My TV sound; an early March weekend project
Copyright 2016 © Troels Gravesen

What do you do on a cold, wet, cloudy and dark early March weekend? Make better TV sound! Definitely something you don't do during summer time. I love my 42" Panasonic TX-P42G10E plasma TV! Unfortunately Panasonic has seized producing plasma screens. I still have to see the cheaper LED screens display better colour fidelity. 42" is the right size for our small living room and viewing distance despite almost considered small by today's standard of 50-65" screens.
Flat screens are trouble when it comes to good sound. As you may have noticed, we can't fool acoustics - at least not much. Due to limited space, producers have to insert tiny speaker drivers into almost no space. Being already more than 6 years old, the Panasonic here is not as skinny as more recent TVs and there are some space for two down-firing rectangular drivers of decent size, but nevertheless, what we hear is reflected midrange and not much more.
First thing to do in removing the rear cover and take the speaker wires to a switch delivering either signal to in-built speakers or external speakers. This way we have both options and it's sooo good demonstrating to visitors what crappy sound they have from their flat screens.
Now, if you don't want to fool around with wires and solder irons, buy a sound-bar to install below the screen. But here we want something more, in fact much more - and for less! Two decent 4" drivers and a small dome comes for almost nothing and the cost of crossover components can be modest too. The SBA alu drivers eventually use here are around 30 EUR/ea. I had the Monacor DT25-N domes on the shelf from former (tube-) TV sound systems and they do very well. The SBA is 4 Ohms SBA12PAC25-4. Actually the Monacor dome is too expensive. Vifa has a similar type at half price, 15 EUR, but probably needs a modified crossover.
I started out with the ScanSpeak 10F8414-G10. If you want it all very simple, these drivers are doing really well and deliver a decent treble, but I felt that given the space available, I could get even more from my 2.5 liter net volume. I could have used the ScanSpeak 12W Discovery as well, but they were not at hand.
PS: No speaker kit will be available for this project and no further instructions will given.
PPS: At MunichHigh-End I told a Panasonic represetative that I had a Panasonic plasma TV and asked if he had anything new that would better, or at least be just as good, as my old plasma screen? "Sorry, no!"

Having installed the switch on the rear panel to allow external speakers I started out using my Discovery 12W speakers. Comparing to the in-built speakers even impressed my wife! But the 12Ws are above size and budget for this project - albeit highly recommended if your budget allows.

As said, I started out with the Discovery 10F drivers. Above and below some images from the workshop.

I had a pair of these SBA 4" SB12PAC25-4 drivers:


Download specs here. Specs for tweeter here.

The shape of the cabinet had to follow the shape of the TV stand.

 
Cabs glued and first coat of lacquer. I also made holes for ports, Ø30 x 70 mm.

 
Left: Tiny crossovers from leftovers and the final drivers. Right: Typical frequency response from flat screen (taken from the web).

 
Schematics and frequency response, the latter not really too bad from a quick'n dirty set-up.

Listening to the two finished speakers from my workshop system really suggest another small mini in a more optimised cabinet and even better crossover components. This 4" alu driver deliver a great mid/upper-mid and transparency as good as it gets. Seriously!

Cabs will be held in place by three 12 mm alu tubes drilled into the stand and cabinets.

 
Cabs were damped with 8 mm felt material. To the right the finished set-up.
Crossover is below the tweeter as far away from the SBA magnet as possible.

What you can hear from the above compared to the in-built speakers is beyond comparison!
The Panasonic manage 10 wpc output, more than enough for the 4 Ohms SBAcoustics.
It's been 6 years since I bought the TV... better late than never.