Help- How does one defeat bass boost in Keiga KG5230 300W plate amp?

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Chasmo57

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Joined 2021
#1
Hi. Veterans members I need your help.
I've had a pair of Keiga KG5230 300W
subwoofer plate amps for ages. Now I have a project to utilize them, (including some DSP) however, specs say they have a built-in (4db?) boost @ 25Hz and that's not needed with DSP.
Years ago, I had a diagram and verbal instructions from Madisound on this very thing, but lost all my archives in a Windows XP hard drive failure.
Does anyone here recall which resistors to change (& what values)?
Thanks for any efforts!
-Charles

Edit: Photos added (hopefully) to help jog your memory 🤔
 

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#3
Okay, some good luck😎 I emailed my pals and one actually found found a diagram in his files, saved as "Keiga.gif", so I hope it helps. Still not sure which resistors.(or caps)need changing. Appreciate help.
-Charles
 

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#4
Chasmo57 said:
Now I have a project to utilize them, (including some DSP) however, specs say they have a built-in (4db?) boost @ 25Hz and that's not needed with DSP.
Click to expand...
Charles,

The PDF from Madisound
http://madisound.com/pdf/keiga.pdf
says "4dB boost @ 25Hz, 15Hz High pass".
Although neither may be needed, you can simply adjust the DSP to the inverse of the boost and no change in the amp would be needed.
If the bottom woofer in your 3 way is ported, you will also want a steep HP just below Fb (box tuning).

Being rated for 4 ohm operation the Keiga KG5230 will probably be OK with dips to 3 ohms, it's over-current protection may kick in if driven to hard at too low of an impedance. Keep the heat sinks vertical and exposed to circulating air to keep it cool.

Art
 
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#7
BRILLIANT! 😀
Exactly what I was looking for. I prefer to defeat the boost in this manner, since I have a limited number of parametric bands in my DSP and want the automatic room correction feature to have all bands available.
Thank you, tikiroo!
-Charles :worship:
 

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