How about this near field micro-monitor idea?

[zx82net]

I was thinking about what might make an interesting project, something which could reach pretty low in a small box, and I came up with this:

A W3-1876 in a 1.4l ported box:
https://www.parts-express.com/Tang-B...909?quantity=1

Crossing over to a TEBM35 at 200~500Hz, depending on what sounds best:
https://www.parts-express.com/Tecton...216?quantity=1
Erin's review of that driver, if you haven't seen it:
https://www.erinsaudiocorner.com/dri...re-bmr-driver/

Here's a WinISD model with both enclosures shown:


Granted this won't go super loud but I'm thinking that's fine for near field use, and it should get very close to 40Hz. I realize chuffing is probably a major risk here, but with the low cross over frequency, I should be able to use a pretty large coiled/folded port without too much risk of pipe resonances in the port. Total air volume will be ~2l, including a 25mm diameter x 45cm port, and ~400ml for the mid-tweeter.

What do you think? Are there better ways to invest 2 liters of my office space?

[tomzarbo]

Sounds promising. Something different!

Here is a link to Wolf's bass toaster concept, and another link to my modified execution of it.

They are interesting and unique little buggers.

http://techtalk.parts-express.com/fo...c-bass-toaster

http://techtalk.parts-express.com/fo...t=bass+toaster

TomZ

[zx82net]

Sounds promising. Something different!

Here is a link to Wolf's bass toaster concept, and another link to my modified execution of it.

They are interesting and unique little buggers.

http://techtalk.parts-express.com/fo...c-bass-toaster

http://techtalk.parts-express.com/fo...t=bass+toaster

TomZ

Interesting. Since I have the drivers, I cannot think of a good reason not to try this.

Sounds like a good candidate for bi-amping this new 4 channel DSP amp:
https://store.sure-electronics.com/product/AA-JA33286
I'm wondering whether Parts Express will be getting a Dayton branded version of this. I wasn't in the mood for waiting, so I've ordered the Sure version.

[Chris Roemer]

I see a 14" LONG 7/8"id port tube for an Fb in the upper 40s. A PR makes more sense (and adds co$t).
Also, the low XO point will want LARGE value caps & coils - also raising the cost.
And that woofer's only 76dB.

[1100xxben]

I built these guys a few years ago and I really like them. They sit on my lab bench at work. I put them in the under $200 category competition at Midwest Audiofest, and they took second place, so they must not be too awful . It's been a while since I looked at the design, but if I remember correctly, they are about 4 liters. There are actually a pair of the W3-1876 (one on the back) and 3 of the Peerless 3.5" passive radiators per cabinet. The "tweeter" is a Peerless 40N25AL01 "full range" speaker. I don't remember too many details about the crossover off the top of my head, but I know it was around 400-500 Hz. The W3 are 4 ohms, so I have them wired in series and as Chris already mentioned... the sensitivity is abysmally low. They do require a decent amplifier to get any significant SPL out, but they dig pretty deep for their size and reach down under 40 Hz. If you're interested in more details, I can dig up the design and let you know.

[jhollander]

Besides sounding good, I remember they flipped quarters pretty good.

[1100xxben]

Ha, that they did!

[zx82net]

I built these guys a few years ago and I really like them. They sit on my lab bench at work. I put them in the under $200 category competition at Midwest Audiofest, and they took second place, so they must not be too awful . It's been a while since I looked at the design, but if I remember correctly, they are about 4 liters. There are actually a pair of the W3-1876 (one on the back) and 3 of the Peerless 3.5" passive radiators per cabinet. The "tweeter" is a Peerless 40N25AL01 "full range" speaker. I don't remember too many details about the crossover off the top of my head, but I know it was around 400-500 Hz. The W3 are 4 ohms, so I have them wired in series and as Chris already mentioned... the sensitivity is abysmally low. They do require a decent amplifier to get any significant SPL out, but they dig pretty deep for their size and reach down under 40 Hz. If you're interested in more details, I can dig up the design and let you know.

I'd be very interested, especially if you managed to model the behavior well with the passive radiators. I tried putting that radiator into WinISD and the curves came out looking so bad I didn't really believe them, like an f3 around 100Hz.

[zx82net]

I see a 14" LONG 7/8"id port tube for an Fb in the upper 40s. A PR makes more sense (and adds co$t).
Also, the low XO point will want LARGE value caps & coils - also raising the cost.
And that woofer's only 76dB.

See my comment above about poor success modeling the enclosure with a PR. (Probably my own failing :-D) The port sounds intimidating to start with, but the internal volume is only 160ml, its easy enough to fold it and make with a 3D printed part, the question is whether the performance will be acceptable.

I would deal with the crossover by using a 4 channel amp with built in DSP, I understand that would be a non-starter for some people.

[LOUT]

I had decent modelling success with one W3 and a single DS135 PR (down into the mid/low 40's with ~50grams added) with 1.4L-1.5L of breathing room. Not sure if that PR is getting too big to be worth while for a build/woofer that's entire purpose is to be as small as possible though.


