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
Eminence Texas Heat Guitar Speaker at AmericanMusical.com
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.
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.
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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):
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
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):
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
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.
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.
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
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.)
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.)
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
I'll check on he books (and possible pdf). Thanks!
Bar
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
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
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
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
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
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
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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.
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.
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Eminence Patriot Texas Heat in bottom ported cabs--Acoustastuff?
Kenpeter wrote:
"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 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."
Thanks for the relief! Turns out the internal volume of those Goldwood bottom-ported cabs is 1.5cu.ft. So my last question on construction (I hope!), should I use Acoustastuff or other damping media, and if so, roughly how much and where should it be placed in relation to the drivers?
For my first setup will use the Hafler TA1100 (nominally 40W/ch@8ohm) -- partly because it's easy to change out because of the PodXT's 1/4" in and R&L channel 1/4" outs, and the Hafler TA1100s 1/4" ins and outs, and partly because my Hafler DH200 (nominally 110w/ch, in reality more like 130, with excellent headroom, and a quite high damping factor) needs some upgrading in the component department.
Any other ideas or info is gratefully accepted!
Bart Brown
Kenpeter wrote:
"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 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."
Thanks for the relief! Turns out the internal volume of those Goldwood bottom-ported cabs is 1.5cu.ft. So my last question on construction (I hope!), should I use Acoustastuff or other damping media, and if so, roughly how much and where should it be placed in relation to the drivers?
For my first setup will use the Hafler TA1100 (nominally 40W/ch@8ohm) -- partly because it's easy to change out because of the PodXT's 1/4" in and R&L channel 1/4" outs, and the Hafler TA1100s 1/4" ins and outs, and partly because my Hafler DH200 (nominally 110w/ch, in reality more like 130, with excellent headroom, and a quite high damping factor) needs some upgrading in the component department.
Any other ideas or info is gratefully accepted!
Bart Brown
Kenpeter -- Just to show you how audio-clueless I am, could you explain -- or recommend a good site or book --- for the basics of this stuff:
"The springiness of the suspension will double when you seal the
back into a box almost the same size as VAS."
What IS "VAS?"
"That speaker's Q was fairly high, maybe close to ideal for an open
baffle."
What is a speaker's "Q?"
I don't know if a high damping factor is as critical in a guitar amp as in an "audio" (or what we used to call in a previous century "hi-fi")amp, but from Walt Jung's original review from Audio Amateur magazine sometime in 1980:
REVIEW: HAFLER DH-200
here's his take on -- among other things I don't understand -- the damping of the DH200:
"While these photos and the discussion of the high frequency THD suggest a healthy HF output capability, the real evidence is in Fig. 8. This photo shows the DH-200's output waveform driving 8 ohms in parallel with 1uF, at an 80V p-p level at 100kHz. As you can see, there is a small (but damped) overshoot with about 20uS of ringing, which indicates good stability, into a very difficult load. You will appreciate the difficulty if you consider the amp's 13V/uS slew rate while driving the 1uF capacitor. To provide this rate of change in voltage across 1uF requires a current of 13 amps!
In their literature the Hafler people discuss at some length the output characteristic of this amp; apparently they feel it an important virtue in controlling undesired components ''kicked back" from the speaker. They rate the damping factor as 150 at 1kHz and 50 at 10kHz. I measured a damping factor of about 400 at frequencies below 1kHz, dropping to about 150 at 10kHz."
Still would like opinions on using Acoustastuff in these cabinets, and if the answer is "yes," where should it go? (Please don't tell me the obvious!)
Thanks for all help!
Bart Brown
"The springiness of the suspension will double when you seal the
back into a box almost the same size as VAS."
What IS "VAS?"
"That speaker's Q was fairly high, maybe close to ideal for an open
baffle."
What is a speaker's "Q?"
I don't know if a high damping factor is as critical in a guitar amp as in an "audio" (or what we used to call in a previous century "hi-fi")amp, but from Walt Jung's original review from Audio Amateur magazine sometime in 1980:
REVIEW: HAFLER DH-200
here's his take on -- among other things I don't understand -- the damping of the DH200:
"While these photos and the discussion of the high frequency THD suggest a healthy HF output capability, the real evidence is in Fig. 8. This photo shows the DH-200's output waveform driving 8 ohms in parallel with 1uF, at an 80V p-p level at 100kHz. As you can see, there is a small (but damped) overshoot with about 20uS of ringing, which indicates good stability, into a very difficult load. You will appreciate the difficulty if you consider the amp's 13V/uS slew rate while driving the 1uF capacitor. To provide this rate of change in voltage across 1uF requires a current of 13 amps!
