How does a high pass filter and Q-Tune relate with subwoofers?

[ckunke002 10+ year member]

I recently got a boston amplifier and it doesn't really go into any detail in the manual about the q-tune and high pass filter knob that it has.

It simply says "Once the high pass filter point has been determined, use the Q-Tune knob to adjust the bass".

Well, what a high pass filter does is cut out the frequencies below the set point and plays the higher notes, and that is the opposite of what I want to do with a subwoofer obviously. The amp also has a low pass knob which I know how to set, but I'm confused on what to do with the q-tune and high pass knobs.

Thanks for any help

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[06goat 10+ year member]

Nothing they are there for hooking up mids to the amp. My guess is the qtune is like a bass boost. So if anything, barely turn it up.

 

---------- Post added at 06:39 PM ---------- Previous post was at 06:38 PM ----------

 

The amp is a 4chan isn't it?

 

[wenn_du_weinst 10+ year member]

I think the qtune is adjusting the slope of the xover.

 

[zako 10+ year member]

It gives a boost at the high pass frequency plus makes the slope steeper. This could be useful to boost lows if you're using a sealed box. Just look at the middle graph on this page:

PASMAG | PERFORMANCE AUTO AND SOUND - Boston Acoustics GTA-400M Amplifier - Page 2

 

[ckunke002 10+ year member]

Nothing they are there for hooking up mids to the amp. My guess is the qtune is like a bass boost. So if anything, barely turn it up. 

---------- Post added at 06:39 PM ---------- Previous post was at 06:38 PM ----------

 

The amp is a 4chan isn't it?

Nah mine is a monoblock. And do I use it if I'm just powering a sub then? It's not like i can turn off the high pass filter so that's what's confusing me, the knobs are just there.

 

---------- Post added at 08:52 PM ---------- Previous post was at 08:51 PM ----------

 

I think the qtune is adjusting the slope of the xover.

The high pass xover? So if I'm using the amp with a sub what should I have it set to? I don't see how a high pass filter could possibly be used with a sub the way I understand it lol

 

[zako 10+ year member]

Nah mine is a monoblock. And do I use it if I'm just powering a sub then? It's not like i can turn off the high pass filter so that's what's confusing me, the knobs are just there. 

---------- Post added at 08:52 PM ---------- Previous post was at 08:51 PM ----------

 

The high pass xover? So if I'm using the amp with a sub what should I have it set to? I don't see how a high pass filter could possibly be used with a sub the way I understand it lol

High pass filters or subsonic filters are recommended for ported subwoofers. This is because those alignments do not provide excursion control below the tuning frequency. For sealed box subwoofers a subsonic filter is not required, but it won't hurt if you set it at say below 20Hz so you subwoofer does not move air at frequencies below the audible range. Now low frequency response of a typical sealed box subwoofer is gently rolling off as you go lower. Some say that this is a good thing because combined with cabin gain function, you could end up with flat response in car. However, should you desire to have a bit more of low end response, you could set on the GTA amplifier the high pass filter at say 20Hz, and then use q-tune to provide a little boost at around that frequency. If you have a parametric equalizer or a very good graphic equalizer, then this feature is not that important.