REL subs with Rowland Amplifiers

Based on the recommendation of a fellow Audiogon member I purchased Aurelex SubDude-HT subwoofer isolation platforms to put under my REL subs. In my opinion it’s a relatively inexpensive way to improve the overall sound of a system with subs...money well spent.

I don't know why, but with the G1 mkII there's a big difference between using the high-level and low-level connections. My wife and I prefer the high-level because it sounds more natural. The orher difference is the REL Carbon Limited's sounds better when placed on  the inside of the speakers.  The G1s sound better behind and to the outside of the speakers...much more open. 

Changed from REL Carbon Limiteds to dual REL G1 mkII. I'm going to compare the high-level connection to the low-level connection to see which one I prefer. 

The G1 pressurizes my room better and I can "feel" the music more with the G1 compared to the CL. I think the CL is a great subwoofer, but the G1 is a better match for my 20’ x 26’ room and my Monitor Audio PL500 ii speakers.

I received the REL Baseline Blue cables. I don't want to exaggerate, but to simply say that the REL Baseline Blue cables makes a difference would be an understatement. Everything and I mean everything is improved relating to detail across the entire audio spectrum. Adding the second subwoofer improved space and equalized my room. I'm willing to say as it pertains to improving detail, adding the Baseline Blue is more impactful than adding the second subwoofer. I guess the stock speakon cables that come with REL subwoofers are either really bad or the Baseline Blue is very good. 

Al,

As always thanks so much for your response. Your post highlights my concern. If I don't ground it properly I will damage my amplifier and/or sub. Like I've already stated, is does work via the low level input, but I'm wondering if it will sound better via the high-level input. For sake of comparison, if the high-level connection is a 100 for sound, what is the low-level connection, 80, 90, 95? I'm not concerned if there's only a slight difference in sound between the two inputs; however if there's a significant difference than I would like to find a way to safely connect through the high-level input.

I'm just so surprised that the compatibility problem between REL and Jeff Rowland amplifiers and other balanced differential amplifiers isn't well documented.

lalitk,
Thanks so much for your assistance.

daveyf,
" Not sure I would want to loosen a screw of the chassis as Jeff suggests." I know it sounds trivial to some, but I couldn't agree more and I'm not going to loosen any screw. I may contact Jeff Rowland and ask about adding a ground connection on the chassis. 

My 625 S2 is Class AB. I already talked to REL and they didn't help.

daveyf and almarg PM sent

Although I'm frustrated with the inability to at least try the high-level input, I ordered a second REL Carbon limited that I should have on Monday. The addition of a single REL has increased my enjoyment of my 2-channel system; so I figure dual subs will be better. I reached out to REL again today in hopes that someone can provide a simple way to use the high-level input without damaging my amplifier or sub. Hopefully someone from REL will contact me tomorrow. 

Thanks, I will send them a email.

I just received a call from REL. They said I could ground the sub/amp by going from the REL's LFE to my Rowland Corus preamp while leaving the black lead floating.

Al,

Do you think grounding the black wire to the chassis of my 625 S2 will result with proper output of the subwoofer?

I should have mentioned at the beginning the most frustrating thing about this situation is my dealer is a REL and Rowland dealer. He has the ability to connect the REL to the exact amp and preamp that I have, but he won't. When I told him about my situation, he said that he would connect the REL to the Rowland 625 S2, but to date he hasn't.

The other frustrating thing is trying to find out the truth regarding the sound quality difference between the high-level and low-level input.  During a telephone conversation two days ago a REL representative told me there wasn't a difference in sound quality between the two inputs, but the high-level input helps facilitate a better blend between the sub and speakers. Yesterday, a different REL representative sent me this via email... Low level input is about 80% of the high level input. If both inputs offered the same sound quality I wouldn't worry about the high-level input anymore. 

I have been corresponding with Justin Magana who is REL’s Chief Engineer. Based on his advice I twisted the red and yellow wires together and connected my REL via the high-level input. The black wire is floated. It worked! I have plenty of output from the sub and absolutely zero hum.

Al,
"So are you saying, then, that the only difference between what worked and what previously didn’t work was twisting the red and yellow wires together, while having exactly the same connections in both cases?" YES

"Or are you saying that the red and yellow wires are now connected to the same positive output terminal of the amp, while you wait for the second sub to arrive which will be connected to the positive output terminal of the other channel?" YES, per my conversation with Justin that's the way I have to connect dual REL subs anyway; therefore there wasn't any risk in connecting the single sub this way. He assured me nothing bad would happen, so I tried it. 

chazzzy007,
Thanks.

