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 Post subject: Re: Need Advice for Bass
PostPosted: June 19th, 2015, 2:38 pm 
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Roscoe Primrose wrote:
You probably don't want to hear this, but you may need to consider a 2-way bass panel... A pair of the 15" drivers mentioned above, plus 4 6-8" drivers, crossed over at 150-200Hz...

Roscoe

I have been thinking that......was looking for a way around it, but with a midrange that only goes down to 500Hz, and really good bass meaning drivers that only are good to 100Hz...........
If I install the Neo8 string, the low frequency doesn't really go any deeper.

I think this is a real problem with Maggies, the lack of mid/upper bass impact (say drum hits) that in a range that the bass panel doesn't do well, and below the midrange. I may try this out with the Eminence 12" drivers I have. For the upper portion of the bass I could use four or so of those GR M165-16's. In series, OTL friendly 64 ohms. Should be about 95dB/watt/meter. The Eminence drivers should get me ~94dB/watt/meter. Pretty close for a single amp solution.

FerdinandII wrote:
f3 of 34 Hz, in a .15ft^3 sealed box
8.5" wide face x however many you want to stack high

http://www.jlaudio.com/6w3v3-4-car-audio-w3v3-subwoofer-drivers-92145


Ferdinand II, those are amazing, as is the JL product line! Thanks for telling me about them. Man, I may need to save my pennies!!!


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 Post subject: Re: Need Advice for Bass
PostPosted: June 19th, 2015, 2:45 pm 
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Joined: March 5th, 2013, 9:35 am
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Location: Highland, MD
Stuart Polansky wrote:
You probably don't want to hear this, but you may need to consider a 2-way bass panel...

I think Roscoe is right. His suggestion is kinda' like my old setup, which gives you a size reference.
There's no substitute for cubic inches - multiple drivers should lower your distortion, and minimize the case of pushing the cone too far out and waiting for it to stop ringing back into place.

It should be fairly easy to add some (one per side?) low-mid drivers to address the narrow response region to get good coverage.

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 Post subject: Re: Need Advice for Bass
PostPosted: June 19th, 2015, 2:46 pm 
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I'd build one with the GR M-165/16 woofers, first....just to see how well the idea works.
$30 per driver v. $150 per, buys a lot of other cool stuff!


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 Post subject: Re: Need Advice for Bass
PostPosted: June 19th, 2015, 2:47 pm 
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The experimental rig in my apartment. These are the M165-16 OB and the Eminence in too small of an enclosure. Not bad. Not great, but with more experimenting........


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 Post subject: Re: Need Advice for Bass
PostPosted: June 19th, 2015, 2:51 pm 
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FerdinandII wrote:
I'd build one with the GR M-165/16 woofers, first....just to see how well the idea works.
$30 per driver v. $150 per, buys a lot of other cool stuff!

Very true! I compared the sound of several "raw" drivers on OB panels. The smoothest sound was these. The Neo8 is amazing, fast and articulate, as long as the 12kHz bump is addressed, but it rolls off very high in the midrange, I'd even say low in the treble. I don't believe the claim of 250Hz on a 9" baffle from the mfr. More like 1.5kHz.

Still, I need to try a line array, but not before addressing the bass issue.


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 Post subject: Re: Need Advice for Bass
PostPosted: June 19th, 2015, 2:53 pm 
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First up is building damping panels to hang on the walls! And corner traps! The bass is amazing..............in the corners! :angry-banghead:


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 Post subject: Re: Need Advice for Bass
PostPosted: June 21st, 2015, 9:53 pm 
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Joined: March 12th, 2013, 12:45 pm
Posts: 39
Location: Annapolis, MD
I have always been fascinated with this idea - seems compact, and ( perhaps with a miniDSP and delay circuit) could be well integrated into an existing dipole panel:

Image

\\Charles

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 Post subject: Re: Need Advice for Bass
PostPosted: June 22nd, 2015, 8:24 am 
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cport wrote:
I have always been fascinated with this idea - seems compact, and ( perhaps with a miniDSP and delay circuit) could be well integrated into an existing dipole panel:

Image

\\Charles



Hey Charles, that looks interesting. Are all the baffles open to the front? In other words, are there just two baffles protruding radially from the corner? Or, are the (-) sides enclosed?


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 Post subject: Re: Need Advice for Bass
PostPosted: June 22nd, 2015, 9:57 am 
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Joined: March 12th, 2013, 12:45 pm
Posts: 39
Location: Annapolis, MD
Stuart Polansky wrote:
Hey Charles, that looks interesting. Are all the baffles open to the front? In other words, are there just two baffles protruding radially from the corner? Or, are the (-) sides enclosed?

All open -- you are using the "walls/room" as the enclosure. This is a 0.5 PI application. The rounded-wedges or triangular baffles would be 'large' to allow the pressurization wave to build without cancellation.
Think four of these >Peerless 12" XXLS< guys.

\\Charles

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"We are all inventors, each sailing out on a voyage of discovery, guided each by a private chart, of which there is no duplicate. The world is all gates, all opportunities."
Ralph Waldo Emerson


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 Post subject: Re: Need Advice for Bass
PostPosted: June 23rd, 2015, 10:21 am 
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While OB bass would be my first choice (Hey, Maggies are OB), I just don't have the room, corners or ability to transport large baffles when I move again.

Since it seems I'll need to have "two-way" bass, I'm re-thinking my approach.

Sonotube bass using the nice Eminence drivers I already have (think cheap for me) THEORETICALLY gives me ~30Hz @ -0.5dB and ~24Hz @ -3dB, that in a vented enclosure tuned to 25.5Hz, two drivers per side arranged in an isobaric clamshell.

Hope to use this to ~80-100Hz .

The upper bass drivers will then mount to new ~24" wide panels (made of two 0.72" thick sheets of Birch plywood) along with the Neo8 and Maggie ribbons, all-in-one. Since I can place the Sonotubes behind the panels, speaker width will be reduced from 102" to 48".

If it sounds good, that size will work.

As an added bonus, the Sonotube bass speakers should be about 91dB/W/M, the upper bass (as low as possible to ~1kHz) ~98dB/W/M [8 per side]; the Neo8 (six per side) ~97-98dB/watt, 1kHz to 6kHz; and the Maggie ribbons from 6kHz up, well, who knows? The ribbons have 1-2 ohm series resistors to reduce efficiency to match the midrange. So, given that they are either 2.1 or 2.7 ohms, I expect they may be as good as 88-89dB/W/M.

Bottom line is that tri-amp should work well with moderately powered Class A2 tube amps! No need for heroics and hideous breeds (hybrid), except for the Sonotubes @ 500WPC!


Eminence T-S:

RE OHMS 6.31
FS HZ 26.59
LE MH 1.49
MS GMS 71.80
QM 9.70
CMS mm/N .4990
QE .440
RMS NS/M 1.2367
QT .420
VAS LTRS 189.11
XMAX MM 4.80
SD SCM 519.45
BL TM 13.13
EBP 60.5
EFF % .78
SPL dB 90.9


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Isobaric Eminence.jpg
Isobaric Eminence.jpg [ 240.81 KiB | Viewed 21699 times ]
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