# Advice on connecting CX2310 and DSP1124P



## Guest (May 15, 2007)

I'm new to Home Theater Shack. I'm hoping someone can tell me if I'm on the right track in connecting my components.

I have an older Carver CT-17 preamplifer/tuner which is capable of Dolby Pro Logic but does not have a dedicated subwoofer output (LFE?). Power is supplied by a Carver M-1.0t amp. My main speakers are a pair of KEF Q15.2 with a new Velodyne DPS-12 subwoofer. I want to use this equipment in stereo mode for music only.

I recently purchased a Feedback Destroyer Pro DSP 1124P on eBay to use with REW for tuning the subwoofer. I want to separate the full frequency output from the preamp into high frequencies routed to the KEFs by way of the M-1.0t and low frequencies routed to the DSP1124P and then to the Velodyne's line level inputs. My problem is creating a mono low frequency channel from the preamp's stereo full frequency range output to the DSP1124P as a mono input. My reading of the Home Theater Shack's forums tells me I can't use a simple Y connector to combine two channels into mono. It also appears that forum members are accomplishing this task using a Paradigm X-30 active crossover which I could not locate anywhere (I got outbid for one on eBay). Then I saw forum input that said the Behringer CX2310 crossover can perform the same function as the X-30. I picked up a CX2310 from a Home Theater Shack member.

So, using the appropriate cables and connectors, I want to route the stereo full frequency output from the CT-17 preamp to the CX2310 crossover; I want the crossover to create two outputs: one, a stereo high frequency signal to the M-1.0t amp powering the KEFs and second, a mono low frequency signal to the DSP 1124P and then on to the subwoofer. Will this work? Am I going to have problems finding cables and connectors for the mixed set of balanced and unbalanced connections on my components? The Carver preamp, Carver power amp, and Veledyne subwoofer all have unbalanced RCA connections. The Behringer CX2310 and DSP 1124P have only balanced connections. 

Any advice you could give me would be greatly appreciated.

Tom Zilinsky


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## brucek (Apr 11, 2006)

> Am I going to have problems finding cables and connectors for the mixed set of balanced and unbalanced connections on my components?


Both those components allow either unbalanced or balanced operation. For unbalanced operation from an RCA to XLR connector, you short pins 1 and 3 for the ground signal and pin 2 is the hot signal. That's a standard connection. You will have no problem finding that cable.

brucek


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## Guest (May 15, 2007)

Thanks for the info on connectors. Next stop Radio Shack or Google. I'm going to assume since you didn't comment specifically on the overall configuration, you think it will work.


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## brucek (Apr 11, 2006)

Will you be feeding your mains with a low and high signal?

By this I mean, does the Carver power amp have 4 channels to accept the left and right low and high separated signals from the CX2310?

EDIT: I just looked up that Carver amp and found that it's stereo...... so I guess I am wondering (after looking at the CX2310 manual) whether you can just use the 2310 as a crossover between sub and mains? The mains left and right channels are each split into a low and high output (in addition to the mono mixed sub out).

brucek


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## Guest (May 16, 2007)

I'm hoping to feed only one stereo signal to my mains. You anticipated my next question ... I guess I'll just have to try it to see. I'm hoping I can set the frequency range of one of the 2 upper channels wide enough to reach from the upper frequency of the sub to the top frequency of my KEF mains and just not use the other channel. 

Worst case scenario is that I have to use both upper channels. The KEFs can be biamped, but I'd have to use my old JVC receiver or my old Denon integrated amp for the extra power. I don't really want to do that, nor do I want to buy another power amp right now.

I took a sight seeing tour of my local Radio Shack today, and just as you said, I'll have no problem finding the cables and connectors I'll need.

Tom Zilinsky


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## brucek (Apr 11, 2006)

> I guess I'll just have to try it to see. I'm hoping I can set the frequency range of one of the 2 upper channels wide enough to reach from the upper frequency of the sub to the top frequency of my KEF mains and just not use the other channel.


Yeah, I'm a bit confused from reading the manual. A few diagrams would have been nice. Behringer manuals are always a bit weak.

I would probably use REW to determine the repsonse of the various channels of the CX2310 and get it set up that way first. See this thread regarding the subject of using REW as a response checking tool for any line level device.

brucek


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## Wayne A. Pflughaupt (Apr 13, 2006)

This crossover is more correctly a 2.1 than a “two-way stereo” (Behringer’s words). Item #14 on Pg. 8 of the manual says that the crossover knob in the “Subwoofer” section adjusts the crossover frequency between the *low signal* and the subwoofer signal. Basically, what you will need to do is use only the “high” output, and sub “mono sub” output. Setting the rear-panel switch to “ x1” will allow the high output to go as low as 44 Hz. You’ll then have to adjust the subwoofer crossover, seperately, to match.

Alternately, you could just use the “low” outputs and find a way to combine them into a mono signal. That shouldn’t be too hard. The sub section apparently will still be active, so you’d have to set the crossover frequency all the way down (10 Hz). That might be a problem with home theater, but not for the music-only application you intend to use. If your sub has stereo inputs, you could just keep everything two-channel all the way to the sub and let it do the summing.

That’s some pretty nice gear you have, and frankly I find the prospect of inserting a sub-$100 pro-audio component in the signal chain a bit disconcerting. I briefly used a pro crossover that cost over $300, and it audibly degraded sound quality. The CX’s +0/-3 dB frequency response spec should raise eyebrows, since we don’t know if the –3 dB above or below 20Hz – 2 kHz, or somewhere in between. Be on the look out for that when you run it through REW to optimize the crossover settings.

