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Location: Latitude 39.56819, Longitude -105.080066 | GK 400RB-III Bass Amp Head, good working condition and clean. 240 watts at 4 ohm, 150 watts at 8 ohms…continuous variable speed fan, 4 band active EQ with 3 voicing filters, effects loop, XLR out with ground lift and pre/post switch, tuner out, mute switch
Excellent condition
$300 + shipping |
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Joined:
April 2004
Posts: 13303
Location: Latitude 39.56819, Longitude -105.080066 | bump |
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Posts: 68
Location: Malden, Massachusetts | Bump?
Or did you mean "Thump"?
Does it "POP" thru the speaker(s) when powering up / down?
http://toddh.net/music/gk/ |
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Posts: 13303
Location: Latitude 39.56819, Longitude -105.080066 | It's been sitting on a shelf in the closet for the last year or so. I will have to take it out and power it up to answer your question. Gimmie a day! |
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Posts: 68
Location: Malden, Massachusetts | Are you out of the closet yet? |
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April 2004
Posts: 13303
Location: Latitude 39.56819, Longitude -105.080066 | Just took it out this morning but haven't fired it up yet. I will make sure I do that tonight. |
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Location: Latitude 39.56819, Longitude -105.080066 | OK....yes and no.
It does not pop the speakers with my 2x10 cab but it does pop with my 15" cab.
What that means, I haven't a clue. |
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Posts: 604
Location: Tampa, FL | Did you try it more than once with each?
If not, it probably means you tried it with the 10" first and then the 15". Probably had some residual voltages hanging around after the first power up or maybe pre-warmed tubes.
Just a thought.
Alternatively, it could mean that it pops a 15" cab but not a 10". :rolleyes: |
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April 2004
Posts: 13303
Location: Latitude 39.56819, Longitude -105.080066 | Yeah...switched it back and forth several times.
I have to admit, every solid state bass amp I have ever had, popped the speakers to some degree. I remember talking to Ampeg about it years ago and they said it was just the nature of the beast and no harm was done. I did find it annoying. |
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Location: SoCal | Call up GK and ask them what they find acceptable.
Fishman states in the manual for the Acoustic Performer Pro that the pop at turn off is normal and causes no damage. |
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August 2004
Posts: 604
Location: Tampa, FL | In the early days, most power supply designs simply placed a switch in line to either a transformer, or a rectifier circuit of some sort. Depending on where in the line cycle you switch it will have a pretty dramatic affect on how the overall amp powers up and the pop you hear are the transients caused by uncontrolled application of power to the sections of the circuit.
Today I think the effect might be diminished by various junk that goes on the gozinta side of things (power factor correction, soft-start etc.). All of this stuff has a tendency to emulate the slow warmup cycle of tubes. Also a general awareness that the pop can be annoying could be all that it would take. A lot of times, this sort of stuff is simply the result of nobody pointing out to the design team that certain things are annoying. |
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Posts: 1673
Location: SoCal | The GK has a 5 second mute at turn on.
I assume the noise is at turn off.
GK would be able to tell you what is acceptable within their design. |
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Location: Upper Left USA | That 's why every Company needs a Board of Fans like us! |
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Posts: 604
Location: Tampa, FL | Generally the power supply filter capacitors will provide a gradual power down (on the order of 100 ms or so) so that any transients your likely to get will be in the single digit hertz range. You might feel it, but you're not likely to hear it.
Then again, I don't have much experience with these particular devices (musical instrument amplifiers) so I could be blowin' smoke. Just offering general electrical observations. |
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April 2004
Posts: 13303
Location: Latitude 39.56819, Longitude -105.080066 | The simplest solution is to have the volume turned off at power on and again at power off.
When the volume is off, there is no popping.
Actually what it is, is the speaker expanding(??). You see the cone flex out. No volume at power up means no popping/flexing of the cone. |
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FOR SALE - GK 400RB-III Bass Amp Head
