biamping questions

[till]

At the moment i use a 8ohm 2way sytem with something like Linkwitz Riley crossover at ~550Hz.

I have 2 amplifiers both with identical input impedance 47k ohms, Zen V4.

Could i do biamping in the following way: for the tweeter use a 6nF cap in series at the input and ~36uF at the output in series with tweeter.

For the woofer 6nF at the input in parallel and 2,7mH at output in series with woofer.

Will it work like it should?

[BillFitzmaurice]

In theory yes, though I won't make any guarantees on the value of the input caps. You'll also have to place resistance between the pre-amp and the cap on the low pass amp or that cap will shunt the highs for the whole system. That resistance will cause an imbalance in the signal levels to the two amps.

But a few points. The 550 Hz crossover seems very low in value, so I hope that's not in error. Second, doing this will result in only a total of a 12dB slope, which is not a lot of protection. And lastly the main reason for an active crossover is to completely eliminate passive components in the speakers. I'd just go with an active crossover, and a digital one at that. What digital crossovers are capable of you just can't get with analog componentry.

[till]

Thanks,

My idea was:

I modifiy the original schemtic from www.passdiy.com



at the input section to something for TD2001 horn like






and for the TL1601a A7 like this



The passive component in series with the tweeter i must keep as its the output cap of the amp. The series inductor of the low amp i don´t know if i will reach the same low pass with something like



24k - 12nF - 24k - 12nF

[roddyama]

Just a thought Till. The 2001's must be getting into their resonance range with a xover of 550Hz. I wouldn't expect the impedance to be even close to a flat 8ohms. You might want to run an impedance plot to see how the driver might react to that 34uf cap.

[BillFitzmaurice]

OK, doing it like that will work as that totals 95kOhm or so total isolation of the shunt cap. Both the amps will be happier not having to work full range so IM distortion will be lowered considerably. Again, I can't comment on the cap values, so you should check the frequency response with a dummy load before wiring the speakers in.

I don't work much with amps anymore so I'm a bit rusty on schematics, but it seems that there should be some interstage caps somewhere in there where you could add an additonal stage or two of HP filtering. Anyplace you can do so would help. especially if it will allow you to eliminate filtering at the output. I suspect Nelson might be some help there.