Guitar Speaker Project: Eminence Texas Patriot 12" speakers great deal - diyAudio
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Old 18th November 2011, 08:36 PM   #1
bartbrn is offline bartbrn  United States
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Default Guitar Speaker Project: Eminence Texas Patriot 12" speakers great deal

No this is not spam, an ad, or a testimonial from a guy who works at Eminence or the store with the deal -- I'm the dufus who's making a stereo practice amp/neighbor-annoyance-system from a Line6 PodXT, a Hafler DH200 100+W/channel MOS-FET power amp, two 1 x 12" cabs (any recommendations for cab design very welcome), and a pair of Eminence Texas Patriot 12" 8-Ohm speakers. You can berate me later about how crazy/stupid/meshugga in gontz I am, but American Musical Supply is offering a PAIR of Eminence Texas Patriot 12" speakers in either 8 or 16 Ohm for $129.95 PER PAIR, with free shipping, plus a bitchin' rebate that gets you an Eminence T-shirt and baseball cap guaranteed to mystify your neighbors. It's not a HUGE deal -- almost everyone sells the 12" Texas Pats for about $75 ea, but $20 is $20, and free shipping, a groovy hat, and a t-shirt are just the icing on the cone:

Eminence Texas Heat Guitar Speaker at AmericanMusical.com
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Old 1st December 2011, 12:36 PM   #2
dangus is offline dangus  Canada
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Doesn't sound like that great a deal. It was about 10+ years ago that I bought 15" cast-frame, 80 ounce magnet Eminences for under $80 each, but then the US buck was worth much more then. MCM part number 55-765. Very efficient. Probably same as the Delta Pro 15".

If you're getting those, use a ported cabinet designed using the T-S parameters, or according to whatever reference design Eminence provides. And preferably a mid/tweeter from 1 kHz up because the frequency response is ugly up higher. It doesn't have a vented pole piece so using a modest power amp would be wise. Some kind of high-pass filter might be helpful since the speakers won't do much bass; maybe a 6h order system using some boost to extend the bass.

Last edited by dangus; 1st December 2011 at 12:44 PM.
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Old 1st December 2011, 03:57 PM   #3
bartbrn is offline bartbrn  United States
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These are not for full-range home audio speakers, but for 2 cabinets (1 x 12" speaker each) as the final audio output devices for electric amplification of a guitar (or ukelele, zither, sitar, lute, harmonica, voice, whatsonever.

I'm afraid I'm totally clueless about T-S parameters, vented pole pieces, and have no idea what a "6h [I assume you meant "6th"] order system" is. However, I would like some advice on:

1. ideal speaker enclosure interior volume

2. whether to use Acousta-Stuff or baffles or nothing

3. what you (everybody) thinks about this design (interior rendering, obviously):

Click the image to open in full size.

which some guitar players like because they can experiment with leaving the bottom port open, completely closed (with a tight-fit plug), or part-open, using a smaller plug or plugs, or just stuffing the port with rags, making the the port larger or smaller until they get the sound they want.

Again, my HP/ATN (Home Practice/Annoy The Neighbors -- the closest one's about 1/8th mile away, he's Scots, 80+ years old, and plays his bagpipes sometimes from dawn to midnight, so HE can't complain too much) cobbed-up system is this: a Line 6 PodXT driving a Hafler DH-200, nominally 100W/Ch though, in reality, it's a considerable bit more, NOT bridged to mono, but in stereo, as many of the effects in the PodXT are stereophonic (like a chorus that rolls off from left to right), thus the two separate cabinets.

Grateful for any help determining the optimum size of these cabinets, which will be 3/4 MDF, covered in JC Whitney El Cheapo trunk carpeting, and for thought on this kind of ported-or-not cab design.

Peace

Bart
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Old 2nd December 2011, 10:25 AM   #4
dangus is offline dangus  Canada
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Yes, that should have been 6th order. I'll blame this flaky wireless keyboard.

Eminence should have a suggested cabinet design; check their website, or guitar forums to see what other people like. If it's for stringed instruments, then low bass isn't necessary. It might even be OK for electric bass since the 2nd harmonics are much louder than the fundamentals. With ported cabinets, the usual thing is to line the insides with something like fiberglass insulation. The main purpose is to prevent standing waves in the cabinet which can sound "honky". Scraps of shag carpet, or eggcrate foam may work. Tube ports are the easiest to adjust (cut shorter, or replace), although do require cutting an actual circular hole. Holesaws, router guides, or lots of wood filler may be involved. If you're lucky with the box design, the box thickness may be long enough so you just need a hole. Nothing wrong with playing around with the port; you could seal it, stuff it with soda straws, foam, or leave it open.

