Sub-less SEOS design for HiFi - AVS Forum
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post #1 of 19 Old 07-03-2014, 04:34 AM - Thread Starter
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Sub-less SEOS design for HiFi

I'm considering building speakers based on the SEOS waveguide. This system will be used exclusivley for 2 channel audio and I'd like to avoid subs. Most of the SEOS designs I've seen assume subs to cover the low end. Is there a SEOS design that will sufficiently cover the low end for HiFi without subs?

Thanks,
CamR.
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post #2 of 19 Old 07-03-2014, 05:51 AM
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The Tempest is supposed to go down to 37 Hz. How low do you want to go? You could build it as a floorstander if you want lower.
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post #3 of 19 Old 07-03-2014, 06:41 AM
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Just build a sub into the bottom of the speaker, either as a stand (separate boxes) or as a tower (one box). You can turn any SEOS design into full range like that. You just need two amplifiers and a pre/pro or DSP to crossover.


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post #4 of 19 Old 07-03-2014, 06:57 AM
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A lot of the SEOS designs (mine, at least) leave the woofer box volume as an open variable. You can make the box bigger (towers is a good way) to dig deeper in most cases. Get yourself the Thiele/Small parameters for the woofer of the SEOS design you are considering, and download a copy of WinISD Beta. (freeware). It won't take you long at all to determine the box volume and tuning needed to get lowest practical response. Then figure the box dimensions that you'll need to get that volume (times ~1.1 to provide for the woofer and SEOS waveguide space taken up).

Some of the woofers can go quite low, if you're willing to have big speakers in the room. Remember: Size, Efficiency, Bass Response -- pick two. Efficient designs often trade off Bass Response for smaller boxes.
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post #5 of 19 Old 07-03-2014, 11:16 AM
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post #6 of 19 Old 07-03-2014, 05:54 PM
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So if you have something such as the Fusion-12 Tempest, or something like I was originally considering that was going to use the Seos-15 with a DNA-360 compression driver over a JBL-2226, would you just sim the sub and build the cabinet specs to get the proper volume for the sub, and how would you need to rework the crossover?

I would imagine that the crossover for the woofer would need to be modified so as to crossover higher than was originally intended being that the woofer no longer needs to reach down below say...80hz as the subs would cover this better?

If so, would taking the strain off the woofer, using a sub for the <80hz stuff have any effects on the SQ of the woofer, (mid)? Would the 2226 be a good driver to use as the mid in a design that has a nice sub for the less than 80hz stuff?
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post #7 of 19 Old 07-03-2014, 11:27 PM
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I embedded dual Dayton UM-15's into each of mine.
Without they go to 30 to 37hz, and With they go to 12-16hz (an entire octave deeper)...



You could just do singles (you don't need two in each) and a nu3000DSP amp for the bottom two of the pair, and whatever 2-ch amp you want for the normal Tempest top part.



If you are big on SQ in 2-ch, I'd recommend the Emotiva XSP-1 preamp, it has quad analog XLR and RCA outputs with quad analog (defeatable) XO's for specifically this sort of active bi-amping config in an entirely analog domain (no extra ADA step). Then you can save money by using normal non-DSP amps, the tried and true Class-AB/H amps Hi-Fi or Pro amps.
I'd also recommend an Oppo 105 as your 2-ch USB or HDMI or streaming NAS wifi or disc player DAC!

http://emotiva.com/products/pres-and-pros/xsp-1
http://oppodigital.com/blu-ray-bdp-105/

That's what I'm using in the above videos.

2hz to 90khz +-0.1db, -133db SNR, like 16vRMS output, on all 8 channels, all 8 channels driven.
Flawless sound, it doesn't get any better. (As you would expect for the money.)

and should you ever want to go to 7.1 it can do that too (hence the 8 channels).

"If Bad Sound Were Fatal, Audio Would Be the Leading Cause of Death."


