I've built an active xover using tl0x opamps using a buffer before the filter stages. The filters are one opamp and two caps and resistors creating a 12db roll off. Now these work fine no problems what-so-ever. Power supply is via two 9v battery packs all built into a 1u case. The input from the dac goes into a pot which then drives the buffer stage which drivers the filters which then drives the amps.
Now I recently got some opa627's and a few opa2134's from BB or TI. Now I breadboarded the opa627's to create a new buffer and filter for the trebble section. I tested this and it worked fine I used it for a couple of days with no problems. Then I acquired some ad797's, I knew these might cause some problems but tried them anyway in the place of the filters op amp. This wasnt a success, so I replaced the opa627's this didnt solve the problem which confused me. So I built the whole lot onto a vero board, using two opa627s as buffers driving two more opa627 for trebble and a opa2134 doing the bass. This half worked, the buffers worked no probs driving the power amp directly and by passing the filter. All the filters also worked independantly of one another with no buffering. Add the buffers and each section works in mono, but try to drive the left and right channel together and it doesnt work. Also if the active xover is powered up and the amp isnt when the amp is turned on (brought out of standby) it thumps like a small pop which shouldnt be there. The buffers driving the power amps dont produce this but all the filter stages do. Im confused by all of this, as all the op amps work, and the circuits are as simple as they get. I think it might have somthing to do with earthing? but Im not sure. I know this may seem a bit vague but does anyone have anyidea what could be wrong?
Any help would be appreciated cheers Matt.
Now I recently got some opa627's and a few opa2134's from BB or TI. Now I breadboarded the opa627's to create a new buffer and filter for the trebble section. I tested this and it worked fine I used it for a couple of days with no problems. Then I acquired some ad797's, I knew these might cause some problems but tried them anyway in the place of the filters op amp. This wasnt a success, so I replaced the opa627's this didnt solve the problem which confused me. So I built the whole lot onto a vero board, using two opa627s as buffers driving two more opa627 for trebble and a opa2134 doing the bass. This half worked, the buffers worked no probs driving the power amp directly and by passing the filter. All the filters also worked independantly of one another with no buffering. Add the buffers and each section works in mono, but try to drive the left and right channel together and it doesnt work. Also if the active xover is powered up and the amp isnt when the amp is turned on (brought out of standby) it thumps like a small pop which shouldnt be there. The buffers driving the power amps dont produce this but all the filter stages do. Im confused by all of this, as all the op amps work, and the circuits are as simple as they get. I think it might have somthing to do with earthing? but Im not sure. I know this may seem a bit vague but does anyone have anyidea what could be wrong?
Any help would be appreciated cheers Matt.