I addition, I suggest doing a listening test, setting your KEF’s side by side, running one side through the Behringer, and one side straight, to make sure you aren’t getting any unwanted artifacts.

Regards,
Wayne


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## Guest (May 16, 2007)

Quote:
"I would probably use REW to determine the repsonse of the various channels of the CX2310 and get it set up that way first. See this thread regarding the subject of using REW as a response checking tool for any line level device."

I read the thread you suggested. It is a little intimidating for someone who has not yet installed REW or plugged in a CX2310 or DSP1124P. Interpreting the graphs correctly could also be a challenge. However, I'm looking forward to giving it a try.

Quote:
"This crossover is more correctly a 2.1 than a “two-way stereo” (Behringer’s words). Item #14 on Pg. 8 of the manual says that the crossover knob in the “Subwoofer” section adjusts the crossover frequency between the low signal and the subwoofer signal. Basically, what you will need to do is use only the “high” output, and sub “mono sub” output. Setting the rear-panel switch to “ x1” will allow the high output to go as low as 44 Hz. You’ll then have to adjust the subwoofer crossover, seperately, to match."

Thanks for this configuration info. I would have missed the "x1" switch info.

Quote:
"That’s some pretty nice gear you have, and frankly I find the prospect of inserting a sub-$100 pro-audio component in the signal chain a bit disconcerting. I briefly used a pro crossover that cost over $300, and it audibly degraded sound quality. The CX’s +0/-3 dB frequency response spec should raise eyebrows, since we don’t know if the –3 dB above or below 20Hz – 2 kHz, or somewhere in between. Be on the look out for that when you run it through REW to optimize the crossover settings."

I read the same warning elsewhere in the Home Theater Shack forum. But I also saw some differences of opinions from people saying they used the crossover with some premium gear without problems. I figured for the price, it is worth a try.

Quote:
"I addition, I suggest doing a listening test, setting your KEF’s side by side, running one side through the Behringer, and one side straight, to make sure you aren’t getting any unwanted artifacts."

This test should tell me if the crossover is transparent in my setup.

I thought of one more configuration that may work and take the CX2311 out of signal chain to the mains. I could use Y connectors at the preamp outs to split each stereo channel in two. I could then send one set of L/R signals directly to the power amp (bypassing the crossover) and on to the mains. The other set of L/R signals I could route to the crossover to the BFD and on to the subwoofer. However, I would be concerned that the differences in signal chain length may give me a timing (maybe phasing is the correct term) problem between the mains and the subwoofer.


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## brucek (Apr 11, 2006)

> However, I would be concerned that the differences in signal chain length may give me a timing (maybe phasing is the correct term) problem between the mains and the subwoofer.


No, that's not a problem. Electricity travels near the speed of light in a wire depending on its velocity factor. This speed is approximated to about a nanosecond a foot. The accepted explaination would be that if you had one wire 50 feet longer than the other, then that signal would arrive about 50 nanoseconds later than the first. Well, this is about 1000 times less than human hearing can even begin to detect, so don't worry about the lengths of your cables and phase differences.

The worry is that the mains would enjoy a full range signal and the sub would be doubling up on some of those frequencies. That's the reason for bass management. If you did this, I would cross the subwoofer fairly low, so as to take advantage of the natural rolloff of the mains.

brucek


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## Guest (May 17, 2007)

Quote:
"so don't worry about the lengths of your cables and phase differences."

Thanks ... that's good news.

Quote:
"The worry is that the mains would enjoy a full range signal and the sub would be doubling up on some of those frequencies. That's the reason for bass management. If you did this, I would cross the subwoofer fairly low, so as to take advantage of the natural rolloff of the mains."

I'm counting on REW, the Radio Shack SPL, and the Feedback Destroyer to help me get the crossover for the sub correct. I'm out of questions on this subject for now. Looking at my calendar controlled by my wife, it may be a couple of weeks before I can dig into this project with vigor. I'll probably have more questions then. I really appreciate your prompt and useful responses.

Tom Zilinsky


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## Chrisbee (Apr 20, 2006)

Tom

I'm sorry I haven't noticed this thread before. I rarely look in on this forum.

I'm using a CX2310 & BFD1124 in my Naim stereo system exactly as you wish to do in your own system. I don't have a receiver though I do use a Yamaha DSP800 processor just to obtain center and rear channels for 5.1 surround on films. 

With the processor switched off I return to pure stereo with the processor completely bypassed by the preamp selection for music listening.

I have the CX2310 between my Naim preamp and my two power amps. The IB sub is driven by a dual mono pro power amp. (EP2500) with the speakers driven by my Naim stereo power amp. 

I used XLR cables throughout. The BFD is used only on the "Low" channels on the CX2310 to feed the subwoofer amp. 

I operate in stereo (actually dual mono) throughout including the feed to my IB subwoofer's dual mono amplifier. 

With an active sub you have a choice of using the mono Subwoofer out on the CX2310. Or using one of the dual mono channels for your sub's own amp. 

It all works a treat and the only thing you'll notice from inserting a CX2310 into your system is the greater clarity, better dynamic range, micro-detail and imagery from rolling off your speakers bass at around 80Hz. The increased sense of reality is remarkable considering the low price of the of the CX2310.


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## Guest (May 22, 2007)

Chrisbee,

Thanks for the assurance I can make this configuration work and that the "inexpensive" CX23120 can improve the performance of a setup with premium gear.

I was thinking of using those 1/4" plugs for the DSP1124P connections but for some reason I didn't like that idea. I'm going to follow your lead and use XLR cables everywhere I can.


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