Adding Subwoofer to CAM's - Using Separates, Best Means Of Connecting Things Up?

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Slapshot

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I ordered a pair of CAM's some months back and couldn't be happier. Wonderful speakers They simply need the augmentation of a small subwoofer in my small room for certain types of music (12.5x9.5). I had seen a couple options about the best way to connect them up to my two channel system comprised of a preamplifier, power amplifier, DAC and streaming/network device. I have the highly rated SVS Mini 3000 subwoofer on the way.
I asked the question as to the optimum way to connect the sub into my system and received a stream of replies, including from a Stereophile reviewer, emphasizing that the only ideal way of correctly connecting it involved some incredibly complex and expensive options. Many of these options cost more than the subwoofer itself! I have to believe there are any number of people here running Omega's, and likely CAMs, with subwoofers. How are you accomplishing this and what has your experience been? Any help would be appreciated. Thanks.

jMelvin

Many believe speaker-level connection is best for sound quality. In fact, Louis told me as much when I ordered my DeepHemp 8. Easy and no need for expensive cables.

Dako

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I agree with jMelvin. Speaker level inputs are best. I have an Omega 8 inch sub and Super 8 XRS speakers. I simply have my main speaker cables with spades under the binding posts on my amp. The I have another set of cables with bananas inserted into those same binding posts. Simple, cost effective and great sounding.

This is the same setup you should consider.

Dave

Dieterle Tool

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Although there are some conditions where speaker level works adequitely, there are a lot of reasons it doesn't: Here is an excerpt from Rythmik's faq's page on speaker level hook up:

"We do sell models with speaker level inputs. But we do think that is a temporary solution rather than a "better sounding" solution. There are many reasons against speaker level inputs (mainly because using speaker level inputs mean the front speakers need to run full range signal):

1) Front speaker cone excursion is not reduced: Cone excursion goes up 4x for every octave lower in frequency. So 40hz needs 4x more excursion than at 80hz. And large cone excursion increases distortion and in particular "intermodulation distortion" (higher frequency (small excursion) signal is modulated by low frequency (large excursion)). The correct way to address this is put a high pass filter (HPF) on front speakers in order to reduce the cone excursion. This issue is particularly bad for ported front speakers as you may notice with full range signal, woofer in ported speakers have far more excursion than that in sealed front speakers. With the cone excursion reduced, the distortion from the front speakers is also reduced and the sound becomes more dynamic and coherent.

2) Bass response is not flat: No speaker designers will concede that his speakers need the help from subwoofers. So they will make their speakers sound more bassy as stand alone. The common trick is "bump then roll-off" which essentially is a high Q roll off with long ringing time. I believe this trick is first used in BBC LS3/5A. The plot below is from a close-mic measurement which does not account for the step up response above 150-200hz as the baffle width reflects more and more acoustic energy. Still it is easy to see this "bump then roll-off" trick. The consequence of this trick is the bass becomes almost one-note, artificial, and fatiguing. To correct that you need a HPF to roll-off the front speakers at frequencies high enough it will attenuate this characteristic. Without HPF, you will still hear emphasis (and therefore coloration) from the front speakers.

3) Not feasible with large ported floorstanding speakers: If your front speakers are large ported floorstanding speakers, they are the most difficult to integrate because those speakers already go down to 30hz or 20hz. Now customers want to extend to 10hz. But the frequencies below 30hz are not very audible. Without a measurement microphone, It becomes very difficult to adjust phase on the subwoofer so that subwoofer and front speakers are phase aligned. If HPF is used, the crossover point would have been increased from 30hz to something like 70hz or 80hz. At those frequencies, it is much easier to tell by ear if phase alignment is correct. In our experience, most customers in this group will return the subwoofers unless they use HPF.

4) Tube power amplifier issue. If your power amplifier is tube-based, then speaker level input method has one additional drawback. Tube power amplifiers are known to have low damping factor (DF). Low DF means the frequency response from tube power amp is highly load dependent. If one connects to 5 different speakers, it gives you five different frequency response curves at the power amplifier outuput. Sonically bass has always been the weakness of tube power amps with bass often perceived as sloppy and under-controlled. Stereophile has been publishing deviation of FR using their pseudo speaker load when reviewing tube power amplifiers. The plots show wavy frequency response. If one uses the tube power amp output to drive subwoofer inputs, the same sloppy/ill-controlled bass from the front speakers will transfer to subwoofer and also make subwoofers sound sloppy and under-controlled.

