My ''TB3'' mini bipole plans

[Salas]

My 4'' (pure cone area, 5 inch driver) bipole plan ended as the 'CB5'. And its here in this forum for you to see:

CB5 bipole floorstander plans

You have a great, and not overpriced, quad of drivers to make a very good speaker.

But I would advise towards a notch, because I am roughly guessing a hump between 500 Hz and 3 kHz when in bipole.

Like this one I sketched over a single driver of yours FR plot:

[rajiv]

Thanks for your reply, much appreciated. I was wondering how one goes about designing a notch filter for such a system, what values to use and so on. I use a single ended triod tube amp with simple cables. Thanks again for your help.
Raj.

[joensd]

I recall that one got more than positive reviews.
There was a thread about that especial speaker as well.

[Salas]

That enclosure mentioned in the above link is a great plan to build. I would build it if I had those RS (Fostex drivers).

In case you feel like trying a notch, and you dont have a calibratd measuring kit (which is to just put you fast in the ball park anyway, nothing like a final judge), you should equip yourself with 0,1 0,15 0,2 0,25 mH coils, 10uf, 15 uf, 5,6uf caps and 2,7, 3,3 and 4,7 Ohm 10W resistors. Start making combinations. Be patient, listen when calm, and take notes. In a week's time and after a dozen trials since the drivers are slack you would probably end up with a better than raw feed sounding notched bipole.

I cant recommend a simpler method. Effective though.

[planet10]

Originally posted by salas
That enclosure mentioned in the above link is a great plan to build. I would build it if I had those RS (Fostex drivers).

I was probably one of those reviewers... these are tiny, and in Tim's implementation with Pine board seem almost weightless. Quite excellent results.

Here are some clearer plans...

I still have some of those drivers.

dave

[Timn8ter]

If you go to my web page and click on the picture of my original hand drawing it will open another window with Dave's very professional version.
http://www.timn8er.com/bipole_voigt_pipe.htm

[Salas]

Did you ever try some angle towards the listener? Maybe 10 degrees upwards. The drivers seem to be situated at a rather lowish off floor plane. I dont know about this design's dispersion, maybe its better off centre vertically and needs no angle.

[Timn8ter]

That thought is included in my commentary.
The second generation of this design was constructed by Scott D up Canada way in which he moved the forward driver to the slanted side to aim the driver at ear level. He reported very satisfactory results.

[Salas]

I always felt bad about losing sensitivity when fighting TB3's natural presence dip with a notch filter (read higher in the thread).
I decided to experiment with a super tweeter. I also wanted to be innovative so to avoid the typical non seamless feeling that super tweeters impart to full range speakers. I chose Audax TW010F1 that keeps well with the very low cost concept of TB3 and it can be found on http://www.madisound.com/cgi-bin/ind...4.3234&pid=122 on nice price.
I checked many positions over a front to back arc and I concluded that when used on top, at a specific position, it blends very well, boosting the presence range without messing coherency.
Just a cap as a tweeter filter proved inadequate distortionwise because of the Audax's high Fs. I ended up with the filter shown below.
Nothing exists between the bipole Tangband 871s and the amp now. Bingo! More sensitive, more dynamic, more open, more power intake, a brand new TB3!
The super tweeter can be easily fitted to any original TB3. It can be tested by being just attached on top with some Blu Tac. Its centre must be 6.5cm from the front top edge & 8cm to the left and right edges. You can play with R in the super tweeter filter if you feel increasing or decreasing its contribution. In my filter the parallel resistors total 0.77R and it sounds right in my room with my equipment. The TB3 revisited works best when you can see its top from the listening position at a low angle.

[Salas]

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