Thanks for the guidance and advice! I will continue to tweak things and see what happens. Damping in the mouths / termini near the deflectors will be much simpler than removing the drivers every time I want to make a change.Damping in the chamber & throat area is the default; you can start to trim excess LF output by adding material above / below the deflectors, as relevant.
Damping material is always most effective at the point of maximum air velocity, which for LF frequencies is near the bifurcated physical termini; you can add some to the deflector surfaces also of course if pets etc. can't access them. And then it's literally a case of adjusting to suit your preferred balance -preferably per channel since few spaces are acoustically speaking completely symmetrical, although the one shown is probably more so than some.
The gain BW you measured is roughly in line with expected, near-raw, albeit with the usual variations you'd expect for room acoustics, mic. type & placement. So it appears to be behaving as intended, which is always a good start. 😉 As an advance suggestion -go easy with the Harman house curve on a direct-radiating wideband. I like it as a basis myself, especially for direct-radiating multiways, but (but) you can end up chasing your tail a bit with any nominal system response curve since it's not ideally accounting for differences in the actual polar / power responses in radically different systems. That's why, say, the so-called 'smiley face' curve with roughly symmetrical peaking LF and HF can actually sound quite balanced for many people since the one tends to cancel the others out. In the case of wideband drivers, with their reduced HF dispersion, tilting it down significantly can sometimes end up causing more of an LF heavy balance than in other setups -especially if you have a large (in relative terms) horn coupling to the room over a wide (again in relative terms) LF BW compared to a sealed or regular vented box.
That hound looks like I feel.
Your point about LF and HF balance is on the mark. It sounds like the test looks. I will aim to balance it better, for a crisper top end.
To provide context around my excitement to get these speakers up and running, this has been my primary sound system for the past eight months:
Circa 1980 Columbia RN-3000 Beat Boy (http://wikiboombox.com/tiki-index.php?page=Columbia+RN-3000). Amazing that it still works and manages to sound pretty damn good, too. I feed the rear audio inputs with an rPi Zero 2W running Moode, into a $7 DAC. Literally everyone who enters the kitchen is compelled to ask what’s going on there. How can something look so odd but sound so good? My nephews from Osaka (both early 20s) had huge grins while they inspected it. When they realized they could use Spotify Connect with it, they were blown away.
Circa 1980 Columbia RN-3000 Beat Boy (http://wikiboombox.com/tiki-index.php?page=Columbia+RN-3000). Amazing that it still works and manages to sound pretty damn good, too. I feed the rear audio inputs with an rPi Zero 2W running Moode, into a $7 DAC. Literally everyone who enters the kitchen is compelled to ask what’s going on there. How can something look so odd but sound so good? My nephews from Osaka (both early 20s) had huge grins while they inspected it. When they realized they could use Spotify Connect with it, they were blown away.
You can’t tease us like that: we need to see the HouseCurve measure of the BeatBox.
Thanks to Gene at Audioholics, I recently discovered a new bass/ subwoofer test track to supplant “ Flight of the Cosmic Hippo” - James Blake, “Limit to Your Love”. As your local herbal products guidance counselor might advise re edibles or tinctures - start low, and go slow.
Thanks to Gene at Audioholics, I recently discovered a new bass/ subwoofer test track to supplant “ Flight of the Cosmic Hippo” - James Blake, “Limit to Your Love”. As your local herbal products guidance counselor might advise re edibles or tinctures - start low, and go slow.
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Okay, you asked for it! (Tone controls set to flat)
Thanks for the recommended tracks. Going to check them out now!
In other news…
I picked up some 40mm PET felt and some polyfill today. Started with the PET felt. They were 30cmx30cm, so cut in half they fit perfectly inside the horn mouths. Tried a three different configurations and finally landed on something that works quite well. I folded each piece in half and inserted it as shown, folded end first, so that they expand to form a triangular shape inside the mouths:
The result tests well and sounds very, very pleasant.
It’ll be dead simple to iron out the remaining warts with a relatively light-handed FIR filter.
I picked up some 40mm PET felt and some polyfill today. Started with the PET felt. They were 30cmx30cm, so cut in half they fit perfectly inside the horn mouths. Tried a three different configurations and finally landed on something that works quite well. I folded each piece in half and inserted it as shown, folded end first, so that they expand to form a triangular shape inside the mouths:
The result tests well and sounds very, very pleasant.
It’ll be dead simple to iron out the remaining warts with a relatively light-handed FIR filter.
The Cosmic Hippo appeals to me much more and sounds very good on these speakers (as configured). The other one… well I am not a big fan of electronically-produced bass to begin with and the music itself isn’t for me. A bit of master-bass-tion. Still, I can absolutely see the utility of it to test a sub.
IIRC there were a couple of those (or similar) in the pilot episode of Miami Vice, which is never a bad thing.
That´s it. You finding that image makes me want to go public with my Voigt tractrix research. Catch me in the thread I am about to create.
