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Author Topic: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)  (Read 17364 times)

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Marvey

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #10 on: February 10, 2014, 12:21:26 AM »
Quote from: OJneg on February 09, 2014, 10:49:54 PM
Damn damn damn! Purrin beats me to it again! If I hadn't been swamped with classes this quarter I would have had my own OB built by now. At this point I'm looking at first order filters + software PEQ to touch things up, similar to what you have I imagine. Still going to use that Alpha 15A driver myself.

Give me a few more weeks and it'll be ready. I promise it'll be even dirtier and cheaper than yours  :)p1

Just wait a bit and you can have my Betas. The woofers I have, at less than $80 each, are definitely the weakest link. I already plan on replacing them with maybe 18" drivers of quality closer to the Cicada drivers.

If you have enough room for an OB setup, you will never go back. The OB sound is really open. Practically removes the walls from the room.
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Maxvla

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #11 on: February 10, 2014, 12:29:42 AM »
Interesting. I've never heard OB speakers. Might help solve my problem with speakers.

Do you think you can get to a point where no sub is needed and reach down to say 30hz cleanly. I'm guessing at least a 15" would be necessary.

Is that any particular baffle material that is better for this implementation? How much are we looking at for a full project cost?

edit: Also, any particular amping needs? It seems inefficient, so will something like a Ragnarok not be able to handle this?
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Marvey

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #12 on: February 10, 2014, 12:33:35 AM »
Funny tidbit when I found out originally that Craig wasn't going to bring the 445 or mk4 amp to the Bay Area meet:


ME:

Craig, those Cicada drivers are awesome. I can't believe the extension in treble for an 8" driver - no supertweeter needed; and also in bass on an open baffle.

CRAIG:

Yeah, their Fs is about 50Hz, but Qts is around 0.7. I've never heard them on an OB, but I've heard of others getting good results. I saw on picture of a guy putting the driver on a glass (acrylic) board once.

ME:

I'll bring them to the meet so you can hear them. These drivers were always meant to be used on OB.

CRAIG:
The old Cicada enclosures didn't use the modern bracing techniques. So what you are going to use as a amp?

ME:

Well, I was hoping that I could use one of YOUR amps since I am using a MOTH driver, but since you are not bringing anything, I'm going to use one of Schiit's. I mean, I would prefer not to use a Schiit amp because I am using your MOTH driver, and that just wouldn't be right to you.

CRAIG:

Oh, in that case, I'll try to bring either a 445 or one of the mk4 amps to the meet.


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Stapsy

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #13 on: February 10, 2014, 01:32:34 AM »
Two speakers set into a stand...finally a DIY speaker that I could build!

What would happen if you shrunk the width of the baffle on the top half with the Moth driver?  I am wondering if I could shrink it down into a smaller size and make an open baffle bookshelf size speaker with one of the full range drivers like the fostex.  I guess I would loose bass extension unless I implemented a separate sub.  Might be worth trying if I could trade off more openness vs increased bass response from a ported bookshelf speaker (which isn't going to be that great anyway from something the size I am considering).
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Armaegis

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #14 on: February 10, 2014, 01:41:20 AM »
I always drive by this place that makes marble countertops and keep thinking I should get some slabs to mount speakers onto.
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Do you think there may be an acoustic leak from the jack hole? ~Tyll Hertsens

Not sure if I like stuffing one hole or both holes. Tending toward one hole since both holes seems kinda ghey ~Purrin

OJneg

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #15 on: February 10, 2014, 01:56:51 AM »
Quote from: Stapsy on February 10, 2014, 01:32:34 AM
I guess I would loose bass extension

Pretty much. Baffle needs to be large with respect to wavelength or else you have an acoustic short circuit. How wide are those baffles purrin?
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Marvey

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #16 on: February 10, 2014, 04:04:25 AM »
You could probably reduce the width of the top half where the Moth drivers are mounted. I kept them wide on purpose to allow for a variety of mounting locations even though I decided on mounting in the middle. The baffles are 24" wide. The other reason was to provide for a lot of latitude (I really didn't know what the TS parameters of the Moth driver were and to this day, I do not trust the published specs.) as I used them solely by themselves with a sub but no woofers.

The consideration for the Moth driver was to run them from a 3-6 watt tube amp (guess which ones) using one capacitor only. I hate passive x-over components. All they do is destroy the sound. But in this case, I was willing to make a compromise - a very small one. Because I was only using one cap, the best I was going to get was a 1st order 6db electrical roll-off. That's not very much roll-off at all to protect the Moth driver from over-excursion (always an issue with OB), so I wanted to make sure I could run the Moth driver as low as possible before crossing over to the woofers.

I haven't done the calculations for this scenario, but I suspect I could have gotten away with no baffle or just a 1-2" lip around the Moth driver if I wanted to crossover at 200-300Hz.

In terms of OB bookshelf - the serious downside to OB is that you need a lot of room - and that means several feet behind the speaker to the wall.
« Last Edit: February 10, 2014, 04:15:54 AM by purrin »
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Marvey

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #17 on: February 10, 2014, 04:12:33 AM »
Quote from: Maxvla on February 10, 2014, 12:29:42 AM
Interesting. I've never heard OB speakers. Might help solve my problem with speakers.

Do you think you can get to a point where no sub is needed and reach down to say 30hz cleanly. I'm guessing at least a 15" would be necessary.

Is that any particular baffle material that is better for this implementation? How much are we looking at for a full project cost?

edit: Also, any particular amping needs? It seems inefficient, so will something like a Ragnarok not be able to handle this?

We'll see how low it gets after some tuning tonight. I haven't run the measuring tools yet. I think an 15" woofer with the right parameters can do 30Hz or very close to it at reasonable SPL. SPL, cone excursion, and digital headroom are the limitations.

LOL, I'm using cheapass oak plywood 5/8". Will add rib supports in the back. I plan on using some more attractive wood pieces, probably CNC'd for a final version. Unlike a box speaker, heroic construction methods are not as crucial to OB speakers.

In terms of amps, 3 watts for the wide-bander. 100+ watts for the woofers. Recommend the highest quality amp you can fine for the wide-bander. Something from Emotiva should do for the woofers.

DCX2496 is a few hundred bucks.
Woofers were well less than $200 shipped.
Suitable wide-banders could be $600 if you want really really good ones.
How much is an Emotiva power amp?

Outside of the quality amp, we are talking less then the cost of a new HD800. This includes drivers, wood, OB woofer processor, and woofer amp.
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n3rdling

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #18 on: February 10, 2014, 04:32:14 AM »
Very cool build, I bet they sound great.  I prefer boxless as well (half the reason I prefer stats), but I would worry a little about the panels resonating a bit - especially the woofer panel.  It looks like you'll have this covered soon.  What kind of support is temporarily in place?
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Maxvla

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Re: Back to Speakers... Again! (Dirt Cheap Open Baffle Speaker Project)
« Reply #19 on: February 10, 2014, 04:45:53 AM »
Pic from side and back plz!
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