New fold for Volvotreter's 38 Hz TH

[Don Snyder]

I don't think anyone has done a double fold of an 8" or 10" driver. If anyone has a good sim of one of these, I'd be glad to do
the fold.

~Don

 

[saddlesore]

Erik - thanks again for all your work. I am going to give your new folds (38hz) a try. Does anyone have a recommended source in the USA for the 4,7mh coils recommended by Erik (wound from 1,32mm dia. copper wire and have a Rdc of 0,26 ohm)?

I no longer have my vision...searching Partsexpress's website via an audio interpretor takes hours, and I get lost once it comes to coils/inductors.

Thanks again,
Steve

 

[littlemike]

@ Saddlesore

Parts Express may be your best bet.

Erse Super Q 4.7mH 16 AWG 500W Inductor, 0.231 Ohm DCR

Parts Express Part #266-924

Here is a direct link

Jantzen offers a toroidal core 14 ga inductor with a much lower DCR, but it is out of stock currently, and more than double the cost of the Erse.

Madisound also carries good-quality crossover components, but the DCR of their laminated-core inductors is slightly higher than the Erse.

 

[JoshK]

I don't think anyone has done a double fold of an 8" or 10" driver. If anyone has a good sim of one of these, I'd be glad to do
the fold.

~Don

I'd love to see this done for the Tang Band 8" W8-740P. I think there might have been a sim of this driver on the TH for dummies thread.

 

[GM]

A single W8 in a two fold is so small in cross section with published specs that I have to wonder if it will perform anywhere near its prediction. Then again, being mildly compression loaded, it may be the way to go once damped:

GM

 

[Bluerex]

A single W8 in a two fold is so small in cross section with published specs that I have to wonder if it will perform anywhere near its prediction. Then again, being mildly compression loaded, it may be the way to go once damped:

GM

After LOTS of forum surfacing, a question... what about two W8 in a fold like Erik's? Sure the TH-SPUD is a great (but commercially protected) design, but would a meld of the SPUD and Erik's layout be a winner?
With all the chat over in the main TH thread, a newbie like me (and I figure there are more of us?) is struggling to distill a coherent design from all the opinions and chest-beating. So how about picking something like this to model, design and build?

Charles.

 

[GM]

How you fold it is immaterial as long as it ~ preserves the design's expansion rate. While doubling drivers requires a doubling of cross sectional area (CSA) along its entire length to maintain the same response, it doesn't reduce the driver's acoustic loading, so may, may not perform well either.

Since the alignment I did is an end loaded one as opposed to the patent applied for SPUD's drivers being well away from its terminus (mouth), some additional damping may be required at this point to quell any HF noise generated by the motor/basket.

WRT navigating a huge thread, you can search within it using the search window at the bottom of each page.

GM

 

[Bluerex]

WRT navigating a huge thread, you can search within it using the search window at the bottom of each page.

GM

Thanks for the search tip GM, I had completely missed that option in all my surfing (not surfacing as previously miss-typed)

c

 

[maxjr]

Does anyone know how the inductor is wired to the 6.5" tang band? is it in series or parallel to the terminals? This is an awesome small build and can't wait to try it out. If someone has a picture, that would be awesome!

Also, I prefer to work with birch ply. Is 1/2" ply too thin? It seems that 3/4" ply would be over kill for such a thin cab. But, then again with 3/4" maybe I can get away with no internal bracing

Does anyone have a plate amp recommendation with a high pass filter suitable for this cab? I'm planning on building one of these for a 2.1 music setup

 

[kahkonen]

compairing the 30hz and the 38hz hornresp input screens (Le showing inductance?) i would say its in series with the sub.

 

[Volvotreter]

Yes, it's in series.

Regards.

Erik

 

[maxjr]

Thanks, Volvotreter and Kahkonen

Can this cabinet be made wtih 3/4" birch plywood and eliminate the bracings due to the stronger wood?

 

[bjorno]

..I'm planning on building one of these for a 2.1 music setup

Can you still purchase the W6-1139g somewhere? I think Volvotreters design would be very good for a smaller 2.1 music setup.

b

PS: I looked at this almost flawless design: See the picture

 

[bjorno]

Edit:Correction of color labeling.

b

 

[ontariomaximus]

re: 38hz TH folded

Intriguing to say the least!

It is designed to be used from 38 to 100hz approx?

What is the function of the inductor?

What is the efficiency and SPL capability?

 

[kahkonen]

Can you still purchase the W6-1139g somewhere? I think Volvotreters design would be very good for a smaller 2.1 music setup.

b

cant find the 1139g, only 1139sg versions of it.

 

[bjorno]

cant find the 1139g, only 1139sg versions of it.

I used the manufacturers T/S for 1139SG, believe they are in fact the same drivers, but probably when volvotreter entered the numbers into HR, he left out the ..SG for ..G only.

More simulations using the T/S for TB-1139SG:See the pictures.

b

 

[Volvotreter]

I agree with bjorno: I also think that the different variants are finally the same (at least for what were doing here). If I remember right, there are slightly different fames available: One be be installed into the baffle and one to be installed from behind.

Erik

 

[ontariomaximus]

Volvotreter has documented three Tapped Horn designs. I liked his 38 Hz version using the 6.5 inch Tang Band, but I prefer a
different fold. Here is a scale drawing of my fold. It's 8.75 x 17.25 x 25 inches using 16mm wood.

Volvotreter Homepage

Hi Don,

Like your fold. One question: How do you measure L34? Or does it really matter?