[centerfield24]

Jeff and Richard

                     Thanks for the response,looking forward to your report.


                                    Thanks Bill

[Dmason]

I have to agree with what Richard states; I have heard NOTHING that sounds like the Red Wine Tripath Treatment into the B200 on open baffle. I state this in the first post of the DarkStar thread. I look forward to your sage assessment, Richard...

With the increased power available to you with the Signatures, if digital EQ is employed by way of iTunes, the amount, depth, and power of the bass available to you will be absolutely stunning.

For those contemplating an OB venture of their own, I have identified another driver that technically is perfect for home audio OB due to the fact that it is designed for open back small cabinet guitar amps, like Fender Princeton. It is the Tone Tubby 8, which can be seen and examined at www.tonetubby.com
I especially like its low Fs=50Hz, Qts=.707 SPL=93db, and nominal Xmax=2mm. Its response curve is flat from 50-5KHz, and it reaches easily to 9KHz, with little in the way of the usual rising response issues, which means tweeters are optional for many people. With the hemp cones there is almost no cone break up so 9KHz means exactly that. They can be had for under $80... we now have Hemp flavoured mains drivers for OB with specs almost too good to be true, for eighty bucks.

[JeffB]

I have just peaked at the response graph for the tone tubby 8".  For both the 8ohm version and 16ohm there is a 16db rise in response between 900Hz and 3.5kHz.  The price is posted as $90 each.
The speaker appears really flat between 50Hz and 350Hz.
I haven't seen many speakers which such a flat graph to 50Hz.
It looks like it would be good with a 2" or 3" wide ranger crossed at about 350Hz.
I wish there were graphs for the 10" and 12" tone tubby's.

[JoshK]

I have no idea, but I am thinking the rising response may be just a function of the fact that it is intended for pro audio use and the measurements are in 4pi space (as opposed to 2pi). 

[markC]

If we knew the LE of the driver, it could be modeled. I emailed them and hope to get a response.

[tubamark]

Edit: Oops-If you were not talking about the Alpha 15, ignore this post.
The info below is still useful, though, to anyone who didn't know where to get Eminence data.
-- Mark

If we knew the LE of the driver, it could be modeled. I emailed them and hope to get a response.

Le is 0.84 mH.

Complete specs for all Eminence drivers available thru www.Eminence.com
They are also great about listing the Xlim or Xmech (driver travel before actual damage) for all their drivers, not just the Xmax ("controlled" linear excursion).  Many manufacturers don't like to provide this info.
Xlim is a helpful spec because if the Xmax and Xlim for a driver are nearly the same, it's more likely that you can accidentally damage a driver on an OB without warning.
In the case of the Alpha 15, the Xlim is more than double the Xmax!

--Tubamark

[markC]

I was referring to the Tubby, Mark. It looks very good on paper, (monitor), but the ability to model it would pretty much seal it for me.
I haven't heard back from Brown Soun with the LE spec. Without it, I can't model it. Without being able to model it, I won't buy it.

[-Richard-]

Hi Mark ~

As an Alpha-15 user... your important information:

"In the case of the Alpha 15, the Xlim is more than double the Xmax!"

is marvelous news!!!... thanks for posting that Mark... it seems that Eminence has built a high
level of performance into that driver!!!! In fact... I have yet to actually see it move while
music is playing... and the bass is incredibly effective... pitch perfect and viscerally "present".

Warm Regards ~ Richard

[painkiller]

Can I ask what material you've used in the baffles on page 5, and in what dimensions?

I'm considering to start a similar project myself. Cheap, easily available parts, simple woodwork. Just my type of diy project.  aa

[Anglo]

Hi


Can someone give me a link to the MJK papers?

Many thanks,

[Graham Maynard]

http://www.quarter-wave.com/OBs/OB_Design.pdf

G.

[iON]

I was referring to the Tubby, Mark. It looks very good on paper, (monitor), but the ability to model it would pretty much seal it for me.
I haven't heard back from Brown Soun with the LE spec. Without it, I can't model it. Without being able to model it, I won't buy it.

Markc, you can model the Tone Tubby fairly accurate without the Le spec. The TT is a guitar speaker good for 5kHz and beyond (some people use them as regular speakers without tweeter) so my guess is that Le is not significantly high. Also, common sim software does not even take Le into account.

BTW, Lynn Olson has published some mlssa measurements on the 12" inch AlNiCo TT on his website ( http://www.nutshellhifi.com/MLS/MLS6.html ). It definitly looks like a interesting OB contender.

Regards,
Jon

[markC]

I like to use a spice program to model and I would definitely require the Le. Sadly, I've had no response to my queries from Brown Soun.

[nullspace]

I was referring to the Tubby, Mark. It looks very good on paper, (monitor), but the ability to model it would pretty much seal it for me.
I haven't heard back from Brown Soun with the LE spec. Without it, I can't model it. Without being able to model it, I won't buy it.

I measured the free-air T/S #s for a pair (the AlNiCo 12", to be clear) and came up with .177 and .191 for Le. All the other numbers were in the ballpark of what they have posted.

