I bought a new car 28 days ago, and I need some tunes.
In this thread I'll document my attempt to squeeze some midbass horns under the dash.
Not sure if it's possible to make them that small, but let's find out!
(BTW, if anyone is wondering why this thread is in 'multi way' instead of car audio, it's because all the horn experts read this forum, not the car audio forum.)
In this thread I'll document my attempt to squeeze some midbass horns under the dash.
Not sure if it's possible to make them that small, but let's find out!
(BTW, if anyone is wondering why this thread is in 'multi way' instead of car audio, it's because all the horn experts read this forum, not the car audio forum.)
The horn in my truck goes 'beep beep'.
And it's in the engine compartment....fidelity in the passenger compartment is not that good.
And it's in the engine compartment....fidelity in the passenger compartment is not that good.
Here's some candidates for my project. In order to make this thing work, I'll need a driver that's insanely small, in order to keep the horn small.
Fostex FF85WK, $38
Thiele Small (measured vs published)
fs) 123.1 vs 115
qts) 0.71 vs 0.55
qms) 4.51 vs 3.3
qes) 0.85 vs 0.68
re) 7.5 vs 7.2
le) 0.49 vs 0.32
horn bandwidth (guesstimate) = 123-434hz
Fostex FF85WK, $38
Thiele Small (measured vs published)
fs) 123.1 vs 115
qts) 0.71 vs 0.55
qms) 4.51 vs 3.3
qes) 0.85 vs 0.68
re) 7.5 vs 7.2
le) 0.49 vs 0.32
horn bandwidth (guesstimate) = 123-434hz
An externally hosted image should be here but it was not working when we last tested it.
Gento SP99023A, $2
Thiele Small (measured vs published)
fs) 201.9 vs 333.8(!)
qts) 0.73 vs 1.17(!)
qms) 3.0 vs 4.93(!)
qes) 0.96 vs 1.54(!)
re) 3.64 vs 3.56
le) 0.25 vs 0.26
horn bandwidth (guesstimate) = 202-420hz
The measurements from Parts Express are so far off, it really makes me wonder if they measured a different driver. (2" Paper Cone Midrange Tweeter 4 Ohm 289-127) I have a whole box of these (for two bucks, why not?) and the consistency from driver to driver was very good, within about 3%.
Patrick,
Did you break the driver to loosen up the suspension before measurement?
Why build a 1 octave horn?
Art
Dayton RS52
This is an oddball option. I basically took one of my RS52s and sawed it in half, to figure out if I could make it work on a horn. The reason that I did this is that it's really hard to find small drivers that work as midranges on a horn. For instance, there are tons of 6" and 8" drivers that can go up to 500hz on a horn, but very very few 3" or 4" drivers that can. I think that this is mostly due to it being such an unusual project; most 3" and 4" drivers are in computer and multimedia speakers, where efficiency isn't a priority, but bass IS.
So 95% of the 3" and 4" drivers have a moving mass that's basically too heavy for a horn.
The Dayton is an intriguing option, because it has a couple features that make it attractive for horn loading. First, it has a low MMS, mostly due to the absence of a spider and a heavy surrond. And second, it's one of the very few drivers under 4" that has a copper cap on the pole, for reducing distortion.
Long story short, you're not going to get bass out of a Dayton RS52, but you (might) get it to play above 500hz on a horn.
The measurements below are of the RS52 with the back cup sawed off:
Thiele Small (measured vs published)
fs) 247.6 vs 383
qts) 0.65 vs 0.77
qms) 3.34 vs 2.55
qes) 0.81 vs 1.1
re) 5.46 vs 5.4
le) 0.32 vs 0.03
horn bandwidth (guesstimate) = 248-611hz
Some of the best sounding setup I've heard to date, including a setup I've done to an Equus was to mount a FR88EX in a pod up on the dash supplemented with a small tweeter like the Airborne RT-20021 without the mounting flange. Very nice flushmount for a very small tweeter crossed active @5k = pure bliss
Built boxes into the door and mount a 6.5" there, as close to time aligned as you can physically get. I use a string for this.
Build a box into the back deck for subs. Depending on the level of "thump" you want, compensate for cabin gain with a shelf filter or model it into the design.
Spelled out like this it sounds easy. Oh lordy it's time and labor intensive! Cosmetics are everything in a build like this 😉
Built boxes into the door and mount a 6.5" there, as close to time aligned as you can physically get. I use a string for this.
Build a box into the back deck for subs. Depending on the level of "thump" you want, compensate for cabin gain with a shelf filter or model it into the design.
Spelled out like this it sounds easy. Oh lordy it's time and labor intensive! Cosmetics are everything in a build like this 😉
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I just moved, and unfortunately I don't even have an amplifier here. (My stuff is still in transit.)
I know that the qms and qts will fall a few percent once the drivers are 'broken in.'
All of these drivers are fresh out of the box.
One 'trick' I use to get better measurements is to excercise the suspension physically, by literally moving the cone by hand. This typically drops the fs qms and qts by about five percent.
As for the bandwidth of the horn, this is going to be a Unity horn (of course), so I'm basically looking for a driver that can 'fill in' below my compression driver.
The TangBand W2-852SH, which I used in this project* may still be the best option for a tiny unity horn.
* Creating The Perfect Soundstage - Car Audio | DIYMA.com
These are great performers. Zaph has independent measurements on his site.
