Mark V 90 EQ Mod?

[batflash]

Hello,

What would it take to change the values of the frequencies on the Mark Graphic eq?. Is it as simple as swapping out the inductors to other values? Specifically, I'd like to raise the value of the 6600hz and lower the value of the 80hz to about 8khz and 65hz, respectively.

Alternately, if that's not possible, I'd like to modify the values of the eq on each of the channel themselves. Specifically the treble. I'd like a wider Q and higher frequency.

Thanks in advance!

 

[Sicman71]

That sounds like a serious job..... I have put a good parametric eq in the loop to help with those similar freq.

 

[bandit2013]

Is that all? It probably does not matter which mark amp you have, all of the parts associated with the GEQ or the trying to make a bright amp much brighter are all located on the main board. The GEQ only has the slide resistors and a few transistors. You would need to remove the main board to replace the inductors (good luck resourcing them in an alternate value, you may be able to just change the capacitor for a different resonant frequency and how that would relate with the differential amp is also questionable). If you need more sweep or change, you can opt not to use the GEQ and use an external one in the FXLoop instead. There are several wide band GEQ out there. If you want more than what you can get in a pedal, there is the rack mount type as well. Boss EQ-200 is a 10band GEQ from 30Hz to 12.8kHz. I have one and use it with my Royal Atlantic. You can also store several GEQ patters for later reference. You could even combine that with the Mark GEQ for tailoring a rough tone to a fine tone. Never tried it with any of the Mark amps though. Just small adjustments will have an impact. It does also provide a graphic shape of the settings. Too bad it does not show the actual signal. External effect would cost you less money in the short run and long run that modifying the amp in case it does not meet your expectations. Also you can remove the external effect from the signal chain, it is a bit hard to remove a hard mod from the amp.