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speekerbldr
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Joined: Wed Nov 21, 2012 5:53 pm

The Corellias Eton 5-200/Seas DXT

Thu Oct 02, 2014 5:04 pm

The Idea:My wife wanted something a bit smaller than our current system for the living room. Ever one to jump on an opportunity to build, I was off. I ended up with the chosen drivers because I've always liked Eton and the DXT was supposed to be a good, clean sounding tweeter so I thought maybe the two would play well together. Fortunately for me, it turns out that they do.

This is the final system FR measurement. It covers from 100hz to 20k. Below 100hz is so affected by my room I left that out. My sound card gives out above 18k or so, so the tweeter appears to give out at that point. There is some smoothing to remove the "jaggies." The lines are +/-5db increments. The small final lump in the high end response is real and is visible in the measurements from Seas.
Corellia_Measure.png
Last edited by speekerbldr on Thu Oct 30, 2014 3:30 pm, edited 3 times in total.
 
speekerbldr
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Posts: 42
Joined: Wed Nov 21, 2012 5:53 pm

Re: The Corellias Eton 5-200/Seas DXT

Thu Oct 02, 2014 5:39 pm

Overall the Corellia is a 9L box tuned to just below 50hz with an F3 in the mid 40s. The box/vent allow for an input of about 20watts before reaching Xmax above tuning.

Corellia_Excursion.png
Last edited by speekerbldr on Fri Oct 03, 2014 8:08 pm, edited 2 times in total.
 
speekerbldr
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Posts: 42
Joined: Wed Nov 21, 2012 5:53 pm

Re: The Corellias Eton 5-200/Seas DXT

Fri Oct 03, 2014 10:55 am

The Box: Here's the Corellia, not quite finished, in White. Overall the Corellia has a nice, full sound but clearly, with such a small woofer it won't do loud, bass heavy material without being rolled off to a sub. For those that have auditioned it though, it gets plenty loud with enough low end that each person has said for their usage they wouldn't need a sub for music. H/T is obviously a separate issue, bring your subs! In my acoustic space the Corellia hits it's F3 at right about 40hz.

Corellia_offset.png
Corellia_offset.png (78.39 KiB) Viewed 2026 times
Last edited by speekerbldr on Fri Oct 03, 2014 11:49 am, edited 1 time in total.
 
speekerbldr
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Posts: 42
Joined: Wed Nov 21, 2012 5:53 pm

Re: The Corellias Eton 5-200/Seas DXT

Fri Oct 03, 2014 11:44 am

The Network: When I first decided on the drivers I was hoping for a crossover somewhere in the 1400-1700hz range to let the DXT flex it's muscle and avoid avoid the slight resonant peak in the Eton driver. In my pair, the breakup measures at more like 5k instead of the 6.5k in the manufacturers graph. In the end I just dealt with it and it ends up doing no audible harm to the sound. The peak did, however help me decide on steeper slopes. After several months of evenings and much patience from my much better half, the Corellia network settled into a slightly asymmetrical 4th order design with slopes centered on about 1500hz. The Eton needed a 3rd order electrical slope with a zobel to achieve the desired slope. The 1ohm resistor in series with the 19uf cap provides an extra bit of assistance with the phase tracking. The DXT on the other hand. That ended up being a challenge to both me and to my SoundEasy. A 2nd order electrical slope provided the necessary 4th order acoustic declination. The 20ohm parallel resistor tames the impedance peak and smoothed the sound a bit. Ah. Now the LCR. Not exactly the most simulation friendly circuit I've ever designed. The resistors and the main network components tame most of the "waveguide" peak the DXT has but after that the driver was left with a chunky little lump from 5k to about 12k. A series LCR would easily take care of that but in this case SoundEasy consistently overestimated the effect this circuit had. In the end the LCR was "built by hand" using alligator clips, trial and error and many separate measurements. Eventually I was able to flatten the peak nicely. If needed, the 3.5 ohm resistor provides some upper end tailoring of the sound. It mainly affects 7k and above and has a greater effect the higher you go in frequency. I've used up to 5 ohms and as little as 2.5 on that one. The 20ohm 'resonance trap' can be adjusted too, though it's effect is broader in range and more subtle in effect. I've used anything from 15 to 24 ohms there.
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Corellia.png
 
speekerbldr
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Posts: 42
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Re: The Corellias Eton 5-200/Seas DXT

Fri Oct 03, 2014 8:07 pm

The LCR: Here's an image of the lump left over after applying the cap/inductor to create the HP slope. It's still fairly large and quite broad. This image was taken before I finalized the LCR and the network as a whole. I'm just showing it so you can see what a peak the LCR tames in the Corellia and what will be there should this circuit be omitted for some reason. The blue line is with the LCR left out completely and I don't remember what values were used in creating the other 2 lines. It's clear however, how vital the LCR is in the design.

Corellia_LCR.png
 
speekerbldr
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Posts: 42
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Re: The Corellias Eton 5-200/Seas DXT

Fri Oct 03, 2014 9:03 pm

A Few Comments: This system was designed to replace a much larger stand mounted system using a 7" woofer. I didn't want to sacrifice sound quality even though I was giving up some volume. In general terms a 5.5" won't keep up with a good 7" in terms of F3. I knew that going in and was ok with it as long as the system stayed full and satisfying and if the smaller driver could at least keep up with the larger one in terms of midrange reproduction. So those were my goals. A smaller, full sounding, satisfying system with mids and treble at least on par with what I already had.

So in the end, was the system a success? To my ears and to those that have heard it, the answer has been a resounding yes. The Symphony's are amazingly full for a 5.5" woofer and can surprise you with the bass depth that they have. As I've said before, they aren't for deep bass and loud volume at the same time but as one listener put it, for 90% of the people that would use it for music, they will be more than enough by themselves, the wouldn't even want a sub.

I've always liked the sound that an Eton driver can create in the midrange and the 5-200 is no exception. It's got a wonderful sound. With the tweeter crossing at 1500, it takes on quite a bit of the midrange sound too but the drivers blend very well and together the two produce a much better midrange than my larger system.

But.. Those are kind of expensive for small speakers can they be worth it? Before I had even completely finished voicing the network I called in a long time audiophile friend and had him listen to them for the first time. After an extended listening session he asked "How much are those woofers?" I told him they were about $160 each. His reply was reply was soft and immediate "Absolutely worth every penny" he breathed out. Since he hadn't commented on the midrange at all during our time, I wondered what he'd thought about that. I myself think it's great, but do others? He said this "You know, the mids and highs were so good that after the first couple of songs I stopped listening critically and just enjoyed the music." I considered that high praise for a speaker and especially one so small.

Is the system then a success? I truly believe so and if you want a small set of high end speakers that can do most everything very well, I think you'll be more than pleasantly surprised.

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