BHK Pre and Power on the Way - REL Subwoofer Question


#1

I just pulled the trigger on two new items: 1. A BHK Pre, and 2. a Signature 250 power amp (due to take delivery later in the week), and had a question: I use an REL T7i Sub, which includes the wiring option of a three-wire configuration directly from the power amp speaker taps. In perusing these forum pages there seems to be contradicting information on this: Some have claimed to use RELs in this manner with the 250 power amp with no issues; others (Including Paul McGowan) indicate that this should not be done because the 250 is a fully balanced amp. So what is the right answer? Should I or should I not use the REL sub with the 250 in this manner? (The alternative would be to hook the REL up to the pre in a “traditional” manner.) A quick scan of the online user manuals didn’t yield any information, but I might have missed/misread something. Any information would be helpful.

Mike


#2

Nice. You’re going to love them!

The Signature 250 is a fully balanced amp and you cannot tie one side to ground feeding a subwoofer.

That said, REL is the only aftermarket subwoofer I would readily endorse. The REL comes with kit or kit can be ordered, that makes this possible. Just check with them.


#3

From my REL S/5 manual, here is the section on connecting to the speaker outputs of a balanced amplifier using the supplied 10 meter cable. Click on the image to see it full sized.

REL-Balanced-Amp-hookup2-1.JPG


#4
Paul McGowan said That said, REL is the only aftermarket subwoofer I would readily endorse. The REL comes with kit or kit can be ordered, that makes this possible. Just check with them.
Paul,

You are a big advocate of servo controlled subwoofers, but REL subwoofers are not servo controlled. What are they doing right to be good without servo control?


#5

Great question and their only potential weakness though you wouldn’t know if from listening. I don’t know exactly but in comparing them to others on the market with servos, they just kick ass and are better. I won’t mention names, but the ones in the market with servos are far and few between.

I have a REL at home and love it. My guess is they EQ it to mimic the servo. Whatever magic REL does is fine by me.


#6
bstanwick said From my REL S/5 manual, here is the section on connecting to the speaker outputs of a balanced amplifier using the supplied 10 meter cable. Click on the image to see it full sized.

REL-Balanced-Amp-hookup2-1.JPG

Thanks for pointing me to this - I just found the same thing in my T7i manual.

Can’t wait for the BHKs to arrive!


#7
Paul McGowan said Great question and their only potential weakness though you wouldn't know if from listening. I don't know exactly but in comparing them to others on the market with servos, they just kick ass and are better. I won't mention names, but the ones in the market with servos are far and few between.

I have a REL at home and love it. My guess is they EQ it to mimic the servo. Whatever magic REL does is fine by me.


Paul, just wonder how you connect your REL and home. Is it the same way shown on the picture or you are connecting it via your preamp?

Allan


#8

I actually use an isolation audio transformer. The run from the AV processor subwoofer output is so long that it picks up a good deal of hum. So I devised a cool coupling transformer that eliminates the hum and gives great bass.


#9
Paul McGowan said I actually use an isolation audio transformer. The run from the AV processor subwoofer output is so long that it picks up a good deal of hum. So I devised a cool coupling transformer that eliminates the hum and gives great bass.
I also have this problem, running SE over some distance to my sub. I have a passive isolating transformer I can use, though. I suppose you insert it in the subwoofer end? http://www.cs1.net/pic/jensen_transformers/CI-1RR_datasheet.pdf

Are you going LFE-mono (split) to both inputs on your coupling transformer, or do you use only one channel on the trafo?


#10

Yes, it goes at the subwoofer end. I am going LFE-mono. The Marantz SSP I use has a RCA output that I feed into the transformer.


#11

My feeling on subs is sealed is preferable/ more musical. Has to be built for it, though. Massive generalization, I know. But I also plug the ports on my two-ways.

Liked JLs better in my system than RELs personally, though I’ve not compared all models.


#12

I tried connecting my REL sub to my BHK250 amp using the red and yellow wires connected to the right and left positive speaker terminals and black wire unconnected as shown. I immediately has a loud steady hum when I turned on the amp. Is there something I can try to get rid of the hum without having to switch to an RCA connection?


#13

The BHK is a balanced output and you need to follow REL’s instructions for connecting to a balanced output amplifier.


#14

I haven’t tried it yet (BHKs aren’t in the house yet) but the REL manual speaks to that issue, saying that you can find a ground somewhere else. I’ll report back once I try a few things.


#15

Michael, any updates of your findings?


#16
a25105 said

Michael, any updates of your findings?


Yes - I am still trying out the BHKs (pre and 250) with different speakers and configurations. So far, I’ve only been using the REL T7i with the “low-level” input (e.g. RCA coming of the RCA output on the preamp). I’ve been communicating with REL; they say the high-level works with the 250 as long as you hook up using the differential configuration as outlined earlier in this thread. I haven’t tried it yet but I will.

Interestingly, with a few of my speakers, the bass on the BHKs is so impressive that I haven’t felt the need for a sub at all. With one pair, though (Linn Magic 109s), the REL is definitely a plus.

REL also suggested that the hum that sometimes happens with the differential hookup is only present when the 250 is in standby mode. Again, I haven’t tried it yet, just reporting what they said.

PS Full write up on my BHK experiences coming in the next few weeks!


#17

Thank you Michael for your update. Looking forward to your full review. I am thinking about getting a T7i or T9i depends on your experience with the BHK 250. Many thanks!


#18

Greetings. I too have a BHK 250 and a REL S/3 sub. I got the S/3 because it was a good match with my speakers (Thiel 2.7). I really like the sub and would highly recommend them but the hum issue when the amp goes into standby has been an issue. i have just gotten used to turning the volume down on the sub when i put the amp into standby. however i was just told there may be a fix in the works. i received this from John at REL “PS has actually just this week released involving replacing an existing chassis bolt with a new one that has a knurled head allowing true earth ground for the chassis and hence no hum when the unit goes to sleep.”


#19
clothes pen said

… I received this from John at REL “PS has actually just this week released involving replacing an existing chassis bolt with a new one that has a knurled head allowing true earth ground for the chassis and hence no hum when the unit goes to sleep.”


I am definitely interested in getting the new chassis bolt that would allow a true earth ground.

#20

same here. Paul, please let us know when it is available and how to get it. Thx!!!