My journey into the world of Bluetooth transmitters begins
Awhile back I finally decided to invest in a wireless gaming mouse, ditching my hardcore dedication to cable that started years ago during my competitive gaming years. Finding no noticeable difference in input lag with Logitech's G Pro Wireless, I finally got around to replacing my Turtlebeach Elite Pro T.A.C., a mixer I use with headphones in place of speakers in my AV receiver setup (I only have monitors, not a TV and I have high-end headphones so why not use them for everything.)
My research brought me to Avantree's Oasis Plus after trying out other Chinese knock-offs that were plagued with poor shielding, Bluetooth quality, range, etc. Avantree seemed like a reputable brand that had been in the audio transmitter space for awhile. They also lay claim to a unique feature, the ability to simultaneously output Bluetooth & wired audio, which is actually true as they are the only device on the market to have this feature for some odd reason. Another unique feature seems to be voice prompts which increases the premium Avantree charges for their device.
Specification
* Bluetooth version: 4.2 *Support profiles: A2DP, AVRCP *Audio codec: aptX-HD, aptX-LL, FastStream, aptX, SBC *Operational range: Class I, up to 50 meters *Input voltage/ current: DC 5V/ 500mA *Operating temperature: -10 ℃ ~ 45 ℃ *Storage temperature: -20 ℃ ~ 60 ℃ *Support sampling rate in optical mode：≤48KHz *Support audio in optical mode: PCM / LPCM (Set your TV audio as PCM/LPCM format) *Product size: 4.49’’* 2.95’’* 1.18’’ (114×75×30MM) *Product weight: 0.20lb (90g)
"The Oasis seems to be built around keeping a Bluetooth device always connected when in Bluetooth + Passive mode as when there isn't a Bluetooth device connected you run into numerous issues."
In terms of specifications it has aptX-HD which means very good sound quality. One feature it lacks that it's competition has is a battery although I can understand why they'd be hesitant to include one as batteries can increase the interference and raise the price even more. At a price of $80 ($70 on Amazon) it still is a good deal. You're getting aptX-HD for 24 bit audio quality, Class 1 version 4.2 Bluetooth (which means it should have serious range) in a tiny package (its about the size of your palm and only 1/5 of a pound.)
The Oasis Plus seems to be built around keeping a Bluetooth device always connected when in Bluetooth + Passive mode as when there isn't a Bluetooth device connected you run into numerous issues. The first of which is when using the bypass + Bluetooth mode there is an electrical hum that lasts 7 seconds then silences for 13 seconds before it starts the hum for 7 seconds again. It goes on forever. This happens if there is no Bluetooth device connected it seems so it must be a hum from the wireless chipset doing a scan for devices. Another issue is that the built-in speaker which is only meant for the voice prompts starts acting as a normal speaker if no Bluetooth device is connected. I noticed what seemed like whispers coming from somewhere in my apartment and found out it was the Oasis Plus. It was playing the audio from my cable TV through it's internal speaker, but at a very low and uncontrollable volume which is obviously a design issue. Once I connected a Bluetooth device to the transmitter the issues stopped.
A few suggestions for the next version of this device:
Make it portable (add a battery)
Add support for Bluetooth 5.0 & LDAC (32 bit audio quality if possible)
Add microphone aux support or add a microphone to the device itself - I would love to be able to route my PC's sound card through here, but it's useless without mic support It would also be nice to be able to connect a phone and take calls.
Better shielding - There's an electrical buzz when running straight 3.5mm from my PC's headphone (just headphone, not a dual line in/microphone port) port to the Oasis transmitter. I don't have this problem when connecting headphones directly to the PC or even when outputting to other mixer devices.
Better sound quality through 3.5mm ports - There is a major difference in quality when using 3.5mm directly on the source device and when going through the 3.5mm port on the transmitter. When going through the transmitter the sound quality drops significantly and is also noticeably muffled.
Better audio detection - As it is now, there doesn't seem to be a signal sent to let connected devices know there's no audio coming through, as a result when I'm using a Bluetooth headphone DAC receiver there's major trouble switching audio between the Oasis transmitter and something like my phone on it because the Oasis is "always transmitting" even when there's no sound. This frequently results in my Bluetooth headphone receiver not switching over if I start playing audio on my phone. Even if I mute things or turn off the TV its no go for switching audio most of the time.
