My open baffle journey

Hi Plott

Really have enjoyed following the developments.

Any new development or are you happy with the result and consider this the final version?

How do you think this speaker handle rock and do you think the 25W Zen Mod amp is powerfull enough?
 
Hi Seve,
thanks!
Yes, I think the speakers are now finished, but never say never... I still have to make the measurements and I also want to try my parallel xo. So, no, they aren't finished :rofl:
I listen to some prog rock, but mainly jazz and singer, so my opinion may not be crucial regarding rock, however, with prog rock I like what I hear. I use the speakers with Zen Mod's Scryer now and earlier with the M2x, and both are powerful enough, so yes, they can absolutely drive the speakers to very high volumes without troubles, with gorgeous sound. My favorite is the Scryer, until now.
 
Hi,
as I'm extremely satisfied with this speaker I didn't really wanted to make any major changes... but then @perrymarshall came along with his OB projects and gave me the idea of a rear tweeter. So today I installed the Dayton Pro-8 compression drivers in a Celestion H1-8050 horn - as a "side radiator". So the tweeters don't interfere directly with the sound, but they do interfere with the "sound event". They give the sound a wonderful airiness, expand the stage, make the overall sound more beautiful overall - a great development. I of course will try it also in a backwards and in an upward radiating configuration.

PSX_20231118_191847.jpg


PSX_20231118_191905.jpg
 
@Vix no, I'm not definitely happy, 'cos it's diy 🙂
Maybe I will try Sonido and maybe a FR with higher price tag too, even if I like the TB very much.
But I definitely will adjust the xo, hopefully this week, in order to get more (but not hotter) midrange, and I also will play with the placement of the rear tweeter.
 
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Hi,
some progress.
I removed the rear tweeter, I think it causes more trouble...
And yesterday I built a new parallel xo 🤣 after reading of tons (gigabytes...) of knowledge...
My old parallel xo version was obviously a dead end, I missed a lively midrange, it was on the darker side.
The new xo sounds really really good, I'm working on the fine tuning of the level of the mids/highs with changing a resistor.
It sounds very similar to the serial xo which I like very much - but it goes definitely deeper.
So, that's for now - but still thinking about a better FR (even if the TB W8-2145 is very good!), maybe a W8-1772?
Here a quick frequency response measurement (red line); the bass is somewhat "boosted", above 400 Hz it is really nice:

PSX_20240105_183229.jpg
 
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Hi,
after some fine tuning here is a more precise measurement with 1/12 dB smoothing (yesterday it was just a q&d cell phone graph).
The low pass frequency of the woofer is at 125 Hz with a first order filter, the high pass of the FR is at 500 Hz, also with a first order followed by a voltage divider.
The bump is still here at 230 Hz for whatever reason; I made a sim for a notch, but there was practically no effect with the calculated values - and it's not disturbing.
There is a significant evil around 10 kHz and I can't handle it. But at the age of 55 I can't hear it 😀 However, it wasn't there with other FR drivers.
The sound? It's smooth, finally without any sharpness or beeing shouty. The bass is with 52 Hz not the deepest, but because if the slight "boost" it's really imprssive. The midrange is very clean and lively, but there is a very thin line between lively and unpleasant, and now I think it could be more lively and I still have to play with the divider. There treble is also very fine without beeing aggressive or overemphasized.
It throws a huge stage, it's wide, deep and high, but it's not surprising, beeing an open baffle😀

freq1.png
 
Hi,
today a huge step (for me at least...)...
Basically, it was very fine what I´ve heard, but there was always some sharpness" (?), or "hot sound" and the frequency response was not really good at 230 Hz (see above), and i could be better generally.
So I thought, I should make a driver only measurement and create my own frd files. And I did.
The results are... wow, I´m speechless. The difference between the published diagrams and real life measurements (in my baffle, in my room, with my equipment) is huge:

Published FR-diagram TB W8-2145 (red line):

FR_Z_2145.jpg


Measured FR-diagram TB W8-2145:

FR_measured_2145.jpg


Published FR-diagram Eminence Alpha 15A (red line):

FR_Z_AE15A.jpg


Measured FR-diagram Eminence Alpha 15A:

FR_measured_EA15A.jpg


Well... as I wrote, the difference is huge. And the EA15A shows in the real life measurement the 230 Hz bump.
I was curious and checked a 230 Hz signal - yes, this is where I got the sharpness, it feels like a higher frequency. Very interesting.
So I feeded the LSim with this new data and had to change some values in the xo. But after all - the bump is almost gone, and the sound is totally different.
"Hot sound" or sharpness are gone, it´s just clean, detailed, great.

And the measurement (1/12dB, listening place, "all") says - yes:

FR_130123.png


A slight bump is still there, but it´s much better blended into the whole response, so no problem (and it´s not disturbing anymore):

Before 10 dB:
PSX_20240113_185515.jpg


Now 3 dB:
PSX_20240113_185539.jpg


Lesson learned, you should make your own frd measurements, the published ones are - for what?
 
Last edited:
Hi again,
"but I know it´s there"... I mean the bump... so I made further changes beause I wanted to elminate it.
What I got is the best sounding xo during my journey and my best sounding diy- and non-diy speaker so far (I checked it against my Sonus Faber too).

The new FR graph (1/12 dB smoothing):

fr140123_2.png


I think I´m finished 🙂
Although there is some pace for improvement in the treble above 8 kHz...
And it only goes down to 52 Hz... maybe a sub?
However, now it sounds so gorgeus 😍