In their literature the Hafler people discuss at some length the output characteristic of this amp; apparently they feel it an important virtue in controlling undesired components ''kicked back" from the speaker. They rate the damping factor as 150 at 1kHz and 50 at 10kHz. I measured a damping factor of about 400 at frequencies below 1kHz, dropping to about 150 at 10kHz."
Still would like opinions on using Acoustastuff in these cabinets, and if the answer is "yes," where should it go? (Please don't tell me the obvious!)
Thanks for all help!
Bart Brown
OK -- I hope these are the LAST last dumb questions:
1. Still would VERY MUCH like to know if I should use AcoustaStuff or some similar batten material in the ported Goldwood enclosures I'm using (see previous drawing and pic), or leave the box empty.
2. What gauge wire should I use from the Eminence speaker + and - terminals to the cabinets' terminal cups, and what sort of jack should I use in the cups? I was thinking, as these are essentially two mono speakers with the stereo output controlled by the amp, that I'd use 1/4" mono guitar-style jacks, as both the ins and outs of the Line 6 PodXT are 1/4" mono jacks. (See above: "For my first setup will use the Hafler TA1100 (nominally 40W/ch@8ohm) -- partly because it's easy to change out because of the PodXT's 1/4" in and R&L channel 1/4" outs, and the Hafler TA1100s 1/4" ins and outs, and partly because my Hafler DH200 -- nominally 110w/ch, in reality more like 130, with excellent headroom, and a quite high damping factor -- needs some upgrading in the component department").
3. STILL interested to know if the Haflers' high damping factor is a "good thing, Martha" for guitar speakers as it is for full-range audio speakers, or if it makes no difference.
4. The DUMBEST of the dumb questions: having never built anything like this, I assume -- I hope correctly -- that the speakers are attached with the flange and foam mounting ring on the OUTSIDE of the box?
YO, it's my birthday (will you still need me, will you still feed me, when I'm 64?), so please gift me with an answer.
Peace, and be wild
Bart
1. Still would VERY MUCH like to know if I should use AcoustaStuff or some similar batten material in the ported Goldwood enclosures I'm using (see previous drawing and pic), or leave the box empty.
2. What gauge wire should I use from the Eminence speaker + and - terminals to the cabinets' terminal cups, and what sort of jack should I use in the cups? I was thinking, as these are essentially two mono speakers with the stereo output controlled by the amp, that I'd use 1/4" mono guitar-style jacks, as both the ins and outs of the Line 6 PodXT are 1/4" mono jacks. (See above: "For my first setup will use the Hafler TA1100 (nominally 40W/ch@8ohm) -- partly because it's easy to change out because of the PodXT's 1/4" in and R&L channel 1/4" outs, and the Hafler TA1100s 1/4" ins and outs, and partly because my Hafler DH200 -- nominally 110w/ch, in reality more like 130, with excellent headroom, and a quite high damping factor -- needs some upgrading in the component department").
3. STILL interested to know if the Haflers' high damping factor is a "good thing, Martha" for guitar speakers as it is for full-range audio speakers, or if it makes no difference.
4. The DUMBEST of the dumb questions: having never built anything like this, I assume -- I hope correctly -- that the speakers are attached with the flange and foam mounting ring on the OUTSIDE of the box?
YO, it's my birthday (will you still need me, will you still feed me, when I'm 64?), so please gift me with an answer.
Peace, and be wild
Bart
Wish I was around when you started this. The answers you got were well meaning, but inexperienced. Your box is way too small, and that speaker isn't really going to be happy with a port, anyway. Best thing you can do is cut a large hole in the back of the box, at least equal to 1/3 the area of the back panel. No stuffing needed.
Use 16 ga. wire. Bigger isn't necessary, and won't fit the pushons. You want .205" pushons, not 1/4". Parts Express number 095-282. Use only Switchcraft 1/4" jacks and plugs, others may be metric.
Your Haflers will be fine. I use a Zoom through my DH120 all the time.
