will the HiVi M3N's work in the Needles?

[nikbrewer]

Re: will the HiVi M3N's work in the Needles?

i kind of like the look of the slot port.

Will the original designed cabinet work fairly well for the M3N? or does the tuning need to change to work well for this speaker?

Thanks

[Sibelius40]

Re: will the HiVi M3N's work in the Needles?

I agree on the slot port.

[patrickm]

Re: will the HiVi M3N's work in the Needles?

i agree... that's how i built mine originally. for the original cabinet, based on the tuning from the model (mid 70s), using a 2" port x 1" length, an equivalent slot port would be 4"w x 1" h x 1.6" long. that's not the greatest height to length ratio, but it should work ok.

if you go 5" x 1" slot, it's 2" long. winisd will figure out other ones for you if you need it.

also, modifying the location of the central divider (the diagonal piece) also seemed to help the response. put the base of it about 1/2" behind the baffle, and make sure the top edge of it ends up halfway between the baffle and the back of the cabinet, and about that same distance (3-4" or so) from the top. this will keep the cross-section of the line as close to constant around the turn as it's worth doing in this cabinet. you may need to make it slightly longer or shorter than the original needle to get it in the right place. last time, i just overcut it and trimmed as needed. (you could add an angled section along the top/back edge, but it's probably unnecessary)

[Sibelius40]

Re: will the HiVi M3N's work in the Needles?

i agree... that's how i built mine originally. for the original cabinet, based on the tuning from the model (mid 70s), using a 2" port x 1" length, an equivalent slot port would be 4"w x 1" h x 1.6" long. that's not the greatest height to length ratio, but it should work ok.

if you go 5" x 1" slot, it's 2" long. winisd will figure out other ones for you if you need it.

also, modifying the location of the central divider (the diagonal piece) also seemed to help the response. put the base of it about 1/2" behind the baffle, and make sure the top edge of it ends up halfway between the baffle and the back of the cabinet, and about that same distance (3-4" or so) from the top. this will keep the cross-section of the line as close to constant around the turn as it's worth doing in this cabinet. you may need to make it slightly longer or shorter than the original needle to get it in the right place. last time, i just overcut it and trimmed as needed. (you could add an angled section along the top/back edge, but it's probably unnecessary)

Wanted to ask a theory question that came to mind after reading your idea - I know that modifications to the box size may be needed, but supposing they aren't...wouldn't changing the position of the central divider also change the length of the slot port? If so, would you be OK leaving a small piece of the end of the "bench" on which the central divider sits jutting into the line or would you also need to shorten that piece of "bench"?

Although I understand the concept, I wouldn't call myself a "transmission line expert" - just wondering whether any small piece jutting out into the line will cause a problem, in theory...

[Thezeek]

Re: will the HiVi M3N's work in the Needles?

How about needles with this bad boy slapped in it?

https://www.madisound.com/store/product_info.php?products_id=8824&osCsid=3e154aee102997c42cb75f655fbd8d2f

[patrickm]

Re: will the HiVi M3N's work in the Needles?

this is basically the same driver as the w3-871 used in the original needle but with a cheaper, flush-mount pincushion frame.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-809

in a 10-minute test with the baffle clamped on, the M3N sounded pretty good, similar to the B3N... i didn't have the exact components for the dragon foal filters though. more to follow.

[nikbrewer]

Re: will the HiVi M3N's work in the Needles?

so, any one have any hard box details yet? I know nothing of t-lines, so if someone can just draw up a side view with demensions, ill go ahead and build these

thanks

[Sibelius40]

Re: will the HiVi M3N's work in the Needles?

so, any one have any hard box details yet? I know nothing of t-lines, so if someone can just draw up a side view with demensions, ill go ahead and build these

thanks

Here is the diagram.

[Wolf]

Re: will the HiVi M3N's work in the Needles?

Here is the diagram.

The terminus length has changed, as patrick said.

He is also going to be reporting on his findings,
Wolf

[patrickm]

Re: will the HiVi M3N's work in the Needles?

so, any one have any hard box details yet? I know nothing of t-lines, so if someone can just draw up a side view with demensions, ill go ahead and build these

thanks

nik - just use that diagram, with the following tweaks:

make the length of the slot port (made of the edge of "A" plus the length of "D" ) that the divider ("C") sits on about 1.6" long. this will shorten the port and raise the tuning frequency a little, which the model predicts will improve overall response.

you can adjust the length of "C" accordingly, so that its top edge ends up in the center of the cabinet an equal distance from the top, back, and front baffle. in reality, since you're only changing D by 1/2" or so, the difference in C's length will be minimal.

