| Re: How can I stop reverb howling on K 100? [message #25343 is a reply to message #25173] |
Sun, 31 July 2016 11:15   |
stevem
Messages: 4758
Registered: June 2004
Location: NY
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Senior Member |
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I did some investigation of the reverb circuit in my K 100-2 rev-1 and my K200-4 who's board with the reverb is a rev-1, both amps where born in 1968 and use the same spec reverb pan.
On my 100 since I got it I have had to have the reverb knob opened up to 1 o'clock to start to hear any verb taking place, on my K200 using the very same pan all I need to do is click the reverb switch on with the knob down and I already have more verb than the K100 at 1 o'clock !
I have checked out the send portion of both amps and they are very close , the 100 will be pushing 4.6 volts into the pan when the amps output stage starts to pull down the power supply , as in clipping, and the K200 will be pumping 4.8 volts into the pan.
The big difference is on / in the recovery amp in the K100 and the K200!
If I drive the recovery amp in the 100 with a 1K tone at -50 DB of unbalanced signal input the output stage is clipping with the reverb pot full open, but only the bottom of the wave form is clipping , the reverb recovery amp needs to hit with -46 DB to start to clip the top of the wave form!
The K200 on the other hand clips at -46 DB , and clips both top and bottom of the wave form equally, and this is with the reverb just clicked on and having the reverb pot fully down!
There is a massive difference between both amps here!!!!
I do not have any more time to dig into this untill the end of the week, but I would have to say that both of these amps of mine have a issue, the 200 has too much verb, and the 100 not enough!
I have a K100-8 who's reverb seems normal that I will check out also just for the hell of it.
Oh, and the K200 is now where near feeding back even when the verb knob is fully open!
[Updated on: Sun, 31 July 2016 11:21] Report message to a moderator |
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