Hey guys...we need a little rallying here... - Page 425 - AVS Forum | Home Theater Discussions And Reviews
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post #12721 of 12729 Old 07-15-2017, 05:19 AM
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Parham & Directivity

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Originally Posted by Eternal Velocity View Post
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[huge snip]
It's easy to even make a 6.5" + cheap 1" dome 2-way sound smooth and inoffensive IE aformentioned BBC dip or to voice for a decent power response, but that's all flawed from the get go. I hope what parham's doing isn't along those lines. I think I'm on exactly the same page as LTD02... directivity matching and driver selection are important...but i'm not willing to place power response before all else including direct response.
Oh, believe me: Wayne Parham takes directivity very seriously, including matching it between drivers (among a lot of other things). Though (obviously) I can't speak for him, I believe that is the reason he uses CD's in his design to start with.
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post #12722 of 12729 Old 07-15-2017, 01:14 PM
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On axis response

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Originally Posted by Eternal Velocity View Post
[snip]
You should start by understanding each abberation in the "on-axis" measurements. What exactly is it that doesn't look good, and why is there? Is it a resonance? If so can it be corrected electrically or does it need to be corrected mechanically or acoustically? Either way it needs to be corrected if it's in the listening window.
[snip]
Like a null 7 degrees off axis?
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post #12723 of 12729 Old 07-23-2017, 08:27 AM
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Blast from the past xover design

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Originally Posted by bwaslo View Post
Hi Erich,

It's those Inductor-Capacitor-Resistor (LCR) strings that go across the CD driver. Can't just take them out, other stuff would need to be adjusted to compensate or it would sound awful. I did run some designs without those LCR, but really think they should be left in. One of the bumps they deal with is at 2kHz, which is a terrible frequency to have a bump at (near where ears are most sensitive). Why go to all the trouble of waveguides and CDs and then cheap out on a few components?

Besides, I'm too lazy to do it all over again![broken link] Did my mass speaker designing this past week, got to get back to some other things now.

I don't really think there is a difference between HT and HiFi design goals. HT might need to play louder (and maybe not), but flat response is still good -- overall response shaping can be added at the receiver or equalizer, better than hardwired into the speaker.

The components inside the dashed-line box (in the schematics) are fixed resistors. The "L-Pad" notation is just to say they could be replaced with an L-Pad if someone wanted to for whatever reason. I wouldn't, myself, L-Pads are just another mechanical part to go bad, fixed resistors are lots more reliable.

Crossovers shouldn't have to change if you just are moving the woofer closer to the WG.
[@]bwaslo[/@] Are all these graphics (plus those from post 21853196) posted elsewhere (or at least the schematic)? Yeah, I know this is five years later, and I'm getting quite an education from reading the whole thread. This design looks to be foundational, not to mention executed using a relatively inexpensive woofer, so I'm hoping there is some way I could see the schematic (I come from the electronics end of the hobby, so I can read the schematic and build the crossover from it)
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post #12724 of 12729 Old 07-24-2017, 01:58 PM
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BWaslo's SEOS12 with Designer12 woofer

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Originally Posted by lloydrmc View Post
[@]bwaslo[/@] Are all these graphics (plus those from post 21853196) posted elsewhere (or at least the schematic)? Yeah, I know this is five years later, and I'm getting quite an education from reading the whole thread. This design looks to be foundational, not to mention executed using a relatively inexpensive woofer, so I'm hoping there is some way I could see the schematic (I come from the electronics end of the hobby, so I can read the schematic and build the crossover from it)
To answer my own question: Yes the schematic is posted of this early reference design -using "Dayton Audio DS315-8 12 inch Designer Series Woofer Speaker Part # 295-434" (IIRC) for the SEOS when it first became available from Erich's DIY Audio Group.

The problem was the graphics that [@]bwaslo[/@] had posted on this thread of the crossover schematic, polar response graphs, etc. were broken. I found a later reference to the forum where the design was posted, but that was broken too, b/c apparently Erich had redesigned his web site in the meanwhile.

