Subwoofer cable question

I want to run a Rel sub from my integrated amps "pre out" and the sub has only 1 "low level" and  the "lfe" input. Do I need an adapter from stereo to mono or do the low level and lfe inputs on the sub act together as left and right input?


Do as the REL recommends.

Use speaker taps with the supplied cable. Simple

+1 tablejockey.

The REL sub should have 'high level input'?

If so this is the best way to go.  Use the supplied high level cable with Speakon or Neutrik connector that mates with the high level input.  The wires go to the speaker outputs on hte amp (integrated amp) as described in the manual.  This way sounds best.

always better to connect rel subs to your amplifier high level outputs for better sound, all rel's since the early 90's have a high level connection


All subs are mono. That's just life below 80.

Stereo subs make a difference?
Answer: It depends. 
This answer can be found in multiple places. Here’s one.

"While low frequencies are less directional, and the direction of a low-frequency sine-wave point-source may be less perceptible, critical to fine music reproduction are low-frequency interchannel phase differences present in true stereo recordings. When reproduced properly with stereo subwoofers (or two full-range speakers), these phase differences are critical to reproducing the sound space of the original concert hall.

Critical even to casual listeners is that if you sum the low frequencies of true stereo recordings into mono by using only one subwoofer, low-frequency interchannel phase differences partially or completely cancel each other, reducing or eliminating low-frequency output levels!

Try jamming a stereo bass signal through one mono subwoofer and you lose a lot of hall ambience as well as bass level.

True stereo recordings are usually classical and other proper acoustic recordings made with pairs of microphones. Most "stereo" pop and jazz recordings are really just multi-miked mono, with each mono mic "panned" someplace between left and right. Pop recordings rarely have low-frequency interchannel phase differences, although they usually have bass information panned one way or another that also should be reproduced through stereo subwoofers if you demand the most accurate reproduction.

Putting the math aside, the best way to demonstrate this is to swap between one and two subwoofers with a real stereo recording, and it will be obvious."

I don't have the sub yet so I didn't know about the included high level cable. So this cable connects to speaker taps on the amp and the other end to sub? Then normal speaker cables go from high level out on sub to main speakers?

Hide45 I can't afford stereo subs at this point. Maybe in the future if "the boss" agrees. 

Here is the facts if you really want to know. There is a left and right channel for a reason. The RECORDING has a left and right BASS TRACK. If you use only a left or only a right from your source as the signal to your subs, HALF of the BASS track is NOT THERE to listen to.

Below 80hz the waves are so long separation is impossible, BUT you still have to play BOTH left and right to get the entire recorded piece. Unless it’s recorded in MONO and mirrors the bass track to both left AND the right, you had better use both left and right source signals IF you want to hear the WHOLE recording.

LFE is a combo of left and right bass tracks with a step baffel bump of +3-10db at 40hz and below.. AT THE SOURCE, not the plate amp.. LFE to LFE works great in HT more so.. Bombs exploding and really loud FARTS..

I say KNOW your equipment first, before using only HALF the signal that’s supplied to your subs as a signal.. It’s not only important to use left and right it’s important to know WHY!!!

With great respect and Regards, your welcome..


Then normal speaker cables go from high level out on sub to main speakers?

No. You leave the main speakers connected to the amp and piggy back the subwoofer cables from the same connections There should be a red, yellow, black wires. Red to one channel + Yellow to the other channel +. Then black to either ground. There is a Neutrik end which attacvhes to the subs high level



Artemus_5 thanks that clears up how the rep works. 

There is a difference in the type of amp that drives the mains too. You wire thing different so you don't hurt the REL amp too.. I think it's class Ds or no third prong on the PC.. I was just reading it a couple weeks back..



Even now after years of clarification still we have members sharing misinformation. Please do a search and read through all the excellent factual information provided by myself, Tim, Duke and of course the research papers by Geddes, et al. These all make perfectly clear the fact sub bass is not directional, there is no "ambience", it is not stereo, and the one sure way to better bass is not to have a bigger more powerful sub but to have it coming from more locations.

If you rely on comments at least filter them to eliminate the ones who don't know, because they never actually did this stuff. For example, I know subs are mono from having run multiple subs every way imaginable. Stereo, mono, L channel, R channel, one, four, five, in phase out of phase all kinds of phase, on and on. Every time you see someone talking about stereo bass, timing, anything like that, do not take it at face value. Dig deep to see where that is coming from. Almost always it is repeating what someone else said, without ever once trying to see if it is true or not.

Do your own due diligence, please.

Yes I think certain amps (? class D) you run Red to Right + speaker output, Yellow to L + Speaker output and Black to CHASSIS GROUND (a screw in metal on the rear).  This is if you get hum doing it the other way.  