Vifa TC7FD00-04 2-1/2" Full Range Paper Cone Driver 4 Ohm 264-1144
Vifa TC6FD00-04 2" Full Range Paper Cone Woofer 4 Ohm 264-1126
I used the TC7 in a 2way system that won the under $200 category at MWAF this year. Very nice little driver. In my case it was kind of a FAST-like application with a passive 2nd order XO at around 550hz to the RS225-04 8" woofer.
Vifa TC7FD00-04 2-1/2" Full Range Paper Cone Driver 4 Ohm 264-1144
Vifa TC6FD00-04 2" Full Range Paper Cone Woofer 4 Ohm 264-1126
I used the TC7 in a 2way system that won the under $200 category at MWAF this year. Very nice little driver. In my case it was kind of a FAST-like application with a passive 2nd order XO at around 550hz to the RS225-04 8" woofer.
Here's the response of one of the Fostex woofers on a nine liter horn, versus *two* of the Gento woofers on a two liter horn. Some observations:
1) the response of both horns is quite peaky, due to the small size
2) the Fostex plays nearly an octave lower, but at the expense of a horn that's over four times as large
3) Due to the lower impedance of the Gento horn, I did the sim with 1 watt into 4ohms, while the other one is getting one watt into 8 ohms
Here's the response of one of the Fostex woofers on a nine liter horn, versus one of the Dayton RS52s on a 1.3 liter horn. Some observations:
1) The Dayton has the lowest QES of all three drivers. Due to this, it works on an extremely small horn (1.3 liters) while still delivering high efficiency.
2) The Dayton has the least 'bass' of all three, but that's the flipside of it's high efficiency and small horn requirements
I am leaning towards using the Dayton RS52 for a few reasons:
1) Due to the low QES and the low MMS, the RS52 arguably allows for the smallest horn possible. While it's true that the $2 Gento *might* allow for a smaller horn than the Dayton, the higher FS and lower QES of the Dayton allows for a shorter and likely smaller horn... And in this project, horn size is the primary goal, since it's going under the dash
2) The Dayton has a voice coil that's positively massive, compared to the Fostex and the Gento (5.1cm(!) vs 1.6cm vs 1.25cm")
3) The Dayton has shorting rings
1) Due to the low QES and the low MMS, the RS52 arguably allows for the smallest horn possible. While it's true that the $2 Gento *might* allow for a smaller horn than the Dayton, the higher FS and lower QES of the Dayton allows for a shorter and likely smaller horn... And in this project, horn size is the primary goal, since it's going under the dash
2) The Dayton has a voice coil that's positively massive, compared to the Fostex and the Gento (5.1cm(!) vs 1.6cm vs 1.25cm")
3) The Dayton has shorting rings
Here's some pics of the Dayton RS52, sawed in half. Gives you an idea of how similar it is to a compression driver.
The tan colored stuff is clay. I used that to find out how high I could push the FS. (Raising the FS increases the efficiency of the horn, increases the power handling, the F3 of the horn, and makes the bandwidth narrower.)
Here's the Thiele Small of the Dayton RS52, with the clay added. Basically shows you how high you can raise the Fb.
Fb) 709hz (vs 248hz free air and 383hz in the 'stock' enclosure)
Qts) 1.9 (vs 0.65 free air and 0.77 in the 'stock' enclosure)
Qms) 6.85 (vs 3.34 free air and 2.55 in the 'stock' enclosure)
Qes) 2.63 (vs 0.81 free air and 1.1 in the 'stock' enclosure)
Re) 5.3 (vs 5.5 free air and 5.4 in the 'stock' enclosure)
Le) 0.5 (vs 0.3 free air and 0.03 in the 'stock' enclosure)
The tan colored stuff is clay. I used that to find out how high I could push the FS. (Raising the FS increases the efficiency of the horn, increases the power handling, the F3 of the horn, and makes the bandwidth narrower.)
Here's the Thiele Small of the Dayton RS52, with the clay added. Basically shows you how high you can raise the Fb.
Fb) 709hz (vs 248hz free air and 383hz in the 'stock' enclosure)
Qts) 1.9 (vs 0.65 free air and 0.77 in the 'stock' enclosure)
Qms) 6.85 (vs 3.34 free air and 2.55 in the 'stock' enclosure)
Qes) 2.63 (vs 0.81 free air and 1.1 in the 'stock' enclosure)
Re) 5.3 (vs 5.5 free air and 5.4 in the 'stock' enclosure)
Le) 0.5 (vs 0.3 free air and 0.03 in the 'stock' enclosure)
This tapped horn is only 11.6 liters. It can hit over 120dB. Note that I added 1mH in series to smooth things out. I think you could fit this into the map pockets in the front doors.
An externally hosted image should be here but it was not working when we last tested it.
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If you want a normal front loaded horn, then this 4" should work nicely for you.
And the link to it: JC4C | Misco Speaker Company
And the link to it: JC4C | Misco Speaker Company
^^ way cool on the tapped horn for the doors.
One idea I'm kicking around is doing an Opsodis arrangement.
Basically low frequencies in the trunk, midbass to the left and the right, and these horns documented in this thread under the dash
One idea I'm kicking around is doing an Opsodis arrangement.
Basically low frequencies in the trunk, midbass to the left and the right, and these horns documented in this thread under the dash
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