I wanted to split some of the discussion off from the Pete Millett crossover PCB thread, but figured it would be easier to start a new one.
Whereas... Pete has never really been happy with his Sallen-Key crossover.
Whereas... I have been more than delighted with my Acheron, a gyrator-based design.
Whereas... I have recently joined Pete in the Great State of Texas.
Whereas... Pete and I are looking for an excuse to get together and do some drinking,
Be it now announced that, if there's sufficient interest, we will be collaborating on a project. Pete has left the grunt design work to me; he'll do the PCB design. We're strongly leaning toward replacing the op-amp gyrators with pentodes, but using the basic cathode follower and servo circuitry from my original design.
Here's the options: this will be a second-order circuit. Most likely to get done quickly is a two way, with the bass section being handled by solid state and the upper section being done with tubes. Sections could be cascaded to give 4th order. If people want the bass to be done with tubes and/or a three-way, that could take a bit longer (my design and bench time are sadly limited these days), but if that's what it will take, that's what it will take. regulated supplies, of course. And single ended, though the enterprising could certainly add input and/or output transformers.
So... is there interest enough to inspire us to put the time in, start the breadboarding, and pop a few Belgian ales?
Whereas... Pete has never really been happy with his Sallen-Key crossover.
Whereas... I have been more than delighted with my Acheron, a gyrator-based design.
Whereas... I have recently joined Pete in the Great State of Texas.
Whereas... Pete and I are looking for an excuse to get together and do some drinking,
Be it now announced that, if there's sufficient interest, we will be collaborating on a project. Pete has left the grunt design work to me; he'll do the PCB design. We're strongly leaning toward replacing the op-amp gyrators with pentodes, but using the basic cathode follower and servo circuitry from my original design.
Here's the options: this will be a second-order circuit. Most likely to get done quickly is a two way, with the bass section being handled by solid state and the upper section being done with tubes. Sections could be cascaded to give 4th order. If people want the bass to be done with tubes and/or a three-way, that could take a bit longer (my design and bench time are sadly limited these days), but if that's what it will take, that's what it will take. regulated supplies, of course. And single ended, though the enterprising could certainly add input and/or output transformers.
So... is there interest enough to inspire us to put the time in, start the breadboarding, and pop a few Belgian ales?
Sounds interesting. I've been looking at triode-based designs, but pentodes could be a possibility. I'm building an Aikido linestage, and there's room on the chassis for a few more tubes. Got any particular bottles in mind? Please don't say EF86, they are like Platinum out here (on the very rare occasion they come up for sale) 
Consider the rest of the world as watching with interest, and may only have access to the likes of Russian tubes for example.
Gary
Consider the rest of the world as watching with interest, and may only have access to the likes of Russian tubes for example.
Gary
Ahh, gotcha. Pentode is cheaper, and so am I.
At line level, the noise won't really be an issue, and a pentode works soooooo well for that sort of thing...
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.
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.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.