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The 7empest

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I've had these speakers sitting around for *literally* a decade, finally decided to actually build them into something :)

MTM using Exodus Anarchy and Seas 27TDFC.  Enclosure is 2cuft tune to 35hz.  They should dig down to 30hz with ease, so we'll see if I add a sub or not.  The baffle will be removable so that I can easily access the crossover, reuse the enclosure with different speakers or reuse these speakers in a new enclosure. 

I had debated on active vs passive but I'd done active in a car for years.  I've never designed passives from scratch since I didnt play too much in HA/HT, so it's an experience I'd like to try.  I'm intrigued by the combination of art and science that goes into the design of a passive network.  My audio skillz are a bit rusty, so the task is a bit daunting.  But I'm relearning pretty quickly...I think? 

Every DIY project needs a name, right? Decided to call these 7empest.  Why? Well, primarily because TOOL is the most badass fucking band ever.  If you don't understand the reference GTFO my thread (no, seriously....go).  It works because the Anarchys are 7" drivers, and what does a tempest cause? Anarchy.  See.  It works.

My woodworking skills leave a lot to be desired.  Right now as long as these are simply functional I'll be happy.  Baffles turned out nice though :) About the only thing that's gone right so far.  This is where we're currently at.

 

 

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Love the name, can't wait to hear your reactions.

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Nice to see you back!  Do you still have a lot of Design Reference stuff?

 

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25 minutes ago, Tirefryr said:

Nice to see you back!  Do you still have a lot of Design Reference stuff?

 

I have 1 set of the 306P 6.5" mids left.  Thought about grabbing a cheap tweeter and turning them into a little bookshelf speaker for my gym if this turns out well.  

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Sweet build. I've been eyeing the Apollo 7 kit over at diysoundgroup. I'd like to try the Anarchy's out in home or car sometime in the future. 

Edited by lithium

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I thought about ditching the Seas and just going with the Apollo's, but I wanted to try my hand at designing the network.  Who knows, this may turn out to be an epic fail and I'll go that route instead  :)

Just placed my PE order for my binding post terminals, a couple caps, T nuts and a few other things.  Should arrive in just a couple days, so the cabinets should be in a position to start running FR sweeps this weekend or 1st of next week.  I may need a bit of help from Sean when I get to that point.  It's been a minute LOL

I also learned that if you drop some items in your cart @ PE and leave them there without checking out, PE will email you a coupon for 10% off after a day or so ;)

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:dancing:

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Welp, as usual this shit is taking way longer than I anticipated.  Didnt help I had to spend all day Sat fixing my dryer instead of working on my speaker project :wacko:

But, progress was made.  Got my binding post plates installed, baffle mounting bracket pieces put on, holes drilled and countersunk, T nuts installed and started on the cabinet damping.  Also realized I forgot about needing to measure the impedance curve....really wish I'd thought about that when I placed my order at PE  >:(  

 

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what kind of foam is that? 

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7 hours ago, lithium said:

what kind of foam is that? 

Seat padding from the craft section of Walmart :) It's 1" thick open cell 

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Sweet, never thought to use something like that. 

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Can at least start FR sweeps tomorrow....finally

 

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Got my impedance measuring jig soldered up today :)  Pretty happy with how it turned out considering how long it's been since I've soldered anything

 

 

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Here's the impedance sweep for the Anarchy's.  Learned a few things:

1) For some reason tuning ended up being 25hz instead of 35hz?  No idea.  I know it's not a measure twice, cut once issue with building the cabinets.  Measurements there are solid.  I figured I'd be off a few hz one way or the other....but 30% was a little unexpected.  I'd considered that maybe it's an accuracy issue with the measurement....but the Anarchy's are infamous for having a cone resonance around 4200hz which is about spot on in the measurement.  So....

2) I had poly fill stuffed in the bottom of the enclosure to start but when I started measuring impedance I had a nearly non-existent impedance peak at tuning.  Removed the polyfill and the impedance peak looks much better than how it was.   

3) I knew about the hiccup at ~4200hz which is a cone resonance.  Not sure what's going on at 150hz...enclosure resonance maybe?  Internal reflection?  Not sure. 

Anyways.  I had the FR sweeps all done, but going to rerun the sweep for the Anarchy's without the polyfill since based on the Z curve I'm going to be leaving that out.     

