adding tone control to active crossover

[Dan2]

i hav just built up Rod Elliott's 2 way crossover (project 8 http://sound.westhost.com/project08.htm) and got one channel working perfect (low pass and high pass)

i am not using a preamp, in other words i have the computer sound card output going to the XO which then goes to a 4 channel car amp (no eq or filters)

i tried converting the last stage of the XO (the buffer) to the tone control circuit on Rod's project 94 (http://sound.westhost.com/project94.htm)

i didnt put in the circuit around U1a - that just looks like a gain control and i dont need that.

attached is kinda what i tried (i doesnt work, there is no music coming out from the low pass channel, just a buzz)

PS the buffer is still connected on the high pass side - i cropped that out of the pic by mistake

 

[Dan2]

ok so i guess that wont work, i will just have to build a seperate pre-amp.

 

[Nico Ras]

ok so i guess that wont work, i will just have to build a seperate pre-amp.

Only low bass comes out of the bass XO, the tone control does nothing in this position. The tome control must be before the XO.

 

[Dan2]

thanks Nico for your reply.

i know the treble setting of the tone control wont work on the low side of the XO, but why won't the bass work?? if for instance i play a low note through a preamp it still boosts the bass, isn't that kinda the same as the circuit i made??

i am just trying to understand these things, and i also want to have the lowest component count as possible.

just thinkin now - maybe i should use the input buffer with the tone control - that should work, right???

 

[Nico Ras]

thanks Nico for your reply.

i know the treble setting of the tone control wont work on the low side of the XO, but why won't the bass work?? if for instance i play a low note through a preamp it still boosts the bass, isn't that kinda the same as the circuit i made??

i am just trying to understand these things, and i also want to have the lowest component count as possible.

just thinkin now - maybe i should use the input buffer with the tone control - that should work, right???

Dan,

first tell me what you want to achieve because if it is the gain of each of the XOs you want to vary then rather do it with the feed back resistor ratios. If it is purely a tone control then it is best fitted befor the buffer feeding the XOs.

The reason you may not see a change now could be that the tone control turn over frequency my be higer than the BASS XO then you will have no effect when it is behind the XO because this filters the signal.

Nico

 

[Dan2]

ok, i have a pair of AIWA speaker that a friend gave me. they are bi-wired, have a midrange driver and a ported subwoofer driver (the port is in the front with the bass driver hidden inside the box.

this XO i got from Rod Elliott's site, and has a crossover frequency of 300hz. after trying it out i think 300hz is too high for the subwoofer, but i also don't know how low i can take the midrange driver. but anyways i digress......

so, as it is now i have connected my comter sound card to the XO, then to a 4 ch amp. with winamp EQ i can just get it to sound ok, but stil lacks a bit of bass. i think think the hi-fi system that came with these speakers had quite a high gain EQ, so that is what i need to achieve.

my friend reccommended the TDA1524 (datasheet: http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/1/TDA1524.shtml) for a pre-amp. maybe i should slap that in before the XO.