I know there are numerous threads on the topic but I just received my C12000 Pre-amp and am trying to figure out the best way to install the subwoofer for a 2 channel setup. My sub is a PSA TV21-IPAL. I've attached the diagrams of both units. I currently have the subwoofer hooked up with one RCA cable going from each 'main' outputs on the top left and right of the C12000, going to the left and right rca input on the Subwoofer. It works, but it just doesn't seem like I'm getting the proper amount of bass going to the 21" sub. I feel like I have something wrong. Any help would be greatly appreciated!
Need Help, C1200 Subwoofer hookup
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That’s what I’d do, run either the L/R unbalanced main out or the L/R balanced main out, whichever you have left over. There’s a crossover control, have you fooled around with that to see if that helps? The room size control might tweak the output a bit as well.
W9TR
Super Member
I have a C1100 so similar. You have two stereo balanced XLR outputs #1 is solid state and #2 is tube.
I would run one output to your main amps, probably the tube out, and run the other via XLR's to the XLR sub inputs.
Both outputs can be turned on and off independently from the remote. Your mains will be running full range in this arrangement since the C1200 doesn't have a crossover.
I would run one output to your main amps, probably the tube out, and run the other via XLR's to the XLR sub inputs.
Both outputs can be turned on and off independently from the remote. Your mains will be running full range in this arrangement since the C1200 doesn't have a crossover.
I do not believe there is a crossover on the C12000.
You are correct about this. However other than the sub, they are completely separate systems. No connections between the two systems. The MX123 is never turned on when the C12000 is being used. Could this still be causing some type of problem?
I tried this and it didn't seem to make much difference. The sub only has 1 XLR input so i could only run the right or left side into it from the pre-amp. Would an XLR 'Y" cable be the answer here? I also want to state the the sub works fine. While hooked up to the MX123 and watching a movie, it just about knocks the house down, unbelievable sub actually!
damacman
Resident Psycho
To clarify, you cannot have cables from both preamps connected to the subwoofer simultaneously - regardless of whether a given preamp is on or off. And you shouldn't really need to do what you're trying to do to begin with.
Traditionally, when using the PassThru feature with a Mc 2-ch preamp, you don't want a subwoofer connected - unless your main speakers are bandwidth limited. So, here would be your choices:
C12000 / MC462 > Main speakers only
Turn the MX123 ON and the Mains become Front L&R via the PassThru feature of the C12000
Now, if you also desire to use the subwoofer on occasion with just the above, then set up the 2 Channel Playback in the MX123 so that the fronts L&R are set to Small, the subwoofer is active, distance settings, etc. Simply turn on the MX123 and set it to the 2 Ch Stereo mode. That's the easiest (and best) way to accomplish what you're after.
One of the challenges, generally speaking, is that most modern AVPs have every single feature under the sun when it comes to managing an active subwoofer. Therefore, it's best to choose a subwoofer that has either no crossover / eq etc or one that has the ability to disable all of that. Otherwise, you've got crossovers cascaded, EQ on top of EQ, etc. Your sub appears to even have a delay setting - a feature that could absolutely screw with the room calibration (Audyssey) of the MX123. Fortunately for you, it looks as if that can be set to 0ms (fully CCW) and the crossover bypaseed (fully CW). So, those are the settings you want with this sub and your MX123.
The picture you posted shows a left and right XLR input on the sub and a left and right unbalanced on the sub, so I don't understand your comment about only 1 XLR input.
I would not leave the both the MX123 and C12000 connected to the sub at the same time, even if one of the preamps is off. (Read the owner's manual to verify this.)
Are you using the same speakers for stereo and HT front or are you just sharing the sub between two sets of speakers?
You need to gain match the sub to main speakers (so they play at the same loudness) which involves the differences in gain between the main speaker amps, the efficiency of the main speakers and the gain and efficiency of the powered sub (which has a gain control). This setup may be different between the two preamps and also if you're using two different sets of main speakers. E.g., if the main speakers are efficient, the sub may not be able to match it's loudness level to the mains even if the gain control is all the way up so then you'd have to attenuate the gain (somehow) on the main speakers amp to match.
If you used the sub output of the MX and ran an automatic setup with a test microphone, the MX would likely automatically match the sub vs. mains output. But the C12000 will not, so you have to figure that out.
I never like contradictory advice and I hope posts #9 and #10 are not. But if they are it's because of lack of clarity in my post #10.
To try to clarify, I think we agree that the MX123 can be used with the subwoofer and the MX will handle the set up and integration with the main speakers automatically if you run through the setup procedures.
Post #9 says that you should not use the sub directly from the C12000 and should only us it with the MX and to use passthrough mode on the C12000.
I assumed (from post #1) that you want to use your sub both ways: with the MX or with the C12000 without the MX in the circuit and with sources connected to the C12000. E.g. you'd want to use the phono preamp in the C12000 and not the MX.
You can use the sub with the C12000 but it won't be easy. You'll have to integrate it manually (gain match, delay, crossover point). You will also have to manually reconnect the sub every time you switch preamps including setting the controls on the sub differently for each preamp every time you switch. You may need to hire someone to help with such an integration setup - maybe a dealer consultant.
Or you could take the advice of post #9 which is a good advice.
To try to clarify, I think we agree that the MX123 can be used with the subwoofer and the MX will handle the set up and integration with the main speakers automatically if you run through the setup procedures.
Post #9 says that you should not use the sub directly from the C12000 and should only us it with the MX and to use passthrough mode on the C12000.
I assumed (from post #1) that you want to use your sub both ways: with the MX or with the C12000 without the MX in the circuit and with sources connected to the C12000. E.g. you'd want to use the phono preamp in the C12000 and not the MX.
