AFL woofer section

[Erik Mandaville]

Until I am able to get the 10AWG wire to wind my own, these were under $10.00 each. Large, heavy, with very fine/thin laminations and large AWG winding. 2.5mH with a DCR that is lower than any choke I have of the same value. I need a finer meter than I have to get the actual DCR. Toroid core chokes of the same mH are probably similar to this as far as DCR.

Midrange and tweeter sections have been placed but not attached to their own board.

[Erik Mandaville]

In addition to winding machines, if one still wants to do it by hand (me), I have been amazed at the number of calculators available online. Only final testing and tweaking by ear is going to optimize a network (as far as preferred sonic attributes, not whether it looks ideal on paper), but there is a considerable amount of information for those interested.

[Erik Mandaville]

It suddenly dawned on me that I had done an AFL network previously, that time using a variable rather than fixed L-pad on the squawker. It was in a thread I suggested an idea to another forum member regarding a certain connection in a type of network. At that time, I was using an SE OTL I had built for yet another forum member, and initially like the results. What I remember about that other autoformerless (AFL) design was that the slightly higher order (12dB) in the tweeter resulted, at least in part, in mildly dulled/veiled sound over time. I used the slightly sharper cutoff for some extra protection for the K77 since I was experimenting with a slightly lower crossover point.

This time around, with the seemingly rather higher output from the BEC tweeters in this fixed L-pad, narrow band pass design, I have decided on a steeper slope, still -- 18dB/octave. This will provide again some added protection due to the even lower x-over point, but probably some mild reduction due to possibly increased insertion losses.

That earlier bandpass, which used a variable L-pad control rather than two fixed resistors, was not a narrow band-pass design like this latest attempt. It was within the *window of qualification* for a narrow BP, but one was not used. I used the calculated figures for upper and lower limits for the general bandpass, but did not make further adjustments needed for the other, which would have been more suitable. However, I did make those provisions in this new network, and is the reason behind my winding my own coils. That older design looked like this:

[Erik Mandaville]

Looking at this, I don't know why I made mirror images of the things. All that did was kind of confuse me when making the driver connections. A hot soldering iron was more handy than a pencil, so I just branded the pos. and neg. markings right into the wood. Part of this network became the experiment done to compare a true autoformerless narrow bandpass to the type 'A' network, which, as much as I liked it before (and it is still a good network), uses a highpass (only) on the squawker.

Here's the newer version that was posted earlier in two channel, and the very latest, completely new one will be posted later today. I found I bought a resistor of the wrong value for the midrange L-pad, so need to get the right one this morning.