet and then mounted to the bottom of the cabinet. They take a good beating so the heavier the better. If those Fender rollers are the heavy duty pop in or removable kind where you mount a flange in the cabinet and they just pop in, they should work fine.

Steve C
Re: Pop sounds with a k-250 when switching off? Plus a bit of hiss at all times... [message #15947 is a reply to message #15943] Mon, 11 July 2011 14:21 Go to previous messageGo to next message
trembling_blender is currently offline  trembling_blender
Messages: 5
Registered: July 2011
Location: Glasgow, Scotland
Junior Member
Thanks so much for the quick reply! Great to hear its basically functioning as normal. Yup, the amp casters are the pop in fender ones, the bars you mentioned are still present so i can just drill into themfix the caster cups that way. Now, my major problem....

I was hoping to gig with the amp this sunday but after playing it for a while today ivd noticed something pretty disturbing. So, aside from the odd scratchy pot, all the knobs work correctly. But...when plugged in to any of the 4 inputs (and im playing chords or digging at the strings) im getting a slight volume drop followed by a bit of crackle. When playing softly, it doesnt seem to be an issue. The best way to describe the sound is like a dying 9v battery, and its more apparent when i start playing hard.

Have you heard of this before and have you any idea what it might be? Ive got a pretty big gig this sunday and my local amp tech is away on holiday (i probably wouldnt have got the amp back in time anyways). Basically, im stuck betwen a rock and a hard place! Is it worth me getting contact cleaner or compressed air? I just dont know.

Please help! Sad
Re: Pop sounds with a k-250 when switching off? Plus a bit of hiss at all times... [message #15949 is a reply to message #15942] Mon, 11 July 2011 18:27 Go to previous messageGo to next message
pleat is currently offline  pleat
Messages: 1452
Registered: June 2004
Location: Belding, Mi
Senior Member
Welcome to the site. I was reading that you have some speaker issues which may be adding to the drop in power. The cabinet if still original speakers and wiring, would be 16 ohm speakers wired in Parallel to make a 4 ohm total load cabinet. If some of the speakers are not working correctly, it could change the impedance of the cabinet, and may be adding to your problem. I'd get good speakers with the correct 16 ohms and make sure the wiring is correct. The best amp in the world plugged in a cab with bad speakers is not going to give you the sound that it could. The other thing I'd check is the white connector plugs that connect all the circuit boards to one another. I've seen more problems solved with a good cleaning of the plugs. I once had a guy give me a power amp that he said was dead. I cleaned the plugs and it runs great. Kustom sent out a dealer memo on the plugs and suggested to cut them out and solder the wires direct to the boards.
The red labeled switch on the back would be an export model. I've seen a few here in the states for sale, but I guess it would be more common overseas.
pleat
Re: Pop sounds with a k-250 when switching off? Plus a bit of hiss at all times... [message #15953 is a reply to message #15947] Mon, 11 July 2011 21:59 Go to previous message
cassent5150 is currently offline  cassent5150
Messages: 341
Registered: August 2009
Senior Member
Diddo on that comment pleat just mentioned about those molex cables that connect the circuit boards together. They will cause alot of issues if they get oxidized. Get you a can of deoxidizer cleaner and do all the plugs a couple times like pleat mentioned. I can only add that it could also be a loose fitting pin connection also in one of the plugs. This was not a good design for the long haul and the best remedy is to solder the wires point to point like the earlier models. If you have a small jewelers screwdriver you can bend in the contacts of the plugs so they fit tight again if cleaning doesn't do the trick. Make sure you have a good speaker cable and the jack in the back of the speaker is cleaned and tight. Did you try running the head in another speaker cab to see if you get the same results?

Steve C
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