Open Baffle speaker with Tone Tubby / Fostex

[anilva]

Folks,

I received my shipment yesterday of 12" Alnico Tone Tubby speakers with Hemp Cone ;-) and Fostex FE126E Fullrange speakers for my Open Baffle project.

I used Borderlinx and from the time I gave green signal for shipment, I got it home in 2.5 days. Just amazing service.

Planning to use the following design as a guide, though I am not using the expensive Lowther but a Fostex. The cross over points are going to be different and I am thinking of 500Hz or so. Any ideas are welcome.

Tiny Alnico Open Baffle

Cheers.
Anil

 

[suri]

hi anilva,

looks like it will be fantastic - the fostex should match better with the tone tubby than the super-fast lowthers -

best of luck!

regds

 

[rikhav]

Hi Anil
Interesting project
These Alnico tone tubby will be used as woofers?
Pardon me for the confusion as i always thought Alnico with hemp cone are full range drivers

 

[asliarun]

Wow, this sounds like a really nice project! What wood are you planning to use? Solid wood, MDF, or marine plywood?

 

[Rajiv]

Hi Anil,

I will be following this project carefully.

I hope to learn from your project when I get down to starting my Altec 605+Altec 416 open baffle project.

As Suri pointed out the Fostex is easier to tame than the Lowthers.


Regards
Rajiv

 

[grubyhalo]

WHOA! Tone Tubbies! Can't wait for you to finish. I will be following this project as well and all the very best!

 

[iaudio]

Anil ji, What made you chose open baffle design?

 

[anilva]

Try and use a crossover point that is not around the baffle peak. I don't know what size baffle you're planning, but if you place the Fostex in the center of a 15" baffle, you will get a sharp ~4-5dB peak at about 900Khz, smack-dab in the middle of the most sensitive hearing range. Cancelling it in a passive crossover can be done with an LCR trap centered at 900Hz, or you can offset the driver slightly. This produces twin peaks of about 2dB each, a more healthy proposition - maybe you can get by without any further tuning if you choose the baffle size and driver location in accordance with the driver FR.

I would lower the crossover point to about 200Hz as the original design. At those frequencies sound starts becoming directional, so if the distance between the drivers is large there may be some loss of summing at low distances, and reflection control will become troublesome. IIRC the Amitys, a similar design, use a 150Hz crossover which I think is spot on for this kind of an arrangement as it uses floor bounce effectively, as well as make the distance between drivers less relevant. Up to 200Hz may be acceptable based on how far you will be sitting from the speakers.

Good luck, it seems like a nice project.

@Cranky - Thanks for valuable inputs. At the moment the size plan is 40" X 18" baffle. Listening distance is around 15'. I would rather offset the Fostex and avoid baffle peak than go in for a LCR trap. I would like to keep the design simple with minimal crossover components.

200Hz is good suggestion for the Xover frequency, but aren't we wasting the extended FR capabilities of a Tone Tubbby and handing over to the fostex too soon. Yes, I do agree with increasing frequency the directionality becomes more pronounced between both the drivers, but there must be a way out. I would like to start this off and see how it measures. I will borrow a friend's RTA if possible. Last resort would be to go active with a Behringer.

@Rikhav - Hemp cone does not mean fullrange. Tone Tubby is a good guitar speaker and not a true fullrange or a woofer. Ofcourse drivers like Omega hempcones are fullrange.

@iaudio - I picked an open baffle for the supposedly transparent and easy reproduction from the drivers without effects of compression or tuning issues. Also it is simple to build from a cabinet perspective. We can also change quite a few things with an OB and can be a live project.

All others - thanks for the good wishes. Will keep you posted on the whole thing is shaping up. Right now in the hunt for bobbins and enamelled copper wire for winding my inductors. Painful to go around these shops with small quantity requirements.

Cheers.

 

[anilva]

Hi Anil,

I will be following this project carefully.

I hope to learn from your project when I get down to starting my Altec 605+Altec 416 open baffle project.

As Suri pointed out the Fostex is easier to tame than the Lowthers.


