PLLXO

neolith · « **on:** 11 May 2012, 08:55 pm »

I recently helped a Maggie owner build a balanced PLLXO for his MMG's. In the process I expanded a spreadsheet I had made for single ended PLLXO's. It is written for LibreOffice (it should work with Open Office as well but I haven't tried it). Once the SE PLLXO is designed, a balanced model is automatically created. I have it posted for download at http://home.comcast.net/~neolith/Stereo/PPLXO1_1st_v2.ods. I want to thank Davey for some guidance with balanced XO's as there is very little info about this as it pertains to audio on the internet.

SteveFord · « **Reply #1 on:** 12 May 2012, 01:34 am »

I can't get the link to work?

neolith · « **Reply #2 on:** 12 May 2012, 04:51 pm »

Sorry, a bit of a typo. Try http://home.comcast.net/~neolith/Stereo/PLLXO_1st_v2.ods.

medium jim · « **Reply #3 on:** 25 May 2012, 03:48 am »

Dead link

planet10 · « **Reply #4 on:** 25 May 2012, 04:39 am »

The link downloads an open office spreadsheet.

dave

Emsquare · « **Reply #5 on:** 25 May 2012, 09:51 pm »

Would someone be willing to import neolith's PLLXO data into Excel? Open Office may be an open source free program but some people, like myself, are hesitant to add more programs to their computers that they're not going to use. This would make it more accessible for people who have an interest in PLLXO's. I hate to see something as potentially usefull as this not taken advantage of.

planet10 · « **Reply #6 on:** 25 May 2012, 11:02 pm »

I just tried that -- doesn't work all that well.

dave

Emsquare · « **Reply #7 on:** 25 May 2012, 11:33 pm »

Nuts. Thanks for trying though. I suppose one can just temporarily install Open Office when needed.

Davey · « **Reply #8 on:** 26 May 2012, 12:14 am »

Try this gents:

http://home.comcast.net/~dreite/Davey/PLLXO_1st_v2.xls

Dave.

neolith · « **Reply #9 on:** 26 May 2012, 01:59 am »

Okay, I transformed the spreadsheet to Excel 2007. The link is http://home.comcast.net/~neolith/Stereo/PLLXO_1st_v2.xlsm. In general, I try to stay away from Microsoft, I run my computer on Ubuntu. I only use Windows for a few programs that just won't run in Linux.

Emsquare · « **Reply #10 on:** 27 May 2012, 01:38 pm »

Thanks offered to both Davey and neolith for making this available. I would wish that a broader group of people would try it for themselves. I don't know if it is one of the ultimate audio accessories but the line level crossover is about the best audio experiences I've ever had.

Davey · « **Reply #11 on:** 27 May 2012, 04:23 pm »

The situation is improving, but I'm still puzzled by the head-in-the-sand mentality regarding line-level crossovers by some audiophiles.

All the tools are here nowadays to assemble a great system in this manner. Abundance of quality multi-channel amplifiers, excellent line-level crossover solutions (both digital and analog), a better understanding of design variable, etc, etc.

You fellas may remember Al Sekela from the other forum. I had fairly long PM conversation with him a few years ago regarding this type of configuration and I even offered to build him a dedicated crossover for his system to evaluate. He considered the idea....briefly....but then concluded the cost/benefit ratio was not acceptable and it made his system "too complicated." Another expensive (matching) power amp would need to be purchased.....another expensive set of loudspeaker/interconnect cables......a speaker-level passive crossover was "simpler".....on and on.
I addressed every issue that he had.....asked him to consider expensive power amps are not required (he could sell his existing amp and get another two for the same money)....consider the cost/benefit ratio of cables

.....consider that (technically) it's a simpler configuration than a speaker-level crossover system....etc....etc.

It was like talking to a brick wall.

Steve (neo), great job with the spreadsheet. It's a nice tool to visualize what's happening with the speaker crossovers, and also help to design PLL's.

Cheers,

Dave.

josh358 · « **Reply #12 on:** 27 May 2012, 05:11 pm »

Quote from: Davey on 27 May 2012, 04:23 pm

The situation is improving, but I'm still puzzled by the head-in-the-sand mentality regarding line-level crossovers by some audiophiles.

All the tools are here nowadays to assemble a great system in this manner. Abundance of quality multi-channel amplifiers, excellent line-level crossover solutions (both digital and analog), a better understanding of design variable, etc, etc.

You fellas may remember Al Sekela from the other forum. I had fairly long PM conversation with him a few years ago regarding this type of configuration and I even offered to build him a dedicated crossover for his system to evaluate. He considered the idea....briefly....but then concluded the cost/benefit ratio was not acceptable and it made his system "too complicated." Another expensive (matching) power amp would need to be purchased.....another expensive set of loudspeaker/interconnect cables......a speaker-level passive crossover was "simpler".....on and on.
I addressed every issue that he had.....asked him to consider expensive power amps are not required (he could sell his existing amp and get another two for the same money)....consider the cost/benefit ratio of cables .....consider that (technically) it's a simpler configuration than a speaker-level crossover system....etc....etc.