Better range - You're getting nowhere near the advertised "295 feet." At most I've gotten 30 feet which is normal for Bluetooth. In terms of line of sight, the moment I walked past something like a TV or monitor that blocked line of sight, the audio would drop or click.
Overall Avantree still has a ways to go with this device. This means there still isn't a proper Bluetooth transmitter on the market after all these years. The design issues means it truly allows simultaneous use of Bluetooth & bypass as once in that mode you can ONLY use both of them at once otherwise you run into issues. It needs better shielding as well as a built-in amp + DAC on the wired end for truly HD audio quality as the audio quality on the bypass end is sub-par. Hopefully with the next iteration they'll fix all of these issues as having the ability to just keep it in one mode and use devices at will while having true HD sound would be a godsend.
*I reached out to Avantree and they gave me a list of the upcoming Bluetooth 5.0 updated devices & the Oasis is not on the list.
3 out of 5 stars
You can find Avantree's Oasis Plus here
Update 04/09/2019:
Avantree has updated their upcoming Bluetooth 5.0 product list page since this review was published and now lists a new Bluetooth 5.0 transmitter/receiver. The model is BTTC-580-BLK & this looks to be the successor to the standard Oasis as it doesn't have apt-X HD listed as a supported codec (the model for the Oasis is also BTTC-500-W while the Plus, BTTC-500P-GRY, has a noted "P" in front of it's generation number.) There seems to be a complete redesign and a possible attempt to be an "Amazon Echo" replacement. Also of note is that it looks as though they've taken some of my suggestions and implemented them into the new device such as a microphone as well as Bluetooth 5.0. There also is going to be Dolby/DTS support and an LCD screen.
Update 03/04/2021:
Avantree released their Bluetooth 5.0 line in 2020. The previous thought of successor to the Oasis Plus is simply a transmitter with a microphone. It doesn't look to work with Alexa at all, but you can use the microphone to control your TV & take calls. It also lacks AptX-HD audio which is confusing. It also lacks features initially flouted such as Dolby/DTS signal support & the higher quality LCD glossy LCD screen.
The new Bluetooth 5.0 Oasis Plus is simply an updated description, nothing more. It is the exact same, but as most companies nowadays they seeming mislead by using Bluetooth 5.0's backwards compatibility as a way to list an older Bluetooth 4.0 product as 5.0 when it is NOT just like they did with 1, 2 & 3.0 products when 4.0 was released.
thanks for the good review, its nice to hear of the issues these type of BT receivers and transmitters can get. Its a weird market no one has really done a decent up to date BT 5.3 transmitter/receiver device although the fioo btr3 pro came close but suffers a nasty audio cut off issue where the sound goes into a sleep mode during a silent scene in a film/tv show which can't be fixed by fiio.
I believe this maybe why avantree has the hiss issue its needed to work around this "sleep" bug/problem.
I am still on the look for a decent BT box which can pass optical into aptx adaptive but its looking like the oasis/plus are still…
I just got an email back from Avantree. It's in spanish so it's not an exact translation :) They said that the preordering of the Oasis BT5.0 has been put on hold awaiting feedback from the first customers before making at available again. If feedback is positive it will be available in a few months, if not they will need to fix it up first to assure quality.
Weird.
Well, at least I know I didn't dream about it :)
Yes unfortunately it looks like they pulled the pages on some of the new products & the links they originally sent me now just redirect to the product support page. The new Bluetooth 5.0 transmitter shown in the review is completely gone as well. Hopefully they figure things out as a proper Bluetooth 5.0 transmitter that uses the LDAC codec is in high demand for this market.
I could swear I saw a new Oasis Plus *Premium* listed on their website for a while back in june/july. When I tried to find it again in august it was gone. I even recovered the link to it from my browsing history but now it just shows a 404 not found. I remember it was a BT5.0 device and they already offered preorders. It's not the above BTTC-580-BLK as it had the classic Oasis design. I wonder what happened... Btw, this was the link: https://avantree.com/category-bluetooth-speaker-adapter-21/long-range-bluetooth-transmitter-and-receiver-avantree-oasis-plus-premium-version.html/?SID=f6548bb8b8f83869af91fddd94b5de17