5) Can lead to damage when connected to fully complementary class-D power amplifier. Our speaker level inputs are designed with single-ended power amplifier outputs in mind. "Single-ended" means the red speaker terminal (+) carrys hot signal and black terminal (-) is true ground. Accidentally touching the black terminals from both channels will not lead to amplifier damage. Some class-D power amplifiers are single-ended while the majority are fully complementary which means the black terminals at the back of power amplifiers are not true ground. Instead, the black or (-) terminal has an opposite polarity of the red or (+) terminal. Accidentally touching the black terminals from both channels can lead to amplifier damage."

Also, is your sub a "Micro" 3000 maybe? See nothing on "Mini". From the stock photo, the Micro does not provide speaker level inputs. Only rca, interconnect from your preamp (secondary) output. I bought a pair of these to try with preamps without a secondary output, BUT I haven't had the need to try it yet.




-Dieter

Slapshot

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Although there are some conditions where speaker level works adequitely, there are a lot of reasons it doesn't: Here is an excerpt from Rythmik's faq's page on speaker level hook up:

"We do sell models with speaker level inputs. But we do think that is a temporary solution rather than a "better sounding" solution. There are many reasons against speaker level inputs (mainly because using speaker level inputs mean the front speakers need to run full range signal):

1) Front speaker cone excursion is not reduced: Cone excursion goes up 4x for every octave lower in frequency. So 40hz needs 4x more excursion than at 80hz. And large cone excursion increases distortion and in particular "intermodulation distortion" (higher frequency (small excursion) signal is modulated by low frequency (large excursion)). The correct way to address this is put a high pass filter (HPF) on front speakers in order to reduce the cone excursion. This issue is particularly bad for ported front speakers as you may notice with full range signal, woofer in ported speakers have far more excursion than that in sealed front speakers. With the cone excursion reduced, the distortion from the front speakers is also reduced and the sound becomes more dynamic and coherent.

2) Bass response is not flat: No speaker designers will concede that his speakers need the help from subwoofers. So they will make their speakers sound more bassy as stand alone. The common trick is "bump then roll-off" which essentially is a high Q roll off with long ringing time. I believe this trick is first used in BBC LS3/5A. The plot below is from a close-mic measurement which does not account for the step up response above 150-200hz as the baffle width reflects more and more acoustic energy. Still it is easy to see this "bump then roll-off" trick. The consequence of this trick is the bass becomes almost one-note, artificial, and fatiguing. To correct that you need a HPF to roll-off the front speakers at frequencies high enough it will attenuate this characteristic. Without HPF, you will still hear emphasis (and therefore coloration) from the front speakers.

3) Not feasible with large ported floorstanding speakers: If your front speakers are large ported floorstanding speakers, they are the most difficult to integrate because those speakers already go down to 30hz or 20hz. Now customers want to extend to 10hz. But the frequencies below 30hz are not very audible. Without a measurement microphone, It becomes very difficult to adjust phase on the subwoofer so that subwoofer and front speakers are phase aligned. If HPF is used, the crossover point would have been increased from 30hz to something like 70hz or 80hz. At those frequencies, it is much easier to tell by ear if phase alignment is correct. In our experience, most customers in this group will return the subwoofers unless they use HPF.

4) Tube power amplifier issue. If your power amplifier is tube-based, then speaker level input method has one additional drawback. Tube power amplifiers are known to have low damping factor (DF). Low DF means the frequency response from tube power amp is highly load dependent. If one connects to 5 different speakers, it gives you five different frequency response curves at the power amplifier outuput. Sonically bass has always been the weakness of tube power amps with bass often perceived as sloppy and under-controlled. Stereophile has been publishing deviation of FR using their pseudo speaker load when reviewing tube power amplifiers. The plots show wavy frequency response. If one uses the tube power amp output to drive subwoofer inputs, the same sloppy/ill-controlled bass from the front speakers will transfer to subwoofer and also make subwoofers sound sloppy and under-controlled.

5) Can lead to damage when connected to fully complementary class-D power amplifier. Our speaker level inputs are designed with single-ended power amplifier outputs in mind. "Single-ended" means the red speaker terminal (+) carrys hot signal and black terminal (-) is true ground. Accidentally touching the black terminals from both channels will not lead to amplifier damage. Some class-D power amplifiers are single-ended while the majority are fully complementary which means the black terminals at the back of power amplifiers are not true ground. Instead, the black or (-) terminal has an opposite polarity of the red or (+) terminal. Accidentally touching the black terminals from both channels can lead to amplifier damage."

Also, is your sub a "Micro" 3000 maybe? See nothing on "Mini". From the stock photo, the Micro does not provide speaker level inputs. Only rca, interconnect from your preamp (secondary) output. I bought a pair of these to try with preamps without a secondary output, BUT I haven't had the need to try it yet.




