CROSSOVER or FILTER?

[xk49w]

<snip>Had the Thumpinator been available when I was looking for a High-pass, I would have bought it instead- the roll off is steeper<snip>

What is the roll off of the Thumpinator? I couldn't find any documentation on this.

 

[1958Bassman]

odk,

yeah, i know what you are saying. that's why i wanted something like a crossover to act at cabinet, that way wherever the frequencies are coming from they would be eliminated.

/s/ Dave

It's always better to stop the frequencies before they ever get to the amp because, even though you may not be able to hear them (or your speakers can't handle them), it wastes amplifier power if you pass them and filter it out at the speaker. The reason so many amps and EQs have a high pass filter is that it.'s not expensive to put it in there and any loss from the filter can be countered at preamp level, with an Op/Amp. Also, passive filters in the cabinet (crossovers are passive filters, too) cause what's called 'insertion loss' and the steeper the slope, the worse the loss is. Usually, it will cost you 3dB, which is hte same as cutting your power in half. Now a good choice. Also, you can't just grab a capacitor that matches the formula- it has to be able to handle the voltage, too. 100W into 8 Ohms works out to 28.3V, so a 25V cap (a common value) won't work for long. Then, there's the issue of how selectively the filter actually works- a simple filter with only a capacitor works at 6dB/Octave, so it's only dropping the level at 15Hz by 6dB. If you want to drop the level at 15Hz by more, you need to add an inductor (coil) in parallel, but in order to not screw up the sound, it needs to be A) large, B) air core and C), not cheap. One alternative is to use an iron core inductor but they don't work in extremely high power applications.

 

[Lonesomedave]

thanks, everybody--keep thoughts coming if you have 'em

from all the aforesaid, i think the thumpinator is the way to go. look at that video from dannybuoy. that thing is amazing and does not seem to affect the sound at all.

i am now officially an SFX disciple.

1958 bassman- i have heard and learned. very helpful

/s/ Dave

 

[sunbeast]

What is the roll off of the Thumpinator? I couldn't find any documentation on this.

It is shown on the graph posted by dannybuoy. Not sure what the exact filter type is, but appears to cut off right below 30HZ. I thought I remembered reading the exact specs somewhere, but would have to dig around to find them again...

 

[IvanMike]

you could always get an alembic sf-2 and use the high pass setting...kinda overkill though if that's all you want to do. A high pass filter before the poweramp will do it, (i'd prefer that to a band pass but i've used band pass types @ 30 hz). Honestly you don't need to go super expensive or get a lot of bells and whistles - just as long as it's a quality unit and can get dialed in right.