Tuesday, 2 January 2018

TPA3116D2 2.1 - Observations

2.1 Channel TPA3116D2 - Observations - Intro

I have recently purchased a TPA3116D2 from ebay, it is a 2.1 channel variant. So it uses two chips one for stereo and the other for a subwoofer.

Official specs put a single TPA3116D2 amplifier at 100w or 2 x 50w (depending on configuration).

This is wildly optimistic as a power rating, at 20V this board will make about 30W, at 24v it will draw around 40W. Remember this is for Two TPA3116 chips, so if you have a single chip variant you can expect half the wattage!

The sound is still very full and loud, so this amp is no doubt efficient but why even the official specs talk of 50W per channel I do not know.

Do not be swayed for your choice, this amp does give good sound and these days even a 3W per channel amp such as the PAM8403, can sound good.

2.1 Channel TPA3116D2 - My Board (From Ebay)

2.1 Channel TPA3116D2 - Observations - Power Supply Choice

For in depth view of TPA3116 power supplies.

The 2.1 Channel TPA3116D2 apparently will produce 100w output at 21v in to a 4ohm speaker. This would point at a power supply being rated at 5A for a single chip. However you will not need a 5A  power supply because the specs for this amplifier are inaccurate. A 2A power supply for a single chip amp and a 4A supply for a dual chip will likley suffice.

If you are  running the 2.1 Channel TPA3116D2  at lower voltages I have noticed the following:

12V / 2A - A wall adaptor used for power provided clean sound at max volume. The max volume was reasonably low however. This was tested using 6 ohm speakers.

14V / 7A - Using a lithium 12v battery pack with a rated output of 7A (fresh off charge = 14v). This provided more volume but lots of distortion much above 60% volume. Thus used 4ohm speakers for stereo and a large 10" 4 ohm woofer for sub.

Note - If you are planning on using 2 x SLA batteries at 12v a piece be careful. Although these are labelled at 12v, often they will hold 15v when fresh off the charger. So it is possible to accidentally supply your TPA3116D2  with 30v which would not be a good idea.

Choose Voltage Carefully - 22V to 24V to avoid disappointment

2.1 Channel TPA3116D2 - Observations - Output

When running a a 4ohm load at maximum volume, with a 20V 4A supply this amplifier draws 30W. Does this mean that this amp is really 30W RMS? I measured this with a wall socket watt meter.

I was expecting some serious output from this amp. I have used 20W (2x10 @8ohm/12v) PAM8610 which  runs on AA batteries, and running this board at a similar voltage, the PAM8610 wins hands down. The PAM8610 is I would suggest a much more efficient chip (?) although my electrical knowledge  is limited.

To power this amplifier to a level where it begins to shine you will need a 20v supply, have a look at some of your old laptop adaptors! They may be perfect. I do not think you will need a very high amperage adaptor. 4A should be plenty. 

2.1 Channel TPA3116D2 - Observations - My Build

I was expecting a great deal of power from this amp, so I built a very large speaker. I used:

  • 2 x 8 Ohm Tweeters*
  • 2 x 8 Ohm Mid Range* (30W rating)
  • 1 x 4 Ohm Woofer (SPL10m.1) (75W rating)
*These are linked in parallel, to give 4 Ohm load. The tweeters have a high pass crossover in form of capacitor. 

I built these in to a 15mm plywood box, which stands around 60cm tall, and requires handles to lift. Most of the weight comes from the wood and and the SPL10.1 which weighs a few kilos on its own! The midrange speaker has their own enclosure inside, to prevent the woofer from influencing them.

I used a pice of plate steel to to mount the amplifier board, using just the potentiometer bolts to secure it. I then cut an extra hole for a plate with RCA connectors. Lastly after first experiments with batteries I installed a IBM think pad power supply which give 20V 4A Supply.

I used a piece of fabric we had lying about to cover the front of the speaker, as I want a neutral "furniture" type look for the thing.

My most pleasing design choice was the use of a piece of 100mm waste pipe for a bass port, this runs side to side at the top of the enclosure, the opening can be used for hand holds for carrying the the speaker. View a similar TPA3116D build here. 

Or view the below video:

2.1 Channel TPA3116D2 - Observations - Sound and Performance

Powered at 20V with 4 ohm loads the sound is fine for loud personal listening. The range of sound is really great, the low frequency oomph being the most pleasing feature. The bass will travel throughout the entire house and vibrates things of shelves nearby. 

The amplifier is not very loud when listening to bass free music, it reserves 50% of it power just for bass, so listening to say vocal rich music is a little underwhelming, although the sound is very crisp and clear at all volumes. 

The sound quality I would rate as excellent, however a bit more quantity would be nice! Especially as the Texas Instruments specs are nearly 600% out.

Update 19/08/2019

I tried to overcome the sound quantity issue via use of a headphone amplifier as a sort of pre-app (the board already has a pre-app though), which boosted the overall  volume considerably. Whether by increased distortion or power over raring I blew my subwoofer, which was rated at 150W soooo. There are things that can be done to increase output. One idea might be a Bluetooth pre-amp which provides a good input level.

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