If you're considering a pair of W3's for more output then I think you might be able to get similar output and bass-depth with a single TCP115-8 in a similarly small (around 4.5L) box for a lot less money.
The pair of W3's should reach equally deep or a little beyond while using a smaller box, but that's somewhat compensated by the TCP only needing about 1/2 the port length/space.

[zx82net]

I had decent modelling success with one W3 and a single DS135 PR (down into the mid/low 40's with ~50grams added) with 1.4L-1.5L of breathing room. Not sure if that PR is getting too big to be worth while for a build/woofer that's entire purpose is to be as small as possible though.


If you're considering a pair of W3's for more output then I think you might be able to get similar output and bass-depth with a single TCP115-8 in a similarly small (around 4.5L) box for a lot less money.
The pair of W3's should reach equally deep or a little beyond while using a smaller box, but that's somewhat compensated by the TCP only needing about 1/2 the port length/space.

I'm far from an expert here, but isn't 50g added mass going to really mess with the transients? I'm not looking at more than 1 W3 per speaker. I figure that should be plenty for near field use.

[Chris Roemer]

I modeled the ND90-PR with 10g added mass. While it IS only rated a 3.5"dia, its generous Xmax (9mm?) should satisfy the 2:1 displacement guide.
1.4L (0.05cf) tuned to the low 50s, w/an F3 right around 50Hz.

. . .

For only $2 more, the ND105-PR w/30g added mass has a modeled F3 of 47Hz. (You COULD get by w/just a single 22g disk, but it works a bit better @ 30g.)

[Misch]

I'm in the process of doing this same idea, using the tectonic with the w3 and peerless passive radiator. Mounted in some minimus 7 cabinets. Will be using a 2.1 TPA 3116 amp for power.

I've tested a single w3-1876 with the peerless in the minimus cabinet as low end fill for a pair of ps95-8 and found it satisfying enough. I listen to mostly metal so that low end is needed. Volume is limited but more than enough for desktop.

[zx82net]

I modeled the ND90-PR with 10g added mass. While it IS only rated a 3.5"dia, its generous Xmax (9mm?) should satisfy the 2:1 displacement guide.
1.4L (0.05cf) tuned to the low 50s, w/an F3 right around 50Hz.

. . .

For only $2 more, the ND105-PR w/30g added mass has a modeled F3 of 47Hz. (You COULD get by w/just a single 22g disk, but it works a bit better @ 30g.)

Thanks for the tip, they come out in WinISD just as you described. Whenever I try to model with that Peerless PR I seem to get strange results.

[LOUT]

I'm far from an expert here, but isn't 50g added mass going to really mess with the transients? I'm not looking at more than 1 W3 per speaker. I figure that should be plenty for near field use.

Most of the added weight is just because some of these PR's have pretty low mass without anything added while others of similar size can start as much as 30grams heavier. I don't think the transient response works that way (with the added weight I mean) though I could be wrong about that....I'm pretty sure the weight just works like the extra air-weight/resistance from a longer port.
The GroupDelay will increase with more weight (just like it does with a longer, lower-tuned port), but a 1.4-1.5L box with a DS135PR+50grams only has GroupDelay peaking around 20ms which I think is good.


The main benefit to the DS135 seems to be the larger VAS.
Even when everything else is pretty ideal for reaching low, most/all of the smaller PR's appear to have too little VAS to get below the low50's or high40's.
The DS135 is the smallest PR I could find that is able to model similarly low like a port can...minus the 18-24inches of port-length, lol.

The smaller DS115 PR (plus ~25grams) is close because of its similarly high VAS, but its smaller size and less movement/XMAX might limit the total output closer to 15watts instead of ~30watts. I think the DS115 PR still reaches a little lower than other similar-sized PR's and it's one of the more affordable PR's.

[zx82net]

Most of the added weight is just because some of these PR's have pretty low mass without anything added while others of similar size can start as much as 30grams heavier. I don't think the transient response works that way (with the added weight I mean) though I could be wrong about that....I'm pretty sure the weight just works like the extra air-weight/resistance from a longer port.
The GroupDelay will increase with more weight (just like it does with a longer, lower-tuned port), but a 1.4-1.5L box with a DS135PR+50grams only has GroupDelay peaking around 20ms which I think is good.


The main benefit to the DS135 seems to be the larger VAS.
Even when everything else is pretty ideal for reaching low, most/all of the smaller PR's appear to have too little VAS to get below the low50's or high40's.
The DS135 is the smallest PR I could find that is able to model similarly low like a port can...minus the 18-24inches of port-length, lol.

The smaller DS115 PR (plus ~25grams) is close because of its similarly high VAS, but its smaller size and less movement/XMAX might limit the total output closer to 15watts instead of ~30watts. I think the DS115 PR still reaches a little lower than other similar-sized PR's and it's one of the more affordable PR's.

Interesting.
For what it's worth, this is a 1.8l box with 50cm of port on the back.

[LOUT]

Would be quite a thing, but that image is giving me Bose (wave radio?) vibes. :p

...I don't miss television infomercials/paid-programming.