Any interest here for PLLXO ?

[MarcelvdG]

This one is meant to be driven from a headphone output, and it mixes stereo to mono. I don't know if Scott ever built it.

https://www.diyaudio.com/community/...b-line-level-calculation.320216/#post-5376188

 

[adason]

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.

If it does not filter for you, do not use it.
Ignore my post then.
I guess my fr response requested by X is nothing.
Yes, lower path is active.
You can't please everyone, certainly not you.

 

[Rob Dingen]

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

Hi Dave I build a lot also and experimented with different buffers discreet, opamp, 2sk170 and a 2sk170 as current source but the best sounding with a lot of drive was the complementair pair of 2sk170 and a 2sj74 with a 20 Ohm trimpot on the sources for the dc offset I did match them.

Rob

 

[MarcelvdG]

If it does not filter for you, do not use it.
Ignore my post then.
I guess my fr response requested by X is nothing.
Yes, lower path is active.
You can't please everyone, certainly not you.

Unless I'm misinterpretating something, the upper path has 0.1 second time constants, so it's a 1.59 Hz subsonic filter. For the record, I have nothing against Sallen and Key filters.

 

[adason]

Buffer, 150Hz passive high path, buffer, passive 150Hz high path.
Not sure how you came up with 1.59Hz.
Measured. Build dozen. One just last weekend.

 

[MarcelvdG]

Maybe I just misread component values; is it 0.1 uF and 1 Mohm, like I thought, or 0.1 uF and 10 kohm? In the latter case, it's a perfectly fine 159 Hz second-order Linkwitz-Riley high-pass.

 

[adason]

Actual response...its 150Hz exactly. Not sure about your equation, but mine is in the schematics. 1Mohm is just to discharge output cap to prevent thump, followed by 10kHz or similar volume pot in power amp.
First high path is 6dB/oct, second close to it.

 

[MarcelvdG]

OK, that explains it. I couldn't read the value of the resistor of the first section, saw that the second section had 1 Mohm and assumed the first had the same value.

 

[pboser]

If one uses a PLLXO for a simple crossover, do you still use a cap at speaker level to protect the tweeter? If so, does that reduce some of the advantage, at least in the high pass section?

 

[adason]

I have recently been using classA amplifiers with cap on output (vfet, f3, lineup) for mid/tweeter section. Absolutely no need for any additional cap for tweeter protection.

 

[Flaesh]

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

Yes, with some succes 🙂 comparing single FR. It was >13 years ago. I don't remember the details

 

[Zvu]

What is your system now ? I remember you were experimenting with large SEOS waveguides.

 

[Flaesh]

SEOS24 with coax (dcx464 now)+15" midbass corner placed, DBA 2+2 subs, trivial minidsp 4x10hd and one channel of DCX2496 for rear subs delay. All boxes sealed. Room is 30'L 14'W 10'H now, the wall visible on the avatar is cutted out.

Back to tread: PLLXO was made accordinly to https://www.t-linespeakers.org, first order IIRC, w\o buffer, HF was FE207 with DHT SE, LF was noname cheap (pseudo)pro 2*12" with ~200W amp.
It was a past life, now I'm *BA bass chauvinist 😎, my DBA tread is somewhere at ASR.