Pass Diy High Low Pass Please

[Nelson Pass]

Originally posted by GRollins
I've been holding off in order to let Nelson do his thing.

I would much prefer that you forge ahead. The likelihood that
we will do the same thing is almost nil, and I'm certain that
what you would offer would have more appeal to at least some
of the audience out there.

[macka]

I see where you are coming from, perhaps you can arrange an X*X crossover, that would cause a twinkle in the eye of the diy Egg Heads.

But surely the complexity or flexibility of a active crossover lies in its ability to mimic the passive version of a pre existing system which more oftern than not is tailored for a flat response and discerning listening tests.

For example, at the moment I'm tackling a speaker building project end to end, its a proven pre engineered design from a local USA icon JBL (the 4345 vintage model) so I already have the hard numbers done for me and graphs and the like.

However, the active mode requires a tailored crossover function at 300 hz to match the existing passive crossover which was engineered to account for mutual coupling of the woofer and midrange drivers.

I reckon this is where the real virtues of active filters are. Of course if you are starting from scratch with drivers and all sorts from Parts Express then that's a whole different ball game. A measure system at least as good as Winairr is required to see which ways up and who's who.

Otherwise its the blind leading the blind and no amount of elaborate filtering will help find the right result efficiently, unless you are prepared to age gracefully by trial and error.

Oops, I see the master has arrived, excuse my ramblings please.

Ian

[GRollins]

Nelson's constrained by marketplace realities. His commercial crossover will be used with all sorts of speakers with all sorts of drivers with all sorts of slopes with all sorts of efficiencies with all sorts of...oh, never mind.
I approached the problem with a slightly different mindset. I've got four modules: 6 dB/oct high pass, 6 dB/oct low pass, 12 dB/oct high pass, 12 dB/oct low pass. Rather than use 12's for everything and shorting past the first pole to make it a 6, I just built a separate 6. Two benefits accrue. One is lower parts count. If you know you only need 6 dB/oct, then why bother with the other stuff? The other benefit is a marginally cleaner signal path.
As I said, I've kinda held off on the crossover topic, but I'll put a brain cell or two on how to structure a writeup so that it'll be clear what I did and why.

Grey

[GRollins]

Besides, now I'll have to think up a name.

Grey

[Samuel Jayaraj]

Grey if you would post your schematics (and perhaps, board layouts) before the end of November '03 and this crossover sounds better than this crossover that I am currently using, The Best Active Crossover - Here! , I will complete your crossover and get it to perform on New Year's Eve at a huge party where 18" Horn Bass Bins(12 Nos.), 12" Horn Mids(4 Nos.) and 2" Compression Highs will be blasted to over 6000 watts of power.

Looking forward to the launch;

[till]

Originally posted by GRollins
Besides, now I'll have to think up a name.

as he said: for the name.

Grey pass? HiLowGrey ?

[df]

TranscendentalGrey

waiting for IlluminatedBrideOfZen

[Raka]

Originally posted by Samuel Jayaraj
Grey if you would post your schematics (and perhaps, board layouts) before the end of November '03 and this crossover sounds better than this crossover that I am currently using, The Best Active Crossover - Here! , I will complete your crossover and get it to perform on New Year's Eve at a huge party where 18" Horn Bass Bins(12 Nos.), 12" Horn Mids(4 Nos.) and 2" Compression Highs will be blasted to over 6000 watts of power.

Looking forward to the launch;

Grollins, you won't this let go, will you?
LEt me think about the name... X-oover-ant?

[GRollins]

The best name I've come up with yet is "The Pass-Over" but I downchecked it for several reasons.
Oh, and another thing, in an effort to simplify the project, I'm going to leave out the opamp part. Otherwise, the thread will try to go in two directions at once, what with people wanting to focus on tweaking opamps (either discrete or chip) and others wanting to talk about the filter. Since my opamps (discrete, naturally) use 2N5457s, which are not popular on the site at this time, people would justifiably want to go for 2SK389s--almost certainly what Nelson's using--for the front end. I ended up using Zetex parts for the back end, which wouldn't be too weird...but it would be an unnecessary distraction to try to cover opamps and filters at the same time. Maybe later--after I recover financially from my most recent crisis--I can afford to track down some '389s and reconsider the opamp part of the circuit, perhaps making it a separate thread.
Plus, I'm still thinking about how to structure the writeup so that it will make the most sense to the most people. On one hand, it's just an adjustable Sallen-Key. On the other, if people are new to active filters, it's going to be difficult to come up to speed. I have always regarded filters as the most nuisance-prone, contrary, and just downright aggravating parts of audio, and I'm sure there are others who probably feel the same way. Part of the problem is the way the literature is written, or not written as the case may be. I want to try to avoid the "and from equation 7b, it is obvious that..." mindset, yet still give some meat for those who want to torture the circuit and see what happens if they crossover to a supertweeter at 35kHz.
If this works the way my stories do, once I come up with a name, the rest will follow as day follows night.

Grey

[mlloyd1]

Isn't it obvious? The "Grey Lo"
mlloyd1

Originally posted by till
as he said: for the name.

Grey pass? HiLowGrey ?