[Mijknarf]

I've been using a Visaton B200/Eminence Alpha 15 combo on an open baffle for a year now.  One area of continuous improvement that I'd like to address is more sparkle on the upper end.  As is often the case... I think I know the direction I want to lead, but never know exactly how to implement.  I would appreciate any advise readers of this post would have.
Background:
1.  Using Visaton full range driven by 2A3 SET amp, no filter componets between amp and driver
2.  Using Eminence Alpha 15 driven bt SS amp with a coil to cut off at ~250Hz
3.  Preamp RCA outputs driving both amps, no crossover
4.  J.River Media Center equalizer used to fine tune





Thoughts:
a) Thinking of trying the Neo3 tweeter?
b) Hook up parallel or series with Visaton?
c) Filter components to use on tweeter?
d) Anything else I need to consider?

Many thanks.
Jim

[versus rider]

I don't know the tweeter you talk about but I have used a 1.5uf cap in series with both the types of tweeter I have to low pass them with good results. Cheap as chips and worth a try, I would run the tweeter parallel with the B200 and try to match the spl of the visaton to the tweeter ( or vice versa )

[rick57]

try the Neo3 tweeter

Zaph Audio found it very good, and it's inherently dipole

[zmyrna]

People say great things about neo3, and the price is great too.
But people who tried it with wideband drivers don't seem to be able to get it blend properly.
They either give up or move up into planar midranges all together.
Some blame the radiation pattern, and others simply the sound character of the two types of drivers.
Tweeters that seem to work well with full/wide range drivers are
a. vintage paper cones
b. controlled directivity drivers, ie horns for under 10k Hz or bullet tweeters for over
c. esoterica such as the Phy-Hp piezo

[el`Ol]

0.68 mH for the B200
3.3 µF 0.22 mH (12 dB LR) for the Neo 3, polarity not reversed.

[Mijknarf]

Many thanks.  I have a starting place to build from.  I'm certainly open to other feedback as well.

[SteveRB]

please keep us posted on your results.

i am interested as well.

[THWO]

Early this year I built an OB system with two Alpha 15A together with an Ciare CH 250:





Soon after finishing I discovered that the treble was the weak part of the setup. Finally I decided to add a tweeter. By eliminating the center conus and placing the tweeter in front of the Ciare I "created" sort of a coax system. However, I placed the tweeter a bit out of center as I beleave this to be advantageous. A second tweeter was simply placed on the back of the baffle.

The Ciare after its surgery:


The original tweeters (Mivoc DT28N):


The front tweeters after chopping off three edges, mounted on an aluminium stripe:


The new "coax" system:


Preparing for the rear mount (tweeters not altered):


Rear tweeters mounted:




Frequency range of the Mivoc DT28N:



The Mivoc is cheap and surprisingly well done. Even with higher levels it does not screem. The combination with the Ciare as now being reduced to a midrange speaker brings the setup to an impressivly higher quality level. Very detailed, yet rich, a big positive surprise at low cost. 

May be an option for your intentions?


Regards,
Till

[jonners]

I also favour the Neo 3, used in dipole mode - i.e. with the back removed.

[scorpion]

Hi Till,

Real nice work, but it is the Monacor DT28N isn't it ?   
I used it in the MJAO speaker with very good result. It can be crossed around 2K without problems.

/Erling

[Mijknarf]

Many thanks for the input Till.  I have yet to make any changes as work has dominated my time of late.  Lots to think about though. 

Jim

[el`Ol]

0.68 mH for the B200
3.3 µF 0.22 mH (12 dB LR) for the Neo 3, polarity not reversed.

This crossover compensates the rising response of the B200 and so isn't ideal for a system with low-power amp and an EQ, becaue it sacrifices the high sensitivity of the B200 from 2 kHz up.

[Mijknarf]

You know... I read a bunch about the shout or rising response in the B200 and I just don't hear it.  Perhaps its my aging ears, or my brain has become acustomed to the effect, not sure.  My B200s are placed higher on the baffle than most I've seen, this, combined with the ~5 degree tip back, points them above my head at my seating position.  This is the location they tested best at during my trials of baffle layout.  Regardless, I probably won't add any filters to the B200 when adding the tweeter as I just want to augment the most upper registers.  I don't know if this is appropriate, but it's what my plan is.

What I have planned so far is:
1.  the efficiency of the tweeter must be better than that of my full ranger (which the Neo3 is)

2.  First order high pass filters would consist of a capacitor in series with the tweeter.  For a 5000 Hz first order high pass filter for a 4 ohm load, C1 = 7.96 µfd.

We'll see what happens (when I have time to get to this).

Jim

[THWO]

Hi Erling,

yepp, you´r right! It is the Monacor DT28N. A bargain...

I originally planned to use this OB project for experimenting, learning and to get more into the theme. And then to return to my slim nice Scan Speaks again...

For about half a year now, these experimental dipoles have been standing in my living room and I still don´t get away from them...


Till

[scorpion]

Yes, once you have heard highbass, midrange and tweeter in full OB
there is no way back. Lowbass is a problem of its own, going lower than 40 Hz,
like I do now with my IB15 basses, I do think OB Bass is the Best.   

/Erling

[THWO]

I agree and think, too, that my Alpha 15As are the weak point in this concept. Especially when you are used to high quality performance, it occurs that there is some "potential for improvement"...
However, as said, for testing and learning this has been a fine project and, overall, I am highly satisfied with the results.

Back to topic - I think the (four) Monacors might meet the requirements without costing too much. It´s charme could be integrating them into a coax with the B200. Precise and stable staging. The Neo 3 seem to enjoy a good reputation, too. However, I can not evaluate how well it may be matched with the B200. And, of course, then no coax-combination.


Regards
Till

[Luigi]

Hi Jim

Tried to reply to your pvte message but computer threw a wobbly so will try here. Sorry for the delay; been overseas and off the grid for a bit.
Yeah, I tried the Neo 3 but it didnt seem to have enough output to my ears; too big of a difference in sensitivity between this and the B200, but the FT17H fostex works better. Just used a cap with this, cannot recall the value offhand, and had it rear firing. It is a cheap and effective fix. Now have gone on to use a minidsp digital crossover, with B and C protweeter in a waveguide and like what this does very much. Also like not having to mess around with caps, coils and the like anymore.