# 2 x EL70 plus 2 x SDX7 = hard to beat combination



## mwmkravchenko

I've been working on a semi full range combination of two EL70's plus some bass reinforcement with SDX7's. The EL70's are great but when you really want to crank it up as is concert level steroe or a great movie you need more help than the two EL70's.

So here is the start of the monster. SDX7's are flat to 30hz. Max SPL within excursion limits:

30 watts power input for all pics.































The EL70's will have their own sub enclosure. They will be an almost perfect match to the two SDX7's. So you get the sweet sound of a good full-range with the umph of a decent bass horn.

Will post pics as I have it built.

Mark


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## Mike P.

Hi Mark, great to see you here! Can you give us a rough estimate of the finished box sizes?


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## mwmkravchenko

Hi Mike

Sure ask good questions!

Width 9" Depth 18.5" Height 34"

Floor standers with the horn port to the back. All the sound tailoring in the world should you car to move about a little here and a little there.

Mark


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## mwmkravchenko

I was reading the SDX10 thread when I got to thinking how loud could the low end of this speaker go?
So a bit of fooling in the simulator and Voila:










150 watts input. So if you go Bi-amped this box can really rock.










Still within X-max. If you have a high pass filter you can even go a little louder than this. Not to bad for just under two cubic feet.

Mark


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## Mike P.

The SDX7 design would need to be corner loaded, correct?


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## mwmkravchenko

These numbers are for wall floor junction or two reflections ( wall + floor ). If you go to a corner with a third reflection ( wall + wall + floor ) you can add another 3 db. 

Mark


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## Ricci

Care to post up the parameters for these horns? What are we talking about here TH designs? The simulated responses look pretty good if so.


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## mwmkravchenko

Ricci said:


> Care to post up the parameters for these horns? What are we talking about here TH designs? The simulated responses look pretty good if so.


It's really a double tapered quarter wavelength resonator. A fancy name for a shape like two funnels spout to spout. If you balance everything out you get pretty good response. If you tap a second driver at the right place it works even better.

I'll post some thing tonight. Still have work to do.

Mark


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## mwmkravchenko

As promised the input screen from Hornresp.










If you have the program mess with it a bit. It really is quite interesting.



Here is one way it can look.










As for completion. I've drawn it out full scale but I have a client that wants something else done. SO first things first. 

Mark


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## mwmkravchenko

Hi guys I'm still working to make a living this week and the project unfortunately has to go on the back burner until next week. Next week I'm in the shop all week and I will have time to get this up and running. Sorry for the long wait.


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## mwmkravchenko

I've been working on the design all weekend along with some others. Will post pics and descriptions tonight.

Mark


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## StereoClarity

Excellent Mark! I look forward to seeing the fruits of your labor soon! I've recently finished up an EL70 build myself. I'll post mine up a little later


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## mwmkravchenko

Hi Steven

This design has been taking me a great deal of time. The horn section has been worked on for over 120 hrs to date. The fold is the hardest part with this unconventional shape. But I think I have licked it. Had a cold bug over the weekend and now I have a couple of days of work before I can put the finishing touches on the bass section. Once that is proven I will plunk in the EL70's I have no questions as to how they sound. Bare with me this will be a pretty good box.

Mark


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## StereoClarity

Can't wait can't wait!!!
:yay2:


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## Ricci

Mark,

Do you have any measurements of a completed system yet? Outdoor 2m GP?


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## mwmkravchenko

Working on it. Been crazy busy in the real world trying to make a living. My daytime job alternates between fine cabinet making and general construction. More of the latter than the former as of late. What I want to do gets knocked out of the ball park all to often by the realities of being an evil genius ( LOL ) MONEY! If only I could figure how to mass produce the money all my problems would be solved! I think that may be a little on the illegal side of things though.

But I have some time this week to get things done. On the block is the bass section of this speaker. It is almost ready. Then there is a 4 driver EL70 Bi-Pole surround. After that there is a computer speaker system with 2 EL70 per cabinet in a 7 liter configuration plus a more or less conventional sub-woofer. So busy I am I am.

When I have something to post I will do so mucho pronto!

