REL High Level Connection When Used with Class D Amplifiers
The spreading proliferation of Class D amps creates a challenge when connecting a REL subwoofer using our High Level Connection. The proliferations is especially common in home theater systems where amp designers are attracted to compact circuit boards and cool running designs in multi-channel amps.
Why? Don’t they just hook up like usual and you connect the red and yellow leads to the hot binding posts and black to ground?
In a word, “No” and this has nothing to do with REL and everything to do with how most Class D amps are designed. For whatever reason, the vast majority of Class D amps do not reference their Black speaker return terminals to ground, a convention that has been in place pretty much since audio was created.
Instead, most Class D amps reference to 10-15 volts ABOVE ground. Why does this matter? Because REL’s have always used earth ground as their reference point. This is done for safety’s sake. Therefore, connecting a Class D amp to a REL that sinks to ground like most amps for the past 70 years creates; 1) a significant current load resulting in heat and eventual damage to the REL (occasionally the main amp, but usually the REL’s input stage) and 2) since the Class D amp is not referenced to ground, it may create hum.
EASY SOLUTION: Always float the ground on the REL High Level when used with Class D amps. Correct, do NOT connect the Black ground wire on the REL High Level Cable. Wait, won’t it hum? In about 70% of the cases, it won’t as the system is obtaining ground through other connections.
But here’s the trick (and it works for 2-channel systems too, so even if you’re a hair shirt 2-channel guy, you will need to memorize this trick and use it) Connect a .1/LFE cable. Yes, a long RCA-RCA cable connected between an unused RCA connector on the rear panel of the preamp/processor/receiver and the REL’s .1/LFE input RCA will complete signal ground and eliminate hum.
Theater: Now, it’s obvious that you’ll connect a .1/LFE cable for theater anyway so this is no big deal, but it IS CRITICAL that you not connect the Black ground lead to the Black binding post on the rear of your amp otherwise you will create aground loop and quite possibly blow up the planet while you’re at it.
2-Channel: Seriously? I hook up a .1/LFE cable for 2-channel, why? Relax, all we are using the .1/LFE cable for is its ground connection to the signal ground bus that is present on the vast majority of pre-pro’s and receivers. You will not be sending an audio signal through this cable, just think of it is an RCA ground cable. There is one final thing to check for on a 2-channel system; please make sure the REL’s .1/LFE Volume control is turned all the way DOWN. Again, we are not trying to send audio through this so we need to ensure we are not accidentally adding weirdly filtered (for 2-channel) bass to our dedicated High Level Connection.
There you have it, a simple fix for still being able to use the oh-so-cool and amazing sounding REL High Level Connection with all those new Class D amps.
When floating the black wire, please cut the bare wire off and tape the end to insulate it against accidental shorting
Note: You connect your left and right main speakers to the same terminals on your receiver or amplifier as the REL high level connection.
how to connect 2 RELs to a class d stereo amp？
You just connect both the red and yellow wires to the right positive terminal and connect the black to a ground. Then do the same with the red and yellow wires on your other subwoofer, but this time connect it to the left positive terminal and use the black wire for a ground.
You'll find detailed instructions in the link below.
Will this connection work for T / 5i with Pioneer a-70da? And isn't it dangerous for the amplifier?
The Pioneer a-70da is a class D amplifier so you would use this connection method.
Connect the red and yellow wires to the positive speaker terminals but do not connect the black wire to the negative speaker terminal. You can merely put some electrical tape on the bare wire to avoid a short, or if you experience a hum from the subwoofer you can connect the black wire to a chassis ground.
If you have any other questions don't hesitate to reach out.
I have a XTZ A2-300 (https://www.xtzsound.com/product/edge-series) class D amplifier and have recently purchased T/zero subwoofer.
I am sure my amp will fall into this problem and the amp doesn’t provide additional RCA output nor chassis ground. What is my option then?
I have a Yamaha RX-V685 Amp. I believe it's a class D.
Once the subwoofer wires are connected to the front speaker connections as shown in the video - presumably I can then plug the normal speakers into the amp left and right via say banana plugs - in the same holes?
i have two class d monoblocks and two rel t7i. how can i connect one rel to one class d amp?
thx for your help,
I followed the instruction and it worked - the hummning dissapeared. BUT the moment the amp powered off - the sub starts hummning again :( - and doesn't power off itself, eventhough it is in "standby" mode.
J ai le même problème que Peter, post ci dessus: En fait ampli éteint le câble noir du
Rel n est plus connecte a la masse de l ampli,et donc le câble enceinte sur lequel est branche le câble rouge ou jaune du Rel se comporte comme une ligne ouverte!
Une belle antenne qui capte le 50Hz,
Seul remède,diminuer l impedance d entrée du Rel par une résistance en parallèle,de l ordre de 10k,ou bien blinder les câble enceintes...
So I’m running a marantz sr5011 receiver with my Rel amp and Samsung tv. I have just changed my tv to a new Samsung and now have a buzz across all speakers (except the rel).
I have the black wire disconnected and using the Lfe. I can get rid of the hum.
I’ve plugged the LFE into the number2 subwoofer connection and the hum is less.
I’m out of ideas now through.
Do I need to ground the black wire?
The hum is driving me mad. Please help
Not sure why you believe you should float the ground (ie., not connect the black wire) and forego the high level connection of the rel to your receiver. From what I see in looking at the description of the marantz 5011, it doesn’t have a class D amp section, so I don’t believe you should be using this Class D connection method.
Thanks for the reply. I did have the black wire connected but have been getting feedback. I’ve tried everything including disconnecting the wire.
With black wire connected how can I be getting a ground loop from the amp
Sorry, but I have to remind you of my ticket - 50373.
It is about the hum from the T9X sub (connected by Hi-level to the PS Audio S300 amp).
The hum appears when amp is switched off.
I have tried both recommended options (RCA interconnection and chassis ground) but it did not help. I hear the same hum from REL as without them).
I would really appreciate any hint.
Hello. -I have a Rogue Audio Sphinx V3 class D amplifier section that I would like to connect to a pair of REL T9x's. Should I follow the same thing with both REL's? eg. "You just connect both the red and yellow wires to the right positive terminal and connect the black to a ground. Then do the same with the red and yellow wires on your other subwoofer, but this time connect it to the left positive terminal and use the black wire for a ground."
Please let me know - thank you!
I set up my REL T9 with my 2013 Onkyo TX-NR626 as an A/B amp. It seems to be OK. Did I set it up correctly or am I just lucky to not have grounding issues on a Class D? If so I should Float the Black REL wire to protect the REL? FYI the unit weighs 22lbs for a 7ch.
Going to a Denon AVR S760H next month. I'm guessing it is a Class D though I'm not seeing any reference to that or A/D. Do you know what the Denon Amp structure is? The S760 weighs 19lbs for a 7ch.
On a 2021 Cyrus One, how are we connecting a stereo pair of subs? Looking at buying a pair of HT/1003 subs.
Tried this method to connect to a Wyred4Sound stereo amplifier but no audio, just a slight hum. Any advice?
hello i own 3 REL subwoofers 2x t/9x subs for the front L/R speakers and 1 x t/5x for the center channel speaker.. i ordered a class D amp from apollon audio (purifi 7040 model) and i have concerns.. can connecting high level to the speakers biding post on the back of the speakers (leaving the black wire float) damage the class D amp in anyway? the apollon audio who sell the amp are against connecting high level and i dont know what to do.. :(
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