You can use the sub with the C12000 but it won't be easy. You'll have to integrate it manually (gain match, delay, crossover point). You will also have to manually reconnect the sub every time you switch preamps including setting the controls on the sub differently for each preamp every time you switch. You may need to hire someone to help with such an integration setup - maybe a dealer consultant.
Or you could take the advice of post #9 which is a good advice.
Ok lots of good stuff to digest here and I really thank everyone for the help! The owners manual for the sub that I posted above apparently doesn't match my sub. I've attached a photo of the one xlr input. Regardless, post #9 seems to be the direction I should head. When I bought all of the components, my intention was to have a clean 2 channel system containing the preamp, the mc462, the mcd12000 and a turntable and connect them to my Focal Electras. (I have Sopras inbound, just sold the Electra's) I also wanted a home theater setup so that is where the MX123 and the MC255 come into play. I have 3 MK S-150's for my fronts and 2 Klipsch rears. I also have 2 of those 21" subs and my inital plan was to just use of the subs for the 2 channel setup but use both of them for movies and what not. I know it's a bit convoluted but my Mac dealer assured me I was on the right track. Now that you know everything that I have, what is the best way to hook it all up? I almost feel like I wasted money at that C12000 pre-amp if I am going to running everything through the mx123 anyways.
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W9TR
Super Member
To answer your 'Y' connector question - using a 'Y' connector that ties two outputs together is not a good idea. It shorts the outputs together, and depending on how the outputs are designed, may cause sonic degradation or a failure. Taking an output and 'Y' ing it to two inputs is no problem.
OK, your last post was very helpful. Got it. Totally separate systems apart from the subwoofers. You do not need to run everything through the MX 123 or use the C 1200 in pass-thru. This is a unique setup but then, hey, not everybody has STEREO 21" subs! How cool is that?
Each sub has three inputs: L, R, and a balanced input. They do essentially the same thing as all three inputs drive a single amplifier in each speaker. So you can hook both systems up to the subs at the same time and only use one system at a time.
I'm not familiar with the MX 123 but looking at the back panel it has two balanced sub outputs, SW1 and SW2. These could go to each sub. The C 1100 has unbalanced outputs you could run to each subwoofer.
You may be able to reverse this setup, but you'd need to dig into the MX 123 manual to see if it has 2 unbalanced RCA sub outputs. Can't tell from looking at the back panel.
You would set up the subs first with the C 1200 to get the levels and crossovers set correctly on the subs for 2 channel listening. This will take a test CD with the right subwoofer setup tones and an SPL meter.
Then you'd fire up the MX 123 and set it up. You do it in this order because the MX 123 has adjustable sub output levels, crossovers, Audessy, etc. where the C1200 does not.
Make sense?
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With the Sopra’s published response down to 33Hz (+/-3dB) you should be able to reproduce most any music that there is accurately. I agree that a subwoofer can enhance bass and if set up correctly (mains high-passed, subwoofer low-passed correctly) it also is a great help if your amplifier were struggling to keep up with the power requirements, but I doubt that is a problem if you are running them from an MC462.
I certainly agree with the above that it should not have two preamps plugged into it simultaneously. Preamplifiers are like having a small / low-power amplifier output on the line-level (whether RCA or XLR), if you hook two preamps’ outputs to the same device you are electrically coupling them and therefore driving into one preamp’s output from the output of the other. Whether this will do harm or not is something that you can ask your dealer (provided he will cover the cost of repairing both if he is wrong), it can also have sonic consequences if it creates a load on the other preamp’s output. If one is balanced and the other unbalanced there is some decoupling, but without having all of the schematics in front of me I wouldn’t say that clears you either.
The current problem with bass output on your 2.1channel setup might be phasing, possibly your speakers are out of phase with the subwoofer and if it doesn’t have a phase switch, you might need to reverse + and - on your speakers (or speaker outputs on the amplifier). Connect only your 2-channel rig to the subwoofer, then see if it sounds okay without the other preamp in the mix.
I certainly agree with the above that it should not have two preamps plugged into it simultaneously. Preamplifiers are like having a small / low-power amplifier output on the line-level (whether RCA or XLR), if you hook two preamps’ outputs to the same device you are electrically coupling them and therefore driving into one preamp’s output from the output of the other. Whether this will do harm or not is something that you can ask your dealer (provided he will cover the cost of repairing both if he is wrong), it can also have sonic consequences if it creates a load on the other preamp’s output. If one is balanced and the other unbalanced there is some decoupling, but without having all of the schematics in front of me I wouldn’t say that clears you either.
The current problem with bass output on your 2.1channel setup might be phasing, possibly your speakers are out of phase with the subwoofer and if it doesn’t have a phase switch, you might need to reverse + and - on your speakers (or speaker outputs on the amplifier). Connect only your 2-channel rig to the subwoofer, then see if it sounds okay without the other preamp in the mix.
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I will definitely double check the phasing. The room is quite large with vaulted ceilings with a loft upstairs so it eats low end like crazy. My 1038be Electras didn't have a chance without a sub.
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Sorry I edited the previous response after you quoted it.
“Eats low end like crazy” sounds more like cancellation than anything, and cancellation (a 180* out of phase reflection) does not go away with more power as more power creates more reflection/cancellation. Placement and room treatments are the better solution.
Have you measured your system’s response in the room to see what reflections might be causing problems? BTDT with a 54Hz cancellation from a back wall, can wreak havoc until you tame that reflection.
“Eats low end like crazy” sounds more like cancellation than anything, and cancellation (a 180* out of phase reflection) does not go away with more power as more power creates more reflection/cancellation. Placement and room treatments are the better solution.
Have you measured your system’s response in the room to see what reflections might be causing problems? BTDT with a 54Hz cancellation from a back wall, can wreak havoc until you tame that reflection.
I meant the control on the subwoofer ...