U frame line array subs with 8x PD186

Very nice

Seems if you can also turn "a bit" louder

Could you also say something about the line array next to u-frames?

Best regards

ede

Your U frames won`t stay such close to the wall? How far into the room are you going to draw them?

Beautiful project. I would also like to know more about it.

Hi!

Things have updated little since my last contribution.

First of all, the PDs did arrive ....






... but unfourtunately I have already scheduled returning them back to the vendor. PD186s didn't have the most quiet motor and ventilation system, and they were not so good choice for dipole/u-frame operation. Regardless, the bass was quite an experience! I'm hoping my final woofers do the same but with more silent operation!!! PD186's did not have a ventilated chassis under the spider, which I thought that they would have

Now I'm wondering what drivers will I ultimately choose...

I have been lookin BMS's woofers like 18S430v2 and the monster 18N860, I will propably go with these. On paper they seem like a wonderful woofers, and they do look like to have a very good ventilation, which could mean that their motor is quiet. Does anybody have some experience with BMS woofers???

http://bmsspeakers.c..._18s430v2_t_data.pdf

http://bmsspeakers.c..._data_2010-03-18.pdf

I have planned that I will buy four 18S430v2s and four 18N860s. From the latter woofers I could , at some point, make monopoles (bass reflex or closed box) and cross them at 40Hz to devastate at the lowest octaves... I think both driver types would also play seamlessly together as all-u-frame system as which I will use them at first.

ede90 schrieb:

Very nice Seems if you can also turn "a bit" louder Could you also say something about the line array next to u-frames? Best regards ede

These dipole line arrays consist of 10x Peerless 6,5" 830874 (http://www.europe-au...peerless\830874.pdf) and 2x Vifa DQ25SC-05/04 (one pointing at the roof) per side. They sound nice and play very loud without any distoryion for a home speakers. I really like how dipoles sound in general, non-boxy and open sound that has good spatial definition. Actually because I liked "dipole kind" fast bass output so much I decided to built dipole line array subs to accompany these line arrays.

I have been planning to upgrade my tweeters to Beyma CP380M compression drivers soupled to 18sound XT1086 horns.

2eyes schrieb:

Your U frames won`t stay such close to the wall? How far into the room are you going to draw them?

Unfourtunately I will use them that close to the front wall at this point. My current room does not allow me to move them much more away from the wall than in the picture. Maybe 10cm more or so... Luckily this is my student apartment, and I will be moving out like in a year.

This kind of placement of dipoles/u-frames reduces the bass output at the lowest freqs, but I will compensate this with DCX2496. The experience with PD186s were very positive albeit the frequency response dropped quite a bit towards the lowest octave.

Thanks also for Velocifero for commenting



Ps. all driver recommendations are welcome!

-Legis

I got one used 18S430v2 for demo, and I got to say what an impressive driver. The motor is quiet and the bass is just wonderful; deep, punchy and clean no matter how hard you drive the woofer. 18S430 can be crossed high as the mids reproduction is also good. The frequency response goes higher than 6,5 inch Peerless HDS midbass!

I was so convinced by the plain performance that I placed an order for 4*18N860 and 4*18S430v2, which I had been planned.

18N860 has a mathematical xmax of +/- 22mm and 18S430v2 has +/- 10mm.

Specs:

- Mathematical displacemet of 15,5 litres (equals 26,5pcs 12" Peerless XXLSs / 8pcs PD2150)
- Power handling over 10kW
- Total cone are 0,97m2



The story continues...

I finally received BMS woofers . I decided to get 4x 18N860 and 4x 18S430v2.

I also tested 18sound's 18NLW9600: http://www.eighteens...view_product&pid=288

and Faital Pro 18HP1020: http://www.faitalpro.com/products/schede/hps.php?id=201070110

Some pictures of 18sound and Faital Pro:

http://i817.photobuc...18S_Faital_ylhlt.jpg

http://i817.photobuc...18S_Faital_takaa.jpg


Both 18sound and Faital had very noisy ventilation system. 18sounds woofer was a-class to what comes to the quality of the craftsmanship and looks of the woofer. However it's performance did not differ from BMS 430v2, to my liking it was actually little worse what comes to sound quality. 18sound's bass was not so punchy, and for those who like good applicability of a woofer, the quality of midrange was far poorer than with BMS 430v2. If the midrange quality is top notch like in BMS, one can use high crossover points and/or 1st degree crossovers.

Faital was not a real sub-woofer, it was very xmax limited. It's midrange performance was still quite good but not as good as with BMS. Faital's advantage is the very low weight (under 7kg a piece).

430v2 was far superior to both 18sound and Faital what comes to the ventilation noise. 430v2's operation is quiet. 18N860's motor is as quiet as 430v2's but at high excursions the ventilation naturally makes some noise. The sound quality in both woofers is just plain fantastic. All in all, the BMS's woofers are hugely capable, long excursion woofers with very low harmonic distortion .



