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


I just received a new Rhythmic L12 sub, and surprisingly did not realize it only has RCA line level inputs. I had purchased it thinking it also had high level speaker inputs to connect it directly to the speaker posts on my power amp.

I have a Cambridge CXNv2 connected to a Schiit Aegir Power Amp through the line level RCA. Now, the CXN does have an additional balanced XLR out, but I can only connect the Schiit Aegir through RCA.

So these are my options and questions:
1. Connect the Power Amp to the Sub using a custom cable with speaker terminals on one end and RCA on the other end.
2. CXN XLR --> Power Amp RCA, and CXN RCA --> Sub RCA
3. CXN RCA --> Power Amp RCA, and CXN XLR --> Sub RCA
4. Return the Rhythmic and get an SVS SB1000 with high level speaker inputs.

In this case I’m not sure what the positives and negatives are about trying to connect the Sub via speaker terminals or RCA line level on the CXN. Or is it even advisable to use a cable that goes from the speaker terminals to the RCA line level inputs of the Sub?

Appreciate any help!
rhern213
@lalitk It’s just a PITA to return plus having to pay for return shipping for a 50lb package. And Rhythmic doesn’t have another similarly priced option. If I end up returning it I’ll get an SVS SB1000 which was my 2nd choice. It’s really annoying because even though on Rhythmic’s website it doesn’t explicitly say the L12 has high level speaker inputs, they have reference pictures on the L12 page that shows a back with the speaker inputs, which I see now is not actually an L12 at all. So while I’m sure it’s not done on purpose it is unintentionally deceiving of what you’re actually getting. If I had double checked before putting in my order I wouldn’t have bought it, but now since I waited 2 months for it and I do think it has the best specs and features I would like to try and get it to work as it should.

@millercarbon I see, the one thing is I just personally hate using any kind of adapters, converters, etc.. on my equipment. Even though it’s cheap and should work with no issues it’ll always be nagging at me that it’s not connected in an optimal fashion. If it were just a temp solution to get the job done I would do it, but I just feel if I’m paying $500+ I want it to work as intended with no additional trickery.

One question is if the input to the Sub is only technically used as a signal, not carrying any loads, wouldn’t I simply be able to use a straight cable from my speaker terminals with RCA’s plugs on the other end into the Sub? This would provide the same function as that converter without adding in extra resistors?

At least they have a 45 day return policy if I can't find a solution I'm happy with.
P.S. to my previous post: A **possible** issue I see in looking at the converter Miller suggested is that its description mentions that it provides "D.C. Isolation for noise reduction." That may mean that it puts a capacitor in series with its inputs or its outputs. Depending on the value of the capacitor (i.e., the number of microfarads) the result could be some degree of frequency-dependent rolloff in the bottom octave or two, depending also on the input impedance of the sub’s amp (which does not appear to be specified).

But given the very low price, there doesn’t appear to be any downside to giving it a try.

Regards,
-- Al
One question is if the input to the Sub is only technically used as a signal, not carrying any loads, wouldn’t I simply be able to use a straight cable from my speaker terminals with RCA’s plugs on the other end into the Sub? This would provide the same function as that converter without adding in extra resistors?

You would be putting much too high a voltage into the sub without the converter. At best the result would be having to use the sub’s volume control near the bottom of its range, where the control’s resolution would probably be very coarse, and where the two channels might be summed together in an unequal manner. Also, if for some reason the sub’s volume control was inadvertently turned up too high while the system is operating damage to the sub would be possible, as well as adverse effects on your ears and your blood pressure :-)

Regards,
-- Al


Use a Paradigm X-20 crossover if you can find one used. Speaker level in - RCA out. Phase, frequency, and level control included.
Here is the actual LOC circuit along with a very succinct explanation
http://www.epanorama.net/circuits/speaker_to_line.html

Study it. This is exactly what I did. It was worth it to me to install this circuit- really nothing more than 2 resistors and one short length of wire per channel- inside my amp. It is however a very simple circuit. Keep in mind it does not matter at all where this circuit is located. When you buy a sub with speaker level inputs the exact same circuit will be used only inside the sub. 

Also like the above link explains these are 1/4 watt resistors. They can be so small because hardly any power goes through them. Regardless of volume. Regardless of your amps power. Regardless of how much you turn it up. The difference between one LOC made for high power and one for lower power is not the resistor wattage. Its the resistor value. The 10k resistor isn't used to pass power. Its used to attenuate. A bigger amp would use a 20k or greater resistor, but it would be the same 1/4 watt value.

What this means, being so small, no heat output, you can put it anywhere. You could practically wire it into an interconnect if you wanted.

Also the parts are like $2. Total. Quality just does not matter. It might if you were using it to listen to the full range signal. In this case though, low bass only, waste of money.

How you do this depends on a lot of things I just can't know. What you like the looks of, for example. What interconnects you're using. What you may or may not be comfortable soldering or modding. You could for example very easily remove the RCA from the end of one interconnect, solder the resistors, and attach the wires at the end to your amps speaker binding posts. Direct from the speaker outs to your RCA ins.

That one link above, just the one page, contains a wealth of information. You just have to figure out your best way of making use of it. I did, and mine works and looks just as good as any professionally built component. Yours can too. You just have to decide how you want to do it. Heluva lot less work than boxing and shipping. Lot more satisfying too.