Consider plywood if these are going to be portable. Vinyl cloth ("leatherette") from the fabric or upholstery store isn't as tear-resistant as carpet, but easier to wipe clean if mud/food/bodily fluids get on it. It may be available in colours and patterns reminiscent of old diner booths or Bangladeshi bus seats.
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Old 8th December 2011, 03:04 AM   #5
bartbrn is offline bartbrn  United States
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Quote:
Originally Posted by dangus View Post
Eminence should have a suggested cabinet design
Well, here are the specs from Eminence. Under "Mounting Information" there'sa line that says "Recommended Enclosure Volume," but how you're supposed to calculate it from the information then given is a complete mystery to me, like so many things in life. Here's the full-boat gen from Eminence for the Patriot Texas Heat 12" 8 Ohm:
---------------------------------------------------
SPECIFICATION
Nominal Basket Diameter 12", 304.8mm
Nominal Impedance* 8 ohms
Power Rating**
Watts 150W
Music Program N/A
Resonance 79Hz
Usable Frequency Range 70Hz - 5kHz
Sensitivity*** 99dB
Magnet Weight 38 oz.
Gap Height 0.31", 7.92mm
Voice Coil Diameter 2", 50.8mm
THIELE & SMALL PARAMETERS
Resonant Frequency (fs) 79Hz
DC Resistance (Re) 7.3
Coil Inductance (Le) 0.54mH
Mechanical Q (Qms) 13.88
Electromagnetic Q (Qes) 0.68
Total Q (Qts) 0.65
Compliance Equivalent Volume (Vas) 50.9 liters / 1.8 cu.ft.
Peak Diaphragm Displacement Volume (Vd) 42cc
Mechanical Compliance of Suspension (Cms) 0.13mm/N
BL Product (BL) 12.8 T-M
Diaphragm Mass Inc. Airload (MMs) 31 grams
Efficiency Bandwidth Product (EBP) 116
Maximum Linear Excursion (Xmax) 0.8mm
Surface Area of Cone (Sd) 519.5 cm2
Maximum Mechanical Limit (Xlim) N/A

MOUNTING INFORMATION
Recommended Enclosure Volume
Sealed Acceptable
Vented Acceptable
Driver Volume Displaced 122 cu.in. / 2 liters
Overall Diameter 12.02", 305.3mm
Baffle Hole Diameter 10.97", 278.6mm
Front Sealing Gasket Fitted as standard
Rear Sealing Gasket Fitted as standard
Mounting Holes Diameter 0.25", 6.4mm
Mounting Holes B.C.D. 11.63", 295.4mm
Depth 5.1", 130mm
Net Weight 8.3 lbs, 3.8 kg
Shipping Weight 10 lbs, 4.5 kgs
MATERIALS OF CONSTRUCTION
Coil Construction Copper voice coil
Coil Former Polyimide former
Magnet Composition Ferrite magnet
Core Details Non-vented core

Basket Materials Pressed steel basket
Cone Composition Paper Cone
Cone Edge Composition Paper cone edge
Dust Cap Composition Zurette dust cap
Hide
Footnotes
* Please consult Eminence Speaker | The most trusted name in audio since 1966. Great upgrades for JBL, Celestion, Jensen, and Fane. for specifications of models with alternative impedances.

** Multiple units exceed published rating evaluated under EIA 426A noise source and test standard while in a free-air, nontemperature-controlled environment.

*** The average output across the usable frequency range when applying 1W/1m into the nominal impedance. ie: 2.83 V /8 ohms, 4 V /16 ohms. Eminence response curves are measured under the following conditions: All speakers are tested at 1W/1m using a variety of test set-ups for the appropriate impedance | LMS using 0.25" supplied microphone (software calibrated) mounted 1m from wall/baffle | 2 ft. x 2 ft. baffle is built into the wall with the speaker mounted flush against a steel ring for minimum diffraction | Hafler P1500 Trans-Nova amplifier | 2700 cu. ft. chamber with fiberglass on all six surfaces (three with custom-made wedges).

**** BETA 8CX, 10CX, 12CX and ACOUSTINATOR™ CX 2008 are coaxial speakers with tweeter sold separately. Published Usable Frequency response contingent upon use of APT 50 HF Driver.

***** Multiple units exceeded published rating evaluated under AES 500 and AES 800 noise sources and test standards while mounted on Eminence's TI-2000 horn in a nontemperature-controlled environment.

****** The average on axis output across the entire usable frequency range when applying 1W/1m into the nominal impedance while mounted on a Community SH 494 horn measured with: LMS (software calibrated) using a 0.25" [6.4mm] supplied microphone mounted 1m from horn mouth, Hafler P1500 Trans-Nova amplifier, 2700 cu.ft. chamber w/fiberglass on all six surfaces (three with custom made wedges). Plane-wave tube response and impedance curves measured with LMS on a 0.75" [19.1mm] diameter tube with adapter to allow for smooth transition to throat diameter and 1W/1m into nominal
----------------------------------------------

Nice to see they're using a Hafler P1500 Trans-Nova in their test setup -- my two amp possibilities are a pre-Rockford-Fosgate Hafler DH200 (nominally 100W/C, but generally more, especially with mods), and an R-F era Hafler TA1100 trans*ana MOSFET amp, nominal power output:
50 wpc into 4Ω, 40 wpc into 8Ω @1kHz, 0.1% THD. One of the nice things about the TA1100 is that it has separate, front-mounted volume controls for each channel -- maybe now I can do that melon-crushing left-right-left-right-left-right opening to Moby Grape's "Omaha!" They had the potential to be the greatest of the mid-'60s bands to come out of San Francisco, but their manager made the mistake of renting them a beach house at Malibu right next to the one where The Byrds were living at the time. Not much work got done -- not musical work, anyway...

