Cascading Followers

[mashaffer]

Is there any reason one can not/should not direct couple cascaded CFs like this?

 

[rayma]

Should work ok.

 

[PRR]

http://www.tubecad.com/articles_2001/Tube-Based_Crossovers/Tube-Based_Crossovers.pdf

 

[JMFahey]

Just curious about what musical program will go through that extreme lowpass filter and what will you drive with it.

You want to communicate with whales or do some sismographic research?

 

[mashaffer]

Subwoofer. The first 1st Order (right after summing amp) is a switchable slope to partially compensate for driver roll off. The next is a 2nd Order at 50Hz.

This could turn out to be kind of fun.



That label on the curves should read subsonic...

 

[PRR]

What is the distortion in U3 when driving that 500 Ohm load?

(The 6dB-12dB loss may be a hint.)

 

[mashaffer]

Yes, I mistakenly thought that I needed the Zout of the driver to be roughly equal to the Z of the filter for it to work properly. Though increasing the impedance makes for larger inductors Hammond does have the 155C at 60H for only $15 each which allows for nearly 10k impedance which reduces losses significantly.

I am also thinking that it might make more sense to locate the infrasonic in the main preamp to keep any record warp or cartride resonance out of the main amp.

 

[Fenris]

Why differing values of cathode resistors for each of the two input tubes?

 

[mashaffer]

Just an oversight. I changed one and forgot to change the other... [Insert sheepish grin]. ☺

Looking further at this idea I think I like Steve's active version better for this. Also I think that the infrasonic filter belongs in the phono preamp as that is where the need originates.