It was like talking to a brick wall.

Steve (neo), great job with the spreadsheet. It's a nice tool to visualize what's happening with the speaker crossovers, and also help to design PLL's.

Cheers,

Dave.

This is a constant source of puzzlement to me. We'll spend a fortune on esoterica that yield only subtle changes, but won't spend a pittance on things that make a major difference, e.g., room treatment, bass EQ, bi-amping, and high slope digital crossovers. Even tone controls. Commercial recordings have, unfortunately, huge variations in frequency balance, yet it's more important to avoid the possibility of minor colorations than it is to fix major ones?

Emsquare · « **Reply #13 on:** 27 May 2012, 11:54 pm »

Quote from: Davey on 27 May 2012, 04:23 pm

The situation is improving, but I'm still puzzled by the head-in-the-sand mentality regarding line-level crossovers by some audiophiles.

All the tools are here nowadays to assemble a great system in this manner. Abundance of quality multi-channel amplifiers, excellent line-level crossover solutions (both digital and analog), a better understanding of design variable, etc, etc.

You fellas may remember Al Sekela from the other forum. I had fairly long PM conversation with him a few years ago regarding this type of configuration and I even offered to build him a dedicated crossover for his system to evaluate. He considered the idea....briefly....but then concluded the cost/benefit ratio was not acceptable and it made his system "too complicated." Another expensive (matching) power amp would need to be purchased.....another expensive set of loudspeaker/interconnect cables......a speaker-level passive crossover was "simpler".....on and on.
I addressed every issue that he had.....asked him to consider expensive power amps are not required (he could sell his existing amp and get another two for the same money)....consider the cost/benefit ratio of cables .....consider that (technically) it's a simpler configuration than a speaker-level crossover system....etc....etc.

It was like talking to a brick wall.

Steve (neo), great job with the spreadsheet. It's a nice tool to visualize what's happening with the speaker crossovers, and also help to design PLL's.

Cheers,

Dave.

Are you finding that more people are open to the idea than before? With web searches and audio forums it's far more accessible now. I thought that Rane's electronic crossover primer was very well written. The Rod Elliot article was the final nudge I needed to convince me to try it. Perhaps it is a little too intimidating for too many audiophiles. But it is a little surprising that you couldn't talk Al Sekela into it. That was all too easy for someone like Al. At best it is a weekend project once you have the necessary items for a trial run. No more of a time commitment than taking home a piece of electronics for a home audition. And potentially far more of a performance gain than most any electronics you can substitute. Yes, you can get yourself into trouble or break something. Yes, it can be a little challenging finding the level match between the drivers. But with a little careful forthought and advice this can be reduced to a minimum.

I very much appreciate the spreadsheets provided. I've not studied them as of yet but I suspect that I'll be using them at some point.

munosmario · « **Reply #14 on:** 28 May 2012, 03:48 am »

Dave, apologies if I am missing something, I thought this thread was about a tool to design PASIVE Line Level X-overs (the "P" in PLLXO)....however, your comment in your last post, although alluding to LINE LEVEL X-overs, because of your mentioning "digital solutions," appears to refer to ACTIVE Line Level X-overs which, as you know, are a different animal than PASSIVE Line Level X-overs. As a result, I sense posters are starting to drift away from the thread’s specific topic into the general benefits of bi-amping using ACTIVE Line Level x-overs. To re-focus (to the extend possible), I am quoting below a post exchange you and I had a few months ago on the subject (in another thread in this circle).

All the best,
Mario

Quote

Davey, if i remember correctly, a few years back you were a proponent of passive line level X-overs (PLLXOs) when bi-amping certain Magnaplanar models and, accordingly, you kindly provided design advice to several users. I have a close friend with several decades of upper high-end audio ownership experience, who benefited from your advice and has been extremely successful (to put it mildly) with a PLLXO you designed for him. Davey, putting aside the lack of flexibility--given that a PLLXO has to be designed for specific input impedances of amps being used and specific output impedance of preamp or source (plus insertion gain losses and balancing issues if bi-amping amps do not have same gain)--what is your current position on PLLXOs (with a bit of focus on Maggies, for the sake of this thread)?
Munosmario
[Unquote]

Quote
munosmario,
My current position is unchanged. They're an excellent option.....and especially with Magnepan's since they can utilize fairly simple filtering.
They're easy to design, but like you say, not really flexible.
Cheers,
Dave.
[Unquote]

kevin360 · « **Reply #15 on:** 28 May 2012, 11:53 am »

Mario,

These threads have a natural tendency to drift. Unfortunately, the format of this forum has a more significant impact on that drifting than does the format of, well, that 'other' site. Regardless, I think Dave's comment was general, even though the specific example he gave related to a proposed active setup – line level is the path less often chosen than it should be.