So, based on the Eminence specs, how would I go about determining a cabinet volume?

Peace

Bart
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Old 8th December 2011, 10:27 PM   #6
dangus is offline dangus  Canada
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This is the useful stuff:
THIELE & SMALL PARAMETERS
Resonant Frequency (fs) 79Hz
DC Resistance (Re) 7.3
Coil Inductance (Le) 0.54mH
Mechanical Q (Qms) 13.88
Electromagnetic Q (Qes) 0.68
Total Q (Qts) 0.65
Compliance Equivalent Volume (Vas) 50.9 liters / 1.8 cu.ft.
Peak Diaphragm Displacement Volume (Vd) 42cc
Mechanical Compliance of Suspension (Cms) 0.13mm/N
BL Product (BL) 12.8 T-M
Diaphragm Mass Inc. Airload (MMs) 31 grams
Efficiency Bandwidth Product (EBP) 116
Maximum Linear Excursion (Xmax) 0.8mm
Surface Area of Cone (Sd) 519.5 cm2

Download some software like Speaker Workshop and enter the appropriate numbers. There must be a tutorial someplace on using it.

Check your local public (or university) library; they may have some books on speaker design. David Weems wrote a couple that are quite accessible. Or there's the "Loudspeaker Design Cookbook". (if you were to google that title plus pdf, you might find a scanned version to read while you wait for Amazon to ship you one.)
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Old 9th December 2011, 12:49 AM   #7
bartbrn is offline bartbrn  United States
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Quote:
Originally Posted by dangus View Post
Download some software like Speaker Workshop and enter the appropriate numbers. There must be a tutorial someplace on using it.
The problem with tha is that I use Macs exclusively, and I have yet to see any of this kind of software for OS X Intel

Quote:
Originally Posted by dangus View Post
Check your local public (or university) library; they may have some books on speaker design. David Weems wrote a couple that are quite accessible. Or there's the "Loudspeaker Design Cookbook". (if you were to google that title plus pdf, you might find a scanned version to read while you wait for Amazon to ship you one.)
I'll check on he books (and possible pdf). Thanks!

Bar
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Old 16th May 2012, 07:52 PM   #8
bartbrn is offline bartbrn  United States
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Well, it's been a while, but here's what I ended up with:

2x12" Eminence Patriot Texas Heat
1x Line 6 POD XT
1x Hafler DH-200
2x Goldwood E-12SP 12" ported box, approximately 1.5 ft³ each


Click the image to open in full size.


Highlights
1.5 ft³ cabinet
Slotted port design
3/4" MDF construction
All joints glued and caulked
Black carpet covering
Dimensions: 18" H x 13-1/2" W x 16" D. Port dimensions: 1-15/16" H x 12-1/8" W x 13" D. Cutout: 11" diameter. Approximately 1.5³, tuned to roughly 55 Hz.

Anybody have any idea what I do next? Like I said, I'm a complete and utter novice at this...

Thanks for your help!

Bart Brown
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Old 23rd May 2012, 01:41 AM   #9
dangus is offline dangus  Canada
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What I would do is find a way to run the box design software. It doesn't need much CPU power to run something like Perfect Box (a DOS application), so any PC you can get your hands on would do, or maybe an emulator. See what port tuning would suit that driver in that size box. Perfect Box has some bugs when it comes to calculating port size/length, so I'd refer to the LDC or other software. But, real ports don't always agree with the simulations, so I'd measure the box tuning then adjust the duct length if necessary (maybe stuff some 2x2 into it to make it narrower if that works).

Another author to look out for is Ray Alden; he wrote Radio Shack's "Advanced Speaker Systems". While the example systems (based on Radio Shack drivers) aren't worth building, there's a lot of good advice in there. I haven't seen "Speaker Building 201", which apparently was done in collaboration with Parts Express. I believe you may find a copy of "David B Weems Designing, Building and testing Your own speaker" online somewhere, if it's legal on your planet. Or it's only $12 from Amazon: Designing, Building, and Testing Your Own Speaker System with Projects

Last edited by dangus; 23rd May 2012 at 01:47 AM.
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Old 23rd May 2012, 06:20 AM   #10
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Location: Dallas
The springiness of the suspension will double when you seal the
back into a box almost the same size as VAS. The consequences
will be an increased frequency of resonance, a greater tendency
to ring at the resonant note, and slightly higher efficiency for mid
notes above the new resonance at the cost bass notes lost below
the new resonance.

That speaker's Q was fairly high, maybe close to ideal for an open
baffle. In a closed or vented box, it will be a little too springy for
its own damping. It will ring slightly too much for clean PA, but
nothing that would work against a single musical instrument.
For your application, its absolutely nothing to worry about.

That port is tuned about right. Low enough you won't know for
sure you are hearing it. But it will stiffen the air for low notes
that otherwise cause large cone motion, and this keeps voicecoil
centered in the gap for highest efficiency.

Last edited by kenpeter; 23rd May 2012 at 06:30 AM.
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