Calling Johan - Seas L26 + L18/L15 + 27TBFCG

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Hi all

DT Seas 3 way - Google Drive

Contains
Sketchup model - finished and proposed bracing (but do your own). L26 in a 60L sealed giving Qtc=0.66 and f3=44Hz
PNG of XO, on axis response and impedance (min ~ 4.3 ohms in the midbass)
Various FRD and ZMA files of the drivers - min phase extracted
I used the following Z offsets for FRD data modeling - L26 = -3.6", L15 = -0.81", Tweeter = 0"
Baffle geometry and driver placement

Please note:
The baffle geometry - I ended up moving the tweeter or L15 over so it was vertically aligned in my test enclosure. I'll update the baffle geometry image with details in due course
there's a few other tweaks I'd like to do. When I get time I will post them here.
 
Chaps - forget a 2KHz crossover. This is seriously flawed with the seas 27tdfc tweeter.

This crossover is far far better. No listening fatigue on a variety of material and no loss of detail. Balance is excellent. Flat response which is "softer" than the BBC dip I had before.

All because I am not asking the tweeter to play too low. Anyone who says the Seas 27tdfc can handle a 2Khz LR4 crossover must listen to very well recording or undemanding music.

This is the crossover with what is available in my parts bin. Not optimised yet ;-)
 

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  • Crossover - 3Khz - with impedance.png
    Crossover - 3Khz - with impedance.png
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Dave- glad you are still plugging away. I'm surprised that you don't like the Seas tweeter at 2k because most people think it can handle that no problem. I'm even more surprised that you like the L15 crossed at what looks like 3k or so, but I'm not questioning your judgement.

Sounds like you and I test speakers the same way. I always look for music thats hard on speakers and then crank the volume to find the limits. People really love this when I do this on their speakers.
 
Dave- glad you are still plugging away. I'm surprised that you don't like the Seas tweeter at 2k because most people think it can handle that no problem. I'm even more surprised that you like the L15 crossed at what looks like 3k or so, but I'm not questioning your judgement.

Sounds like you and I test speakers the same way. I always look for music thats hard on speakers and then crank the volume to find the limits. People really love this when I do this on their speakers.

I have this annoying habit of not quitting :) The harder a problem is, the more likely it is that I will stick at it to solve it.

It really is a case of making compromises.

I am also really surprised. A lot of people love seas 1" domes at 2KHz - or even lower. The distortion plots say it's fine - no problem.

However, my ears tell me otherwise. There's something missing from those measurements.

I rechecked, re-measured etc... to make sure it wasn't a wiring issue. I swapped tweeters out - also tried a non-grille version (27TDFC), the metal 27TBFC/G version (with extra attenuation due to increased sensitivity) and now back to the 27TDFC/G.

I'm sure the 2KHz xo has better power response as the L15 is really at its beaming limit at 3KHz. Solution? - listen to the speakers toed in. Other people in the room will just get a more rolled off response.

I don't have a lively room either. Heavy curtains (drapes), carpet on the floor. I have a high ceiling too, so that wasn't adding to the forwardness / harshness.

However I believe vertical lobing has improved with the steeper slope. I can do the stand up test and subjectively, there is less change to the sound.

Even though both mid / tweeter were level matched - which was confirmed by measurements. A simple listening test showed me something was not right. I listened midway between mid and tweeter - about 1m distance. With the 2KHz crossover - on most tracks, the tweeter dominated the midrange. With the 3KHz crossover - both drivers are equally contributing to the sound.
 
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