to answer Sibelius40's theory question -- you can have a small item jut out into the line with minimal difference, though it will have some effect in theory. in the Copper Project, marty used a couple 3/8" dowels as braces to hold the stuffing, and found no practical difference. those were in the middle of the line, and the round shape will help keep the air flowing pretty smoothly. you could probably have an edge jut out into this line, but i think based on what you propose, you'd be changing the line's taper (ratio of small end to large end areas) but not the slot port -- without changing D, the slot port is the same. what i think you could do is take a half inch off D, and change the positioning of C to change the length of the port by 1/2". mount on top of C for the base amount (1.6"), and mount flush with the bottom edge of D to add 1/2" to the port (2.1", close to the original). you would be changing the taper a little though. might be worth it for testing just to see.

[Sibelius40]

Re: will the HiVi M3N's work in the Needles?

nik - just use that diagram, with the following tweaks:

make the length of the slot port (made of the edge of "A" plus the length of "D" ) that the divider ("C") sits on about 1.6" long. this will shorten the port and raise the tuning frequency a little, which the model predicts will improve overall response.

you can adjust the length of "C" accordingly, so that its top edge ends up in the center of the cabinet an equal distance from the top, back, and front baffle. in reality, since you're only changing D by 1/2" or so, the difference in C's length will be minimal.

to answer Sibelius40's theory question -- you can have a small item jut out into the line with minimal difference, though it will have some effect in theory. in the Copper Project, marty used a couple 3/8" dowels as braces to hold the stuffing, and found no practical difference. those were in the middle of the line, and the round shape will help keep the air flowing pretty smoothly. you could probably have an edge jut out into this line, but i think based on what you propose, you'd be changing the line's taper (ratio of small end to large end areas) but not the slot port -- without changing D, the slot port is the same. what i think you could do is take a half inch off D, and change the positioning of C to change the length of the port by 1/2". mount on top of C for the base amount (1.6"), and mount flush with the bottom edge of D to add 1/2" to the port (2.1", close to the original). you would be changing the taper a little though. might be worth it for testing just to see.

Thanks for the "theory" answer - from the pics you attached, I see what you are suggesting for the slot port in order to shorten.

The pic I attached is the Needles original design specs, but I am all in favor of modifying the enclosure to improve response. On the diyForum, another person who created a TL enclosure called the TABAQ posted some response graphs showing some rather imperfect results from the original spec Needle cabinet and TB driver (then more showing why his design was better). Clearly, one can get closer to perfection with this enclosure and I look forward to Nik's results.

[nikbrewer]

Re: will the HiVi M3N's work in the Needles?

thanks, ill get to work on it tomorrow

[Wolf]

Re: will the HiVi M3N's work in the Needles?

Keep us posted! I'm interested to hear how these "Dragonflies" turn out...

Later,
Wolf

[patrickm]

Re: will the HiVi M3N's work in the Needles?

ok, some verdicts are in... and the winner is...

the M3N.
the bass is a little clearer, perhaps a few Hz deeper, and the top end is a good bit better than the B3N using wolf's and zaph's filters. I seem to recall tweaking zaph's filter at some point to try and give it a little more sizzle, but i still dont' think it was this good. kudos to wolf -- i may never buy another B3N...

the caveats:
-- both of my enclosures were clamped shut, and i can't guarantee they were perfectly sealed. but i did tape over the edges and tried a couple different clamping methods (without any noticeable differences in sound) and the M3N was still better.
-- my port is a 4"x1" slot port 2.1" long. these were already built, so i can't evaluate the 1.6" port from the model right now. but i'm already impressed with the upgrade to the M3N, so i can't imagine it'll work out worse than the default cab with a B3N.
-- i didn't have the exact dragon foals components. my 1mH was a p-core, and the 5.6 uF was closer to 5.79 uF. i tried to unwind the inductor from .10 mH to .095 to compensate.

obviously, there is not limitless bass, but it's impressive for a 3" driver. "in your eyes" from peter gabriel seemed like one of the better songs to highlight the better points of this design.

anyhow, hope that helps, nik. sorry for the delays. now i guess it's time to finish those rs150 TL's...

[Wolf]

Ka-Ching!

and the winner is...

the M3N.
the bass is a little clearer, perhaps a few Hz deeper, and the top end is a good bit better than the B3N using wolf's and zaph's filters. I seem to recall tweaking zaph's filter at some point to try and give it a little more sizzle, but i still dont' think it was this good. kudos to wolf -- i may never buy another B3N

Thank you for your results and opinion! I like the M3N more than the B3N/S, and always have. Needs more taming, but just plain sounds better!

So- Who's building some 'Dragonflies'?? :D
Thanks, Patrick!
Wolf