Think I'm getting confused again🤨

All vinyl is cut mono-ed below 60Hz so there is 0 difference for LPs and not noticeble for dgital tracks.

Much ado over nuttin’.

Experience in running stereo subs can

be chalkedp up to ignorance.

It’s NOT stereo subs if both left and right signals are used in reproduction.. There is a BIG difference.. Wording count’s.. Stereo is greater than the sum of its parts, there are THREE distinct channels, left right and phantom center from TWO channels.. This isn't hard to understand..

IF you ran all your subs off just the right channel do you think all of the bass track on the source recording will be reproduced?

The only question that needs to be answered. A buddy a musician that is has a nice little recording studio in his home in Shelton WA. Can show anyone that wants the two different, but complete tracks, it takes to make up a single bass track..

Simply put, Bass guitar on the left and drums on the right, what do you think it would sound like if you only used the right channel?

BTW he is a serious bass player and stringed guy period. From a harp to a piano. He can explain the recording process pretty clearly.

I KNOW people are mixing mains that have a full signal with systems like mine that don’t pass a bass signals through their monitors, I use separate enclosures..

Same with my servo plates, hook up a single RCA to either plate and you will leave out 1/2 the signal. Very EASY to hear on my rigs..

Directionality or the fact subs can’t produce a center bass phantom tells you something. There is no separation from left to right, it is not reproduced in stereo it is reproducing TWO separate tracks to complete the actual way it was produced.

HOW SUBS are hooked up is REAL important in MY system, I have no idea what anyone else does.. if 1/2 the signal makes you happy.. By all means hook up your subs any way you like.. LOL

Yup fastfreight it’s pretty important too. REL say is will hurt their amp, NOT YOURS, I would question that one..:-) I don’t want to hurt anything.. It’s MINE after I pay for it.. LOL


Since 99% of bass guitar or drums is above true sub frequencies no worries.

By all means you should feed both channels summed to the subwoofers.

After that it does not matter.

OK a kettle drum, and a double bass, how is that...:-)

I understand SUB means below the threashold of normal hearing and goes to the FEELING senses. But 40 hz and up I can hear and feel and up to 250hz. It is still bass.

From 80 to 300 is VERY directional.. The exact reason I split hairs and cabinets. Subs are subs. Midbass is midbass and everything else above that is in it’s own enclosure too and for a good reason, vibration and timing.

You cannot put BASS and mids and highs in the same cabinet without digital correction.. I quit that silly idea 25 years ago, because distortion and cabinet resonance issues. BASS cabinets are different than mid cabints that are different than a Highs cabinet.. They even use different dampening materials (stuffing) and cabinet material are treated with different products.

Rubber line is best for resonance while LOW RES is best for dapening..

It’s funny when you make speaker you understand speakers, I thought the mechanics of it were pretty easy to understand.. I guess not for everybody..:-)

My set up looks a little weird, but bring one bring ALL your Mics and measure, it will blow your mind the super low distortion and clarity of sound.. Under 5% distortion 25 years ago when I went from bottom firing subs, and inner tube decoupling all the bass enclosures.

I got a new one coming up first one in 10 years. First standmount I’ve done.. Planars and Ribbons. Maybe by spring... How long did it take Noah to build the boat fellas? Just askin’


With any REL being used in a 2 channel system, the best results are with the supplied REL neutrix cable. This allows the subwoofer to receive & mirror exactly the same signal that the speakers are getting. This allows the REL subwoofer to  blend perfectly with the main speakers. The RCA's are for 5.1 or greater home theater use allowing the LFE channel to be mixed more accurately with movie use. The end result is achieve the perfect 2 channel playback without  sacrificing LFE playback for movies. At the end of the REL cable, there 3 leads & depending on the type of amp, there are a couple of configurations. I would strongly suggest contacting REL customer support for the right configuration. I have sold RELs and currently own 3 vintage ones on 3 different systems & they are connected differently per REL's recomendation.

I want to run a Rel sub from my integrated amps "pre out" and the sub has only 1 "low level" and the "lfe" input. Do I need an adapter from stereo to mono or do the low level and lfe inputs on the sub act together as left and right input?

My suggestion is connect the left and right pre-out from your integrated amplifier to the input of a stereo to mono converter, and connect one of the mono output from the stereo to mono converter to the low level input on the subwoofer.

The LFE input on the subwoofer bypassed the internal low pass crossover, it is only useful for AVR/processor LFE or low-pass sub-out connection and not suitable for integrated amplifier’s pre-out.

I hope this answers your questions.


IF you ran all your subs off just the right channel do you think all of the bass track on the source recording will be reproduced?

