***Full Range Driver Build***

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Peter J

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***Full Range Driver Build***
« on: 26 Dec 2013, 03:48 am »
Danny, if this is too far astray from your circle, perhaps you can move it to appropriate place. Since you've got some full range drivers on the horizon, I thought this might be interesting to some.

Some time ago I bought 2 pairs of Mark Audio CHR-70s from a poster here. This was around the time Danny was helping me with Desktop speaker and I was kinda taken with full rangers at the time.  They sat and sat...and sat.  The idea's been cooking in the back of my mind for some time. Some of you know I sorta like contemporary looking stuff and the metal drivers just begged for this look...well, in my mind at least.




I took this design,



but wanted to give it a different look, so ordered some panels from a supplier for fronts and backs



and changed the port to side slots, (probably violating some cardinal rule of speaker design)







With prefinished material, the mating of parts is a little different. I machined a "furniture joint" to conceal the joint between box and front/rear.







 I prefer to cut driver rabbets and thru-holes with templates, here's a sequence of shots on how that's done. I make the template with Jasper Jig











Assembly is a little different too. Can't have glue oozing all over, so  a small bead of PL Premium and just enough glue in biscuit slots to get the job done








More later as I progress.

jcotner

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Re: ***Full Range Driver Build***
« Reply #1 on: 26 Dec 2013, 04:02 am »
Man I sure do like your shop.
Of course it may be because we have a lot of the same tools.  :D

lacro

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Re: ***Full Range Driver Build***
« Reply #2 on: 26 Dec 2013, 01:16 pm »
Peter...
There are amateurs, and then there are "Pros"  Nice work :thumb:

With these single driver builds is there any electronics involved at all? Is it just speaker terminals wired directly to the binding posts?
« Last Edit: 26 Dec 2013, 04:10 pm by lacro »

Peter J

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Re: ***Full Range Driver Build***
« Reply #3 on: 26 Dec 2013, 02:50 pm »
Man I sure do like your shop.
Of course it may be because we have a lot of the same tools.  :D

I do like tools...

Peter J

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Re: ***Full Range Driver Build***
« Reply #4 on: 26 Dec 2013, 03:01 pm »
Peter...
There are armatures, and then there are "Pros"  Nice work :thumb:

With these single driver builds is there any electronics involved at all? Is it just speaker terminals wired directly to the binding posts?

Thanks!

I've run across some designs that have minor "control" electronics...perhaps low frequency cut-offs? but not crossovers in the strictest sense. In this case directly wired...binding posts to driver. I'm straying from original design in box damping and I added a brace as you can see. My knowledge is limited in the speaker design arena, but a box that contributes nothing seems intuitively right to me.

 Stay tuned...

Danny Richie

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Re: ***Full Range Driver Build***
« Reply #5 on: 26 Dec 2013, 03:06 pm »
I don't mind you posting that.

You'll have to build a pair with our new drivers and make a comparison though.  :D

I tested that Enabled deal on a couple of my M-130's. I never could find any effect measured or heard. I am surprised it is still being done to drivers.

You build nice looking cabinets Peter.

Peter J

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Re: ***Full Range Driver Build***
« Reply #6 on: 26 Dec 2013, 03:32 pm »

You'll have to build a pair with our new drivers and make a comparison though.  :D

I tested that Enabled deal on a couple of my M-130's. I never could find any effect measured or heard. I am surprised it is still being done to drivers.

You build nice looking cabinets Peter.

I'm in for the comparison, Danny.  I have way more want for new speakers than need it seems. Building them is some sort of Zen drug for me :o Needed a fix and had these drivers. I'm waiting to mainline with your upcoming open baffle designs.

I've eyeballed the drivers and read some of the theory on Enable-ing. It's one of those things in the audio world that kinda puzzles me... I just don't know what to make of it.

Danny Richie

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Re: ***Full Range Driver Build***
« Reply #7 on: 26 Dec 2013, 04:09 pm »
Quote
I've eyeballed the drivers and read some of the theory on Enable-ing. It's one of those things in the audio world that kinda puzzles me... I just don't know what to make of it.

I have learned to be open minded to various tweaks. I have been surprised before. But in this case I found no evidence of any effect or change from the process. And I did many measurements that included spectral decay on and off axis. I found that it had about the same effect as drawing a smiley face on the cone with a magic marker.

jcotner

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Re: ***Full Range Driver Build***
« Reply #8 on: 26 Dec 2013, 04:27 pm »
I found that it had about the same effect as drawing a smiley face on the cone with a magic marker.

You actually did that?
Couldn't resist, it's all the leftover Christmas candy.  :hyper:

mlundy57

Re: ***Full Range Driver Build***
« Reply #9 on: 26 Dec 2013, 04:42 pm »
Peter,

As far as the slits go for a port opening, I don't know for sure on speaker cabinets but when I am tuning a wooden flute I can cut the end off until I get the note I want or I can drill holes or cut slots at the proper spot on the sound chamber as long as the volume of the slots equals the diameter of the bore.

The same principle may apply to speaker cabinets

Mike

Peter J

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Re: ***Full Range Driver Build***
« Reply #10 on: 26 Dec 2013, 04:58 pm »
Peter,

As far as the slits go for a port opening, I don't know for sure on speaker cabinets but when I am tuning a wooden flute I can cut the end off until I get the note I want or I can drill holes or cut slots at the proper spot on the sound chamber as long as the volume of the slots equals the diameter of the bore.