I conducted little testing with two 18N860s. First couple of bass test tracks (never mind the audio&video quality :)):

Bass, I love you: http://www.youtube.com/watch?v=WqxwNkwt17g

Opus Dei bass test: http://www.youtube.com/watch?v=hoZ82ffdEgQ

And then some hunting for the maximum linear excursion with 20Hz sine tone from different angles:

#1: http://www.youtube.com/watch?v=_W0mXucfDXI

#2: http://www.youtube.com/watch?v=U4n_oCvwTcE


The point in which the excursion gets nonlinear is somewhere 50 - 55mm p-p (approximated with eyes, the videos might understate the excursion a bit). This is very very respectable excursion indeed, and it exceeds both the specified and mathematical xmax.

Very nice to get some information about ventilation noise of those drivers. You can't derive that from published data.
What you call max linear excursion would be max excursion without mechanical compression to me. At the demonstrated excursions most parts of the voice coil should have left the linear magnetic zone already.
Does the stretched accordeon surround limit the maximal excursion before the voice coil can get in touch with the pole piece?

2eyes schrieb:

Very nice to get some information about ventilation noise of those drivers. You can't derive that from published data. What you call max linear excursion would be max excursion without mechanical compression to me. At the demonstrated excursions most parts of the voice coil should have left the linear magnetic zone already. Does the stretched accordeon surround limit the maximal excursion before the voice coil can get in touch with the pole piece?

Correct. The response can still be "linear" (e.g. THD <10%) even though that the voice coil has left parly the magnetic gap. How far the excursion stays linear, depends on the woofer and the application.

I don't have a clue of the woofer's THD% in those displacement values on the video but the point in which I stopped increasing the volume was the point in which the cone's movement went highly nonlinear. The change is more radical than the film shows; after certain point even 0,5dB increment in volume makes tho cone's movement slightly uncontrolled and at the same time the THD naturally jumps like 10dBs or more (can be slightly heard on the video). The woofer keeps it's control quite good up to that point. I have not tried to displace the 860's cone for more than that.

However I also tried to displace the 430v2's cone in the same manner with 10 - 25hz sine tones and got little different reesults. I conducted that 430v2's suspension limits the movement to +/- 15-16mm. If I increased the volume after this point, nothing happened; spl stayed the same and distortion did not increase - as said, nothing happened. I think that this is the case also in 860 - one cannot bottom out the woofer. The suspension of the 860 might stop the motion at +/- 38mm, who knows, but I'm not the one who tries that :).

+/- 15mm is by the way double the specified linear excursion of 430v2. This is usually the point in which the woofer bottoms out. It seems that the BMS has made the motor longer than normal like for example in the 18sound driver I mentioned previously (it has +/- 14mm mathematical Xmax and +/- 35mm Xdamage)

Which surprised me was that the motion of the 430v2 was quite controlled all the way to the point in which the suspension stopped the game. I could not get it's response same extent uncontrolled than with 860. I think one could drive 430v2 with quite good sound quality all the way to the limits in a box. Not in dipole however, due to the poor sensitivity of the lowest frequencies Well, maybe the two last 2-3 millimetres of the excursion are wise to be skipped in every application... These last millimetres are always the most expensive millimetres soundwise. The suspension did not however make any knocking/clicking sound or anything like that.

Legis schrieb:

2eyes schrieb: Very nice to get some information about ventilation noise of those drivers. You can't derive that from published data. What you call max linear excursion would be max excursion without mechanical compression to me. At the demonstrated excursions most parts of the voice coil should have left the linear magnetic zone already. Does the stretched accordeon surround limit the maximal excursion before the voice coil can get in touch with the pole piece? However I also tried to displace the 430v2's cone in the same manner with 10 - 25hz sine tones and got little different results. I conducted that 430v2's suspension limits the movement to +/- 15-16mm. If I increased the volume after this point, nothing happened; spl stayed the same and distortion did not increase - as said, nothing happened. I think that this is the case also in 860 - one cannot bottom out the woofer. The suspension of the 860 might stop the motion at +/- 38mm, who knows, but I'm not the one who tries that :).

I talked too hastly. The suspension of the 430v2 did not actually limit the excursion, it was due to the amplifier, which gain trim did not affect the gain in the last couple of steps .

I conducted new test, in which I controlled the gain with my pre amp. I stopped harassing the 18S430v2 at approx 45-50mm p-p, because I don't know the actual x-damage of the 430v2. http://www.youtube.com/watch?v=H4d6-5pBdCU

Because the 430v2 moved so good I conduted the test with 860 again. this time with only one woofer driven. The results were clear; the first time I shoot those videos, while I was driving two woofers, the amp clipped and caused the sudden rise in distortion and out-of-control movement. When I drove only one 860 I was able to go to the suspension's limits (approx. 60mm p-p). At this point the suspension started to make a faint clanking sound. At least I think it was the suspension and not the woice coil bottoming out, which I, think could move another 10-20mm more. Here's the official max-displacement of the 860: http://www.youtube.com/watch?v=EB-_bDMDjtE

2eyes schrieb:

Does the stretched accordeon surround limit the maximal excursion before the voice coil can get in touch with the pole piece?

I got response from BMS to this question. By hitting the top plate(?), the spider limits the cone's movement to a point in which the voice coil is 5mm away from the bottom piece and protects the voice coil from destruction.