Regards,
John

[Dmason]

I have auditioned both 10 & 12 Tone Tubby Alnicos, and they are spectacular on open baffle.

The combination of the hemp cone and Alnico magnet puts them in their own league, entirely. With the 10, my favorite, when I used active contouring, I could wrench all kinds of treble band information from them. My ears are perfectly happy with frequency extension to 9kHz, and the TT 10A did the trick. I can highly recommend them to you; these drivers are designed for open back cabinets, so open baffle is just a continuation on that theme.

If you tried the 12 mounted in the JE Labs configuration, a simple 1- order filter for your choice of tweeter, with attenuation, you would pretty much be guaranteed success; it has a nice low Fs, which, when combined with its ability to move some air, and the boundary gain offered by the JE mounting-level, it picks up lots of lower register. www.nutshellhifi.com   MLSSA Gallery and would therefore be very easy to tie in bass drivers. These are my favorite new production open baffle drivers, based on what I have heard, and their simplicity in implementation. They can be ordered sans dust cap, TT can provide measurements associated with designing a phase plug, which  can be made and installed, to complete the picture.

A++

[iON]

Markc:
Yes, I understand your concern. Some comments though, the inductance formed by the electrical equivalent of the mechanical compliance will be magnitudes higher than the voice coil inductance. Also, the dc resistance will dominate the impendance over the mid range while phase angle will move asymtotically towards 45 degrees in the upper range.

Yes, if you're going to do optimized crossover design I can understand that you'd like the exact Le value (along with error margins). If not I believe you can get satisfactory results just picking a fairly general (guitarr speaker) value of Le lets say 0.5 mH.

Anyway, i hope you'll get you answer from Brown Soun. Good Luck =)

Regards,
Jon

[iON]

Dmason:
Awesome! I've sketched/modeled on some OB TT designs during the winter but I haven't really heard about any succesful builds. Its incuraging to hear that the concept is usable.  You dont have any pics or additional info?

[Dmason]

iON

Unfortunately I don't own a digicam, twice I have looked into them, and was abit overwhelmed by the "learning curve," as to what I should be looking for. Now, I wish I had gotten one several years ago...

As for modelling, either of the Tubbys will play low enough that bass implementation is easy. There is alot of effort going into designing exact crossovers, passive solutions, where active solutions are better in my mind, and easier. First, with a driver as sweet as the Tubster, they sound best with flea powered single ended tube amps, and 2 watts will blow your doors off here. Use of some sort of "pre amplifier" with dual outputs will allow one to use leads into the flea amp employing a shunt cap at the appropriate Fs to relieve the outputs and mains drivers of all lower register signal, a happy thing for both, which optimizes the situation on an order of magnitude far beyond spending mo' money for "better stuff," ...Second, just about any narrower width baffle will allow a "larger" diameter cone to roll in the magic 180Hz area, which then makes the use of a pair or two pairs of bass drivers, powered by high damping factor switching amplifiers, with their low pass adjustables, really easy to contend with. You sit on the floor with a drink, and tweak levels and passes until it sounds right --to you--

As far as getting additional measurements from Tone Tubby, do not agonize over the likelihood that these may not be forthcoming; they do their measurements independently, and more importantly, these guys are tuned into the guitar end of things. They are wooly Bay area rockers who aren't very concerned with audiophool measurements, because it is "fringe element" stuff to them, in their own words. (is anyone surprised that the invention of HEMP cones took place in Sonoma County?) the blessing here is that they found out a way to make something amazing out of all that lumber that wasnt making it into the final product. Next will be high grade machine oil made from the seeds but I digress...

My OB design will employ a pair of Lambda IB15 bass drivers power by BASH plate amp or two, and separately powered Alnico 10, with a phase plug, which, with the proper measurements of dust cap width, distance from pole piece to cone circumference, can very easily be turned on a lathe. It aint rocket science, just a good thing to do, especiallyl with a larger diameter cone, whose beam-point is fairly low, dont know what it would be, but likely in the area of 4kHz with the 10" ... I feel success coming, with a baffle of 18" wide, by no more than 33-36" high, and possibly a little tweeter just to fill in some audiophool-approved "air."

[painkiller]

My OB design will employ a pair of Lambda IB15 bass drivers power by BASH plate amp or two, and separately powered Alnico 10, with a phase plug, which, with the proper measurements of dust cap width, distance from pole piece to cone circumference, can very easily be turned on a lathe. It aint rocket science, just a good thing to do, especiallyl with a larger diameter cone, whose beam-point is fairly low, dont know what it would be, but likely in the area of 4kHz with the 10" ... I feel success coming, with a baffle of 18" wide, by no more than 33-36" high, and possibly a little tweeter just to fill in some audiophool-approved "air."

Sounds really nice. Any idea of a matching tweeter that can be used with a simple crossover? Kind of like Bastani's directly coupled wideband and tweeter with series capacitor? I'm a total newbie with crossovers (more of a dac/amp guy here), but to me it looks like the tone tubby can be combined with the Eminence woofer like the Visaton as the efficiency is somewhat in the same range?

[ttan98]

......Kind of like Bastani's directly coupled wideband and tweeter with series resistor?

should read tweeter with series capacitor...