Regards
Rajiv

Rajiv,

You are a blessed soul with those kind of rare vintage drivers with you.

Regards

 

[grubyhalo]

...200Hz is good suggestion for the Xover frequency, but aren't we wasting the extended FR capabilities of a Tone Tubbby and handing over to the fostex too soon. Yes, I do agree with increasing frequency the directionality becomes more pronounced between both the drivers, but there must be a way out. I would like to start this off and see how it measures. I will borrow a friend's RTA if possible. Last resort would be to go active with a Behringer...

That's the exact reason I was at one point thinking of having the TT's handle most of the mids. Any reason why Rajiv's Econowave idea might not work for you if you choose to use it above, say, 1KHz? You could still use helper woofs below 200 Hz, I'm thinking. Ofcourse, it's totally moot now but just curious about the reasons behind your decision...

 

[anilva]

That's the exact reason I was at one point thinking of having the TT's handle most of the mids. Any reason why Rajiv's Econowave idea might not work for you if you choose to use it above, say, 1KHz? You could still use helper woofs below 200 Hz, I'm thinking. Ofcourse, it's totally moot now but just curious about the reasons behind your decision...

12" drivers near 1KHz will show up quite a bit of directionality and off-axis response problems. Therefore better to keep it lower. I chose this design purely for simplicity's sake and not indulge in waveguides and horns. Yes, I plan to complement this with a sub woofer for lower frequencies. TT will not go below 70Hz or so, unless heavily equalized, which I want to avoid.

 

[grubyhalo]

12" drivers near 1KHz will show up quite a bit of directionality and off-axis response problems. Therefore better to keep it lower. I chose this design purely for simplicity's sake and not indulge in waveguides and horns. Yes, I plan to complement this with a sub woofer for lower frequencies. TT will not go below 70Hz or so, unless heavily equalized, which I want to avoid.

Ok, cool. Thanks!

 

[Adhiraj]

so how is it going so far?

 

[anilva]

so how is it going so far?

The baffles are getting made. My carpenter wanted to show off his skills by doing something solid in multilayer MDF for the base and finished in rich glossy DUCO paint in bold color (not decided on the shade, but if I have to match the tone tubby, it will be red).

Have decided on the crossover points of 200 Hz, 12 dB for low pass and 500Hz, 12 dB for high pass going by MJK designs and simulations. Will get to a point when I will become desperate for the inductors. Still hunting for someone who will wind for me. Last resort is doing it myself with hand.

Will show the WIP pictures as soon as something shapes up.

Cheers!

 

[Sidharth Trehan]

@ Anil bhai
Have been following the thread closely Anil bhai and yes, eagerly waiting for these to come up.

 

[iaudio]

Anil ji, So the Tone tubby will make it sing:yahoo:, and the duco glossy paint will make it bling! Waiting eagerly for WIP pictures.

 

[grubyhalo]

I think red would look fantastic too. Any inclination towards multi-coat automotive paints?

 

[jon morgan]

Why not use a home theater pc to tame any peaks from the baffle mounting.? You could use a program such as this to do the crossovers keeping all passive components out of the signal.

I've been noticing a lot of DIY enthusiast talking of this lately. All I hear are good things about it. Here's the Thuneau crossover and a site that explains how this works.

Transient Perfect loudspeaker DSP tools . Windows DSP speaker crossovers.

Luxury Home Theater Systems can be affordable. Learn about Home Theater set up

Hope it helps!

 

[anilva]

Folks,

Here are the Work-in-Progress pictures of my Open Baffle with Tone Tubby and Fostexs.

The dimensions are 38" X 20" with a 15 degree slant built using a 1 1/4" MDF at the minimum width (it goes to over 2" at the base).

The OBs will be finished in DUCO after applyig all the automotive putty and buffed using rubbing polish. My wife is going to decide the shade of DUCO that we need to apply.

They have come out quite nice and solid. There is a slight taper towards the top and chamfered on the side to a small angle.

Cheers.

 

[suri]

Folks,

Here are the Work-in-Progress pictures

??? you missed posting the pictures