Below 80 Hz, yes. The recording studio examples you are talking about is different. Drums, bass, etc have lots of output above 80Hz. This higher frequency output is what determines stereo L and R and gives us imaging. Below 80Hz simply does not do that. It is not a question of how it was recorded. That doesn’t even enter into it. Because the waves are so long, when playing back it no longer matters.

The proof of that is while you can hear a difference in the recording studio you cannot with just the subs at home. I have run them every which way just to prove this to myself. Also a lot of subs that have L and R channel inputs, if you look at the circuit diagram they are summed inside. L and R are there for convience.

Can’t say as I blame them. If the cost is an extra irrelevant RCA connector vs answering this same question a hundred times a day till the heat death of the universe I would throw in the RCA too.

Thus, clearly, the device above is useless, unnecessary, superfluous, and ill-advised.

I would buy another sub as 2 subs are easier to integrate into your room. Otherwise, +1 imhififan has the best answer. In my opinion all subs I've tried sound better when driving through the low-level inputs.

Also a lot of subs that have L and R channel inputs, if you look at the circuit diagram they are summed inside. L and R are there for convience.

NO! If your main speakers are small monitors and started roll off at higher than 80Hz , if you connect only one channel to the subwoofer, you will loss some information from the other channel even the recording below 80Hz is mono!

A lot of bassist use stereo basses. Bridge or rear for tight,clean tone. Neck or front for depth. We also use stereo chorus effects, sound processers blending triple sub octives and octive up effects, stereo delay and on and on. They are not recorded in mono! Listen to Chris Squires bass on 'Yours Is No Discrace' sweeping left to right. This isn't your daddy's bass.Maybe your  set up or room is smearing the bass, but stereo bass exists. Sorry for the rant.


I don’t have the sub yet so I didn’t know about the included high level cable. So this cable connects to speaker taps on the amp and the other end to sub? Then normal speaker cables go from high level out on sub to main speakers?

Richard Edmund Lord (REL) originally designed his powered "Sub Bass System" to accommodate systems that lacked any preamplifier outputs and using tiny speakers with limited low frequency output. Hence the high or speaker level connectivity to the amplifiers speaker outputs.

There are many other subwoofer brands that offer high level connectivity as an option yet suggest using the more direct to the source low level (RCA / XLR) connection of the preamp outs as do professional and commercial installations.

I would never recommend one unless the only option was no sub at all. Do some more homework.

 I agree that sub freq are not locatable so it would seem that one output  might work.  But if there are two identical "low" signals in the outputs or as suggested, they are kept different for stereo,  wouldn't it still be true that half of the voltage output (spl) is missing if only one rca is used?  Hence a stereo to mono or Y adapter might be advised?  To those who say that you'll lose stereo info I have to think that the total effect is there this way anyway but as mono.  Which if below about 80 is how we'd perceive it anyway.  If you hear differences from L to R its prob above 80 in your mains.

OP, no the speakers aren't daisy chained after the sub in the REL hi power set up.  Their preferred connection is to run the leads back to the same speaker taps used for the mains. The amp isn't supposed to "see" the additional load.  Go to REL website and download the User Manual.

The REL Acoustics site has several "how to connect my subwoofer" videos.

The instructions vary for different amps (class A/B vs. class D) and set-up scenarios (active speakers vs passive speakers, TV, soundbars).




Just follow REL's directions and see how you like it with one sub.  Your results are largely room and placement-dependent, so pay attention to the placement and setting recommendations in REL's (and other) YouTube videos on the subject.  Ignore the diatribe about multiple subs, the need for a mono summer, etc. until you've properly set up your one sub.  You'll likely be very satisfied with the result and can ignore the rest.

YUP if you produce it you know it.. It’s how the information is recorded. This just ain’t rocket science. There is left and right information on the mediun down to 2hz for all I care. The FACT is, it is recorded different and mixed different than a single mono left or right RCA or XLR is providing in a playback system.

With Daytons DSP or their 1000 watt plate amps they are summed, but just hook up the left or the right not both RCA/XLRs 1/2 the signal goes away, On my daytons anyways..

As far as listening, listen to Stanly Clark.. or my buddy Kenny Bassett.

sub/bass Mono playback my A$$.

Like I tell people DBA and Swarm is a low cost solution to good bass. BUT it’s STILL not THE best. A 7.5 is about the best I’ve heard.. Servo bass column arrays are 10s, they are that much better.. I’ve have a 3rd too, OB servo arrays, Better than MY DBAs anyways..

I used 4 tall boys 12,15, with a 15" passive.. They were powerful passive subs with 4 1000 watt daytons bass amps in the 1980s and 90s. NOT 2020.