Yes, you can mount the speaker outside the box. Get some 1/4" T-nuts, or better yet, hurricane nuts. Use 1" x 1/4" bolts, the black aircraft grade that take an Allen key. Their small heads will fit in the the holes in the thick cardboard gasket, and you're less likely to slip and poke a hole in the speaker than you would be using a screwdriver. Don't overtighten the screws! Go about 1/4 turn after they seat - the back gasket is thin.
Good luck, and happy birthday!
Keri
Use 16 ga. wire. Bigger isn't necessary, and won't fit the pushons. You want .205" pushons, not 1/4". Parts Express number 095-282. Use only Switchcraft 1/4" jacks and plugs, others may be metric.
Your Haflers will be fine. I use a Zoom through my DH120 all the time.
Yes, you can mount the speaker outside the box. Get some 1/4" T-nuts, or better yet, hurricane nuts. Use 1" x 1/4" bolts, the black aircraft grade that take an Allen key. Their small heads will fit in the the holes in the thick cardboard gasket, and you're less likely to slip and poke a hole in the speaker than you would be using a screwdriver. Don't overtighten the screws! Go about 1/4 turn after they seat - the back gasket is thin.
Good luck, and happy birthday!
Keri
Eminence Patriot "Texas Heat" 12" speakers: boxes not good, speakers not good?
Thank you for the birthday greetings and your advice, but I have to ask some questions about your post. First, I began this thread on 18th November 2011. You've been a member since Feb 2010, so I have to assume you were "around." Much more importantly, though many of the first replies I got seemed to assume -- due to deficiencies in my explanation of what I was trying to do, I'm sure -- that what I was attempting to build was a full range audio speaker, most everyone eventually got the correct gen: I was building a two-cabinet guitar speaker system with a Line 6 PodXT front end and a Hafler TA-1100 or DH200 power amplifier. Certainly most of those who replied certainly seemed to know what they were talking about, but what do I know? Please explain to me your reasons for the broad-brush description of the previous-to-you 'well-meaning" responders as being "inexperienced." I certainly don't want to be led astray, in my near-total ignorance, by misinformation, from anyone.
Again, as Parts Express/Dayton built this ported cabinet specifically for a 12" speaker (usually, I know, a subwoofer in an automtive environment), I don't quite understand why my "box is way too small, and that speaker isn't really going to be happy with a port, anyway." Could you please expand on your reasons for that statement?
Also -- again, my apologies for my ignorance, but if I knew this stuff, I wouldn't have to come here to ask questions -- please explain this: "Best thing you can do is cut a large hole in the back of the box, at least equal to 1/3 the area of the back panel." The area of the back panel, which measures 18"H x 13.5"W = 243sq. in.; 1/3d of 243sq. in. is 81 sq. in. ; therefore, at a minimum, a hole "at least equal to 1/3d of that area" -- using the formula r = √(A / π) -- would have a radius of 5.0777", thus a diameter of 10.155" -- that's an awfully big hole, to my way of thinking. As for the port, it can be closed, or even adjusted, by means of baffles or an old shop rag.
Thanks for the hardware info. By "Zoom," are you referring to something like the Zoom G3 Guitar Amp and Effects Simulator?
Thanks for all the info. I hope you'll excuse my blockheadedness and explain the questions I've raised.
Thanks!
Bart Brown
Thank you for the birthday greetings and your advice, but I have to ask some questions about your post. First, I began this thread on 18th November 2011. You've been a member since Feb 2010, so I have to assume you were "around." Much more importantly, though many of the first replies I got seemed to assume -- due to deficiencies in my explanation of what I was trying to do, I'm sure -- that what I was attempting to build was a full range audio speaker, most everyone eventually got the correct gen: I was building a two-cabinet guitar speaker system with a Line 6 PodXT front end and a Hafler TA-1100 or DH200 power amplifier. Certainly most of those who replied certainly seemed to know what they were talking about, but what do I know? Please explain to me your reasons for the broad-brush description of the previous-to-you 'well-meaning" responders as being "inexperienced." I certainly don't want to be led astray, in my near-total ignorance, by misinformation, from anyone.
Again, as Parts Express/Dayton built this ported cabinet specifically for a 12" speaker (usually, I know, a subwoofer in an automtive environment), I don't quite understand why my "box is way too small, and that speaker isn't really going to be happy with a port, anyway." Could you please expand on your reasons for that statement?
