Why won’t my low latency BT transceivers do LL?

[bluesman]

I just got a pair of BT transceivers with the latest Qualcomm chip for AptX HD and low latency. One’s transmitting 2 channel audio from a TV optical out & the other’s receiving it and feeding a Wadia DAC via optical.  They pair quickly, but the LL light is out on both and the latency is obvious compared to the TV audio.  SQ is excellent.
 

There’s no support at all on line for mine or any other similar HD/LL BT transceivers.  The only thing I can find in all of the manuals and FAQs is that transmitter and receiver must both support the codecs. I have identical units on both ends - so why won’t LL activate?

[bluesman]

Go figure........ today the low latency function works perfectly!  I powered both units down to move them into another room and set them up for wireless MC from the OctoPi, my 6 in - 8 out Raspberry Pi MC project and the subject of the next Value Proposition article.  When I booted and paired them again, low latency was working fine.  I'd paired one with standard Bluetooth speakers before I set up the two transceivers for LL, and I probably didn't power it down long enough before connecting it again.  It sat overnight before I set it up today, which seems to have let it reset.

 

Low latency HD Bluetooth is really good!!!  I just finished watching Get On Up (the movie about James Brown) using this rig to connect the back HT channels, and there's no audible latency at all between the hard wired fronts, the sub, and the BT rears.  It also works fine in a hybrid 5.1 audio system with the fronts and sub hard wired to the RCA outs of the OctoPi and the rears driven by low latency BT (also fed from the RCA outs). 

 

It also works fine for full wireless 4 channel MC using each of the BT transceivers to drive a pair of regular latency BT speakers (in this case, Edifier R1280DBs).  The latency is the same on all channels using identical BT transmitters and speakers with similar distances between them and no sources of physical or electrical interference.  And the latency's not audible because the entire system is delayed by the same amount.  I'm looking for good inexpensive LL BT speakers, but there aren't many on the market yet.

 

I've been acquiring and evaluating a few different types of HD / low latency BT transceivers for this project and an upcoming piece on the versatility of wireless.  The unit that prompted this question is the Rainyb, which is $42 and (now that I know it works) well worth it!

 

[The Computer Audiophile]

The first thing that comes to mind is distance and the second is interference. Can you temporarily place them a foot apart and run the same test?

[bluesman]

45 minutes ago, The Computer Audiophile said:

The first thing that comes to mind is distance and the second is interference. Can you temporarily place them a foot apart and run the same test?

Did that when I first unpacked & paired them.  They’re only 15 feet apart now and have direct line of sight - and there’s no other transmitting device in the living room. The network center (gateway, router, switches, NAS, etc) is in a different room.  And these BT units function perfectly except for the low latency feature.

 

Everything I read says that the “devices” at both ends must support the same codec.  I took this to mean the transmitter & receiver, which is why I bought two identical units. Now I wonder if this means that I have to pair with a BT device (‘phones, speaker) with integral AptX LL capability.  If I can’t figure this out by Monday, I’ll return these.