-Dieter

-Dieter, thanks very much for that information. You are correct that I will be using the SVS Micro 3000. I actually have a pair of AudioQuest splitters, a syou show in the phot being delivered tomorrow. I will give them a shot given the issues you have pointed out concerning using speaker level connections. Especially as I am using a tube amp.

Dieterle Tool

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  • I don't know what it is, but I wunt it.
^ Yep, try both ways for sure. Also try SVS support if you haven't already. That looks like a nice sub with some flexibility, they should be able to help out.

opnly bafld

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  • Kegger/Blueglow/diy SET KT66/88
1) Most subwoofers don't high pass on the RCA inputs.
2) Don't buy tiny speakers with a bass bump to use with a subwoofer or if you don't mind a bass bump why does adding a sub change that.
3) Never had a problem integrating a sub with large speakers (actual I found it much easier many times).
4) Most people I know that use tube amplifiers are especially adamant about using speaker level.
5) Use whatever speaker level hook up that is necessary for your particular amp.

or
6) Use the RCA connections if you want (and have a system that supports it).

Slapshot

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  • Posts: 138
1) Most subwoofers don't high pass on the RCA inputs.
2) Don't buy tiny speakers with a bass bump to use with a subwoofer or if you don't mind a bass bump why does adding a sub change that.
3) Never had a problem integrating a sub with large speakers (actual I found it much easier many times).
4) Most people I know that use tube amplifiers are especially adamant about using speaker level.
5) Use whatever speaker level hook up that is necessary for your particular amp.

or
6) Use the RCA connections if you want (and have a system that supports it).

I spoke at length to SVS and they were extremely helpful. They even looked up the manual for my Conrad Johnson preamp. They informed me that using the second audio output and connecting that to the audio input connections at the sub were definitely the way to go. Just need to locate a pair of interconnects of sufficient length now,

Kray

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I have both a tube amp and a solid state.

My SS is best with speaker level connector to my REL (using the special neutrik speakON) 3 wire connection)
My tube is best with RCA connection from my 2nd output on my preamp. which I have a Y connector to send a single connector into the REL. This way I could also use two subs left/right if I every wanted.

Above connections are completely silent.
If I use the speaker connection on tube amp, the REL audibly hums.

opnly bafld

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  • Kegger/Blueglow/diy SET KT66/88
If I use the speaker connection on tube amp, the REL audibly hums.

What amplifier? Some need to be hooked up different.
2 Subwoofers, another way to solve the hum problem.  :D

Kray

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What amplifier? Some need to be hooked up different.
2 Subwoofers, another way to solve the hum problem.  :D

421a

I only have the speakon 3 wire cable.




RDavidson

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I use CAMs with an SVS sub. I've had this setup for years. I use line level (RCA) connection for my sub from my preamp. Everyone has different systems, rooms, and experience. Use the simplest connection, which is also what SVS is recommending to you.

For the record, I've never understood why folks believe speaker level connection is best for a sub. Maybe in some cases it is better, but it just seems odd to me. I'm hoping someone can explain the technical advantages even if it may not be best for all situations. But I digress. Here is why speaker level connection seems odd to me : In a typical system with separates, one would connect their preamp to their main amp with a line level connection. From there one would connect the amp to the speakers with a speaker level connection. A subwoofer has an amplifier. That amplifier is connected to the bass driver via speaker level connection. So...why is the connection of the sub to the system treated differently than the line level connection of main amp to the preamp? I've seen some argue that by hooking the sub up via speaker level connection that the sub is better able to integrate with the mains because the mains and the sub are receiving the signal from the main amp at the same time. The problem is that's not really true. You have to remember there's another amplifier in the chain, the one that's in the sub. From there, the signal goes through more circuitry (including likely a crossover and phase control) then finally makes its way to the bass driver. In essence, the sub is being moved further down the line and receiving the signal a bit later than the mains due to insertion of the sub's amp and crossover circuitry in the chain. Doesn't it make more sense (perhaps in more cases than not) to hook the sub up via line level connection where it would receive a signal at (theoretically) the same time the main amp would receive a signal? Would this in most cases make integrating with the mains easier? :scratch:

At the end of the day, perhaps the connection method matters very very little, because one has to place the sub in their room for best integration with the mains anyway. Proper placement trumps whatever advantages speaker level or line level connections may have versus each other all day long.

opnly bafld

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  • Kegger/Blueglow/diy SET KT66/88
421a

I only have the speakon 3 wire cable.


Check with the builder first to see if this is okay, some tube amps like Decware SE need a jumper for the black wire to both negative posts to eliminate hum.
Do not do this to any amp without checking if this okay and will not damage the amplifier.