So I did a thing to my TriTrix kit.

[jfeenin]

This is my first post here. I had tried to join back in 2018 when I originally was building my TriTrix kit but for whatever reason try as I might my account never got approved. Nonetheless the kit build was straight forward and all went well. They sounded pretty good to my ear. Need a Sub for the lows but I expect that out of any speaker with smaller drivers.

Fast forward 4 years. As much as I like how these sound there have been some things that I've wanted to change. The feet I put on them originally were functional but to be honest ugly as sin. Also the black on black front just wasn't doing it for me. So, I finally decided to do something about that and bought myself a nice piece of Walnut to redo the face. In the process I re-ordered the speakers from an MTM orientation with the offset tweeter to an all centered TMM configuration. I've done a decent amount of woodworking but I am no pro speaker builder so I admit I was a bit anxious about this messing up how good they sound.

I also used the extra wood to make new attached pedestal bases that I think are much more fitting to the speaker. In the end they sound as good if not better than before to my ear and they look a lot better to boot.

[Geoff Millar]

Looks cool, very nice baffle and finish: I'm curious about the sound, as the drivers are in different places compared to the original MTM design - what you prefer about the sound, compared to the originals, please? No big deal, just curious.

Thanks

Geoff

[jfeenin]

To my 50+ year old ears they don't sound all that different. The only thing I can say is my impression that the highs from the tweeter are a little more prevalent. That could just be in my head but I am actually quite happy with the way they sound. I had considered putting an 8" 8 ohm woofer in the sides behind the tweeters in parallel to the 2 front woofers with a 1K low pass filter on it to give it a little more low end. Maybe something like the cheap HiVi M8N that doesn't go much above 2KHz anyway but goes down to 29. That would make them 4 ohm overall and I think the tweeters have enough high to offset that but I'm not so sure I want to mess with what is right now a very good thing as they are.

[Geoff Millar]

Thanks for those comments: I prefer the look of a TMM, and that the tweeters are at a better height for your ears, so I've sometimes wondered whether a MTM design would still sound good with the driver positions changed.

Geoff

[DeZZar]

To my 50+ year old ears they don't sound all that different.

They look great and I'm glad you are happy with the sound!

Just note that baffle position is actually very critical to the crossover and original design. By moving the tweeter - especially to a position where it appears to be equidistant to three edges - introduces significantly different baffle diffraction than what the original crossover was designed for.

Just to illustrate - here is a simple comparison of the diffraction pattern for a 25mm tweeter sitting in an MTM offset position VS a top center position

Here is the likely diffraction pattern catered for in the original crossover:


And where you're potentially at now:



Its great that they sound as good or better to you in this case, but just something to bare in mind particularly for anyone else reading this - normally a change in baffle position, especially this significant, equals a whole new crossover design.

The other thing to consider is that an MTM layout is a very specific design pattern and relies on the two woofers forming an exact mirror image either side of the tweeter axis - in this case the radiation pattern and axial response has been altered as the woofers are now different distances from the tweeter axis.

I had considered putting an 8" 8 ohm woofer in the sides behind the tweeters in parallel to the 2 front woofers with a 1K low pass filter...

Please, definitely don't do this - you really can't just add more woofers to an existing box with the same shared air space/volume and expect to get more bass. You are mostly likely to end up with less. Again to illustrate.....

..here is a single woofer in a 27L enclosure tuned to 39Hz. This produces an f3 @37Hz


...and here's what happens if I just simply add another woofer (that is exactly the same) without changing anything else. f3 is now up at 50Hz. I've lost bass extension. I'll gain maybe 3-6db in output depending on how it's wired up, but now only able to produce bass down to 50Hz.


This is the effect of just adding a second of the SAME woofer...slapping in TWO additional random woofers into the same air volume.....potential disaster. There are also many other reasons not to simply combine woofers into the same air space but I think the above alone is reason enough not to entertain this.

[jfeenin]

While it is not equidistant it's close. The center of the tweeter in this case is 4" from the top and 3.75" from the sides. Close but not quite. Sometimes that's all that matters. Mostly what matters to me is that they still sound good and if they didn't, well I'd have to go back to the lumber store LOL.

As for the additional woofer note that I said I "had considered" but yeah I decided not to at least for now and yes your comments helped table that idea permanently.

I was aware of the whole changing an MTM design and the equidistance from the tweeters and that I must admit was part of my initial concern of how they would sound. A bigger concern to me was that these are TL and by moving that top woofer lower I am pretty sure I effectively shortened the TL. Like I said though to my ear they sound great though. Of course these are my office speakers. They are powered by a little bluetooth class D amp and supplemented by a small 8" powered sub.

I must admit some day I would love to build myself some bigger mains to put in the living room maybe something like the Anthology's listed on the Speaker Design Works page. Except in my mind I would want to incorporate a 8' or 10" powered sub into an extra enclosure added to the bottom. That would make it taller I know but having the subs in the same footprint would be kind of nice. That's a someday thing at best though right now.