Affordable Surround Sound System? - MTM or MMTMM using Dayton TCP115-4 or HiVi B3N

[JerriAZ]

Greetings everyone! It's been a while since I've been on the forums. Hope everyone has been doing well.
I'd like to get some input from any and all of you regarding some ideas I've been messing around with in my head -- I want to try and make an affordable speaker that I could for a surround sound system. Some of the design constraints I have been considering are:

1. MTM or MMTMM design -- each speaker could be used as the center, right, left, ect. They would all be symmetric.
2. Not too large in size
3. The closer to $50 per unit the better
4. Driver sizes less than or equal to 4"
5. Speaker impedance needs to be close to 8 ohms
6. Tweeter could be a full range driver. I can't hear past 14kHz anyways lol

Here are the drivers I have considered for the designs.
MTM:

Dayton Audio TCP115-4 -

https://www.parts-express.com/dayton...4-ohm--295-415

Fountek FE85 -

https://www.parts-express.com/founte...river--296-717

The TCP's would be wired in series to 8 ohms, so their overall sensitivity would remain around 87dB. The FE85 would be used as a tweeter (has ~86dB sensitivity). I was thinking of having a crossover point somewhere around 2kHz.
The drivers themselves would cost ~$33 for a single unit assuming I buy enough of them for a 5.1 system.

MMTMM:

HiVi B3N -

https://www.parts-express.com/hivi-b...frame--297-428

Fountek FE85 -

https://www.parts-express.com/fountek-fe85-3-full-range-speaker-driver--296-717

The B3N's would be wired to 8 ohms overall (~87dB if I did my math right). The FE85 would again be used like a tweeter. Again I was thinking of crossing them over around 2kHz.
The drivers themselves would cost ~$41 for a single unit assuming I buy enough of them for a 5.1 system.

I chose the FE85 over a tweeter because I liked it's impedance, sensitivity, cost and I think I would have a little more flexibility with my crossover.

So, what do you guys think of either of those designs? Pros? Cons? I would appreciate any constructive criticism.

[tom_s]

Using a 3" as a tweeter will mean the treble will get progressively more directional. That's why most tweeters are 1" or smaller.

Craig (PWRRYD) recently built an MTM using the TCP115's. I'm pretty sure he used the Dayton ND25FW-4 tweeter. I'm sure if you PM him, he'll share the details.

[kenrhodes]

Are you using a subwoofer? If so pick the fe85 and do a mtm with a tweeter. Like a mtm quark. I bet they would sound great and could make for a very nice set of speakers. This also spent up some options for full range speakers as surrounds of you want to save some money.

[kenrhodes]

Also might I suggest:
http://techtalk.parts-express.com/bl...-foals-writeup

I love mine. These could make a great 5.1 for a smaller room.

[PWR RYD]

Thanks Tom. I might start a thread in the gallery with final pictures, xo schematic, measuresments, etc.

[PWR RYD]

Ok, I started to create a thread in the gallery but this forum's poor function made me give up. If you are interested I have a thread about this project on another forum. Feel free to PM me with any questions. Here is a link to that other thread. Details are about half way down the second page.

[JerriAZ]

Thanks everyone for the responses. I'll pm you, Craig, and go from there for now.

[Chris Roemer]

Some things that make small speakers sound like large speakers is extension, and adequate Xmax to make use of that extension. That's why the ND90-8/Aura NS3s work so well as small drivers in pretty small boxes. THOSE can do 50Hz w/4mm of Xmax (and 10mm of Xmech!). A (horizontal) MMTMM SHOULD be set up as a 2.5 way (added XO expense).

[JerriAZ]

Some things that make small speakers sound like large speakers is extension, and adequate Xmax to make use of that extension. That's why the ND90-8/Aura NS3s work so well as small drivers in pretty small boxes. THOSE can do 50Hz w/4mm of Xmax (and 10mm of Xmech!). A (horizontal) MMTMM SHOULD be set up as a 2.5 way (added XO expense).

I thought about using the ND90's and would like to use them, but unfortunately that would increase the cost of each speaker ~$40... And I'm trying to keep things more budget friendly. Do you think the something similar could be achieved with the B3N's? Or I guess I could do a MTM using the ND91-4...

I forgot to mention to everyone that these will be run with a sub... I know I mentioned a 5.1 system which implies there would be a sub, but I never explicitly said there would be one.

[davidroberts]

Try Googling "Overnight Sensation center channel", it is a MMTMM with the B3N.

Curt Campbell has a WMMTMM tower called the Cinderella and a MTM called the Scrappy on his site.

I built the side firing version of the Cinderella and have been very happy with it.

[JerriAZ]

Try Googling "Overnight Sensation center channel", it is a MMTMM with the B3N.

Curt Campbell has a WMMTMM tower called the Cinderella and a MTM called the Scrappy on his site.

I built the side firing version of the Cinderella and have been very happy with it.

That is almost exactly what I was thinking! Thanks for sharing. Except I didn't think about/realize how large the enclosure could be for all 4 drivers. That might be a deciding factor in deciding which route to go...

[PWR RYD]

If anyone is interested I just posted the baffle layout in the other forum thread.

[Jeff F.]

If anyone is interested I just posted the baffle layout in the other forum thread.

That's a nice looking speaker! How do I get an invitation to the forum?

[bsl100]

I agree with Chris regarding the ND90-8. Its been used extensively in the Sprite, Pico Neos and Wolf PC builds. For low end extension, you need to port them in around 4L enclosures like the Sprite and Pico Neos. I have built the Sprite with the ND20FA-6 tweeters. Its a great combo and opens up the sound by giving a lot of air and off axis response. All I did was add a 1st order HPF (9Khz) and a 11db L-Pad on the tweeter. I used a slightly modded Sprite contour/BSC filter (0.9 mH coil with a 16 ohm resistor) for the ND90-8. For an MTM, you shouldn't be going over budget by too much. The results will be rewarding. Remember to put the ND90-8's in a minimum 4L enclosure after accounting for ports, crossover and driver displacement.

[bsl100]

Just to add on to my above post... You might need a lower L-pad (maybe around 8db) on the ND20FA-6 if its used in an MTM design.