Any interest here for PLLXO ?

[coresta]

Hi ! I've been working successfully on this type of crossover and ask myself if somebody would be interested in using these on a home multiway system ... I'd see a "plug and play" black box with a CF tube amplifier inside .
Freqs would be fix ,12dB slope only.

 

[badman]

I've thought about using PLLXO- I can fairly easily add 2 more channels to my big class D amp to do so.

 

[planet10]

I use PLLXO all the time. Each needs to be specific to the application. Usually 1st order. Adding a tube buffer is a can of worms.

dave

 

[PeteMcK]

1st order works well with well behaved drivers for the woofer/mid xover, but if you need to add a buffer for higher orders, you might as well go fully active...

 

[planet10]

but if you need to add a buffer for higher orders, you might as well go fully active...

I am not so sure about that. I have yet to find an active topology that doesn't intrude... mind you i haven't tried everything.

I am intending on experimenting with buffered PLLXO ... buffered with something like B1 like circuit

dave

 

[PeteMcK]

re:"mind you i haven't tried anything" - me too, I'm happy with the 1st order pllxo in my system...

 

[planet10]

re:"mind you i haven't tried anything"

That should be everything, not anything.... i have tried a lot of stuff. All op-amp based thou. Salen-Key, State Variable, and an op-amp buffered PLLXO are among those.

dave

 

[coresta]

ok , i tried many solutions, and decided to swap OPamps ... but each PLLXO needs an input buffer , so the tube solution seems to be the best . http://retro-forum.com/viewtopic.php?f=14&t=15223&p=95390&hilit=PLLXO#p95390

 

[hasselbaink]

ok , i tried many solutions, and decided to swap OPamps ... but each PLLXO needs an input buffer , so the tube solution seems to be the best . http://http://retro-forum.com/viewtopic.php?f=14&t=15223&p=95390&hilit=PLLXO#p95390

Hi Coresta,

This looks like a very special and rare application. Looks like there are inductors in there as well.

More generally speaking; my experience is that when applying a PLLXO you need a preamp with enough gain and low output impedance because of the insertion loss in the filter.
2. order filters are doable as long as there is gain enough in the amps.

Best
Kris

 

[coresta]

Kris , gain is mandatory in RCRC structure ... according to my filters shown, reactive of LCLC cells give a very weak insertion loss.... and astonishing good sounding results ! that's the interest of my project !

 

[SAC]

I am running four way stereo speakers off PLLXOs, a mix of first and second order.

Insertion loss is handled through use of a couple of OEP brand transformers. Transformers work great if the preamp has enough clout. I imagine a passive preamp for example would not work with this solution.

I use an Excel spreadsheet to calculate the values needed and printed a chart for easy reference. I have however heard such a calculation works for one crossover, but that multiway xovers change the math and then it gets really complicated. I think Minidsp would suit my four way open baffles better.

 

[tiefbassuebertr]

I want to know commercial products in this kind - the only that I found on the web is this:
http://vinylsavor.blogspot.com/2020/04/the-passive-line-level-crossover.html
https://www.marchandelec.com/xm46-pllxo.html
Thanks for advices.

 

[planet10]

PLLXO with chokes require very large size chokes which might be difficualt to find or make, Thomas likely made his own.

dave

 

[MarcelvdG]

Just being curious: what does PLLXO stand for in this context? I immediately thought of a phase locked loop with a crystal oscillator, but that's clearly not it.

 

[Zvu]

Passive Line Level X(cross) Over

 

[MarcelvdG]

Thanks!

 

[Zvu]

I think that member @Flaesh uses it for some time with success.

 

[adason]

Passive line level crossover works best when buffered.
Like this:
https://www.diyaudio.com/community/threads/simple-active-crossover.368702/page-4

 

[AllenB]

Back in the day, avoiding buffering was part of the goal.

tiefbassuebertr, would you be prepared to design your own?

 

[MarcelvdG]

Passive line level crossover works best when buffered.
Like this:
https://www.diyaudio.com/community/threads/simple-active-crossover.368702/page-4

If you refer to post #62 of that thread: what is passive about it? The lower section is a second-order Sallen and Key active low-pass filter and the upper section essentially doesn't filter.