You adjust the weight on the passive with putty for the room.. Mechanical Q (uality) old school.. Learn how to add bass and subs to your room without DSP other than a PEQ LOL I had a guy teach me.. Brian Cheney of VMPS, I never met a guy like him.. HE sure knew BASS.. THE 90s fellas they didn’t even call it DBA or Swarm back then.

BTW it still wasn’t as accurate as Infinitys’ STEREO servo bass columns on an AIR BAG decoupling system.. 90s fellas.. I'm not Granpa Bass BUT darn close..:-)

Again Mono my A$$.. The results is mono, the source signal is stereo.. plain and simple.

Even my midbass columns 100-300hz IMAGE a center phantom speaker.

Think about that one..


Thanks guys for all the info. I can't afford 2 subs at this time. I was really just trying to find out how rel subs are connected. I understand that now and will try the default setup and see how it goes. If I reach a point where I can afford a second sub I will revisit this issue but for now there is no point. Opinions on REL vs SVS?

"Think I'm getting confused again"

If you chose REL, the instructions suggest using the suppied cable as instructed-speaker taps.

"Opinions on REL vs SVS?" Go back to being confused, if you're hoping for a definitve answer here. Both will be fine, but that's just my opinion.



Don't confuse the LFE with the .1/LFE. One is for low level 2 channel connection and the other is for home theater. I didn't have much success using the Neutrik Speakon connection; mine sound better with the low level RCA connection.

Guys. The question was how to cooect a Rel sub. It doesn’t deserve a treatise on the inner working of the bass signal. It’s not necessarily wrong. But the op has noted, it is confusing.

On a positive note, it wasn't snarky or mean spirited. So thanks


Guys. The question was how to cooect a Rel sub. It doesn’t deserve a treatise on the inner working of the bass signal.

exactly - it's about helping the op, not about geezers boosting their self esteem... let’s just help the poster OK?

Thanks for all the suggestions. I think I will look for an affordable rel and use the speakon cable as it saves me the cost of buying a relatively long ic cable and seams simple and straightforward. 

Good choice  @emiliop  You'll wonder why you waited so long after getting it set up.

Also, if you haven't seen this  thread, maybe you should. might give you some tips


Thanks. But Don't be too hard on us geezers. But FWIW, by the time you get to be a geezer, self esteem is usually way down the list of priorities. AAMOF, some shed the need completely after a lifetime of assault on our self esteem.



i actually consider myself a geezer... am over 60 now! hard to fathom...

have a great thanksgiving!!

SVS is a great sub.. A lot better design.. Go for it.. front ports or IB (no port).

Better choice for sure..


oldhvymec +1

Or any other brand than the one you settling for. Read their two paragraph installation instructions. Essentially, place the sub in a corner which is usually the worst location for most rooms. Then reduce the volume until the sub doesn't draw attention to itself. (Said with great sarcasm) It's simple all right.

For perfectly acceptable and reasonably priced custom length interconnects go to Blue Jeans Cable or Monoprice cable. 

The right subwoofer system will last longer than all your other audio upgrades. Well, unless low frequency becomes interactive and too much fun.

REL is very clear on thier instuctions on hooking up the Sub.  Cable is included.  They also have excellent tutorial videos.  Just go to thier web site.  

High level sub inputs are there only because the majority of customers do not have the abilty to run low level inputs and do not want to afford an appropriate cross over. They are the poor man's way of running subwoofers. To do it correctly your preamp should be connected to a two way crossover which then runs to amps and subwoofers. 

@emiliop , you can get a "y" connector to "mono" your signal for the sub. 

OP what kind of integrated are you running? There might be another way. I'm no expert but what are you working with?

I run a ZPre 3 in a tape loop on a C20 or MX110z. It adds a Remote for me, a fixed frequency Sub out for a passive sub and line level RCA for sub or main speakers..
I use it for subs only. The C20 or MX110z runs the main speakers via a MC225,240,275.

I paid 300.00 for it I think.. The use of a second preamp use to be pretty common.

Remember though there is a LOT of gain. You better have pretty good routing skills too. LOL Noise can be an issue because of the gain. Mine is still VERY quiet behind routing primarily.

Over the last couple of years, WEAVES and ribbons and very little use of shielding has netted me some fairly low dollar (cost wise) but high quality results in cables.. Really HIGH quality.. To the point of spending more money on cables to increase the sound quality, seems a little crazy to me..

I like the Helix from Mr. Wonka too. 
You won't find a product that produces higher SQ. You may find something you like the sound of better, but it's not because the product is better. I found usually it just takes a little time to sink in. Just because it cost more doesn't make it better.. LOL