2 Attachment(s)
2405H purchased for my L200's - are these things legit?
Hello everyone,
I last posted about cutting some holes in my L200 cabinets for 2405h slot tweeters. You all had some great input but life got in the way and I simply didn't have time to move forward with it. I also had some difficulty finding a clean pair of drivers. Well, I finally pulled the trigger and bought what appeared to be a really clean pair of 2405h with original diaphragms! A holiday gift to myself.
They just arrived today. Upon unwrapping the first one, I noticed that it smelled like fairly fresh spray paint. It was easily flaking off. No big deal, but not quite as "mint" as they appeared in the pics and some small paint chips fell into the slot and could be seen on the diaphragm. When I unwrapped the second one, one of the pieces to the left and right of the phase plug (half-moon shaped piece) fell out in my hand. It had glue behind it, looked like Loctite 401, stuck to both the horn and the piece itself. I did multiple searches and could not find a 2405h with one of these pieces removed or missing. Seller told me to glue it back in (which I did), but something seemed a little off about that solution since I noticed paint overspray on the back of that piece and the horn behind it when it was removed. The piece also had a notch on the back of it, as though it was supposed to be resting on something to align it and hold it in place when mounted (with that piece out, the entire horn assembly was smooth, like a 2402).
I decided to take the magnet off and check the diaphragm as neither phase plug was completely parallel with the openings. I found that the alignment pins on the magnet were not present. The holes to receive them are on the horn assembly, but no pins to go into them. This has me concerned that the diaphragm is not aligned correctly. On a more serious note, I'm worried that the horns themselves might be 2402's with 2405 pieces glued in place - that might be just me being paranoid, it just seemed odd that those things would come off so easily and they were packed extremely well.
I'm willing to overlook the paint job and gluing/adjustment even though I paid good money for these, it is worth it just to be done with them. However, if they're miss-matched parts or not authentic, I'm not sure I want to proceed using them in this build. I've attached a couple of pictures for reference and can take more if that would help.
Any suggestions are much appreciated. Happy holidays!
Nik
Glued-on wedges are correct, except on very early version.
Quote:
Originally Posted by
hjames
The front "snout" on those doesn't look right. Something is weird about those front pieces - they should not be glued into place!
I'm at work and don't have access to blow-away diagrams, but - ship them back for a full refund and buy elsewhere!
Glued-on wedges is the factory method of attachment. :yes: The exploded diagram doesn't reveal this detail, as the 2405 horn is an assembled part.
The outer horn is actually an 075/2402 machined casting, with the wedges installed to make the slot.
The inner phase plug (aluminum version) is basically a 2402 casting with a different profile machined onto it.
It's hard to tell from your pictures, but it looks like the horns were re-painted with the wedges removed, then the wedges were glued on again. Glued painted surfaces is probably why they didn't stay put, along with what is apparently a poor job of re-painting them in the first place.
I have one or two very early 077/2405 drivers that actually have the outer horn drilled along the outer circumference and the wedges are attached with a machine screw into a threaded boss on the back side of the wedges.
I'll see if I can find them and post pictures to this thread.
LHS member subwoof posted pics about this some years ago; perhaps you can search his old posts.
He also wrote me about making his own wedges with some clever use of liquid epoxy and masking tape over the 075/2402 horn mouth, pouring the liquid into the horn throat while propping it up at the correct angle and letting the epoxy level itself out and harden.
One thing to watch for:
Most -if not all- AlNiCo ring radiators used two alignment pins to align the diaphragm and outer horn, with 2 alignment holes drilled to accept the pins AND a flat and a deep groove cut into the outer horn for the diaphragm. The groove is cut just deep enough to contain the diaphragm but shallow enough to still clamp the diaphragm's outer mounting ring.
Ferrite versions did away with the alignment dowels, and instead cut a shallow groove into the top plate of the motor to center the diaphragm AND a shallow groove in the outer horn to align the horn to the motor. The alignment pin holes are absent on the later "Ferrite version" outer horn.
You cannot use the early "alNiCo" motor outer horns (easily identified by the presence of the two alignment pin holes) on the later "Ferrite" motors, or the diaphragm outer ring won't be clamped tight and the diaphragm will likely buzz...:crying:
On another note: The ONLY difference between the D8R075, D8R076, and D16R2405 diaphragms is the width of the moving part of the diaphragm, dictated by the width of the inner and outer clamping rings: the 075 rings are narrower, yielding a wider diaphragm, which shifts it's operating range down to ~3KHz and a rolloff beginning ~12.5KHz; the 2405 diaphragm rings are wider, therefore the diaphragm is narrower, with an operating range from ~7KHz on out to ~22KHz.
Credit goes to LHS member 1audiohack for finding and posting the differences between the three aluminum ring radiator diaphragms. :coolness:
The diaphragm material and the voice coil assembly is identical among all three, confirmed by a rare forum post by Mr. Greg Timbers himself. :applaud:
