808Bs in a Model 19 clone kinda thing

[airboss]

Greetings Lads and Laddies:
It's been awhile since I've posted here. Got all tied up in big yachts etc. No room for big speakers.

I'm accumulating drivers for "a" version of my favorite speaker of all time. I was able to obtain a pair of reasonably priced 808-8Bs (symbiotic label) that I'll be using with my H811B horns.

Looking over the forum I've seen lots of conjecture and smart thinking about crossovers. There are two "apparent" mod 19 crossover schemes out there. Quite different in form factor. I dunno about function. Most are bypassing the hi-cut feature and inserting a "preferred" fixed value for mid cut. I don't see 35 ohm L pads available anywhere anyway.

The original literature says the 802 was an 111.7db at 1 watt driver. The 808-8B is a 104db at 1 watt driver. Hmmmmm. Will it still be that low with the 34647 diaphragms? Bill is doing them at GPA, along with re-coning my 416s

Boxplot generates a very simple one inductor, one capacitor and two resistor fixed pad for the horn. I don't think the program will allow me to export the scheme to show you for that one, and anyway, I'm inclined to build the original N1201-8A except that the horn driver isn't the same so the scheme isn't the same. See? Conundrum eh?

Somehow I doubt that I'll need horn attenuation so much as horn boost but I don't know what the numbers are for an 808-8B with a 34647. Time to e-mail busy Bill or does someone know?

Oh, most important, what order crossover is the N1201-8a? 6db/oct, 12db/oct, 24db/oct etc.

Your most kind and gentle responses will be very much appreciated. Oh, the boxes will be as close to the MOD 19 plan I've found as I can get them. Did anyone re-draw that in clean form so a guy can read it? If I could get a clean file, or even a large one, my nephew can blow it up as big as I need on his printer/plotter at work. I suppose I could re-draw it but all I have is Visio which will do it after a prolonged and dangerous wrestling match.

Danny Hall

[GM]

808-8B + 34647 = 802-8G, ergo efficiency is the same for a given horn. The earlier 802 rating was measured on a much larger, higher gain horn than the G's 511, so it's an apples n' oranges comparison. That said, all the 802 AlNiCo gauss published specs I've seen have been the same, so factoring in that early 802s are ~tonally balanced in A7 apps without shelving, they apparently are ~104 dB eff. on 511s also.

So, in an M19 clone some shelving will normally be required even if backed up against a wall, making cloning the N1201 with its adjustable CD horn EQ seem a good plan, though for highest SQ, substitute the pots for fixed resistor L-pads once dialed in.

It's a hybrid to account for time delay, CD horn EQ, so not a pure anything.

Cab and XO plans: Jeff Markwart's Corner - Phase Corrected Crossovers

GM

[airboss]

Thanks GM:
Most clear, especially after reading the Markwart's stuff. I'm going to drive these, for now, with a very early (am/fm simulcast) Harmon Kardon receiver. (6V6 type) I'll have to go to work on the noise. Normally that doesn't bother me much as I'm just a casual audiophile. Mostly a musician. Stuff hums. But Jeff's cautions indicate I'll have to sub in at least some metal film 1 watt Plate resistors and be very careful about grounding.