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DIY K-Horn / EV Sentry frankenstein speakers

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colebb

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hello all!

I made a post in the general Speakers forum and it was suggested I post here as well. This post is also intended as an update to my previous post, linked here:
C

Thread 'DIY klipschorn clone frankenstein project'

hello all!

I recently came into a pair of corner speakers based (somewhat loosely, perhaps) off the original klipschorn platform. I know they'll be a bit of a project and I'll be planning on replacing essentially the entire top hat (or at least the internals). I know that it's very unlikely that I'll achieve something close to identical to a true k-horn but I'm hoping to get as close as I can while also achieving the best possible sound within my constraints.

First question, aside from checking for obvious physical sturdiness and inspecting the joints of the bass bin for any obvious...
  • colebb
  • corner horns frankenstein klipschorn
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since my last post, I ended up deciding upon the EV sm-120a horns and I picked up some EV 1824m drivers to go with them. I also bought a pair of the Crites CT-120 tweeters.

I still haven't had a chance to lug the bass bins up from my garage to my apartment where I have a couple of corners to put them in so the assessment of the bass bins is still pending. I did notice that the woofers appear to be 12" so I'm half-expecting to need to buy new woofers and expand the mounting hole to accommodate, but I'll cross that bridge when I come to it. another option would be buying (or building, though I expect it to be outside of my skillset) another set of bass bins which already have the right size holes for 15" woofers. I've had that option in the back of my mind as well, in case the bass bins I have don't end up being well constructed enough).

given that the midrange horns (and, depending on who you ask, the drivers) are straight from the EV Sentry III and IV, and the tweeters are quite similar (as far as I understand) to the Sentry's T350, and given that the Sentry IV crossed with the woofer at 400hz, I think these components could fit well with the K-horn bass bin clones that I have. I know that the mid-horn combo I have is usually crossed closer to 500-600hz but the Sentry IV does cross it at 400 (which is why I chose the Sentry IV's crossover). it's my understanding that by mounting the SM-120 onto a baffle might help extend the low end a bit and make the 400hz cross sound a bit more full.

I also picked up some crossovers from the Sentry IV. I've had one person suggest to me that I should instead pick up some type AA or ALK Universal crossovers in order to tap into the classic k-horn sound (which I am indeed a fan of).

I've also been considering opting for a Pioneer SF-850, as I found one for a bit cheaper than the passive k-horn crossovers I listed above, and I like the idea of being able to mess around with values to suit the drivers a little more closely. I also believe I have three amps available to me (which I believe would be necessary if I wanted to use a three way active crossover).

I'd be happy to have any feedback about any and all of this. I'll edit this post to add a few pictures, as I've taken a few since my previous post, though really all I've done is mount the tweeters in the top hats that came with the speakers and then drop the mid horns on top of that. my plan with the mid-horn baffle would be to make it as wide as the existing top hat; no plans in mind yet regarding aesthetics but that is pretty low in my list of priorities.

thanks everyone!
 

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22frank said:
What is in that box between the bass bin and EV SM120A? My EV SM120A above the stock K400/K77
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the box is the top hat that came with the khorn clones I initially purchased which set this adventure into motion.

the tweeter I have mounted in there is the Crites CT120.

I think that I've settled on the ALK Universal III crossover for this set. it might not be the last crossover I get for these speakers but figure it wouldn't be too hard to resell if I decided to upgrade in the future. I'd read in a few places that the Pioneer SF-850 can color the sound in a negative way (unlike the more expensive Pioneer D-23, which I'd like to pick up someday in order to tri-amp my bozaks (pictured below the SM-120 and top hat in my photo)
 
yeah the initial pair of speakers I picked up (for peanuts) are a homemade "clone" (in quotes because I do acknowledge that they're not an exact copy). I finally got them up into my apartment last night and they sound pretty good, though due to my baseboards they can't get right up against the wall. I'll probably build some false corners in the next few weeks, which should help a bit.

depending on how good they sound once I get the false corners on there, I have been considering picking up a pair of Bruce Edgar-built khorn cabinets that are for sale (last time I checked, at least) and then getting some 15" woofers. but to be honest, they sound pretty good as they are right now, so I may talk myself into waiting until I actually have the money to spend on new woofers ;)
 
If the 1824 have the phenolic diaphragms they'll top out at 7k or so before they start to drop. But they'll do 500hz no problem.
 
I'm hoping to cross them at 400hz on the low end. the data sheet for the sm-120 does specify 500hz as the low crossover point but the ev sentry iv crossed it at 400hz (and the data sheet for the 1828m lists it at 300hz so I think it'll be ok)
 
It'll work, but may get honky. It'll be interesting to hear how it works out for you, I've long enjoyed my 1823m, but every attempt to get them that low failed. Never got my hands on a set of sm120 though...
 
I appreciate the input and I'll certainly let you know how it ends up working out. from what I've read, the horn itself helps and I'm hoping to make a baffle with ~8" on either side which should help a bit with the low end, though we'll see how much difference that makes
 
hello all!

I'm back with what might be a bit of a silly question (please forgive me if so; I've still got a lot to learn).

I noticed the other day that the woofers currently installed are 8 ohm, whereas to my knowledge, Klipschorns and EV Sentry IVs (and, crucially, their crossovers) rely on 4 ohm woofers. if I'm understanding the physics correctly, using a woofer with 8 ohm impedance with a crossover built for a woofer with a 4 ohm load effectively moves the crossover point to a lower frequency (please correct me if I'm mistaken on that). there's part of me that's pretty tempted to just buy some Crites woofers, though the woofers themselves seem to be in decent enough condition and if there's something simple and cheap I could try first, I'd love to postpone needing to buy new woofers until I've got a lil more money saved up.

can I just add an 8 ohm resistor in parallel with the woofer or will that reduce the power to the woofer too much? I believe that's possible but again, I may be misunderstanding the fundamentals.

and if so, would it be better make adjustments to the crossover or is it fine to add it to the woofer terminals?

also, I recently (impulsively) picked up the Minidsp UMIK-1 calibrated microphone in order to at least be able to empirically assess the different stages in development of the fine tuning of these speakers (I am not planning on using any sort of software-based or digital EQ / room correction; the calibrated mic is strictly for taking measurements). I'll post the SPL graph of my first measurements if anyone is interested.

the SPL graph does show a pretty considerable dip around 300-400hz, though I suspect/hope that correcting the impedance mismatch may help with this a fair bit.

thanks again to all of you for the help and input!
 
I bought used Cornwalls that had 8 ohm woofers & they sounded like crap.

replaced them with correct 4 ohm woofers and they have been singing ever since

It makes a big difference. No you can't just add a resistor
 
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