Big 2-way - cardoid

[TimVG]

Just trying out some stuff with some scrap wood as due to the covid situation, all of my hobbies are gone for the time being and I need something to do.

Parts: XT1664 horn and 18Sound NSD1480N, Faitalpro 15FH500


Midrange/bass cabinet:

Top cabinet

Naturally, I put in a quick crossover (made sure it summed properly). Sounds good!

 

[TimW]

Where the heck are you?

 

[TimVG]

A small church in the school where I also work. Not being used at the moment. Convenient for gated measurements.

 

[TimW]

Cool. Are those holes in the side of the bass cab meant to create a cardioid radiation pattern?

 

[hex168]

Very nice! Can you provide any details on your cardioid cabinet? Seems to work well.

 

[TimVG]

Cool. Are those holes in the side of the bass cab meant to create a cardioid radiation pattern?

Yes.

Very nice! Can you provide any details on your cardioid cabinet? Seems to work well.

Basically trial and error. The idea to create out-of-phase leakage through the holes by means of delaying the sound through resistance (in this case, rockwool). It's already a pretty wide cabinet, but it does help a bit compared to a fully closed cabinet. In spring I'll probably do some ground plane measurements outside to get better resolution in the low range.

 

[TimVG]

Decided to whip up some decent cabinets for further testing. Unfortunately the plywood I bought was terrible, but since this is just for testing it'll have to do. Should be finished somewhere next week.

 

[abdo123]

Dutch & Dutch 8C on a dime!

I love this!

Does the horn loading have anything to do with the messiness in the last octave?

 

[TimVG]

Probably the compression driver breaking up - but could also have something to do with the compression driver/horn mouth transition. Part of me wants to find out, the other part just wants to get a working system first.

 

[TimVG]

Since you mention the 8C, the idea isn't really to use this as a full-range system (although I guess with enough power on tap it could be equalized to have decent extension and maintain plenty of SPL) but rather as efficient and powerful satelite speakers (if that word still applies to something rivalling the JBL M2 in size)

 

[Colonel7]

Since you mention the 8C, the idea isn't really to use this as a full-range system (although I guess with enough power on tap it could be equalized to have decent extension and maintain plenty of SPL) but rather as efficient and powerful satelite speakers (if that word still applies to something rivalling the JBL M2 in size)

Interesting project. How many satellites are you planning? And what were the 2 test tracks to kick off the thread?

 

[bigjacko]

It works surprisingly good! Do you have websites that share the knowledge that leads you to here? Thank you very much.

 

[TimVG]

Interesting project. How many satellites are you planning? And what were the 2 test tracks to kick off the thread?

Just the two - I started with this project because there wasn't much to do due to covid, in the meanwhile things are returning back to normal. Something else I'd like to try is a big 15" coaxial driver.

The two test tracks are: And so it goes (King's Singers) and It had to be you (Paul Kuhn)

It works surprisingly good! Do you have websites that share the knowledge that leads you to here? Thank you very much.

There used to be a good deal of info on @kimmosto 's website but it seems to have been removed. I suggest browsing through DIY audio for DIY cardoid speakers.

 

[TimVG]

An update. Finally finished the two new mid/bass cabinets. Well, the plywood has so many voids in it I'll have to make new ones at some point, since these look like crap, plus already I'd do some things slightly differently looking at it now.



Another problem is this stack is so big, it's unsafe for me to try and climb a ladder with any of it. So no detailed measurements as I wanted to at this point I'm afraid until I can get help or design a new platform.

I have made some basic measurements however, since I wanted to put an initial crossover in place.

Please don't mind <300Hz as I have to do some ground plane measurements when weather allows. Measurement distance was around 1,5-2m - sorry, I didn't have much time to do things 'right'. This is after 30 min of fiddling around.

Also I was using the minidsp HD as a DAC and I'm getting a weird 10kHz brick filter, playing around in windows didn't seem to make any difference. Didn't have this issue before with a different DSP and using my fostex DAC/volume control.

On axis centerpoint between woofer and horn + reversed phase to show summation.

On-axis (green) / horn height (blue) / woofer height (brown) at measurement distance to give an impression of vertical behaviour

And finally 0 - 45h - 90h (eyeballed it) to give an impression of how this thing radiates sound. Although we already kind of knew from previous posts since the horn top was already measured properly.

 

[TimVG]

Some in-room MMM measurements. L/R and average. No EQ above 350Hz. 4 subs below 80Hz. Due to the cardioid and constant directivity behaviour of this system, there's a less pronounced downward trend as you get with traditional forward firing cone/dome systems.

 

[Absolute]

Mighty good job! I'm impressed. Happy with the sound?

 

[TimVG]

Mighty good job! I'm impressed. Happy with the sound?

Very happy. I made one EQ adjustment on day 1 (-1,5dB, Q=1 @4,5kHz) but after that there was nothing to do, imho. The biggest difference with my Genelecs or other traditional speakers (I've also owned Revels before, among others) is spatial presentation. It's much easier to listen 'into' a recording with these monitors. One more aspect, which you could say is bias on my part, although I'm always doing best to stay objective, is a certain clarity in the upper bass/lower midrange. If you take a track like 'Yesterday - The Persuasions' - many systems can present it in a manner which is tonally correct, but not every system, to my ears, presents it with the correct texture (sorry for the subjective lingo) for lack of a better word. This seems to be a quality of systems that maintain directivity down that upper bass/lower midrange.

I'm not sure of any other studies, but this thesis by Olli Kantamaa correlates with my findings. I just stumbled on this paper through ASR a couple of days ago, so I wasn't influenced by it.

 

[5meohd]

I want to build these too...

 

[voodooless]

I’ve been lurking here for a bit This looks really impressive! Have lots of questions though: What kind of bass response do you get out of these? You seem to use subs below 80Hz, but from the first post they seem to fall of just below 200 Hz already? Then why the massive cabinets?

 

[TimVG]

I’ve been lurking here for a bit This looks really impressive! Have lots of questions though: What kind of bass response do you get out of these? You seem to use subs below 80Hz, but from the first post they seem to fall of just below 200 Hz already? Then why the massive cabinets?

For the most part this is due to using windowed measurements. Also, I was mostly interested in the measured differences between a sealed enclosure and how the position/size of holes and various amounts of absorbing materials impact the cardioid behaviour in the upper bass, so I never really tuned the system down to the low range. Due to terrible weather during summer I was not able to perform ground plane measurements, so I still have no definite data on what's going on in the bass range in terms of extension or dispersion. Luckily for my intended purpose I could do this tuning in-room situ. I'd also modeled the driver in the cabinet and figured out the (simulated) baffle step compensation, and from the in-room measurements I wasn't too far off. In any case this system's biggest strength isn't lower bass. EQ'ing down to 80Hz anechoically shouldn't be a problem though.

The massive cabinets (you get used to it) are simply so I wouldn't have to use stands. I also have to option to close off the bottom portion of the cabinet from the upper part, fit an extra driver, and turn them into a three way, if I'd feel the need. But honestly in due time I'll probably just make nicer cabinets, this was just proof of concept.