Indoors groundplane, 50cm from the mouth.  There is too cold outside atm so i'm waiting for better weather conditions to make some outdoor measurements.  

However my indoor measurements seems to match some simulations out there.

Brown: Cubo15 extended, RCF L15P200A, driver in chamber

Blue: Cubo 15 extended, RCF L15P540, driver in chamber

Green: Tham 15, L15P200A

Orange: Tham 15, L15P540

(P200A is 4ohm version, not sure which variant but this one has kapton voicecoil former.. maybe reconed?)

Listening tests:

Cubo has somehow more "aggressive" low end but it sounds a bit hollow. Bass beats / transients has some kind of echo in it. Weird sound but might be good for some type of music.  

 

Tham has very precise sound through the pass band and overall better sound quality. More clear punch than cubo.  P200A(K) clearly better driver here.

Test equipments: UMIK-1, calibrated,  Room Eq Wizzard. 

I had two dual cabs with PD154, and they made some serious noice. Had a great kick and good LF response... But... 

As stated above, they sound a bit odd. Hollow and dry. But oh my they did make some serious SPL!

Tham is more controlled to my ears, not saying cubo is bad but for me its far from being nice to listen many kinds of music. It just dont work that well, maybe I should give it a second try w/ different drivers - as well as for tham. 

I'm designing smallish sound system now, having 4 x "fun enough" bass cabs (smallish power alley effect you know..).  

Well, actually i made four SS15 for a mate, at the same time i made my Cubo 215.

Tested side by side. Four SS15 in one stack and two Cubo215 in another stack. 

And you are spot on regarding SS15. Very musical and well defined. Clearly sounded more smooth. 

Loaded with the recommended Eminence driver. 

I know its not a completly fair comparison as its two very different drivers, but SS15 sounded the best and Cubo had a very clear advantage in SPL. 

No measurements done. Only listening :) 

Which version of cubo.. standard/extended/extra?

But yes PD154 is indeed different league compared to eminence 3015lf. 

Mine are loaded with 18Sound 15LW2400, and throat is modified al la XOC1 (and a lot of extra bracing). They happily handle a couple of kW each... love the sound, output and size and weight! 

The ringing affect is based off of Standing Waves. It is very common in some horn designs. Such a ringing effect can give some users the perception that the cabinet offers more bass. Taming standing waves can be rectified by using wadding in a reflex/sealed cabinet. However in horns, many of times, such issues cannot be fixed so easily due to the nature of the design.

I commend you for taking the time to literally measure your cabinets. You have moved to the next level of cabinet design. There are many who solely rely on cabinet simulation design software as their only means of end results.

 

Best Regards,

Ekstra extended. Actually the extra extended version saw daylight because i wanted to use PD154 in the design. So Johan modified the design to fit PD154 :) 

A SS15 with the 'Cone Correction' Throat mod is hard to beat apart from the lowest frequencies. Best built out of something thicker that 12mm ply. Probably up to 103dB/W efficient.

The Tham15 is a lot smaller though and that makes it the right choice for some.

I just spent an hour or so trying to get better sound from cubo for my taste (DSP and EQ work) and now its much better / flatter. 

I know, going to make open field outdoor measurements soon (10meters / 28.3volts) which is my standard method.

I usually dont care if the driver is 4 or 8 ohms especially if comparing different drivers (except the load for amp or when designing passive crossovers), overall pass band sensitivity is the thing to look for.  Thats why I never adjust curves for drivers having different impedances or DC resistance but I do mention it if necessary. So just add 3dB for 4ohm driver if you want to :)

I have two versions of L15P540, old and new (almost brand new actually). Old version has smaller vent hole and less ribbed cone (4 vs 5 ribs) but they work. 

You are comparing an old driver versus a new driver. The older driver has been used more and broken in thus, the differential in the Qts & fs. Its like buying a brand new pair of shoes of the exact brand in addition to model number and wondering why the older shoes feel more comfortable.

Your limiting factor is not the speaker but, more so the enclosure. The loudspeaker cannot give you more for the cabinet does not meet the requirements needed for the loudspeaker to deliver an extended frequency response.

This is why TS Parameters of Loudspeakers are measured in Free Air as the loudspeaker is not restricted  by enclosure limitations. The vast majority build cabinets too small for the loudspeaker. This is why every large loudspeaker placed in a small enclosure requires a lot of equalisation and use a lot of excursion to deliver those lower notes at a significant sound pressure level.

Best Regards,

Some manufacturers actually gives parameters for "broken in" drivers and it makes sense - depending how long does the driver take to mostly "break in".

Just remember the fs, Qts and, VAS are the most important figures when designing a box. Nothing has changed in 50 years. Get a good understanding on how those symbols dictate the overall response of a loudspeaker in an enclosure and, you will be far ahead of the majority of Do It Yourself builders on the Internet.

Best Regards,  

Anyway I need to look for more 15" drivers to be measured with different cabs like Tham.  15TBX100 seems to be a good candidate, or cheaper alternative 15PS100.

Short video, tham in action, low power but there was good amount of bass!

A Speaker will only loosen up based on its environment. If you are swapping a speaker in different boxes on a constant basis, that speaker will break in according to the box that gave the loudspeaker enough room to move freely.

If you are looking for a speaker that offers minuet deviation from it's published TS Parameters look to wards Eminence or the old Made in England Celestion.

B&C, Faital Pro, Electro-voice, Beyma, Fane, in addition to, RCF drivers will offer significant changes on their Parameters once measured in free air based on my experience.

You should also focus on one design and disregard the one(s) that do not meet up to your requirements. If the tham 15 gives you what you are looking for from a tonal standpoint, you do not need to focus on the cubo 15. Get rid of the cubo boxes and build more tham bins. Don't get caught up spending a lot of money on drivers to band aid a box design in which, all in all you really do not like the tone it projects when, you have a next design that satisfies your tonal requirements.

Best Regards,

 

I have designed two ml-tqwt enclosures for 4 and 6" full range drivers and they are amazing.  The openness and good integration of bass frequencies with upper band is so good.   

Just punished my tham15 @ 1kW of power, oh my.. it slams hard!  And it has much better cone load compared to cubo. P540 was not happy in cubo (over excursion and flapping etc) but no problems in tham.  Brutal thing being so small but requires careful EQ settings.

At 40Hz, P540 is about 3dB louder and overall flatter bass response. 

P200A has a lot bigger VAS (190 vs 100) and much lower FS (33 vs 56) while Qts, BL etc are pretty close.  Maybe this will help choosing the drivers for Tham 15.  It does like low vas high FS drivers according to this.

(I have actually noticed the same with HOG scoop. Low VAS medium FS the best and of course, strong motor).

Now let's test the same drivers in cubo 15...

and how about mk2? the one with 45' corners