Also -- again, my apologies for my ignorance, but if I knew this stuff, I wouldn't have to come here to ask questions -- please explain this: "Best thing you can do is cut a large hole in the back of the box, at least equal to 1/3 the area of the back panel." The area of the back panel, which measures 18"H x 13.5"W = 243sq. in.; 1/3d of 243sq. in. is 81 sq. in. ; therefore, at a minimum, a hole "at least equal to 1/3d of that area" -- using the formula r = √(A / π) -- would have a radius of 5.0777", thus a diameter of 10.155" -- that's an awfully big hole, to my way of thinking. As for the port, it can be closed, or even adjusted, by means of baffles or an old shop rag.
Thanks for the hardware info. By "Zoom," are you referring to something like the Zoom G3 Guitar Amp and Effects Simulator?
Thanks for all the info. I hope you'll excuse my blockheadedness and explain the questions I've raised.
Thanks!
Bart Brown
You're welcome.
Trouble is, I don't often look in the PA folder. There are others that know more than I and they seem to field the questions adequately.
Perhaps I should have specified, "inexperienced in building cabinets for guitars speakers". Only kenpeter seemed to realise what you were up against and suggest an open baffle.
If you were to run a simulation in a typical box design program, it would suggest a box of almost 10 cu. ft. for flat response. So, at 2 cu. ft., the box you have is "way too small". If you simply block the port, you'll have a roll-off starting around 150Hz, and since the low E on a guitar is 82Hz, I think you'll find it sounds "thin".
Box design software is intended for hifi speakers, and it makes assumptions that don't apply to guitar speakers. Most notably, that the speaker's suspension is linear. Guitar speakers have suspensions that become stiffer as the excursion increases. This feature allows a guitar speaker to handle a much greater dymanic range than you'll get from recorded music. Otherwise, the speaker would bottom out when you plucked a string. What this means is, with a ported design you won't get the lower bass assumed by the program because the speaker isn't going to increase its excursion at the same rate as a linear hifi speaker.
Yes, it is. The idea is to make the box "open", that is, prevent it from loading the speaker and adding air pressure to the speaker's suspension. It's just a common observation that a box with 2/3's of the back covered sounds good, so I figured a hole that big would be a good place to start. If it sounds 'boomy', you can always make it bigger.
The bottom line here is this: you're using a speaker that was meant to work in an open backed combo cabinet. To make it work in a closed or ported box, you would need a really big box to avoid losing bass.
Yes, I have an older G2 that lets me test speakers with more different amps than I can afford.
(BTW, you'll probably want to turn off any "cab sims" in the PodXT)Glad to help, and no need to apologise. We all started somewhere, sometime. I just happened to start back in the '60s.
Again, my apologies to those that did try to help. It was not my intention to slight you. I just wanted Bart to understand that what works for hifi does not work for guitar speakers. The theory is the same, but the mechanics and end results are different. Since a guitar cabinet is actually part of a musical instrument, we don't want flat response, and resonances are good!
Eminence Texas Patriot 12" speakers, Goldwood E-12SP cabs
Thanks for the well-elucidated reply, and my apologies for not replying sooner. Yesterday -- happy birthday not -- I apparently tore a tendon from the muscle and tendon grouping that makes up the rotator cuff of my right shoulder. I sure hope that's not the case, as I had to have rotator cuff surgery year before last on my LEFT shoulder, and whatever I did yesterday felt exactly like the complete tendon tearaway that I suffered then. The surgery itself isn't so bad, but the recovery and physical therapy is horrendous, and my left shoulder is still not back to normal in range of motion, and its strength is about half what it was. I'm 64, and I don't heal as quickly as I used to... at least I haven't gotten to the point where I have to have my wife accompany me to the bathroom, if you know what I mean...
I've been a Mac-only user since 1989, and I'm not about to switch, and I have yet to find an Intel Mac OS speaker simulation program or online calc page. If anyone knows of such a beast or beasts, please let me know.
Also, please understand I'm asking these questions because I want to learn, and do this job right, not to be a PITA!
What if I don't block the port? Here's what Goldwood says about the dims, volume and its tuned frequency:
<< 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.
Speaker Cutout: 11" diameter. Approximately 1.5³, tuned to roughly 55 Hz. >>
55Hz is considerably less than 82Hz. and apparently creates the correct frequency, SPL, and harmonics to blow the rusted rear fenders off the usual rat-bag 1978 Toyota loaded with this size woofer we hear at 2AM 'round these parts. Why would the open port, and the 55Hz tuned frequency of the Goldwood cabs, not suffice to get well below the 82Hz claimed as the frequency of a guitar's Low E string?