"Ricred what sub are you upgrading from and what improvements are you hearing with the Carbon limited? I have an S5 SHO." I had a JL Audio F112 v2. The REL Carbon Limited totally disappears compared to the JL Audio F112 v2. I'll make more comments in a couple of days.

Al,
 I initially connected the red wire to the right positive channel and the yellow to the left positive channel, with the black wire floated. Now I have it connected to the right positive channel, but the black is still floated. I was told that if I don't hear a hum, the amp and sub are properly grounded and I won't have any issues. 

daveyf,

The black wire is floated and not connected to anything. I'll have dual subs and will receive the 2nd sub on Tuesday. That's why I was advised to connect my single sub this way.

calvinj,
I'm excited that everything is working like it is suppose to.

daveyf,
"If you are not connecting the black wire, I would be concerned that you are not grounding the sub." If it wasn't properly grounded I'm assuming I would hear a hum? I assume REL's Chief Engineer wouldn't tell me to do something that would damage my amp or sub.

daveyf,

Are you suggesting that there's no benefit to connecting DUAL REL subs, one to the left channel and the other to the right channel, with the red and yellow wire connected to the positive speaker post on each and the black wire floating? 

Al,
If leaving the black wire floating was an issue, wouldn’t I hear a hum, reduction in output, or some sonic indicators that something is wrong?
I don’t understand the issue with how I have it connected?
This is directly from REL's Chief Engineer: What I would do first, is combine the RED/ YELLOW wires of the REL you have now to one channel and see how that works.
When you get the second REL, you would have to do this anyway, because you want to dedicate one REL to each channel.

I would also like to say thanks to astewart8944. He was the first person to suggest connecting both wires to the same positive terminal and floating the black wire. 

calvinj,

My thoughts comparing the JL Audio F112 v2 to the REL Carbon Limited in my system/room. This has nothing to do with sound, but the JL Audio F112 v2 is built like a tank and is packaged significantly better than the REL.  My initial thoughts on REL vs JL Audio, comparing a single Carbon Limited to a single JL Audio F112 v2. The REL has more affect on the mids and highs than JL Audio. The mids and highs have more detail with the REL. I think JL goes a little deeper, but doesn't allow you to hear the different shades of low level information like REL. You can feel the JL a little more, but it doesn't provide the nuance of the REL. The REL totally disappears, but no matter what I did with the JL Audio I could tell it was there. I choose the JL Audio F112 v2 for a HT only system. For music only I choose the REL Carbon Limited. My system is a combination of 2-channel and HT. I listen to music 80% of the time, so I prefer the REL for my situation. If it was 50/50 or 80% HT I prefer JL Audio, because it has more bass impact. For now the REL is located in the same spot as the JL Audio was. I'll pickup my 2nd REL from FedEx today and start the process of dialing in both subs.

daveyf,

"What made you pick the Carbon Limited?" I was originally looking at a single No. 25 or dual S5s. After a long conversation with the dealer about my main speakers, the fact that I had a single JL Audio F112 v2, and I listened to music the majority of the time he recommended the Carbon Limited. If it didn’t work in my system I had the opportunity to return it. I was purchasing right at the time that REL was discontinuing the S3 and S5, so I eliminated the S5. I talked to REL and a few other people that convinced me that dual Carbon Limited subs were a better fit than a single No. 25. I’m extremely satisfied with my choice.

I'm ordering the Signal Cables today:)

calvinj,
I've owned dual subs several times and never thought much of it. At one point I had dual JL Audio F110s with the JL Audio CR-1 external crossover and preferred a single JL Audio F112 v2 without the CR-1. I added a second REL last night. Let me just say, it isn't the bass, but adding a second REL just opened everything up a tad more. My wife was listening to her favorite song and said for the first time she could hear fingers slide down the guitar. She went on to say it's easier to hear the music. So, if you get results like I have, as a music lover you owe it to yourself to get a second 212se.

