• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

SY/Pete Millett Crossover

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Well, I have this red board that seems to have found its final resting point at 100 WPC using 6HJ5's. It should cover the bass real well. I have a powered sub (SS) with a LPF to cover the bottom octave that the main speakers can't do, and I have several types of plain old green boards that say Tubelab on them in flavors from 2 WPC to 50 WPC for the high frequencies, but I won't even admit to what I have been using for a crossover. I am 110% sure that whatever you two cook up will work better.
 
The world is full of EF91 (I've forgotten what they are in the USA).

I think 6AM6. Actually not very common here. Also 6064. Unfortuately different pinout than all the normal US types. There's always 6AU6/EF94 (low current and cheap) and 6EJ7/EF184, to name a couple...

Did I say I'd be interested in boards? I'd be interested in boards. Even if they're red.

Actually, I'm thinking bright yellow, with black silkscreen.

Think honeybee.

Really.

I could be convinced to invert that (black soldermask, with yellow silkscreen).

Pete
 
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Hi SY, I've been looking for a 2 way that I can use to feed my ss amp <350Hz and my Fairchilds >350Hz.

And really, how much outside inspiration do you need as an excuse to pop open a Belgian Ale anyway? Don't be silly.
 
Surely it's the principles that are important here, not the details of particular valves? We're talking about the differences between two topologies (Sallen & Key vs gyrator). Further, once low-pass and high-pass have been defined, any number of "ways" of a crossover can be built simply by adding more basic building blocks. Having said that, if a standard stereo PCB was formed from a cascade of a high-pass followed by a low-pass (with provision for removing the link between the two), a single board would make a basic 2-way crossover, but multiple boards would make more complex crossovers.

It would probably be nice to include pads for passive baffle step equalisation.

The world is full of EF91 (I've forgotten what they are in the USA).

Did I say I'd be interested in boards? I'd be interested in boards. Even if they're red.

I'm very interested hearing more about the differences between Sallen-Key topology and the gyrator. What is responsible for sonic differences? Why should I go with the gyrator instead of a Sallen-Key design? I am at a decision point myself as to which way to design. I will be building 2 way and 3 way systems and am thinking of a modular construction.

Thanks,

Michael
 
I'm very interested hearing more about the differences between Sallen-Key topology and the gyrator. What is responsible for sonic differences? Why should I go with the gyrator instead of a Sallen-Key design? I am at a decision point myself as to which way to design. I will be building 2 way and 3 way systems and am thinking of a modular construction.

Thanks,

Michael

Billam, JAES v26 n6, p426, 1978, "Harmonic Distortion in a Class of Linear Active Filter Networks"

VERY enlightening paper.
 
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