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Last edited by BassThatHz; 07-03-2014 at 11:33 PM.
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post #8 of 19 Old 07-04-2014, 04:10 AM
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Quote:
Originally Posted by BassThatHz View Post
I embedded dual Dayton UM-15's into each of mine.
Without they go to 30 to 37hz, and With they go to 12-16hz (an entire octave deeper)...

http://www.youtube.com/watch?v=z_Q7y1yLaC4
.
They look great and the specs are impressive.
I wish I could hear them.
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post #9 of 19 Old 07-04-2014, 04:48 AM - Thread Starter
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Quote:
Originally Posted by bwaslo View Post
A lot of the SEOS designs (mine, at least) leave the woofer box volume as an open variable. You can make the box bigger (towers is a good way) to dig deeper in most cases. Get yourself the Thiele/Small parameters for the woofer of the SEOS design you are considering, and download a copy of WinISD Beta. (freeware). It won't take you long at all to determine the box volume and tuning needed to get lowest practical response. Then figure the box dimensions that you'll need to get that volume (times ~1.1 to provide for the woofer and SEOS waveguide space taken up).

Some of the woofers can go quite low, if you're willing to have big speakers in the room. Remember: Size, Efficiency, Bass Response -- pick two. Efficient designs often trade off Bass Response for smaller boxes.
Very helpful. Thanks Bill. This will get me going.
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post #10 of 19 Old 07-04-2014, 04:54 AM - Thread Starter
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Quote:
Originally Posted by SpinMonster View Post
They look great and the specs are impressive.
I wish I could hear them.
Quote:
Originally Posted by BassThatHz View Post
I embedded dual Dayton UM-15's into each of mine.
Without they go to 30 to 37hz, and With they go to 12-16hz (an entire octave deeper)...

http://www.youtube.com/watch?v=z_Q7y1yLaC4

http://www.youtube.com/watch?v=ifDoZKN_MSc

You could just do singles (you don't need two in each) and a nu3000DSP amp for the bottom two of the pair, and whatever 2-ch amp you want for the normal Tempest top part.



If you are big on SQ in 2-ch, I'd recommend the Emotiva XSP-1 preamp, it has quad analog XLR and RCA outputs with quad analog (defeatable) XO's for specifically this sort of active bi-amping config in an entirely analog domain (no extra ADA step). Then you can save money by using normal non-DSP amps, the tried and true Class-AB/H amps Hi-Fi or Pro amps.
I'd also recommend an Oppo 105 as your 2-ch USB or HDMI or streaming NAS wifi or disc player DAC!

http://emotiva.com/products/pres-and-pros/xsp-1
http://oppodigital.com/blu-ray-bdp-105/

That's what I'm using in the above videos.

2hz to 90khz +-0.1db, -133db SNR, like 16vRMS output, on all 8 channels, all 8 channels driven.
Flawless sound, it doesn't get any better. (As you would expect for the money.)

and should you ever want to go to 7.1 it can do that too (hence the 8 channels).
Impressive! Is that a SEOS-12 or SEOS-15 there? Is the Tempest essentially a separate enclosure? What XO do use? Do you have build page or plans available?
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post #11 of 19 Old 07-04-2014, 09:52 AM - Thread Starter
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Sharing volume of Tempest with a sub

The Fusion Tempest 12 internal volume is 2 cubic feet. The optimal volume for the Dayton um12 sub (vented) is 4 cubic feet. Can the base of Tempest be extended with an additional 2 cubic feet so that the sub can effectively "share" the volume with the Tempest? Would this require a different XO for the Tempest drivers if the sub is bi-amped?
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post #12 of 19 Old 07-04-2014, 10:08 AM
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No, you have to have separate compartments for the woofers. A 2 cu ft and a 4 cu ft. You can use the same Tempest XO, just use the receiver's LFE output for the sub's amp. You'd need binding posts for the Tempest part, and binding posts for the subwoofer part.


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post #13 of 19 Old 07-04-2014, 12:52 PM
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Quote:
Originally Posted by CamR View Post
Impressive! Is that a SEOS-12 or SEOS-15 there? Is the Tempest essentially a separate enclosure? What XO do use? Do you have build page or plans available?
You could use either a SEOS-12 or a SEOS-15, I went with the 12 cause it was cheaper and I was building 7 of them so cost was a factor.
Each UM-15 It's in their own sealed 2.1cuft chamber inside the speaker.

The top is a standard DIYSoundGroup XO that I built externally, so that it would be optional for active or passive amplification, cause i'm anal like that.
I could have used the analog XO's in the XSP-1 but I chose to use a digital DCX instead, as it clashed with my TRUE XX.4 design; not for SQ reasons. The DCX is much more flexible but has the extra ADA step.
You don't need a DCX or miniDSP unless you want stereo bass out of each speakersub, like my system has.
LFE from your AVR will be mono-summed or a dedicated movie track (i.e. also mono).