OK, if you say so...
Are you talking here about full-range audio speaker design software? Because if you're not, this is where I really get confused: "The idea is to make the box "open", that is, prevent it from loading the speaker and adding air pressure to the speaker's suspension. It's just a common observation [Why? Whose?} that a box with 2/3's of the back covered sounds good, so I figured a hole that big would be a good place to start. If it sounds 'boomy', you can always make it bigger... The bottom line here is this: you're using a speaker that was meant to work in an open backed combo cabinet. To make it work in a closed or ported box, you would need a really big box to avoid losing bass. [/QUOTE]
If this is so, given that the Goldwood cabs are 18" H x 13-1/2" W, wouldn't it be easier to just cut a rectangular in the back 1/3 of the 18" height (= 6") x the 13-1/2" width (I realize these are all outside dimensions -- this is just ball-parking), yielding a 81sq. in. "port" that's 1/3 of the original rear box area (18 x 13.5 = 243sq in/3 = 81sq. in.).
BTW, I've read many back and forth arguments of "open" vs "closed back" cabs, the general consensus -- if there is one -- tending towards the "don't matter with a small driver of 15W to 40W, probably matters with a 1000W Marshal stack"-- I'm certainly not qualified to judge!
Indeed... though it might make some really interesting noises!
Thanks again for your help -- any other opinions/tips/ ideas about guitar speaker design and/or rotator cuff injuries greatly welcomed.
BTW, my audio speakers:
1 pair of immaculate ca. 1978 DCM Time Window 1s*
1 pair Jendrejack-modified Micro-Acoustics MA-1s* (yes we're talking ancient history here, folks)
1 DCM powered subwoofer*
Adcom GTP-450 Tuner/Pre-amp
Hafler TA-1100 and DH200 power amps
Audio-Video receiver Denon AVR-3312CI
*All speakers, plus a center-channel Yamaha and a pair of Altec-Lansing rear surrounds, are currently connected to the Denon AVR-3312CI
Thanks for the well-elucidated reply, and my apologies for not replying sooner. Yesterday -- happy birthday not -- I apparently tore a tendon from the muscle and tendon grouping that makes up the rotator cuff of my right shoulder. I sure hope that's not the case, as I had to have rotator cuff surgery year before last on my LEFT shoulder, and whatever I did yesterday felt exactly like the complete tendon tearaway that I suffered then. The surgery itself isn't so bad, but the recovery and physical therapy is horrendous, and my left shoulder is still not back to normal in range of motion, and its strength is about half what it was. I'm 64, and I don't heal as quickly as I used to... at least I haven't gotten to the point where I have to have my wife accompany me to the bathroom, if you know what I mean...
I've been a Mac-only user since 1989, and I'm not about to switch, and I have yet to find an Intel Mac OS speaker simulation program or online calc page. If anyone knows of such a beast or beasts, please let me know.
Also, please understand I'm asking these questions because I want to learn, and do this job right, not to be a PITA!
What if I don't block the port? Here's what Goldwood says about the dims, volume and its tuned frequency:
<< 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.
Speaker Cutout: 11" diameter. Approximately 1.5³, tuned to roughly 55 Hz. >>
55Hz is considerably less than 82Hz. and apparently creates the correct frequency, SPL, and harmonics to blow the rusted rear fenders off the usual rat-bag 1978 Toyota loaded with this size woofer we hear at 2AM 'round these parts. Why would the open port, and the 55Hz tuned frequency of the Goldwood cabs, not suffice to get well below the 82Hz claimed as the frequency of a guitar's Low E string?
OK, if you say so...
Are you talking here about full-range audio speaker design software? Because if you're not, this is where I really get confused: "The idea is to make the box "open", that is, prevent it from loading the speaker and adding air pressure to the speaker's suspension. It's just a common observation [Why? Whose?} that a box with 2/3's of the back covered sounds good, so I figured a hole that big would be a good place to start. If it sounds 'boomy', you can always make it bigger... The bottom line here is this: you're using a speaker that was meant to work in an open backed combo cabinet. To make it work in a closed or ported box, you would need a really big box to avoid losing bass. [/QUOTE]
If this is so, given that the Goldwood cabs are 18" H x 13-1/2" W, wouldn't it be easier to just cut a rectangular in the back 1/3 of the 18" height (= 6") x the 13-1/2" width (I realize these are all outside dimensions -- this is just ball-parking), yielding a 81sq. in. "port" that's 1/3 of the original rear box area (18 x 13.5 = 243sq in/3 = 81sq. in.).