Dave provided his kind assistance to me a few years ago when I gave the PLLXO route a go with my MMGs. I highly recommend that approach with the MMGs and, although the crossover is fixed, it is not only easy to try different component values (hence, XO points), but it's dirt cheap too (a benefit of working in the small signal realm). Regrettably, other changes pushed me back to the dark side, but that's not so bad.

munosmario · « **Reply #16 on:** 28 May 2012, 02:41 pm »

Kevin360, thanks for your kind words….I am fully aware of the “drifting” propensity in AC threads…sometimes becoming an intriguing but fun stream of consciousness that gravitates around the main topic...and sometimes turning totally irrelevant going completely out of orbit.

The point in my post was to bring back the focus on the “Passive” aspect to avoid the risk of a known proponent of the PLLXO approach to inadvertently kill or totally dilute neo’s (Steve’s) thread’s very important contribution. As I am sure you know from experience, the main problem or inconvenience of a PASSIVE Line Level XO is the need to have the adequate resource to accurately calculate value of components…if you do not have the knowledge to manipulate generic CLR circuit design modeling programs (some available free of charge in the net), you will need to bother someone like Davey to get your PLLXO component values every time you change equipment components or you feel like experimenting with different PLLXO parameters.

neos’s spread sheet—hopefully—changes all that. Those PLLXO formulas available in the web can only calculate one XO leg at the time (Hi pass or Lo pass in a two way XO, for example). They are useful only to calculate hybrid PASSIVE Line/Speaker level XO’s (one leg Line Level and another remaining Speaker Level, in the two way XO case). As I said before, prior to neo’s contribution in this thread, to accurately calculate a full PLLXO you were in need to have the skills or access to some one capable to operate a generic CLR circuit design program (or willing to teach you step-by-step how to use one).

Cheers,
Mario

Davey · « **Reply #17 on:** 28 May 2012, 04:07 pm »

Yep, sorry for blurring the distinction between active and passive line-level approaches. My intention was to advocate either option as preferable to a speaker-level approach.

I think part of the "issue" with the PLL approach is the cheapness. Some audiophiles equate "quality" with price, and then some DIY'er comes along and declares you can achieve a superior result with a couple of bucks worth of parts from Digikey.

Eyes roll, eyebrows raise, etc.

The main thing I always highlight to folks considering the passive approach is the potential for unknown variables altering the result from what's expected. Generally, you don't have to consider that aspect with an active line-level crossover.

Cheers,

Dave.

planet10 · « **Reply #18 on:** 28 May 2012, 07:11 pm »

Quote from: munosmario on 28 May 2012, 02:41 pm

As I said before, prior to neo’s contribution in this thread, to accurately calculate a full PLLXO you were in need to have the skills or access to some one capable to operate a generic CLR circuit design program (or willing to teach you step-by-step how to use one).

This resource for PLLXOs has been around for a long time.... http://www.t-linespeakers.org/tech/filters/passiveHLxo.html

Mario

munosmario · « **Reply #19 on:** 28 May 2012, 10:27 pm »

Quote from: planet10 on 28 May 2012, 07:11 pm

This resource for PLLXOs has been around for a long time.... http://www.t-linespeakers.org/tech/filters/passiveHLxo.html

Mario

Sorry Planet10 but those formulas in the link you provided are the incomplete solutions I was referring to. They are not the same as the complete modeling that davey's and neo's approaches provide. Those in your link are simplified formulas that allow for accurate calculation of one Hi-pass filter or one Low-pass filter but do not take into consideration the electric effect on the closed circuit that results from the interaction of the two filters--when operating simultaneously in parallel. To do that using those formulas, you have to perform a lengthy and painful manual iteration which requires the introduction of adjustment parameters (in a sort of trial-and-error fashion).

Davey's computer modeling approach (as I know it--Davey, please, correct me if I am mistaken) provides an optimized solution at computer speed (actually it takes the computer a little while to perform all the necessary iterations before reaching the optimized final solution). It provides accurately the desired cut off frequencies for the desired XO filters when used simultaneously (connected in parallel to the source--including the respective power amps) and while taking into consideration all electric interactions of the filters with i) source output impedance, ii) amplifiers input impedances, iii) gain insertion loses, iv) amplifier gain differences, and v) interconnect resistance (and capacitance if you wish).

I have not tried neo's approach yet, but, based on davey's endorsement, I expect it to do quite the same. Goes without saying, if accuracy in filter calculation is of no primary concern, by all means, go ahead and use those simplified formulas (say, if your listening room is far from optimal, one more random error in the frequency response domain should not matter that much...if you are really lucky serendipity may strike and the errors may compensate).

All the best,
munosmario