Mycroft Community Forum

S-Pipe Myford audio engineering

3-1/2" BMR Full-Range Speaker BMR Full-Range Speaker - Tectonic TEBM65C20F-8 $14.39
100WATT CLASS D AUDIO AMPLIFIER BOARD - Wondom TPA3116 $26.90

I actually have a 8 cm (3.3") HiFi fullrange driver on my desk and a cheap TPA3116 China import amp on my desk.
Then I found some info about the above especially with how I intend to mount the speaker.
The speaker sounded good but felt the amp in mid range vocals was lacking sort of harsh sounding but for size extremely loud.
Then I came across something new with what the hell is a Balanced Mode Radiator so after reading it seems so perfect for application and the same cost my curiosity to BMR got the better of me.
That lead to me thinking the amp was woefully cheap even though effective and would get a Sure electronics model than what is a clone.

So I am waiting for the above to be delivered which might take time at the moment.
Which is good because the BMR technology has really thrown me into an area of total unknown, I am no expert but I like my audio gear so had some ideas about speakers but now I just don’t know.
I was basically stealing a design from Google and by finding the Tectonic by accident I realise they use BMR technology and not the conventual cone I first purchased.
I sort of had the rough idea that in a 110mm tube with a cabinet depth of 50mm creates almost 2 litres of volume.

So then crazy ideas of a base reflex spiral came to mind which would add approx 25mm of depth.

Its very possible to get a tuning frequency of 50 Hz with a crazy 300mm port length that a spiral would allow.

So yeah my original idea was very much a guesstimate and a suck it see project but the BMR technology has me in uncharterted waters.
Can you even do a Bass Reflex with BMR and is it even necessary or detrimental?
I will just build it without and add one and give my opinion on tonal quality afterwards but currently haven’t a clue which will win and also any height saving is a bonus.

So I thought I would just kickstart the basic building block of my S-Pipe Myford design.

I am going to concentrate on this post on the amplifier as I am planning on listening to Myford as an occasional internet radio player.
Since I got my first Alexa and currently a new Google Home model I have noticed my audio use has changed.
My stereo has been relegated to home cinema and my decent pair of headphones only get occasional use .

So this brings me to Class D amplifiers and until I started this project my opinion of them was they where pretty crappy at the price point I was looking at.
The better TPA3116 models have definately changed my mind on this but again like Car audio specifications much you have to take with a pinch of salt.

I have gone for a 100watt because it ain’t 100watt by anybody standards and all the Class D kit gear is specced the same.
Firstly the specified rating is driving 2 Ohm with a TDR of 10% on most data sheets.
Go to 4 Ohm and you halve the wattage possibility of the amp but considering 2 Ohm speakers are relatively non existant so enjoy.
So then we are at 50watt but 10% of that is distortion!
So the reality they need to be backed down to approx 30-40watt.

The 30watt RMS, 60watt max of the chosen Tectonic is a pretty good match in right in the ballpark of the casual music player / AI that I intend.
But 100watt rated! What total BS and they are all the same so just beware.

I am presuming my crazy spiral baffle will not render much more bass and even with conventual cones would of been more gimic than effect, but whilst I am playing I might aswell suck it and see.

I have spent a fair old time now googling but there has been a huge emergence of technology for a decade or more where Class D amps, Dacs and freaky sideways speakers you have quite a bit of choice to what you may wish to complete, for a range of pockets.
If you look at the datasheets for the speakers the power response fo -90/90 degrees on the tectonic is best described as freaky as with my concept of audio not sure how it does it?

Its been a while since I needed a Wondom and a first to test a high performance one. For a TPA3116 its pricey but it will give me a reference to some of the cheaper ones I test as really wanted to get into a price range roughly equivalent to the speaker.
There are an array of approx £15 audio modules that are really interesting at the moment even USB DAC boards!
I have been quite surprised that the £10-20 does contain some kit that provides a quality that is exceptionally good value for money.

So I will be giving them a review and is it worth it test.