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Vifa DX25BG60

Good news, spent a little time today with the measurement rig. These mounted directly into a cutout for the XT25 - which proved helpful. 

They are sort of flush mounted on an 8.5" wide baffle with 3/4" roundover on both sides (not on top edge), centered 3" from top. 

They stand a little prouder than the XT25, so I taped over the edges to help minimize those reflections. I don't think it really matters one iota, though. 



Here is a distortion sweep taken at 97dba at 1/2M:



2nd order dominant, ~50db or greater above 1K on the odd order shit. My guess is with a LCR across the terminals and a proper crossover in place, I see no reason not to cross at 1500. I didn't take it any louder since I am too lazy and sore right now to go diving into my toolbox for a bunch of components. Maybe the next guy can go bonkers with that?

I did take the time to do some compression testing, though. I started at 87db (set using pink noise A-Weighted) and going up in increments of 1db using ARTA built in stepper upper feature thing:



So yeah, that was blasted effin' loud, and it looks like there might be 0.1db of compression on the last sweet or three. Hard to say, though, without doing some more in-depth analysis. Considering I started the sweeps about as loud as most people are ever going to crest speakers designed around a tweeter like this,I would offer compression is not exactly a primary design consideration on this little tank. 

Some whoreizontals:



Some oddities between 2 and 4 because baffle, but otherwise it rolls off like a champ. That is out to 45degrees at some pretty arbitrary setpoints. I will go back sometimes if all of a sudden something jumps out in the off-axis, but the filling in of the blanks is to be expected on a flat baffle, and the void at ~12K shows up fairly early off-axis. Wanna know what I think? I think the way it dips at 12k off-axis will earn this tweeter a sweet reputation for handling Sssssssss - just my opinion, however. 

I was kinda sorta hoping to grenade it on the baffle - I want to take it apart and see how it is built. It performs really well on paper, it remains to be seen how well it can be implemented. While it may not be as low distortion as some other tweeters out there - it measures up where it matters. Keep in mind when I set my levels, I did so to pink noise, A-weighted. I then proceeded to 64K sine the shit out of it. You guys know what thats like. LOUD. TOUGH on Mr. Tymphany. 

For a quick reference, here is a 90db 1M sweep of an RS28 in-cabinet:



Anywhoo, as always my measurements are not to be used as design files as I generally ignore a few things like voltage and quasi-infinite baffles. It is my belief that the DX25BG60 would work as a replacement for the RS28 on a quality level, while offering a smaller faceplate and similar build quality. The cast aluminum faceplate is badass. Your mileage and opinions may vary, but it measures quite well - I think I am looking forward to a project using them. Iron Driver Iowa, anyone?
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jhollanderJasonP

Comments

  • Excellent write up. https://www.parts-express.com/peerless-dx25bg60-04-1-silk-dome-tweeter-4-ohm--264-1478

     Looks like the faceplate is removable. The xt25 tg is similar but once you remove the faceplate it would be difficult to mill out the underside.

    @jr@mac Any chance you can take off the face plate and snap a pic for me please?
  • I can. 
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  • Unless I smoke a voice coil, that is as far as they can safely be torn down. The dome assembly is glued under those wedgey looking doohickies.
    jhollanderdcibel
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  • That looks doable thanks. Maybe ill go that route it may work for xt25s as well. 
  • @D1PP1N How are you coming up with the WG geometry?
  • Css offered to help me draw 1 tweeter up. Otherwise trial my fire. Seems like standard is approx 1.5-2" depth round WG with a oval shaped cup. Probably 6-10" round or try to mimic the diysg seos waveguide shape. Meeting the tweeter flush and the initial angle seem like pretty important dimensions to nail. 
  • Expect to do considerable experimentation. Relationship from surround to throat can play a lot of games, as well. 
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  • Great write up JR.  Thanks for sharing.
  • And one more thing: that face plate looks like a beast.  Remember when the old Lionel train sets had diecast speed controllers built like that?  Now everything is cheap ass injection molded plastic.
    jr@macS7910
  • Might be able to attach it to the faceplate directly and see what that does. 
  • Plastic face plates have some benefits.  The XT was easy to cut and add new screw holes


    jr@macFacegreywarden
     John H, btw forum has decided I don't get emails
  • while offering a smaller faceplate and similar build quality

    I'm fairly certain they both have 4.125"/104mm faces.

  • I've used that tweeter 1/2 dozen times, wonder why I was thinking it used a 110mm. Hmm.
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  • 104mm =~ 4.10"
    greywarden
  • Thanks JR. That was most helpful. I'll have to snag a couple to play with.
  • 104.0000000000000 mm = 4.094488188976378 in
    deadhorse - leviathan - harbinger - shockwave (wip)
  • Get a new calculator?
    ............. could you hum a few bars.
  • SS D2604/833000 per Zaph Audio:



    This looks somewhat similar to the DX25BG60. His are taken quasi-infinite baffle, of course. 
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  • Will you be getting around to giving them a listen?
  • Not for awhile. Cold here, and no heat in my garage :-(
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