Hartke Bass Attack
This is a really old thread. But since I just spent some time messing around with my bass attack, thought I'd throw in my 2 cents. Hopefully, other members looking out for more info on this pedal can use this thread as some sort of reference.
To begin with, this pedal is not true bypass. (I initially thought it was.) The EQ part of this pedal is forever going to be switched on. Though it has a pedal switch that says on/off, it is no way true in the truest sense of the term on/off. So even if you have got both LEDs turned off, the bass attack will colour your tone. That said, you can actually use the Bass Attack as an EQ pedal if you so wish. =) Though, you can get a smaller EQ pedal. =P
As mentioned by bro Z3r0_G, the pedal has an overdrive function to it however it may or may not float your boat. This function is accessible through the Harmonics knob. I have found that for a warm and punchy sound, you might just want to go easy on the harmonics knob. Just a little notch would suffice in giving you some warm tube tones. Of course, to each his own, and you may want to spend some time on this magical knob to figure out what truly floats your boat. As always, if you're nitpicky and have the change to spare, getting a separate OD pedal would be a good investment.
Adjusting the Harmonics knob though, will affect how you may want to adjust your Brite and Mix settings as when you engage the On/Off switch, these three will be activated (along with the EQ). I have found through fiddling about (Admittedly I am not 100% certain on this.) that playing around with the Brite setting will give your tone some transparency. Transparency here meaning to say string noise (plucking, finger movement, pick attack) can be heard.
The final key in this trinity of knobs is the Mix knob. The Mix knob essentially sets just how much of the dry signal you want effected. However, this is not a touch and go knob. Tweaking it too much can result in a sound that's too gritty or dirty. That said however, as the Mix knob is in the trinity of knobs engaged by the On/Off switch, you will have to adjust the three in tandem.
Now the Shape knob, is another magical knob that you might want to play around with for sometime. You can get a variety of tones from playing around with it. It is a preset EQ sweep, ranging from 90Hz to 1kHz, applying a notch filter to the selected frequency setting of the EQ curve. Some people say the change is not noticeable (I was one of them.) I suggest when you test this pedal out to well... not to go easy on the amp's master volume. Or you could use a good set of headphones and then you'll notice it. Tone has always been a matter of preference and awareness I feel. And some of us, can get quite impatient in searching for it. So be patient, and you'll hit gold.
So if you've been patient in reading my write-up, you will find that with this baby, it's all about being patient and fiddling around with it. =) I apologize for my less than stellar write-up on it but I do hope that it will help you someway or what in making your decision on it. Cheers!