Hartke TX600 EQ question

[Autobot22]

Hi all, I recently bought a Hartke TX600 amp and am a bit puzzled as to how the EQ controls work. If there any other owners out there, or anyone who understands this stuff, who can answer my question, I’d be very grateful.
The amp has ‘frequency’ and ‘shape’ knobs which according to the manual and various all the on-line resources I can find adjust the position and size of the mid frequency notch. That suggests to me that the frequency is always attenuated, never boosted, at the chosen frequency. But my ears tell me otherwise - it sounds like the shape knob does boosts the frequency once past 12 o’clock. Plus, the manual states that the shape control alters the mid frequency between +11/-3dB. I understand that to mean the knob indeed boosts the frequency up to 11dB compared to 12 o’clock.
Any advice very welcome.

 

[itu]

This is called "semi-parametric mids". Shape attenuates (down to -3 dB) or boosts the selected frequency (up to 11 dB).

Fully parametric would give the possibility to adjust the Q-factor, which is the width of the boost/cut. Here the Q is constant.

You can compare this semi-parametric to a wahwah pedal. While playing, try to turn the freq, when the shape is at zero or 10.

[Autobot22]

One thing I don’t get...even with the shape setting at 12 o’clock (supposedly no boost or cut) turning the frequency knob clockwise seems to make everything ‘louder’. Frequency knob fully anti-clockwise, everything sounds dull and muted, no matter what the shape knob is set at. I think I’ve got cloth ears, as I can’t make it out :-(

[Cuzzie]

Hmmmm is it like a mixture of the old tone stack where 2-10-2 is flat on the EQ and then play from there like the VXL pedal?

If you haven’t started from flat may be a good time to reboot and your from there?

if it’s anything like the VXL pedal there is a nice tone lurking

Edited August 4, 2020 by Cuzzie

[funkydoug]

Yeah I think hartke used a tone stack approach on those amps, so the 'tone dials' are interactive, like on an old valve amp (think vox ac30, fender twin etc). It's not like an  equaliser, where each dial is a separate cut and boost.  There is a good explanation  here: https://www.guitarworld.com/reviews/hartke-tx600-head