Mark


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## Ricci

Keep us updated.


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## mwmkravchenko

Not dead yet!

Bass section to be tested is going together today and I will be able to test something or the other tomorrow.

High section is a snap.

Mark


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## mwmkravchenko

Ok gents a bit of an update. The low end of the design is almost ready for testing. 

Here are the specs::reading:










Mark


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## mwmkravchenko

Well gents the tests on the concept design have passed with flying colors and this one is next batter up. 

Problem is now I have to make a set for my Dad! See what happens when you let people listen to good sound. It is contagious! 

The box will be a slimish tower design around 42 inches tall. The height is there so that when you sit down you have the fullrange drivers on axis with you ears. Makes for the best image presentation from the recordings.

Can't wait to put it through it's paces.

Mark


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## Mike P.

Post some pics of the build! :T


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## mwmkravchenko

Not dead yet!

They will be singing this week. Almost done the bi-pole surrounds and these babies ( the EL70 + 2SDX7's ) are next on the totem pole.

Mark


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## mwmkravchenko

Ok now there has been a bit of an adaptation. I'mleaning to 4El70's with their inherent 94 db spl/ watt. This will give me the head room that we all crave when listening to music. Nothing more annoying than a speaker that almost sounds right!

This of course requires a redo of the low end section. I have done the theoretical design but need a practical test bed to make sure I get where the computer tells me I'm going. 95 to 96 db/watt with a floor firing mouth is the goal. That will allow some room for baffle step compenation and a change in height to 42 inches allows the fold and two extra drivers. Maybe even a cool tweeter.. Neo 3 looks like a good candidate.

Mark

Always thinking. A creative mind needs some fertilizer.


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## mwmkravchenko

Thinking along these lines. I want a tower with as close to 100 db/ watt efficiency that I can get. So here is the latest amount of number crunching. I'm going with this one. Eight EL70's in a sealed enclosure sized to create a hump in the response to negate baffle step diffraction. They will crossover to 4 NEO 3's for the high end. The low end below 8o hz will cross over to two TRIO8's in a front loaded horn. 

Large cabinet? Yep but small foot print. As of the latest space requirements I'm look at 9" wide by 14" deep by 60" high. Tall will give you a great sound stage. The horn will be floor firing and good down to 25 hz minus 6db. So almost fullrange. A sub may be needed by the diehards among us. But this is the final version of this beast. crossovers will either be acoustical or acoustical plus low order electrical. So it should sing as sweetly as can be. I made a center channel speaker for Binary a while back with four EL70's. Used full range it is quite impressive. Eight per side will be as close to effortless sound as you can get for a decent price.

Mark


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## Binary

I love my center! Crossed at 80 its absolutely amazing.

I'm glad i went this way with my center, and it seems i'm going to have to audition those towers when mark builds em. listening to the center with some absurdly clean towers will be interesting to say the least. I'm currently using Cerwin Vega M-100's as my mains. and although they are great for parties. they aren't quite as refined as my tastes are becoming. 

But when my other half starts complaining about the bass, i gotta shut the sub off  (its best to pick your battles.) At least the Vega's can still put out some pretty decent movie bass. The EL70's are quite the amazing little speakers. I even tricked my cousin into thinkin the sub was on when i had only the center playing~


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## mwmkravchenko

Hi Adam

I think you have a secret death wish to get evicted! Test in the shop where there is no people. Then listen in the house or in your case your house.

Still think I should go piano black or a fancy genuine imitation veneer?

Mark


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## Binary

honestly, for the amount of work its worth, i'd say piano black. but only because you've got some pretty easy technniques for doing it by spray. It'd probably be faster and less expensive with a finish that i cant do anything but stare into...

Evicted!? naw... just have my equipment damaged by the significant other. lol.

Oh! make that two votes for piano, Laura thinks glossy = sexy.


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## mwmkravchenko

Ok gents this design has morphed so much that it is nothing close to the original aims of this thread. So I will basically declare this thread closed. A new thread will be opened shortly to flesh out the details of the design and the actual design is in the works. So watch and wait this will be a good one. Finally a set of mains to call reference level.

Mark


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