BTW, I've read many back and forth arguments of "open" vs "closed back" cabs, the general consensus -- if there is one -- tending towards the "don't matter with a small driver of 15W to 40W, probably matters with a 1000W Marshal stack"-- I'm certainly not qualified to judge!
Indeed... though it might make some really interesting noises!
Thanks again for your help -- any other opinions/tips/ ideas about guitar speaker design and/or rotator cuff injuries greatly welcomed.
BTW, my audio speakers:
1 pair of immaculate ca. 1978 DCM Time Window 1s*
1 pair Jendrejack-modified Micro-Acoustics MA-1s* (yes we're talking ancient history here, folks)
1 DCM powered subwoofer*
Adcom GTP-450 Tuner/Pre-amp
Hafler TA-1100 and DH200 power amps
Audio-Video receiver Denon AVR-3312CI
*All speakers, plus a center-channel Yamaha and a pair of Altec-Lansing rear surrounds, are currently connected to the Denon AVR-3312CI
Very sorry to hear about your shoulder. I do know what you mean, and would appreciate it, kind sir, if you would not refer to the Micro Acoustics as "ancient history". I was selling them the first year they were out! (Do you have the full speakers or the tweeter arrays?)
Okay, other stuff....
For design software your best bet may be Unibox, a spreadsheet that runs in Excel or Open Office.
UniBox - Unified Box Model for Loudspeaker Design - Kristian Ougaard
Going back to some earlier questions you had, there are 3 main speaker specifications that determine the proper enclosure size:
Fs - the fundamental resonance of the driver in free air.
Qts - effectively, a ratio of several other specs that determine 'how much' the driver will resonate.
Vas - the key to it all, an expression of the driver's compliance (i.e., how stiff the suspension is) in terms of box volume.
Now, you'll note that the driver's diameter isn't in the list (although it is included in the calculations for Vbs). My point isn't to explain all this stuff, but merely to point out that the Goldwood box isn't going to work for just any 12" speaker, it will only work for those with the proper Fs, Qts, and Vas.
Let's look at it another way. In trying to produce low bass frequencies, a speaker has to move four times farther for every octave lower. That is, if a speaker moves 1mm at 100Hz, it will have to move 4mm at 50 Hz to produce the same volume level. If you look at an assortment of the sub-woofers I suspect the Goldwood was designed for, you'll likely see Xmax specs (the maximum excursion the speaker should make) in the range of 4mm to 6mm. In contrast, your Patriots have an Xmax of .8mm.
Below you'll see a graph produced by WinISD of a Texas Heat in the Goldwood box. That's what will happen if you don't block the port. In my experience, such a tuning sounds a bit "woofy", with a sort of false bass. But, I expect you'll try it out and make up your own mind.
The "common observations" I referred to are those of players on several forums, including The Gear Page, My Les Paul forum, and the TDPRI. It takes a fair amount of skill to separate the wheat from the chaff when it comes to forum opinions. The most opinionated people tend to have the least experience; they're fighting hard to convince themselves (and others) their one purchase was a good one.
As far as 'open vs closed' discussions go, remember they're mostly talking about properly designed closed cabinets with speakers that were intended for such use. The short of it is, open backed speakers sound more diffuse (dare I say "open"?) and airy, whereas closed cabinets around more focused and the bass is more solid. Basically, our ears know what they're listening to. There's a loss of bass with an open back, the trade off is, there's more sound spread around the room and the more natural feeling of an acoustic instrument (which are also omni-directional). Wattage has little to do with it, other than the fact most players using a 100 watt full stack these days are playing heavy metal and want that solid chunk for palm-muted chording. On the other hand, look at Keith Richards - with an array of 4 Fender Twins, he's got 400 watts of open-backed swagger.
Again, we know the speaker will sound good in "free air" so without starting over and building a bigger box, I'm of the opinion your best bet is to convert the Goldwoods to "open backed" cabinets, ala combo amps. If it's easier to cut around the edges of the back panel, go for it. I just thought there might be bracing in the way (what the Brits call 'fillets' and we sometimes call 'cleats').