The same principle may apply to speaker cabinets

Mike

That's what I theorized, Mike, for better or worse. 1 1/4" x 6" = 5/16" x 6" x 4. I think I know that this might cause port chuffing, but can't imagine that much air volume and velocity coming from this driver, but that's seat-of-pants engineering and not really based in science....perfect for the audio world :icon_twisted:

Peter J

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Re: ***Full Range Driver Build***
« Reply #11 on: 27 Dec 2013, 06:27 am »
Moving right along...

 I'm damping panels with this, gone up in price some since I last  used it, $38 for 6 sq. ft.







And lining with this, I'll use some Dacron fill too, but stuff through driver hole, since there's no removable back like plan suggests...probably shooting my foot








Gluing back just like front





A new speaker is born...well, almost. Cool thing about prefinished materials is once it's assembled, it's close to being completed!





rajesh

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Re: ***Full Range Driver Build***
« Reply #12 on: 27 Dec 2013, 07:04 am »
Looking nice, hope it would sound nice too. :wave:

@Danny, pleasantly surprised that you are coming with single driver kits. What is the status and when are they expected?

Peter J

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Re: ***Full Range Driver Build***
« Reply #13 on: 28 Dec 2013, 07:39 pm »
Houston, we have liftoff...


This shot sorta highlights the 3d grain in the sides, hard to see in photos




The front and back come with a protective "peel coat", fun to pull off for the first time!








And then




playing to the messy shop, someone should clean it up  :oops:





I tried to get a shot of the grain in the metal look RTF, hard to capture




Peter J

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Re: ***Full Range Driver Build***
« Reply #14 on: 28 Dec 2013, 07:56 pm »
Larry PMed me about felt. Here's what and where for anyone else interested

http://www.ebay.com/itm/MULTIPLE-SIZES-Blue-Max-40-Ounce-Recycled-Felt-1-2-Thick-Area-RUG-PAD-/130869723608?pt=US_Tools_and_Accessories&var=&hash=item1e787181d8

With only 30 min. playing time, I imagine they've got some breaking in to do, but here are some initial impressions.

Two things strike me as noteworthy about the single drivers I've heard. First is coherence, there is something unique sounding about having all frequencies emanating from a single point. Second, bass. I'm truly surprised by the bass these and the desktop speakers I made produce. It's not tactile like a bigger driver, but it's certainly noticeable...heard but not felt, I guess would be a good way to describe. My slot ports seem to work fine, but like any other port, I don't think you'd want them against a side wall.

Within their limitations, they are pretty amazing. Won't rock the house or rumble the movie soundtrack, but for a smaller music system, I could easily live with 'em.

Looking forward to Danny's entry into this market.


Peter J

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Re: ***Full Range Driver Build***
« Reply #15 on: 5 Jan 2014, 12:36 am »
These are headed to Texas. Danny's agreed to measure their response and give some listening impressions, of which I'm curious.

After listening to them for a  week, I've formed some impressions of my own, but won't go into that at this point. I'm interested in understanding how what I hear translates into measurable parameters. I know the sun doesn't rise and set there, but I'm hoping to gather yet another bit of knowledge. I'm just perpetually curious, I guess, and figure one can't learn too much about the hobby...right?

Also, having heard several of Danny's designs, I can say that our inclinations in speaker voicing seem to run parallel, and frankly, I trust his ears more than my own. I'll be building something with his new drivers and looking forward to comparing.

 

The saga continues...

mlundy57

Re: ***Full Range Driver Build***
« Reply #16 on: 5 Jan 2014, 12:51 am »
I take it you built the crates for these too. How do you go about building crates to safely transport large speakers?

Mike 

kc8apf

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Re: ***Full Range Driver Build***
« Reply #17 on: 5 Jan 2014, 02:29 am »
I'm interested in the crate construction as well.  I've been using cardboard boxes, styrofoam corners, and thin foam sheets.  It works but a crate seems more durable.

Peter J

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Re: ***Full Range Driver Build***
« Reply #18 on: 5 Jan 2014, 07:04 am »
I'm a fan of crates, shipped some pretty big and heavy stuff around the country with no damage...knock on wood. (there's a pun there somewhere). It sometimes helps that I have scraps in the shop already, but in this case I bought a dozen 1x2 furring strips and  a couple of sheets of 1/4" plywood underlayment. It's light and plenty strong. I had the foam. For bigger stuff I scale up to thicker ply and foam.

Essentially, I'm building a box that provides air space all around speaker and then hot gluing foam strips in this space. In this case I used 1 1/2" foam so my crate interior size was 3" larger that speaker in all dimensions. I like to put the frame on the outside like an exoskeleton so it gives hand holds to the shipping monkeys, in this case UPS. My thinking is that it will get dropped less if there's something to grab onto. Although I think it could survive a fair amount of abuse, I rather not test more than necessary. I glue and staple the all but the removable lid which is screwed on. At the very least, these will see two or three rounds of shipping.

I think the photos and graphics will do a better job explaining than more words...

First off, one needs a good helper for artistic inspiration and fitting purposes





EPS insulating foam is easy to come by and has worked well in the past



And the crate itself, speaker is wrapped in dry cleaning bag, a roll of which I somehow ended up with :?










Here's an exploded view so I could exercise my limited Sketchup skills




JLM

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Re: ***Full Range Driver Build***
« Reply #19 on: 5 Jan 2014, 11:04 am »
Danny,

From what I've read efficacy of EnABL is driver dependent and intended for extended range drivers (not sure your M130 quite fills that bill).  I had Bud Purvine (EnABL inventor) treat my Fostex F200A drivers and it improved midrange resolution and opened up the treble sound significantly.