wyred 500st mk11 and rel sub r528

Connecting the red and yellow wires to the amps positive speaker posts is a high level input for the Rel. Not sure why they suggested using the lfe for ground. I have heard of problems with differential amps and/or class d. I had no problem with my Bryston B100 (uses differential amps) and my Aavik U300 (class d) and connecting the black wire to either negative speaker post. But I also have a Rel B3.

As with many REL subs, the manual for the R528 (see page 6, pdf page 7) suggests connecting the black wire to a chassis screw on the amp when connecting at speaker-level to an amp having balanced (or bridged) outputs, assuming the amp does not provide a suitable circuit ground connection point on its rear panel.

Many people do that, and in most cases it will work fine. Depending on the internal grounding configuration of the amp, however, there is a possibility that a large hum could result. So if you try that, when powering up for the first time be sure to have the sub's volume control turned down, and bring it up slowly.

I am not sufficiently familiar with your Oppo, and how or if it is connected to the amp, to be able to comment on the suggestion of providing the REL with a ground via an LFE connection.

In any event, though, if connecting the black wire to a chassis screw is not feasible or does not work satisfactorily, an excellent approach would be to solder the black wire to the ground sleeve connection point of an RCA plug, connecting nothing to the center pin of the plug. If you are connecting the amp's inputs via XLR, then simply insert that plug into one of its unused RCA connectors. If you are connecting the amp's inputs via those RCA connectors, use an adapter such as this one to implement that connection.

I would strongly recommend that you do NOT make the common mistake, in the case of amps having balanced or bridged outputs, of connecting the black wire to a negative output terminal of the amp. Depending on the internal grounding configuration of both the amp and the sub, that creates at least a slight possibility of damaging the amp. And even if doing that appears to work satisfactorily, as in Xti16's case, it is not ideal from a sonic standpoint if only one sub is being used. What would happen in that situation is that instead of the input circuit of the sub summing the signals for the two channels together, it would give approximately 10 db more emphasis to the channel to which the black wire is connected than to the other channel, according to my calculations.

Regards,
-- Al

HI Al
The Oppo has dedicated RCA and XLR outputs for two channel play back via a 32bit Dac which I am using for my front mains and they go too my w4s amp. I have a 5 channel B&K amp for center and rear surround speakers. The Oppo also has outputs for FL,FR,SR,SL,RR.RL,SW for those people who only want the player for hometheater use. I got the w4s amp because it had balanced inputs and the B&K didn't. Rel said because I had the .1lfe connected that it would act as a ground for the sub and to not connect the Black wire on the speakeon wire only the Red and Yellow to the left and right positive leads on the w4s. I really want to keep the Rel in my set-up because my Sonus Faber Pianos need that extra boost in the mid area they just sound fuller. The manual also shows connecting the Rel via the Low-Level input, but I'm not clear on where to connect on the Oppo or if it is going to do the same as the speakeron.

Mike

The manual also shows connecting the Rel via the Low-Level input, but I'm not clear on where to connect on the Oppo or if it is going to do the same as the speakeron.

REL's theory is that connecting at speaker level rather than at line-level/low level is preferable, because it results in the sonic effects of the amplifier being reflected in the signals provided to the sub as well as in the signals provided to the main speakers. Not everyone agrees with that theory, but I see no reason not to proceed in that manner.

I got the w4s amp because it had balanced inputs and the B&K didn't. Rel said because I had the .1lfe connected that it would act as a ground for the sub ....

Yes it probably would provide an adequate ground, given that the Oppo is connected to the W4S amp. The reason I say "probably," though, is that if the Oppo is connected to the amp via XLR's there is a possibility that the design of the amp is such that the ground on the XLR connectors (pin 1 on those connectors) might be connected to the amp's chassis, rather than to its circuit ground. Which would still probably work ok, but might result in the same hum issue I indicated could arise if the black wire were connected to a chassis screw.

Also, not being familiar with the Oppo, I'm not sure if doing that would result in an LFE signal being sent into the sub that would be unwanted for two-channel listening.

In any event, my suggestion of soldering the black wire to the ground sleeve of an RCA plug, and connecting that plug to an RCA input connector on the amp, is virtually certain to work, and may provide a ground that is "better" (i.e., sonically preferable) than a ground that is circuitously provided via the Oppo. Although connecting the black wire to a chassis screw on the amp is also worth trying.

Regards,
-- Al

I have been told by W4S that the pin location on the Balanced input is 1 Ground 2 Negative and 3 Hot. On the Oppo 2 and 3 are reversed but Oppo has in there set-up menu a way to invert that so they are the same, but I'm also not sure how it's grounded via the XLR input and that is the reason I got the W4S amp to use the XLR outputs from the Oppo. So if I understand what your saying is to connect the Black to the chassis on the W4S or use the XLR inputs and connect the Black to the Right or Left RCA input on the W4S.

So if I understand what your saying is to connect the Black to the chassis on the W4S or use the XLR inputs and connect the Black to the Right or Left RCA input on the W4S.

Yes, those are the alternatives I am suggesting, but be sure to note that I referred to connecting the black wire to the ground sleeve of an RCA plug (that would be inserted into one of the amp's RCA input jacks), ***NOT*** to the center pin of the RCA plug.

Regarding XLR pins 2 and 3, even if those are inconsistent between the Oppo and the W4S everything would still work fine. The only consequence would be an inversion of signal polarity, also referred to as absolute phase, the audibility of which is controversial, at least on most recordings. And which could also be corrected for by reversing the + and - connections to the speakers, although that would also reverse the polarity for any other sources that may be in use.

Regards,
-- Al

I would strongly recommend that you do NOT make the common mistake, in the case of amps having balanced or bridged outputs, of connecting the black wire to a negative output terminal of the amp. Depending on the internal grounding configuration of both the amp and the sub, that creates at least a slight possibility of damaging the amp. And even if doing that appears to work satisfactorily, as in Xti16's case, it is not ideal from a sonic standpoint if only one sub is being used. What would happen in that situation is that instead of the input circuit of the sub simply summing the signals for the two channels together, it would give approximately 10 db more emphasis to the channel to which the black wire is connected than to the other channel, according to my calculations.

Regards,
-- Al

I moved the black wire to the chassis ground on the Avvik U300 and heard no difference. I'll leave it there since connecting to the speaker binding post may cause a problem.

I moved the black wire to the chassis ground on the Avvik U300 and heard no difference. I'll leave it there since connecting to the speaker binding post may cause a problem

Al - My Bad. I heard no difference because the tracks I played at the time had no extended lows in the music. After playing around with some tracks known with deep lows I found the Rel B3 wasn't doing anything. So in MY case I returned the black wire to the speaker output post. Here is a link to the U300 specs. Not sure what the virtual ground is.
http://www.aavik-acoustics.com/u-300.html

Hi George,

I see nothing in the description of the U-300 indicating that it has balanced or bridged outputs, although there are some references to input circuits being balanced. And my understanding is that the issues you referred to in your initial post regarding class D designs (not having balanced or bridged outputs) just involve certain (perhaps just older) ICEPower modules which by design have very large DC offsets (tens of volts) on both the + and - output terminals.

I couldn't find a manual for the U-300, but usually the manual for an amp having balanced or bridged outputs will include statements cautioning against grounding the negative output terminals.

Also, after looking at the manual and the schematic for the Bryston B100 you referred to earlier, it appears to me that while a lot of the circuitry is differential the outputs are not.

Best regards,
-- Al

Thanks Al - Guess I have been lucky