My speaker build link in my sig has more details of the build.


My system is a true x.4, so I have (more than) stereo bass.
So when I play a song like this, it plays in the correctly intended phase.

https://soundcloud.com/bassthathz/st...rasonic-woofer
So if mono LFE AVR users tried to play this song here, they would just get nothing coming out of their subs.

Where as my system, play it correctly:


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post #14 of 19 Old 07-05-2014, 07:40 AM
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I am still curious about the differences in SQ that would be apparent with a typical Seos-15 or Tempest 2-way design where by adding a sub to the same enclosure and then not having to run the original woofer down any lower than say...80hz cowherd it could hand off to the sub.

Say we take a Fusion-12 Tempest, and modify the cabinet to house a UM12 that will be crossed to the stock Tempest driver at 80hz. Would crossing the stock Tempest woofer to the sub at 80hz, have any benefits with regards to SQ as then it would not have to reach down as low, and in theory, have an easy job to carry out only going to 80hz making it cover only the mid-range?

Last question, would a JBL-2226 still be a great driver if used in a design that would have it running from only 80hz to 900hz, crossing over to a sub for the bottom end, and a Seos-15 + DNA-360 up top?
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post #15 of 19 Old 07-05-2014, 09:21 AM
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I noticed a significant decrease in (subjective) harmonic distortion in the mids when crossing the mid-woofer high (100 to 200hz), as opposed to 37hz...
I assume more of the voice coil is in the gap and less moving mass momentum, thus less "ringing"?

The higher the SPL, the more appreciable the difference was.

For example, mid harmonic distortion is now inaudible at crazy db's:

Only a golden-eared SQ nut like me would notice the difference though.
(Probably not very hearable via youtube, but that never stopped me from trying regardless. LOL )

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post #16 of 19 Old 07-05-2014, 10:15 AM
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^I suspect this is right. I think you should bring the crossover up by an octave or more to get any benefit for the mid woofer.
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post #17 of 19 Old 07-05-2014, 01:42 PM
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Quote:
Originally Posted by Martycool007 View Post
I am still curious about the differences in SQ that would be apparent with a typical Seos-15 or Tempest 2-way design where by adding a sub to the same enclosure and then not having to run the original woofer down any lower than say...80hz cowherd it could hand off to the sub.

Say we take a Fusion-12 Tempest, and modify the cabinet to house a UM12 that will be crossed to the stock Tempest driver at 80hz. Would crossing the stock Tempest woofer to the sub at 80hz, have any benefits with regards to SQ as then it would not have to reach down as low, and in theory, have an easy job to carry out only going to 80hz making it cover only the mid-range?

Last question, would a JBL-2226 still be a great driver if used in a design that would have it running from only 80hz to 900hz, crossing over to a sub for the bottom end, and a Seos-15 + DNA-360 up top?
What you're describing is the exact same thing as running the tempests at a 80 hz crossover from the receiver and having a subwoofer, so you can easily do what you are saying. I suppose if you change the ports and volume so the Tempest is tuned at 80 hz, it could possible get a couple dB gain there. I think most people run their tempests with subs crossed at 80 hz. And then if you want, maybe run them full range for music with no sub.

JBL 2226 would be good at those freqs, it can't go too much lower than 80 hz anyways.


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post #18 of 19 Old 07-06-2014, 07:51 AM - Thread Starter
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What is the ideal tuning and volume for the mid woofer enclosure of I incorporate a um12 sub?
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post #19 of 19 Old 07-06-2014, 11:35 AM
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Quote:
Originally Posted by BassThatHz View Post
I embedded dual Dayton UM-15's into each of mine.
Without they go to 30 to 37hz, and With they go to 12-16hz (an entire octave deeper)...
Curious, why all the drivers in front, instead of the two bass drivers on the sides (or front/back) in a dual opposed configuration to cut down on vibrations? Looks?

Also, your setup probably sounds better with the higher crossover not because of a basically irrelevant factor (THD) but because of smoother frequency response in your current configuration. Remember that floor bounce is often in the 100-200Hz octave. With a "flanking sub" setup like yours it's very easy to put the bounce in the stop-band for each driver, as you seem to have done. So the FR in the upper bass is likely a good bit smoother than it would be with a lower midbass-woofer crossover.

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