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Careful! An EL34 is/was the original version, European, using five electrodes, three of them grids. One of them is called the suppressor grid because it suppresses unwanted radiation from electrons recoiling off the plate. Yes, it was invented, made, and patented by Mullard. A 6CA7 is an...

Hey, Retrovert, do you have the dB/Watt sensitivity for the B200Zc? I'd love to have that to compare with the B200Y!

You seem to be talking about the physical conformation of the tube's elements. What some of us mean by "Winged C" is simply the logo trademark on the glass. There is a "C" for "Svetlana" and a pair of stylized wings at left and right. The importance of this is that the Svetlana EL34 tubes...

Tall & slender vs. short & fat agrees with my experience. And by "wings" did you mean the Winged C logo? The "C" in "winged C" refers to the original Svetlana brand; the "C"being equivalent to a Russian "S" for "Svetlana." The manufacturing was changed from the original factory to a different...

twiii, that's a great post, very helpful, thank you. And if you can dig out the Tobin circuit for the Z tweeters, I'd love to get my hands on it.

This thread is meant partly for my observations, partly for my questions, and mostly for participation by any and all, on the Bozak tweeters. I own a number of Bozak B-200Y (Alnico magnets); and a number of B-200Zc tweeters (ceramic). First of all, my B-200Y tweeters all have a nice...

Yes, I have been busy building them. They are both built, and are now in my basement listening room. Work presently centers on crossover tweaks to get them voiced nicely. I'll get more photos up soon.

I did use birch plywood from Home Depot. It appeared to be of high quality. I encountered just one void about one inch wide and 1/2 inch deep, that showed up on while cutting a speaker hole. I filled it with wood chips, sawdust and glue. No voids on any panel edges. I used it for all but...

I love that custom console with all the McIntosh gear. The B4000 next to it makes it even nicer!

I decided to go with Baltic Birch plywood. Not for looks, but because the BBC made that choice after testing various materials; and because plywood is a bit lighter than MDF. Under construction and coming soon! I think "Mini Symphony" might be a nicer name than "Symphony 1/2!" I'll probably...

Bozak B4000 Symphony; KLH 12; KLH 6; Dahlquist DQ-10.

It could be a difference in how speaker power ratings have been thought of. A speaker might be rated at 30 watts, meaning that that's about what it takes for the speaker to play loud without damage. Or, and perhaps later in time, the rating might be intended to allow more for instantaneous...

Hey, Klipschorn, I'm about ready to put this contraption in the mail. Did you send a PM? I'm not much of an IT guy, don't know where to look for it. I just need to drill one more hole wire it wire it and box it up.

That the B200 tweeters have a foam behind the cone seems to be one of those things that "everybody knows," (like the Leonard Cohen song). Whether it's true, well, I don't know; I never took one apart to see. But "everybody knows," (whoever they are). It looks like the slot does make more of...

Your slot-loaded curves show what looks like about an 8 dB shelving starting around 4K, for on-axis. I'm thinking this could be caused by the foam backing behind the cones. It gets stiff with age--like me. It looks a little more severe, maybe 10 dB, for the 30 degree off-axis curves. Am I...

I think I can set up the test fixture so it will be reversible. It's almost done.

It's about 6ft^3. Minus the volume for the X-over and, if I use the horizontal array, the volume of its enclosure. Minus the cover over the midrange. Yeah, maybe closer to 5 ft^3 then. One woofer. Sealed. So you think it's OK to have the tweeter beams crossing over? Maybe we can try it...

Yep. I feel your pain. I ordered a leather camera case for Italy, and watched the tracking go from Italy to France To London to Chicago with just hours between each step (maybe 8 or 10 to cross the Atlantic). It was in and out of customs in Chicago in an hour, and to St. Louis the next day...

So I cleared my woodworking bench and I plan to work up the tweeter holder this weekend. Looking forward to it. Not sure what you have in mind as a wider assembly. Do you mean to leave some space between the tweeters? Your address for receiving PayPal should be your email address. Best, Rob

I just did order another pair myself. Yes, why don't we go ahead with it. I think the two way shipping cost, in the long run, will seem insignificant compared to the enormous contribution to audio science we are making. I can send you the amount, whatever it is, via PayPal. I ought to work...

@klipschorn: Do you need another couple of B200Zc to make up a four-tweeter test column?

Off axis, the slot seems to smooth out ripple in the frequency response. On axis, it does not seem to. That makes sense: On axis, the waves don't encounter the slot edges; so the slot is effectively not there. At 30 degrees off axis, the slot comes into play. Am I reading it right?

At Klipschorn: Let's go with the melting butter analogy. And let's start with the tube/slot being infinitely short. We are sure that as we extend it's depth, at some point we are bound to hear it. The unknown is just how deep it has to be before it becomes audible. So as the tubes depth...

My interest in diffraction (in the present context) isn't about cabinet edge diffraction. Regarding the slotted tweeter array, I'm only talking about the sharp 90 degree corner where one wall of the slot, e.g., in a 3/4" panel or a 1/4" panel, meets the front plane surface of the cabinet or...