My WT2 works fine. I was somewhat disappointed to discover that I can't work with the program, like look at files and stuff, unless the device is plugged in.
Upon inquiry, I was informed that was their approach to copyright protection.
No big deal for me 'cause I only have one computer, but I'd prefer not to have a bunch of gear hangin' off it all the time....
Here's what I got using the typical -6, -8, and -10 dB taps with 8 and 16 ohm "standard test fixture" loads.
Actual impedance curves of the CD/horn systems would be more revealing. I don't think WT2 can take voltage drive measurements so you'll have to use something else. I think SoundEasy can. I think SoundEasy can also pound out an electroacoustic equivalent circuit. I could be wrong, you'd have to ask TimG.
Interestingly, the rolloff frequencies don't shift (not by the octave I'd expect with conventional LC), but the Q's sure do.
I'd try both driver impedences and see which gave the best response, probably. Lemme see how tough it's gonna be to yank that stuff and haul it over to Mr. Widget's....
4660 crossovers evidence charring where the parallel 39-Ohm resistors overheated. This pair, though not "A" version, has 2425J's in it. Phase of HF driver is reversed from schematic - see yellow/blk going to the 3.9-Ohm resistor there.
RTA response curves of 8-Ohm (top) and 16-Ohm 242xx drivers, 2346 horns, and the least burnt of these two crossovers.
8-Ohms is better, I'd say, but I'd want to try a bunch of drivers to be sure. Looks like the difference in response follows Lancer's voltage drive curves nicely....
I tried measuring the tapped inductors there (right) but get bogus results. They're 3.3 mH across all right, but the measurements at the tap don't add up to that.
The leads from the unused taps are clipped short and twisted together. A bad idea, I'd think; they should not be connected. That relies on the enamel alone to prevent them from shorting. Looks like it held up through the fires there, though....
Insight: The N4660 crossovers are the 3110A circuit with mid set to minimum and HF boost set to max. That crossover was spec'd for 16-Ohm HF drivers.
Bonus tracks: Third RTA curve is with 8-Ohm 2426H running on N3134 (the 4430 crossover) set to "0". I can dial them nearly flat with more HF boost. There's a familiar signature there, tho, too much response at 8 - 10 kHz, sooooo ...
Fourth curve is using "AM" crossover from Quick and Dirties (raised 5 dB). Mighty pleasant sounding, I don't think I'll be givin' high priority to rehabbing them N4660's.
For the 16-Ohm drivers, maybe a tweaked version of N200t3 with HF boost? Sometimes I get lucky....
They won't add up. Please run three WT2 arbitrary plots. Set the sweep from 500 Hz to 2 kHz and the sweep points to 6. First data file should be the two end leads of the tapped autotransformer. Second and third data files should be from the tap to each of the end leads. All the leads should be taken out of the circuit for measurement.Originally Posted by Zilch
I tried measuring the tapped inductors there (right) but get bogus results. They're 3.3 mH across all right, but the measurements at the tap don't add up to that.Yeah, I wish JBL wouldn't do that!If they are cut wrong you end up with an open circuit and have to solder them together.
You are obviously taking the time to study numerous schematics and examine their similarities/differences and impact.
JBL 1.55 mH tapped autotransformer.
Five leads.
For our purposes:
Inside lead labeled IL
First tap labeled T1
Second tap labeled T2
Third tap labeled T3
Outside lead labeled OL
IL to OL = 1.53 mH @ 1 kHz
IL to T1 = 0.37 mH @ 1 kHz ~ -6.0 dB
IL to T2 = 0.53 mH @ 1 kHz ~ -4.5 dB
IL to T3 = 0.78 mH @ 1 kHz ~ -3.0 dB
OL to T1 = 0.41 mH @ 1 kHz ~ -6.0 dB
OL to T2 = 0.27 mH @ 1 kHz ~ -7.5 dB
OL to T3 = 0.15 mH @ 1 kHz ~ -10.0 dB
Target specs were -3, -4.5, -6 and -6, -8, -10
Are you going to run the measurements as asked above and post them Zilch?
Yup. This evening, yet.
Re: 1.53 mH inductor: So, for different attenuation ranges, you just invert the inductor?
[There are people MUCH more clever than me doin' this....]
Thanks to Techbot for gettin' the complete Everest white paper posted.
The really smoked one. They're lucky the church didn't burn down.
1) Top to bottom
2) Top to tap
3) Tap to bottom
Same results as I got with the meter, basically, that I thought were bogus:
Looks like about 30W into the driver would concurrently exceed the 20W rating of the two parallel resistors. How hot they gotta get to set the glue ablaze?
There's no evidence of overheating on the inductors themselves, thankfully.
[It's dumb to put hot melt glue or silicone RTV on power resistors, of course. HEAT SINK would be a better idea....
That'd be pretty loud, tho. They were heapin' a might of praise at 1 kHz to accomplish ignition....
Crazy horn:
Hi fellow forumites,
Matthias and I intend to buy the single 4660 / Everest horn for sale on Ebay. The sole purpose is to make glasfiber casts of it.
It is too early to give the specifics of colour, weight, price, and shipping from Germany, but the casts will be made available to our fellow forumites in due course.
Please don't outbid me ...
Jan D.
PS. Three months ago, we won another auction for an Everest horn, and Matthias paid for it, but the seller never shipped it.
Well, CRAP!
I thought that had been worked out for Matthias....
Ok, so wired in one way you end up with a 10 dB drop (0.3 mH secondary), wired in opposite and you end up with a 3 dB drop (1.7 mH secondary).
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