New MJK Baffle Article

[mor2bz]

i am working on some but am not there; the speakers were taken apart
for finishing of the wood so i did not get a listen.

if there is too much treble i have a bottle of dammar at hand for the
little driver.

if the bass extends to 60 hz. i think i would be quite happy. i have tried
integrating a sub at freqencies of 100-150 and was not happy. by using
the sub as an active crossover i was always able to get good integration
with the main driver, but could here the damage done to the signal.

for sure i will report back as soon as i hear one note from them

 

[patch]

It appears to me that the super-clarity or dynamics most audiophiles are obsessed with is some kind of artificial flavor that, albeit pleasant or exciting to listen to, is not found in reality

For me, for quiet listening of recordings of natural vibrating instruments (such as the voice, cello, trumpet), the most nearly "real-sounding" loudspeakers have been open baffle and dipole designs, multiple drivers.

Most of this work in reproducing a "reality" seems to center on the drivers, their limits, and doing anything reasonable to make the most of what they can give. (Well, maybe not assembling a device to freshen-up exhausted electrons). Speaking of super-clarity, Mr. King's using the 103 as a case study was brilliant. Getting quality sound from an unmodified 103 was a summit achievement.

 

[planet10]

f there is too much treble i have a bottle of dammar at hand for the
little driver.

I am very wary of a full damar coat on the banana cones... it significantly stiffens things, and can exacerbate any cone resonances.

Better to start with the puzzlekoat pre-treat (as if you were going to EnABL them -- which i recommend anywy)

dave

 

[BHD]

Better to start with the puzzlekoat pre-treat (as if you were going to EnABL them -- which i recommend anywy)

I'm going to do a couple of thin coats of puzzlecoat on the 103's in my OB's next week and will report the results. I also have phase plugs finally on the way.

🙂

 

[ctaudio]

Anyone else have a go at this?

I have built a pair with the exact components and dimensions as described in the article. I’ve been listening to them for a couple of weeks now. They are simply amazing. The sound is so much cleaner, so much more focused. I have not listened to my B&W 804 since.

 

[mor2bz]

thanks planet 10 regarding the dammar. i have yet to use the puzzlecoat.

i also have a very nice amp that is treble-shy, so that may be the ticket.

god, i can't wait to hear these things. my buddy is driving me nuts with
his feet dragging.

 

[MJK]

I have built a pair with the exact components and dimensions as described in the article. I’ve been listening to them for a couple of weeks now. They are simply amazing. The sound is so much cleaner, so much more focused. I have not listened to my B&W 804 since.

That is great to hear, thanks for the positive feedback.

 

[patch]

For a pair of 103s I used a thin coat of clear GE silicone glue around the rim and down 1/8th or so over the diaphram. Sends the "brisk" quality Fostex seems proud of right out the window, thank goodness. Rendered the 103 a usable midrange in my 3-way mules.

 

[SteveA]

with the 108es

I am building these using the Fostex 108es's (with 2 dB attenuation as suggested). I plan to put the baffle on a base or pedestal (sp?) of about 1.5". Should I include this in the overall height? Would it be best to move the baffle forward on the base?

The base would be 1.5X10X24".

Comments/thoughts appreciated.

SteveA

 

[scott_m]

Patch,

Where is Blue, Oregon?

Scott.

 

[patch]

that is a small b.

No census boundaries for blue Oregon; its wide open, a mindset, and a lot bigger than than those lands marked off as the State of Oregon, USA.

 

[ronc]

I wipped up a pair, sounded good.(simple enough) Still i went back to my big ole horns.
I believe once you are use to the " horn" sound its hard to accept less.
The major difference between the OBs and the A166 is LF response and image. The LF fills the room in the horns,its more realistic, the Obs are a bit more "open". But sufffer from image position and punch.
ron

 

[scott_m]

Thanks Ron. Did you use the drivers Martin specified? By the way, I still have a completed pair of your first horns designed for the 206 fostex. They're in storage - I started assembling them when we put our previous house on the market, 3+ years ago. Our new home will be inhabitable in early 2008, so I'll be able - finally - to mount the drivers and listen to them!

Scott.

 

[ronc]

Thanks Ron. Did you use the drivers Martin specified?

I used my old 108s. I believe with an L pad the sound would have been more balanced, but i didnt have one handy. In my room i was getting around 60 Hz. However i didnt run the signal generator or SPL meter so i really cant say with assurance.
Still sounded very open like OBs should, it just lacked that "horn" punch that i am used to.

ron

 

[MJK]

Ron,

A low end of 50 to 60 Hz sounds about right.

If you are using the older version of the FE-108XXX then the driver is a couple dB too efficient. A difference of 1 or 2 dB in the balamce between the woofer and the full range driver will make a huge difference in the sound of the speaker system. The bass will sound weaker and thin if the full range is too efficient.

I think if you added the L-Pad you would get closer to what you like, however the OB bass is not an enclosure "resonance" generated bass so it will sound different. A crude analogy might be comparing the difference between bass reflex bass and TL bass. There is a difference in the sound and some people prefer one over the other.

 

[ronc]

I will find my L pads and give it a try. (let the purists flack begin).

I do like the OB sound as its a very spacious and open sound thats about the most simple build possible, i even made these and did not contract it out.

ron

 

[sreten]

I will find my L pads and give it a try. (let the purists flack begin).
ron

Hi,

A small level difference over a wide range does make a huge
difference, it should be the first point of tuning. The second
point would likely be compensating for significant peaks or
broad emphasis, which interacts with the first somewhat,
the third possibly by-passing any attenuation in the top
octave or so (if a supertweeter is not being used).

Once values have been settled on, rebuild with quality components.

🙂/sreten.

 

[MJK]

First pictures of the design using the FE-108E Sigma (padded down 2 dB) are now in my gallery. Really nice looking build! Congrat's Mike.

 

[mor2bz]

Mr. King, please pardon my ignorance (again) but what in the design
makes for the difference in the two xover frequencies (about 200 for
the bass and 400 for the treble)? Is it the high qts of the bass driver?
thanks for your reply if you have the time or interest. mine are STILL
not built. I hearby swear that i will post my first stereo pics on the
net for this project and provide more comments than you may care to
hear.

 

[MJK]

what in the design makes for the difference in the two xover frequencies (about 200 for the bass and 400 for the treble)? Is it the high qts of the bass driver?[/B]

I am using the hump in the baffle response to extend the woofer up and the full range down in the frequency range. You can see this in Figures 6 and 11 by looking at the driver's infinite baffle response (dashed red curve), the finite open baffle response (dashed blue curve), and the final driver's combined response (solid red curve) for each driver. The solid red curves extend past the original crossover slope curves for the driver on the infinite baffle shown as the dashed red curves.