Cool find at Target

[joeybutts]

On a whim while at the Target with the family I decided to pick up a pair of these heptagon cups as they looked like a 3" driver would fit perfectly in the opening..... low and behold ..... 😏😏😏

Has anyone done any work with the nd91 full range to improve sound a little bit? Going to try porting this soon just to see what else happens. At $4 for the cup hard to argue with how fast you can get these finished and going....

[Wolf]

Looks like you might have molested your ND91 in the process? Or was it a bad one with the wrinkle to start with?
Later,
Wolf

[joeybutts]

Hahahahaha yeah, this is a driver that got replaced in my heliumbt due to being dumb. Figured I'd throw it in and check out if it fits and basic response to ear. The PS95 drops right in as well and is about to trade places.... just for giggles 😏

[Millstonemike]

The PE Bassbox for the PS95 lists 122 Hz in 0.1ft³ sealed or 68 Hz in 0.11f³ ported. You could try an outside port for the cup by integrating a PVC pipe stand.

Te cups are cool.

[donradick]

Has anyone done any work with the nd91 full range to improve sound a little bit? Going to try porting this soon just to see what else happens. At $4 for the cup hard to argue with how fast you can get these finished and going....

I love target, and just found a small solid wood box that's perfect for a little amp project.
Gotta now go and try to find that little hex container - where was it in Target?

Joey - I used The Sprite filter, and it added some baffle-step and that improved the sound greatly:
https://sites.google.com/site/undefinition/sprite

[joeybutts]

Awesome!! Yeah, pvc port stands would definitely be cool.

I found them in the aisle with the wooden letters in the arts and crafts/office supply area. They had a bunch at mine, I'll try and get back there soon to pick up a bunch.

Oh yeah! Sprite filter, forgot about that. Thanks for the mention!!

[Paul Carmody]

Dude, a heptagon? That's awesome!

[ronk]

I was planning to build coffee container speakers (image 1) with the TB W3 1364sa. I saw that off a website and ordered parts including 2 TB drivers, coils and resistors from PE. I went to Target today and found these containers (image 2). The volume of the Target containers according to my calculations is about .08 cu ft which is exactly what is recommended for sealed for the TB W3.

I will get my parts tomorrow.

One question I have is the baffle step correction. Image 3 has my drawing of it as suggested by the website I got the idea. Given the diameter of the Target container is 5.5 inches instead of 4 inches, will that make a big difference? Another question is, what is the purpose of the 8 ohms resistor parallel to the driver? My understanding of baffle step is just an inductor and a resistor.

Thanks. Ron

[tomzarbo]

$4? Yeah, a pair of enclosures for $8 is kind of a must-do. Nice find!

TomZ

[---k---]

Straw out the side for an exterior port?

[Chris Roemer]

ron, the 8n (ohm) parallel resistor basically turns the 8n W3 into a 4n load - which THEN has the BSC filter applied. In a sim it looks like that filter is good for about +4dB, but the top end of that driver still looks pretty 'hot".

[ronk]

^. Thanks Chris, as I will probably use it with a receiver and not a t-amp, should I omit the 8 ohm resistor so I get a more benign 8 to 11 ohm impedence?

There are 2 peaks in the TB, according to the manufacturer 's specs, one at 8 k and one at 16 k. I probably can't hear the 16 k sizzle. Any simple fix for the top end sizzle? Thanks Chris.

The Target cannister is melamine. I will need to see if my old carbide bit still works. Melemime
should be innert.

[joeybutts]

Paul, it's exactly what I thought!

Thanks Tom! For the cost and time savings, priceless.

Ryan, I do have some 1/2" diameter straws in the house.....

The ps95 sounds soooooooo much better and doesn't seem to give up as much low end as I thought it would to the nd91. Also gets a bit louder by my ear test. 🙄 I think the ps95 may be a fantastic mini BT option.

Next is porting this thing.

[make_some_noise]

Hahahah that is funny. I've been looking at small wooden bowls, boxes, and all sorts of things the last few days to use as strange enclosures for a set of small speakers I want to build for a gift. Those cups were one of them! As far as making an ND91 sound better.... Some BSC shaping would help. When I was looking at those cups, one of my thoughts was putting these on top and going 2-way.

https://www.parts-express.com/hivi-t...plate--297-414

[Chris Roemer]

Most 4n "nominal" speakers drop to 3ohms at a couple spots in their imp plot. W/that 8n parallel resistor, THIS one maintains at least 4n - you could almost call it 6n nominal.
If you KNOW your receiver won't like that, you can swap that 8n resistor for 16n (or 15n) and you'll maintain at least 6n across the board (i.e., a nominal 8n speaker).

AFA the top end goes, you COULD add a 0.25mH series coil between the parallel resistor (to gnd) and the driver, but first I'd probably just see if you can enjoy them enough just by listening to them a bit off-axis.