7empest Anarchy Impedance Image.jpg

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Okay so I guess this is the starting point for the FR.  We will see how it goes from here :)

Also that hiccup at what turns out to be approx 120hz in the Z graph shows up as a -1db dip in the FR response :/ 

7empest Raw FR Measurements FINAL.jpg

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Weird how much lower the tuning came out, maybe you can seal the port and see where its at for a sealed enclosure. 

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10 hours ago, lithium said:

Weird how much lower the tuning came out, maybe you can seal the port and see where its at for a sealed enclosure. 

Yeah it's a little odd.  But honestly now that I'm working on the xover I'm not mad.  On the woofer side the response is flat down to 30hz with an F3 in the mid 20's.  I can live with that :)  

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So with a little help I came to realize that the dip in my initial measurements from 2-3khz was likely an issue with my measurement system somewhere.  So I went through and created a new cal file to basically pretend it didn't exist :) My new initial measurements look a little different than above, but eliminating that dip in the tweeter response is really the main difference.  Spent way more time than I care to admit working on different xover sims, but I learned a bit each time.  I'm far from an expert but definitely better than when I started a few weeks ago.  Came up with 3 main xovers that I'm going to try.  This is probably my favorite.  The response isn't the flattest, and the reverse null isn't the best of the bunch...but it's the only alignment that is a 2nd order on both the mids (with a tank filter) and tweeter so the part count is the lowest and it's the simplest design.  I think there's something to be said for simplicity.  Guys like Zaph and Jeff Bagby (RIP) always tried to design with the least parts possible. 

I have $160 worth of crossover components on their way to me from PE. to try all three designs.  So hopefully out of that I'll be able to make something that sounds decent :) I just went with non-polarized electrolytics for the caps because, well, they were 1/10th the cost and I'm a tight ass with money, the actual sonic differences are arguable at best, and I may have something in the next couple months that'll require some cash to fund properly.  We'll see.  

7empest 2nd Order Schematic.jpg

7empest 2nd Order Null.jpg

7empest 2nd Order FR.jpg

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Here's probably one of my top contenders as far as phase and response go.  4th order on the woofer with a zobel and tank filter, tweeter is second order.  My last crossover is just a variant of this - slightly different values for some of the inductors and caps to shape the response a little differently.  But overall layout is the same.  I have a 5ohm resistor on the tweeter to drop the response a little to keep it from being on the bright side, but I am also going to try a 4ohm which would bring the response from the tweeter up to pretty close to flat.  We'll see which way sounds best in reality.

7empest Xover FINAL Opt 1 Schematic.jpg

7empest Xover FINAL Opt 1 Null.jpg

7empest Xover FINAL Opt 1 FR.jpg

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Looks sweet. Planning to take measurement or just audition them 

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17 hours ago, lithium said:

Looks sweet. Planning to take measurement or just audition them 

Both.  The other measurements were all done outside.  I'll probably measure these inside just to make my life 183x easier.  

I should have all the parts in by tomorrow.  And I happen to have Mon and Tue off as well :) So I'll probably spend most of the next 4 days demo'ing and measuring them to see what ends up working in reality

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Holy shit dude.  Nice work.  Somehow I completely missed all the measurements.  Work life balance has been terrible lately.  Curious to know what you used although it seems I am really late to the convo.  Out of all threads, not sure how I didn't see this.

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9 hours ago, ///M5 said:

Holy shit dude.  Nice work.  Somehow I completely missed all the measurements.  Work life balance has been terrible lately.  Curious to know what you used although it seems I am really late to the convo.  Out of all threads, not sure how I didn't see this.

Thanks :) I measured in REW with a Dayton EMM6 mic and M-audio Mobile Pre mic preamp. Z curves were taken in Limp.  Modeled the xovers in a mix of Xsim and WinPCD.  Those graphs and schematics are from Xsim because at the time I couldn't figure out how to model the tank filter in WinPCD (although I've since figured it out).

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And, it's alive!  I literally spent HOURS figuring out why I had no tweeter on the right channel.  Finally came to discover that one of my jumper wires were bad :(  It was incredibly frustrating trying to track down the issue, and I dont handle frustration well.  Curse words were said (and muttered, yelled and spewed) 

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