So I decided to start playing around with my subs. REL says the high-level connection is "superior " to the low level connection method. I think all systems are different, so I decided to compare the sound of the high-level connection to the low-level connection. Initial thoughts on high-level connection using stock REL speakon cable vs low-level connection using Audioquest RCA Boxer subwoofer cable. The low-level connection has more bass output and you can feel it more. Not night and day, but it’s easily discernible. I think with the low-level connection you loose a little detail and resolution. I had to turn my amp and preamp off to disconnect the speakon cables and connect the RCA cables, so that may account for a slight loss of detail and resolution. It usually takes 30 minutes for everything to sound normal again. The other issue may simply be the AQ cable is better than the cheap cable that comes with REL subs.
I've already ordered a REL speakon cable from Signal Cables. I should have it bye Thursday, so I'll see how much difference it makes.

daveyf,

I ordered two 7’ cables with spades from Signal(one per side). 

oem-wheels,

"I just came across this "post" about how REL subs shouldn't be driven by a true balanced amp like the Rowland.. Not only won't work right but its dangerous." That's true if it isn't connected the correct way. I talked to Jeff Rowland and one of the Chief Engineers of REL that told me how to connect everything. As a matter of a fact a friend that owns Rowland 925 mono-amps uses REL subs and told me how to connect my RELs. I believe he's had his setup for a couple years and has never had problems. 

calvinj,

I received the upgraded Signal cable for high-level connection yesterday and connected it last night. My initial thoughts are I prefer the sound via the low-level connection. To my ears the bass is more defined and it integrates just as well. The subs disappear no matter what connection method is used. I’ll compare the sound of the different connection methods over the weekend and let my ears determine what sounds best. I know what REL thinks about the high-level vs low-level input, but how many REL owners have actually compared the sound of the high-level vs low-level in their system?

No matter what REL claims I submit that the end user owes it to themselves to try both inputs. All systems are different and you never know what sounds best unless you try both inputs. I still prefer my REL Carbon Limited to the JL Audio F112 v2 for 2-channel. I consider adding the RELs to be one the best Audio decisions I've ever made. 

I've gone back and forth between the high-level and low-level inputs. I prefer the low-level input...bass is more dynamic, tight, and articulate; the mids and highs have more detail and just sounds more alive.

I think in theory REL is correct; however listening is the final judgement. If I or anyone else prefers the sound of the low-level input over the high-level, what REL claims is mute.

daveyf,

I don't know the answer to your question. I can only tell you what I hear. I'm using Audioquest Boxer subwoofer cables for the low-level connection and the Signal speakon cables for high-level, so both cables are the same quality.
Now that I've decided to use the low-level inputs I'm curious to hear opinions on if there are any significant difference between subwoofer cables?

Yes, my subs are setup for 2-channel on the inside of my speakers. They're in the same place I had my JL Audio F112 v2. 
My methodology is pretty simple. I played three songs with the high-level connection,  turned my amplifier off and switched to the low-level connection. I repeated the same sequence three times. I used nine songs, some were very well recorded, others just music that I'm very familiar with. 
Now I will sell the Signal speakon cables and borrow an Audioquest Wolf or higher subwoofer cable to hear if it makes a difference. 

As I mentioned earlier, one REL representative said because the high-level and low-level input uses the same board there's minimal difference in sound quality between the two,  while another REL representative suggested the high-level input was 100 and the low-level was 80. When I talked to Jeff Rowland he told me to just use the low-level input. 

daveyf,
Jeff Rowland and I talked for several minutes about REL, but it isn't my place to post our discussion. 
I reached out to REL again this morning to make sure I wasn't missing something regarding how the subs were connected. I have no problem staying with the low-level input, because that's what sound best in my system. 

Al,
Is there a logical reason why when both subs are connected through the high-level input with the REL supplied speakon cable no hum is audible,  but when  I use the Signal speakon cables the hum is clearly audible?  This is with no RCA cable  connected to the RELs LFE inputs and into my preamps outputs. Of course connecting RCA cables to the LFE inputs and my preamp's output eliminates the hum when the REL supplied speakon cables or Signal speakon cables are used. 

