REL .LFE input

For what it's worth I have a REL Studio 3 paired SF Guarneri Mementos powered by JRDG Model 7's modified by JRDG to Class D.  At the time I set this up REL Support provided me with a "Digital" Neutrik cable.  No hum and great sound.  A couple of years ago had to send in the REL Amp for servicing.  Great support and everything works very well.

@yakbob 

Thank you for the reply. I’ll check it out. 
 

regards 

Ron 

@ronboco , most people seem to be happy with the Signal Cable Speakon cable over others and at a much lower cost than the REL Blue. I’m going in that direction for my 212se.

I apologize for going a little off topic but has anyone compared  the bass line blue cables from REL to the standard cables that come with the sub? Were they noticeably better and worth the cost ? Thank you 

Ron 

Sorry to hear that, wish I could be more help.

I did. No joy. 

Did you try the rca grounding suggestion from REL?  I read that having the sub plugged into the same circuit as the amp can make a difference as well.

Well the wiring checked out to be good. 
 

I had the hum issue on class D monoblocks. I followed RELs procedure for Class D fully differential amp connection and it hummed like crazy. I then connected using both leads (+ and -) and it’s dead quiet. There’s some risk though as REL says not to do that.

I thought the .1 connection had to come specifically from a receiver with.1 output as it bypasses the internal xo in the sub, so you can’t connect from a pre out on a standard preamp to the.1 input. Maybe I misread that part in one of the posts above.

Have you tried this:
 

I just got two T/5x subs and got them set up no issues, that doesn’t help you but the rca trick on the webpage above might.

I don’t know the answer to your Speakon dilemma, but I do believe it is inadvisable to use a Y adapter from stereo pre-out to LFE in, nor would I connect one channel. The correct solution is a buffered summing circuit, but you’re going to have to DIY, if all else fails.

I did check with REL, they gave me the same responses as in the video that was posted above, which I tried, and yet has not worked. I will look at the cable though and the internal wiring and such, that seems like a good place to look. 

Reaching into the cobwebs in my memory here, but,

Doesn't REL have some precautions or special procedures  for accommodating high-level connections on Class D Amplifiers? Perhaps you've been there and done that already.

Your Technics SU-G700 is called Class D by many reviewers, but Technics insists that it is "digital" not Class D.

Anyway, some REL support on this sounds appropriate. 

Good luck to you.

I had a similar issue with my REL T9x. Was emitting a hum at around 60 cycles but only when using the vinyl rig. My connection is also the hi level input. I ended up replacing the wire with a set made for me by bluejeans cables. They do make a custom set that is very nice for the money. Problem went away so there may be credence to checking the cable itself. 

Cheers. 

Also wanted to share this post from a user on audio aficionado, it could be the speakon connector internal wiring:

“I’ve been disappointed with the stock 10m Neutrik cable that came with my REL T-zero sub. It’s a great little sub for a medium/small room, and serves duty in my 2.1 home office setup. The cable originally came mis-wired, but I did not know. It took a lot of troubleshooting to find my initial hum was located at the Neutrik connector. Then it involved a lot of finicky fiddling to get it in the correct position, with the cord laying in the perfect position so the sub would fire but not hum. Eventually I got fed up enough to take the connector apart. There were three wires, and four Phillips head tiny screw clamp connectors for the tinned ends of the wires. I immediately saw it. Wow, that’s the culprit! Loose wiring, especially the yellow wire. There were four possible locations for the wires, and the three wires. I double checked their locations. The yellow wire was almost dangling loose in the wrong place. Flopping around in there. I corrected the wiring, and made sure the connections were snug. I fired up my system, and lo and behold she worked beautifully. I really love this little sub, but I just didn’t trust the cable.”

I did. I tried floating it and connecting it to the grounding lug on the amp. 

@last_lemming , did you try disconnecting the ground from the amp end of your speakon wire while using a single RCA between the sub and amp as outlined here?

Thanks for the responses.
 

The REL only has one input so I can’t do left and right. I do not have any TV components hooked into my integrated it’s just a turntable and a streamer and all of these pieces of equipment plugged into the same outlet onto a dedicated line.

I’ll try just plugging one of the outputs from the integrated into the LFE input and see what happens if the hump persists I’m not sure where to go from there.

Why not just use the left and right low level inputs? Or does your REL not have them?

My understanding is bass around 100hz and under is not stereo. 
 

If you want to be sure just buy a 2 into 1 splitter. LH and RH outputs will be summed into a single plug for your sub. 

In most cases, the hum is caused by having a cable box or satellite dish being grounded at a different point in the house and you trying to feed the audio signal from the tv/monitor to the system.   Disconnect that input on your integrated and see if the hum goes away.  If it does, then the solution is a Jensen Iso-Max. Fix the hum - do not use the low level input.

@last_lemming

Have you consulted with REL regarding hum? The high level speakon connection is the ideal way to connect REL subs. I own a pair of REL’s and they are dead quiet using high level connection from my Integrated. You may have too much gain, try ‘floating’ the yellow wire and connect only red wire to positive binding post. Please make sure to mask the exposed yellow wire with electrical tape before turning on the sub and Integrated. 

My guess is it's up to the mix on each recording.  The bass is often positioned in the center, and that mix has equal bass on both channels,  so you would be fine.  Again, it would depend on the mix.