Not to worry. I found the forum http://www.hificircuit.com/community...r12-woofer.11/

and the (revised) crossover schematic https://www.circuitlab.com/circuit/w...12-delta12lfa/

This would be a good "entry-level" DIY project to get started using the most excellent (by all accounts) SEOS waveguide, as the woofer is relatively inexpensive, yet it's still a very capable speaker. Note that you can utilize Erich's own DNA-360 Compression Driver to save some money while not sacrificing performance.
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post #12725 of 12729 Old 07-24-2017, 03:14 PM
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Quote:
Originally Posted by lloydrmc View Post
To answer my own question: Yes the schematic is posted of this early reference design -using "Dayton Audio DS315-8 12 inch Designer Series Woofer Speaker Part # 295-434" (IIRC) for the SEOS when it first became available from Erich's DIY Audio Group.

The problem was the graphics that [@]bwaslo[/@] had posted on this thread of the crossover schematic, polar response graphs, etc. were broken. I found a later reference to the forum where the design was posted, but that was broken too, b/c apparently Erich had redesigned his web site in the meanwhile.

Not to worry. I found the forum http://www.hificircuit.com/community...r12-woofer.11/

and the (revised) crossover schematic https://www.circuitlab.com/circuit/w...12-delta12lfa/

This would be a good "entry-level" DIY project to get started using the most excellent (by all accounts) SEOS waveguide, as the woofer is relatively inexpensive, yet it's still a very capable speaker. Note that you can utilize Erich's own DNA-360 Compression Driver to save some money while not sacrificing performance.
lloydrmc,

Glad you found what you were looking for. Truth to tell, I don't even remember that design (getting old). Probably have it on an old laptop computer somewhere, but you've saved me the trouble of looking.

The DNA360 driver can not only save some money, but at least with the ones I've measured, is singificiantly smoother than the DE250, too. Much smoother than the Dayton rendition, too.
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post #12726 of 12729 Old 07-24-2017, 03:52 PM
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Originally Posted by bwaslo View Post
lloydrmc,

Glad you found what you were looking for. Truth to tell, I don't even remember that design (getting old). Probably have it on an old laptop computer somewhere, but you've saved me the trouble of looking.

The DNA360 driver can not only save some money, but at least with the ones I've measured, is singificiantly smoother than the DE250, too. Much smoother than the Dayton rendition, too.
While we're complimenting the DNA-360, I'll mention that I'm using the DNA360 in an active design with aggressive DSP. I have boosted the output to be flat all the way out to 20 kHz without any ill effects at all. It would seem that real world content contains very little energy in the last half octave. The only signals that ever push the output levels up high enough to be of concern are the sine sweeps that I use for measurement. FWIW, I am able to confirm these facts by observing the peak indicators on my Motu 16A audio interface.

The only complaint I have with the CD is the narrowing of directivity around the 17 kHz break-up frequency, yet this the audibility of this feature (albeit in my room with lots of diffusion) is so subtle that I'm probably the only one who will ever notice. Maybe some day I'll feel adventurous and try out a Beryllium CD, but I don't know if I could find with comparable low frequency extension. The sound I get is incredibly smooth, as good or better than any dome speaker I've heard, and with all the wonderful dynamics that a CD brings to the table.

Edit: In case anyone is wondering whether extension to 20 kHz makes an audible difference, the answer for me is a strong YES! That's despite the fact that my ears tap out at around 17 kHz using sine waves. Apparently sine waves are of limited use for assessing the upper frequency limit of hearing.
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post #12727 of 12729 Old 07-24-2017, 03:57 PM
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DNA 360 Compression Driver

I see that the DNA360 compression driver shows as out of stock? Anybody have an idea when they will be available again? I like to snag a pair.
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post #12728 of 12729 Old 07-24-2017, 04:30 PM
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Anyone try the BA CD? Only found one review online and he loved it.

Be phrams do more than just extended FR. I'd love to hear a pair someday.
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post #12729 of 12729 Old Yesterday, 02:00 AM
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Originally Posted by Carl_Huff View Post
I see that the DNA360 compression driver shows as out of stock? Anybody have an idea when they will be available again? I like to snag a pair.
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Bummer! I hope it's temporary. I'd like to pick up a couple more for the surrounds that I'll get around to building some day. (I already have the horns.) If not, I guess I'll look at the B&C DE-250 or maybe BMS 4550.
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