opamp. buffer, or hybrid for mu=1 ?

[baald]

Hi,

i'm designing a bass manager along the lines of the ICBM.
Basic signal path will look like this:

input -> buffer -> summing amp -> (buffer) -> output

I'm wondering what opinions are regarding using a buffer such as BUF643, or using a regular opamp (I'm thinking AD843 for it's reputed bass performance) at unity gain for the buffers.

Also, when used driving line-level signals, should i use a "hybrid" (ie buffer on output of opamp)? Does that fact that the summing amp will be inverted change that advice (specifically re the output of the circuit -- i can use the summing amp out put or put an extra buffer on it)

thanks for help
baald

[myhrrhleine]

Originally posted by baald

I'm wondering what opinions are regarding using a buffer such as BUF643, or using a regular opamp (I'm thinking AD843 for it's reputed bass performance) at unity gain for the buffers.

Also, when used driving line-level signals, should i use a "hybrid" (ie buffer on output of opamp)? Does that fact that the summing amp will be inverted change that advice (specifically re the output of the circuit -- i can use the summing amp out put or put an extra buffer on it)

Personally, I like the op-amp at unity gain method. Something like the OPA134 or AD604.
The hybred is not needed unless you drive really weird loads.
An OPA134 driving an AD811 is a good choice for such a load problem.