Integrating tweeters with b200 - preserving efficiency

THWO · « **Reply #20 on:** 22 Oct 2009, 08:05 am »

Till

jonners · « **Reply #21 on:** 4 Nov 2009, 10:04 am »

The best solution to this problem that I've found so far is to use Beyma T2030 dome tweeters (95dB) mounted at the top of the baffle and firing upwards. The B200s are run full range.

SAC · « **Reply #22 on:** 3 Dec 2009, 04:25 pm »

Quote from: Rudolf on 22 Apr 2009, 05:06 pm

Quote from: mcgsxr on 21 Apr 2009, 07:25 pm
I don't need dipole tweeters, I can live with monopole treble from 5K or 10K on up.

Thoughts?

I question both proposals.

I´m fully convinced that the ongoing uneasiness with the B200 treble stems from the gross difference between on-axis and off-axis SPL in that area. Following the dipole pattern of the midrange with a dipole pattern for the treble has convinced almost everybody who has tried it - although not with the B200 AFAIK.

Rudolf

I have followed his thread with interest since I am similarly experimenting with dual alpha 15s, the B200 with diy phase plugs/magnet mount, and the neo 3pdr in free air.

I want to say that Rudolphs comments above reflect my experience yesterday. After adding the neo3s in rear fire as opposed to the B200s alone I found the treble suddenly more agreeable/less shouty. Better yet, the whole audio reproduction was much, much more enjoyable. I even took the 0.5 inductor off the B200 and found the sound improved again. Wish I'd tried it earlier.

Next mod for me is a PLL BSC.

markC · « **Reply #23 on:** 8 Dec 2009, 03:10 am »

If you want to use a tweeter with the B200, you've got to kill the B200 @ 2K-2.5K. Unless someone has way different positive results than my experiments, that I could listen to, I stand by this statement.

SAC · « **Reply #24 on:** 27 Dec 2009, 11:36 am »

I finally got a chance to cross the b200 to the neo3pdr open baffled and crossing around 1khz. I did bi-amp and do this by a PLLXO.

Much better sounding! I remember reading that any decent tweeter would "clobber" the B200 in the treble department and that has certainly been the case for me. I had tried the BSc, the notch filter, rear firing tweeter at 2khz and then 10khz, but none to compare with this two-way arrangement.

I was unsure of trying this due to the complications others suggested such as phase cancellations and the like, but the sound is incomparable now. I doubt I will go back again in this set-up.

P.S. tri-amping dual alpha 15s+B200+neo3 pdr was amazing! Even my wife from the other room noticed a huge change had taken place, it now sounding "like a movie theatre".

scorpion · « **Reply #25 on:** 27 Dec 2009, 11:19 pm »

Did you cross both B200 (LP) and Neo3 (HP) around 1 kHz ?

/Erling

SAC · « **Reply #26 on:** 28 Dec 2009, 12:33 am »

Hi Erling,

I used an excel spreadsheet to do the math for me and did not have the exact values (50K input impedance amps). To be honest some of the XO points chosen were the result of whatever parts I had to hand. I am no expert (that's an understatement) so I welcome criticism of my arrangement as follows;

B200 low-passed 12db from 600hz -
Resistor 5k
C 53nf
C 5600PF
R 50K

NEO3 high passed 6db from 1000hz -
R 5.6K
C 28.44nf (I only had 22nf so I guess the -3db XO point is 1500hz!?)

Of note, I read a comment explaining PLL cross-overs do not actually achieve the theoretical attenuation, i.e. 12db XO actually works out as 8-10db.

Sean

scottw · « **Reply #27 on:** 28 Dec 2009, 09:05 pm »

Hope this isn't too far off topic.

This is in regard to the waterfall (CSD) plot for the B200 posted on the first page of this thread. I assume those undulations (the "mess") between 2k and 5k are caused by break up or resonance of the cone? This seems a pretty typical region for an 8 inch cone to start having trouble.

Is there any indication that the disturbance in this region could be, in part, caused by reflection off the basket/frame of the speaker? Has anyone ever ran a CSD plot before and after lining the inside of the frame with felt or other material to reduce the reflection?

Scott