Alright - where even to begin? I've been an enthusiastic Edifier products user over the past two years, currently owning 5 different models of their powered bookshelf speakers. As of late, I've been eyeing compact subwoofers in the 8" range that I could add to my particular system to enhance the lower bass response. I am (was) particularly searching out inexpensive, yet competent 8" subwoofers to place under my computer desk since that's where I have my active bookshelf speakers positioned.
Now to be fair, there are several outstanding (other brand) 8" active subwoofer models on the market, but those models are priced higher - usually between $299 and $499 - and as I discovered, you tend to get what you pay for in most cases!
There is just 1 review on You Tube of the Edifier T5, and that one was done by Zeos Pantera, who I enjoy watching for a number of reasons. So I took a chance and ordered the Edifier T5 on Amazon. My reasoning in choosing the T5 (initially) is that I had previously also owned the Edifier S350DB 2.1 system and the T5 is basically the same woofer as in that system (albeit configured differently).
OK - so the T5 arrived - it looks great and definitely has a nice, weighty (and solid) feel to it (which is good). In the rear you have both RCA inputs and outputs (as opposed to many subwoofers that have only RCA inputs) - which was very important to me, but I soon came to realize that I had misconceptions about that aspect of the T5. In addition, it has one of the smallest (if not the smallest) enclosure that I've seen on 8" subwoofers.
You see, in the "other" more expensive subwoofers I alluded to above, they also offer both RCA inputs and outputs - but (and this is a huge "but"), in those cases you could use any powered speaker, run the music source cables (like from a Preamp or DAC) to those subwoofers, and then use additional cables attached to the "output"connectors of the subwoofer to run to the RCA inputs on your powered speakers. What occurs in "those" (a bit more expensive) subwoofers is that you can then choose a select crossover frequency (usually, 60, 80, or 100 Hz) to filter out the bass - meaning, that anything below those frequencies (you choose one) would be handled by the subwoofer, whereas all the frequencies above would be channeled to your speakers. This obviously takes the pressure off the 4", 5", or 6" woofer/midrange drivers in various bookshelf speakers and allows them to effortlessly focus on mid-bass and midrange frequencies.
The Edifier T5 subwoofer, however, does "NOT" filter frequencies like the more expensive versions do (i.e. Emotiva and Presonus). With the T5, the RCA inputs and outputs are just for pass-through (nothing is filtered or channeled between subwoofer and speakers). So in effect, if you try and connect your T5 to your active speakers this way, all you are doing is reinforcing (amplifying) the lower frequencies that your active powered speakers are trying to handle also. Now do note that the T5's do have a knob ranging from 50-60 HZ t0 160 HZ and if you set this to a desired low frequency cutoff, what this means is that the subwoofer will only reproduce the low frequences below the cut-off you select. However, again - the full frequency response is still channeled to your main active speakers. So choose your low frequency cutoff wisely here so you don't double-up or reinforce low frequencies that your active speakers already product.
Alright, so how did I use the T5? After trying the method above - and after I came to find out that no filtering takes place and the signal is just a straight pass through - I connected my Edifier R1850DB's bookshelf speakers using the dedicated 3.5MM subwoofer output on the rear of those speakers. I used a 3.5 MM to RCA Male set of cables, connecting to the T5. Now on the rear of the T5 is a knob showing bass frequency filter settings ranging from 50 to 160 HZ. I set this to between 70 and 80 HZ (everything in between the 50 to 160 Hz area are not marked specifically - there are just a bunch of notches, leaving you to try and decipher what is what). Remember, you get what you pay for here.
Well, so how does it perform? This T5 does best as an under-the-desk unit, connected to desktop speakers - let's say in a desktop computer scenario. I first tried the T5 in the living room and to be honest, it did not have the impact one would expect when watching dynamic movie scenes, and at times you'll hear "chuffing" coming from the port. However, when I transferred it upstairs to under my computer desk - attached to my Edifier R1850's - the combination provided a fairly nice balance (once I settled on the right frequency range for the T5 to handle).
Now here is a question that nobody has been able to provide an answer to this date. To begin with, since the T5 is an Edifier product, let's arbitrarily use the Edifier R1850DB's as the bookshelf speakers for the purpose of this particular question (since they have a subwoofer output connection in the rear of the active speaker). When connecting the 1850's to the likes of the T5, do the active speakers automatically "recognize" the subwoofer and then send low frequencies (below a certain point - and what is that particular frequency?) to the subwoofer? Or, does the subwoofer handle just a certain frequency range (below 160 Hz), thereby just reinforcing the same or similar frequencies that the speakers are handling? No one could ever answer this and I've asked this a million times on various forums. Edifier was remiss in not providing this information with the T5. It would most certainly be nice to know that a speaker will automatically recognize the subwoofer (when connected) to a model that has a subwoofer output on the rear of the desktop model. And furthermore, it would be nice to know that when recognized, what frequency do the bookshelf speakers automatically select to filter to the subwoofer?
Sound quality-wise, do keep in mind that we're dealing with an 8" woofer here - nothing revolutionary. It can certainly add bass, but I must confess that the quality of this bass and extension is limited to around 38 hz. I also have a 10" subwoofer by a well known audiophile brand (with RCA inputs and outputs that provide low frequency filtering and channeling) and the quality of bass from that unit is phenomenal and well balanced with any bookshelf speakers you add.
So in the end, for a super budget 8" subwoofer model, the T5 is a quality product - but then you do get what you pay for and for around $130 USD, there isn't anything revolutionary about it. You may be asking, "well, why not then just use the 10" subwoofer you also own?" Quite simple - it's much too large and my knee hits it every time I go to sit down by my computer. Thus my search for a smaller 8" model.
I'll be keeping the T5 because I believe it does quite well from 40Hz on up and at $130, it is an ideal match for many of the powered Edifier speakers. I do intend to getting one of those "other brand" 8" subwoofers (either a Emotiva or Presonus) that features an actual crossover filter that channels anything above the selected low frequency cross-over point on the subwoofer to the active bookshelf speakers..
In the end, how we use our audio products becomes subjective and no two folks will agree. If you're looking for a serious low-frequency contender in the compact 8" subwoofer arena, the T5 just may do - but for others, it may not provide what you are looking for in terms of general low bass reinforcement - but at least you won't be paying an arm and leg. I'm currently actively using it - it does the trick - but I do know there may be better choices out there if you are willing to spend a few hundred dollars more.
I did edit this review to update my assigning it 4 stars now (up from 3). And I am currently using the wonderful PreSonus Eris E5 XT 5.25" Near Field Studio Monitors. Using the Edifier T5 with these monitors provides a nice balance and I've been quite happy with this match-up.
There is atleast 60% more cables tucked and tied underneath.. 