Update:
As I mentioned before, it was quite simple to create an FIR filter and use it in CamillaDSP (via Moode) to get a super-smooth response. It sounded very, very good.
It didn’t take me long to realize that this would be moot with any other sources. I did bring a select few records with me to Japan and plan to buy a TT some day, and the TV is an audio source as well. Besides that, it just seemed like the “right” approach was to continue adjustment of damping and dial the speakers in closer to ideal, so that they sound good with any source, regardless of DSP.
I bought 2 more 30cm x 30cm x 40mm pieces of PET felt, cut them precisely in half (as I did last time), and sandwiched them into the horn mouths with the existing pieces. Two pieces, folded in half and interlocked, which doubled the quantity and also increased the density (via compression).
Before running any sweeps in HouseCurve, I always play a couple of very familiar tracks to get an initial subjective impression of the sound. In this case, one song was enough; Dire Straits - In the Gallery. Amazing! Very close to perfect for my taste! I did notice something, though; I needed to increase the volume on my pre-amp a bit to get to my typical listening SPL. Of course! It’s the damping! So then I really cranked it up and I noticed that driver excursion was very much under control, and the sound was very tight and coherent even at these higher levels. This was very different than before this latest damping change. I mean, it sounded good before, but it started to fall apart a bit at higher SPL. Now, it’s super solid. I can easily push these speakers well beyond what I find reasonable SPL and they remain poised, tight, crisp.
So I did some sweeps:
Still heavy at the bass end, but not nearly as bad as before and honestly it suits my taste perfectly. My mind tends to fixate on rhythm in music, so rich, warm bass is always welcome. Really pleasing to listen to without any DSP.
Having said that, I went ahead and generated another FIR filter for my Moode player. The results sound almost too perfect. It feels like cheating. As you can see, I used a manual curve fit in order to allow only cuts (to avoid clipping).
As I mentioned before, it was quite simple to create an FIR filter and use it in CamillaDSP (via Moode) to get a super-smooth response. It sounded very, very good.
It didn’t take me long to realize that this would be moot with any other sources. I did bring a select few records with me to Japan and plan to buy a TT some day, and the TV is an audio source as well. Besides that, it just seemed like the “right” approach was to continue adjustment of damping and dial the speakers in closer to ideal, so that they sound good with any source, regardless of DSP.
I bought 2 more 30cm x 30cm x 40mm pieces of PET felt, cut them precisely in half (as I did last time), and sandwiched them into the horn mouths with the existing pieces. Two pieces, folded in half and interlocked, which doubled the quantity and also increased the density (via compression).
Before running any sweeps in HouseCurve, I always play a couple of very familiar tracks to get an initial subjective impression of the sound. In this case, one song was enough; Dire Straits - In the Gallery. Amazing! Very close to perfect for my taste! I did notice something, though; I needed to increase the volume on my pre-amp a bit to get to my typical listening SPL. Of course! It’s the damping! So then I really cranked it up and I noticed that driver excursion was very much under control, and the sound was very tight and coherent even at these higher levels. This was very different than before this latest damping change. I mean, it sounded good before, but it started to fall apart a bit at higher SPL. Now, it’s super solid. I can easily push these speakers well beyond what I find reasonable SPL and they remain poised, tight, crisp.
So I did some sweeps:
Still heavy at the bass end, but not nearly as bad as before and honestly it suits my taste perfectly. My mind tends to fixate on rhythm in music, so rich, warm bass is always welcome. Really pleasing to listen to without any DSP.
Having said that, I went ahead and generated another FIR filter for my Moode player. The results sound almost too perfect. It feels like cheating. As you can see, I used a manual curve fit in order to allow only cuts (to avoid clipping).
PRaT (pace, rhythm & timing) rules! Welcome to my world of critical damping.
Thanks! It is more challenging than building a monkey coffin, but well worth the effort! I didn’t anticipate this much damping material, despite plenty of evidence from other members’ builds of this and the other Woden Megaliths.
Thanks Zia! We need to catch up, man!
Agreed! Thanks for the encouragement on the damping (and Scott as well, of course). I did begin to investigate your diagram on the “close enough” circuit to test critical damping. The first thing I needed was my amp output impedance. I found a thread on another forum that described the process in detail, but there was an error in the instructions that resulted in me calculating a negative value for my amp output impedance (which seems impossible to me). I know exactly what the error is in the instructions, but this makes me doubt the accuracy of the entire post. I looked elsewhere and didn’t find anything that provides complete, step by step instructions with correct math.PRaT (pace, rhythm & timing) rules! Welcome to my world of critical damping.
@GM , thanks for the link. However, I am not keen on running my tube amp with no load. The instructions I found before also warned against this, and recommended using a light load (say 25 ohms) and then bigger load (say 5 to 8 ohms) and then doing the math. Too bad the math was wrong, otherwise I would have been fine.
EDIT: Wait, you pulled a fast one on me… first you just linked to the calculator. I’ll check out that thread.
EDIT: Wait, you pulled a fast one on me… first you just linked to the calculator. I’ll check out that thread.
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