PS: If you're looking for more opinions, you might have the mods move this thread to the "Instruments and Amps" forum.
(Do you have the full speakers or the tweeter arrays?)Okay, other stuff....
For design software your best bet may be Unibox, a spreadsheet that runs in Excel or Open Office.
UniBox - Unified Box Model for Loudspeaker Design - Kristian Ougaard
Going back to some earlier questions you had, there are 3 main speaker specifications that determine the proper enclosure size:
Fs - the fundamental resonance of the driver in free air.
Qts - effectively, a ratio of several other specs that determine 'how much' the driver will resonate.
Vas - the key to it all, an expression of the driver's compliance (i.e., how stiff the suspension is) in terms of box volume.
Now, you'll note that the driver's diameter isn't in the list (although it is included in the calculations for Vbs). My point isn't to explain all this stuff, but merely to point out that the Goldwood box isn't going to work for just any 12" speaker, it will only work for those with the proper Fs, Qts, and Vas.
Let's look at it another way. In trying to produce low bass frequencies, a speaker has to move four times farther for every octave lower. That is, if a speaker moves 1mm at 100Hz, it will have to move 4mm at 50 Hz to produce the same volume level. If you look at an assortment of the sub-woofers I suspect the Goldwood was designed for, you'll likely see Xmax specs (the maximum excursion the speaker should make) in the range of 4mm to 6mm. In contrast, your Patriots have an Xmax of .8mm.
Below you'll see a graph produced by WinISD of a Texas Heat in the Goldwood box. That's what will happen if you don't block the port. In my experience, such a tuning sounds a bit "woofy", with a sort of false bass. But, I expect you'll try it out and make up your own mind.
The "common observations" I referred to are those of players on several forums, including The Gear Page, My Les Paul forum, and the TDPRI. It takes a fair amount of skill to separate the wheat from the chaff when it comes to forum opinions. The most opinionated people tend to have the least experience; they're fighting hard to convince themselves (and others) their one purchase was a good one.
As far as 'open vs closed' discussions go, remember they're mostly talking about properly designed closed cabinets with speakers that were intended for such use. The short of it is, open backed speakers sound more diffuse (dare I say "open"?) and airy, whereas closed cabinets around more focused and the bass is more solid. Basically, our ears know what they're listening to. There's a loss of bass with an open back, the trade off is, there's more sound spread around the room and the more natural feeling of an acoustic instrument (which are also omni-directional). Wattage has little to do with it, other than the fact most players using a 100 watt full stack these days are playing heavy metal and want that solid chunk for palm-muted chording. On the other hand, look at Keith Richards - with an array of 4 Fender Twins, he's got 400 watts of open-backed swagger.
Again, we know the speaker will sound good in "free air" so without starting over and building a bigger box, I'm of the opinion your best bet is to convert the Goldwoods to "open backed" cabinets, ala combo amps. If it's easier to cut around the edges of the back panel, go for it. I just thought there might be bracing in the way (what the Brits call 'fillets' and we sometimes call 'cleats').
PS: If you're looking for more opinions, you might have the mods move this thread to the "Instruments and Amps" forum.
Attachments
MODERATORS! PLEASE MOVE THIS THREAD!
Sorry to steal from "Extreme Makeover: the Doghouse Edition," but I agree that it would be great if the mods could move this thread to the "Instruments and Amps" forum, I somehow missed seeing that particular forum -- probably because my initial posts here were regarding DCM Time Windows, which I've resolved by finally finding and buying an excellent pair -- but I truly think there would be more interest and input into this stitched-together Frankenstein of a stereo guitar amp in that forum.
Hope they move it!
Thanks for your help and patience -- you've explained much that I had NO idea about.
Bart
Sorry to steal from "Extreme Makeover: the Doghouse Edition," but I agree that it would be great if the mods could move this thread to the "Instruments and Amps" forum, I somehow missed seeing that particular forum -- probably because my initial posts here were regarding DCM Time Windows, which I've resolved by finally finding and buying an excellent pair -- but I truly think there would be more interest and input into this stitched-together Frankenstein of a stereo guitar amp in that forum.
Hope they move it!
Thanks for your help and patience -- you've explained much that I had NO idea about.
Bart
Definitely helps to send a PM to a moderator.. - Status
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