Update from my last couple of posts. I haven't sold my Signal cable, so I decided to try the high-level input again. The last time I did, I had a RCA cable going from both RELs LFE(volume turned all the way down) to the preamp out, while connecting the subs to the amplifier via the Signal speakon cable. REL told me to do that as a way to ground the subs. Today I decided to try the high-level input again. I still used the Signal cable, but this time I didn't connect the RCA cable from each subs LFE input to the preamp as a means to ground the subs. This time I received an audible hum. The weird thing is with the standard REL speakon cable I don't hear a hum, even though it's connected the same way as with the Signal cable. Based on my findings, because of the "grounding" issue, in my situation I don't think using the high-level input is optimal. In my situation using the low-level input is clearly better. I will contact Rowland tomorrow to see if it's worth sending my amplifier back to them to add a grounding "screw". I think that's the only way to have a fair comparison between the two connection methods. More to come!

davefy,
If you read my post dated 9-21-2019, "I have been corresponding with Justin Magana who is REL’s Chief Engineer. Based on his advice I twisted the red and yellow wires together and connected my REL via the high-level input. The black wire is floated. It worked! I have plenty of output from the sub and absolutely zero hum." PLEASE NOTE NO RCA CABLE WAS CONNECTED AND IT DIDN'T SOUND GOOD TO MY EARS. I clearly have listened to the high-level connection with the supply REL speakon cables. 

"The red to right positive, the yellow to left positive and the black to either negative connector." PER MY CONVERSATION WITH ROWLAND AND REL CONNECTING ANY LEAD TO THE NEGATIVE CONNECTOR  WILL DAMAGE MY AMP, SUB, OR BOTH.

I have two options:
1) use the low-level input connected via RCA cables
2) send my amplifier to Rowland and have him add an external ground screw that will enable me to safely connect to the high-level input

davefy,
"I did notice that Richard turned down the low level connection...BUT I believe that the connection to the low level bypasses the connection to the high level once the RCA ic is connected to the preamp/sub. Since he had sound, I would suspect that the sub may have been out of the system blend and the mains were being solely listened to." 

I DON'T KNOW HOW TO MAKE MYSELF ANY CLEARER. IT WAS NOT, I REPEAT NOT CONNECTED TO THE LOW-LEVEL INPUT. BOTH REL SUBS WERE CONNECTED TO THE LFE INPUT, PER REL THAT ESTABLISHES A GROUND CONNECTION FOR THE SUBS. CONNECTING TO THE LFE INPUT DOESN'T BYPASS ANYTHING; IT'S USED  AS A WAY TO GROUND THE SUBS TO PREVENT HUM. I WAS LISTENING TO THE HIGH-LEVEL INPUT PERIOD.

daveyf,
You are correct my Signal cable has the red and yellow cables together and each cable has a Speakon end at the sub and a red/yellow connector and a black connector ( at the amp end). 

daveyf,

You do realize that the .1/LFE and low-level inputs are different? Although I didn't use .1/LFE I thought it was understood I wasn't referring to the low-level input. Since you won't listen to me, I have attached emails that I received directly from REL.

DIRECTLY FROM REL:

Richard,

You had been running the RELs low level. Instead of finding a place to connect the BLACK wire to the chassis, you can use RCA cables to make the signal ground connection.
I would connect between the pre-amp and the LFE RCA input of the RELs. The collar of the RCAs will provide the same connection that the BLACK wire if the high level cable would make.
Simply leave the .1/LFE Level control at minimum.

When you have a component system like this, all the components need to share the same ground reference. This is typically the signal ground of the system and is shared by both the pre-amp and the amplifier.
What I am instructing you to do is access the signal ground by connecting the PRE-AMP to the REL.

Yes, you can use make the RCA to RCA connection while still using the high level connection.

There are two input channels to the RELs.
1) the high level/ low level channel and
2) the LFE channel.

Each has it’s own level control.
The ground connections for both the these channels are connected internally to the REL. So connecting the RCA collar is like connecting the BLACK wire of the high level cable to the signal ground at the pre-amp.

I've already sent Rowland an email requesting the cost of adding an external ground screw. Hopefully they will respond tomorrow and I will ship my amplifier to them before the end of the week.

Al,
I’m assuming if the Signal Cable is picking up EMI from something nearby to cause the hum, adding an external ground screw on my amplifier won’t eliminate the hum?
Silly me the hum is being caused from the REL not being grounded. When I connect an RCA cabke from the REL's LFE to my preamp the hum isn't there. Unfortunately I don't like the way it sounds when connected like that, because all of the dynamics are missing. 

After talking to Jeff Rowland via email today I decided to continue to use the low-level input of my RELs with RCA cables. My only question now is how much of a difference subwoofer cables make? I'm going to call my local dealer for a home audition of Audioquest's Wolf subwoofer cable to compare against Audioquest's Boxer and Wireworld's Equinox.


On a side-note, I just have to say what a class act Mr. Jeff Rowland is and he provides outstanding customer service.