TCP115-4 desktop speaker

[jasonb]

I'm going to be simulating a crossover for a compact desktop speaker using the new Dayton TCP115-4, and if I can get a nice looking simulation with a reasonable crossover parts count and cost I'll be building a pair. My goals are something 3 liters or less in volume that will play down in to the 50's comfortably. I've seen a lot of successful designs using the Dayton ND series woofers but wanted to try something different. The new Dayton TCP115-4 looks promising in about 2.5 liters. I'd like to crossover relatively low to avoid the ragged response above 2500hz so the tweeter that I'm considering is the Dayton ND28F-6. It's got a nice low Fs, is compact, reasonably priced, and shouldn't require a very complex crossover.

Here are links to the woofer and tweeter:

https://www.parts-express.com/dayton-audio-tcp115-4-4-treated-paper-cone-midbass-woofer-4-ohm--295-415

https://www.parts-express.com/dayton-audio-nd28f-6-1-1-8-soft-dome-neodymium-tweeter--275-040

I'll try and post all my steps here in this thread as the design progresses.

Jason

[Jake]

I'm interested, surprised your the first post trying this woofer. I personally would've liked to see a cheaper tweeter pairing considering the price of the woofer.

[wogg]

That's the woofer utilized in the new MK402, I suspect the lack of activity on there is due to the potential difficulty beating that price for a DIY design once cabinet and crossover are factored in. I'm sure that pre-built speaker could be improved upon though, so go for it!

Edit: While checking for another topic, I found a review of the MK402 here. Based on those measurements I'm sure you could do better with that combo. Make it so!

[Brian Steele]

Looks like a nice tweeter to use for your suggested build. I used it crossed over low as well for the redesign of my Mini-Mes, which uses an "upside" down (woofer over tweeter) configuration and the result sounds great.

[jasonb]

Here's the proposed enclosure. ***EDIT, I pulled the enclosure drawing because I had an error, will re-post once finalized*** 3 liters gross using 1/2" material should net me around 2.5 liters after bracing, port, drivers, and crossover displacements. Tuning is 55hz for now, I'll probably experiment with tuning a bit lower once I build a test enclosure. The sim below was done at 30 watts, I plan to power these with some sort of small desktop amp.

[ceiol]

looks great. That tuning and box design looks great. I just purchased a set of the TCP115-4 woofers also -- I want to pair them with the ND20FB-4 tweeters since I bought a bunch of them for a smokin' deal on the classifieds forum here.

Here's a quick-and-dirty crossover that I made in XSim. I used -0.25 for the woofer offset.

Woofer is, of course, the TCP115-4 and the tweeter is the ND20FB-4

Pretty good freq response. A decent amount of baffle step. A good reverse null and decent phase tracking.... but I'm a newbie and I'm sure that it could be improved a lot by the experts here

[ceiol]

(I don't mean to hijack your thread -- I'm here for the learning. If you want me to delete the above post, I totally understand. Just say the word.)

thanks

[Derekj]

Following - i'm working on a TWW with the same woofer - looking forward to updates!

[jasonb]

(I don't mean to hijack your thread -- I'm here for the learning. If you want me to delete the above post, I totally understand. Just say the word.)

thanks

I don't have a problem with you posting it here, it looks like a promising design. But if you plan to develop it further or get input from others it might make sense to start a new thread.

Cheers,

Jason

[ceiol]

I don't have a problem with you posting it here, it looks like a promising design. But if you plan to develop it further or get input from others it might make sense to start a new thread.

Cheers,

Jason

good idea

I like your enclosure tuning -- can you share the port ID and length?

[jasonb]

good idea

I like your enclosure tuning -- can you share the port ID and length?

Port details are yet to be determined. First thought was a skinny slot port out the front similar to the Audioengine A2+ but it will probably end up being a round port out the back with a large flare. Much more then about 1 square inch of port area and length starts to become a problem even with one elbow. A passive radiator would be a good option for this enclosure and tuning but I'm trying to keep costs down.

Jason

[tom_s]

That looks like a great project! I have no doubt you'll end up with much better sound than the MK402. Since you're building this as a desktop system, how will you determine BSC? I've never seen any rules of thumb on this for desktop systems. But I guess it all depends on the desk size, distance from the wall, and even if they'll be placed on small stands or risers.

[jasonb]

That looks like a great project! I have no doubt you'll end up with much better sound than the MK402. Since you're building this as a desktop system, how will you determine BSC? I've never seen any rules of thumb on this for desktop systems. But I guess it all depends on the desk size, distance from the wall, and even if they'll be placed on small stands or risers.

It's a tough call, a desk is a terrible place to put a speaker to start with. I'l likely end up using these speakers in a few different situations. Desk at work, nightstands in the bedroom, etc... Most of the time they will be within 2' or so of a wall and often on a flat surface. I'll start with 3db for now.

What is the best way to model that? All the FRD tools assume full baffle step. Because this is such a small speaker baffle step starts pretty high, it would be good if I could accurately model the reduced baffle step instead of just estimating.

Jason

[jasonb]

First crossover attempt for this one, details to follow in next post.

Jason

[jasonb]

Above is the first crossover attempt. I have a few points to think about yet:

- All crossover values have yet to be corrected to standard part values
- The crossover is pretty low but this speaker will be mainly used for near field listening. Thoughts on this?
- Not sure if I should attempt to flatten the tweeter response any more? I'd like to keep the parts count down.
- I tried this woofer without a zobel, couldn't get anything that resembled a nice crossover slope

I'll attach my .frd and .zma files if anyone wants to have a go at it, other details are as follows:

- Listening distance was at 3m, I should correct to 1m
- I have the woofer at -.013m Z offset, that's my best estimate since I don't have the drivers on hand
- I used Response Modeler to do my driver simulations
- I created a file to offset the baffle step by 3 db that are included in the simmulated FRD's so that flat response in PCD would represent 3db of baffle step compensation