Bi-Amping with dual DIY ST35's

[MLVA123]

I am going to build a second ST35 and then drive my woofers on the new one and use my first kit for the horns. What do you guys think of a mod to include a crossover circuit? Any reasons why / not to include it within the amp chassis? Or is it better to use active crossover and split the input signals?

[Shannon Parks]

What do you guys think of a mod to include a crossover circuit? Any reasons why / not to include it within the amp chassis? Or is it better to use active crossover and split the input signals?

Mike, I am no expert on bi-amping by a long shot. I am a Googler, though, and "bi-amping + active + passive" seem to dredge up a ton of info. I do know a few guys have built their stereo 35's for the purpose of bi-amping, but I haven't heard how they were setting them up. Maybe I'll shoot off an email to one of them.

Shannon

[Thermion]

You may want to wait and build a set of eiclones for the woofers. They will have more bass punch than the ST35, and you will still have the sweetness of the EL84s on the tweeters. Sounds like a great combination for bi-amping.
:headbang:

There have been some articles in Glass Audio with active tube crossover designs. I will try to find the year and volume.

JT

[EWBrown]

This is on Gary Kaufman's site:

http://www.the-planet.org/active.html

Keep it hollow-state...

/ed B in NH

[EWBrown]

Another (cheaper) approach for the tweeter / midrange half of bi=amping is to reduce the value of the input cap and the 2 caps for the grids of the EL84s, from 0.1 uF to a lesser capacitance appropriate for the desired frequency.

Xc = 1/(2*PI*F*C) F in Hz, C in Fd,

or Xc = 1,000,000/(6.28 * F * C) F in Hz, C in uF

/ed B in NH

[MLVA123]

Perfect Ed!
Just what I was looking for! Now if I could have adjustable capacitance, so I could 'tune' the crossover frequency....

[Guest]

You may want to wait and build a set of eiclones for the woofers. They will have more bass punch than the ST35, and you will still have the sweetness of the EL84s on the tweeters.

How far away are the red boards from being available? I think i'm going to drop the cash for the blue board, but i'd entertain the tought of building EIs instead if they're not too far from availability.

Thanks,
drew*

[Shannon Parks]

You may want to wait and build a set of eiclones for the woofers. They will have more bass punch than the ST35, and you will still have the sweetness of the EL84s on the tweeters.

How far away are the red boards from being available? I think i'm going to drop the cash for the blue board, but i'd entertain the tought of building EIs instead if they're not too far from availability.

Thanks,
drew*

The best answer I can give is October-November for production boards (yeah, September is almost here). Don't worry - 98% of the work is done and they'll be worth the wait! It's going head-to-head against an Eico HF-87 this Wednesday.
Maybe I should post a pic soon...

Shannon