Sub wiring help, high level speaker terminal to RCA line level Sub inputs

Wanted to post a follow up. I've spoken to all 3 companies in the mix, Rythmic, Cambridge Audio, and Schiit, they all said to use the RCA line out with a Y splitter. They said the speaker post connection would at best sound the same, but have the side affect of potential distortion so there's no real point in using that connection unless the sub was made to use them.

I tried using the amps speaker post output anyway, the volume levels were not incredibly different, they were about 25% louder than the RCA line out. In the end I couldn't really notice any difference in sound quality between either one when volume matched. So I'm going to stick with the RCA line outs using a Y split for peace of mind.

Now I have one last question, I've been using BJC LC-1 cables to my power amp, but for now only had left over cheapo component video cables I was testing to the subwoofer. I would like to get RCA's that are Y split themselves to not have to use an added Y adapter. However BJC cannot make the LC-1 cables in Y configurations, only their MSA-1 cables which don't have the same gauge, shielding, etc..

So I'm not sure if it would be best now to use 2 higher quality LC-1 cables attached to the separate Y-adapter, or use 2 lesser quality MSA-1 cables already Y split and eliminate the use of the adapter.

Or is there another cable company that can make better quality custom Y cables for the same price as BJC?

LC-1 cables plus a pair of Audioquest splitters would be a much safer bet IMO than MSA-1 cables in a y-configuration, and the greater the length of the cables the more true that would be.

While there have been various reports and/or claims here to the effect that "splitters degrade the sound," my belief is that in most of those cases the reported findings result not from the splitter itself, but from some combination of impedance incompatibilities that can arise when a splitter is used; ground loop effects that can sometimes occur when an output is used to drive two separate components; and increased loading of outputs by cable capacitance, that can result when an output is split and is used to drive two lengthy cables.

I couldn’t find an output impedance spec on your streamer, or a spec on the capacitance of the MSA-1 cable. However given its small diameter and its double-shielding I suspect that the capacitance of the MSA-1 is far higher than the very low capacitance (12.2 pf/foot) of LC-1. If the sum of the capacitances of the cables to the two destinations is high and the unknown output impedance of the streamer is also relatively high the result would be rolloff and/or undesirable phase shifts in the upper treble, that would affect the signals received by the main speakers.

Also, if the resistance of the small shields of the MSA-1 is higher than the corresponding resistance of the larger shields in the LC-1 that could increase the chances that a ground loop issue might arise, depending on the unknown internal grounding configurations of the three components.

Based in part on my own experience with the Audioquest splitter as well as on my technical understanding of the situation I would have no qualms whatsoever about using them. And if that approach were to prove to be unsatisfactory (which I very much doubt in this case) I would feel certain that the cause is something else, such as an impedance incompatibility which your initial results already suggest is most likely not present.

Regards,
-- Al

Wanted to post a follow up. I've spoken to all 3 companies in the mix, Rythmic, Cambridge Audio, and Schiit, they all said to use the RCA line out with a Y splitter.

This is what you call CYA. Both methods are at best the same. Both methods run the risk of introducing a bit of distortion. Think about it. But the distortion of the LOC affects only the bit going to the sub, and is simply never going to be heard. (Done it, so experience here not opinion.) With the Y however then whatever distortion it makes goes right into the amp and comes right out the most high resolution high hearing sensitivity part of the system. Not taking sides just let's be clear. Its so true, already you are asking what is the best part to use. Whereas with the LOC it just doesn't even matter.

Where the CYA comes in is even though its definitely not the best way to go SQ-wise, it is definitely the lowest risk of customer screwup. Which people think businesses mostly try and make good stuff. When really the hardest part of all is making stuff their customers can't screw up.

@millercarbon I see what you mean. One thing is why would any possible distortion be present through the pre-outs but not through the speaker outs? I don’t think the power amp is doing anything to make the signal out of the pre-amp cleaner. I figure it’s just amplifying, which whether done through the RCA outs, or eventually through the power amp and speaker terminals, it’ll still be there. Unless the argument is based on the the Y-adapter itself causing the distortion, not the pre-out signal.

One other thing that I was thinking about is the effect on the audio signal after being amplified multiple times over if using the Speaker level outputs. So the pre-amp is slightly amplifying the signal, which is then fed to a power amp that is again amplifying the signal even more, which then in this case would be sent to a 3rd amplifier which would be amplifying a signal that had to be lowered by resistors in between, before finally reaching the Subwoofer itself.

Just in a logical sense to me going though that cycle seems like it has the potential to introduce more distortion to the sound than going one straight shot to the power amp.

One other thing that I was thinking about is the effect on the audio signal after being amplified multiple times over if using the Speaker level outputs. So the pre-amp is slightly amplifying the signal, which is then fed to a power amp that is again amplifying the signal even more, which then in this case would be sent to a 3rd amplifier which would be amplifying a signal that had to be lowered by resistors in between, before finally reaching the Subwoofer itself.

Just in a logical sense to me going though that cycle seems like it has the potential to introduce more distortion to the sound than going one straight shot to the power amp.

Both approaches are capable of providing excellent results in many systems, and both approaches have their potential pitfalls. Some of my previous posts in this thread have described pitfalls that can occur in each of those cases.

As I’ve mentioned earlier potential pitfalls of the preamp-to-sub approach include the fact that the signals that are reproduced by the main power amp and the main speakers can under some and probably many circumstances be adversely affected by the input impedance of the sub’s amp, or by the capacitance of the cables connecting the preamp to the sub, or by both, notwithstanding how counter-intuitive all of that may seem. Although it appears those issues probably won’t occur with your particular equipment.

If all potential pitfalls are avoided, or do not apply to a given system, driving a sub via the power amp outputs has the potential advantage of providing the closest sonic match between the signals that are provided to the sub and to the main speakers, as was mentioned early in the thread.

Regards,
-- Al