efjay
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Post by efjay on Dec 14, 2012 15:16:43 GMT -5
I have a UPA-2. I want to add a subwoofer to my system but my pre-amp does not have either a second set of variable outputs or a dedicated subwoofer output. Is there any reason I can't hook the UPA-2 to the sub's high level (speaker level) input then output to the speakers (assuming I wish to use the sub's crossover) or piggy-back the banana plugs utlizing the high level input? I assume the answer is that there would be no issue but better safe than sorry.
Thanks in advance.
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Post by AudioHTIT on Dec 14, 2012 15:41:19 GMT -5
If your subs have the high level (speaker) ins and outs, then it should work fine.
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Post by Jim on Dec 14, 2012 15:43:08 GMT -5
Do you know if the sub woofer's crossover works on the high level inputs?
Also, whether you can do it - somewhat depends on the impedance of the subwoofer and your speakers. You'd be running in parallel - so it would dramatically lower the impedance.
What kind of sub do you have and what kind of speakers?
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efjay
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Post by efjay on Dec 14, 2012 16:01:08 GMT -5
I haven't chosen a sub. My speakers, a pair of Canton bookshelves are 8ohms. But, I've always understood it to be that a powered sub does not present any load to my amplifier.
As for the crossover, I can't answer that as I haven't bought picked a sub yet. Several I've looked at have a 80hz filter when using the high level output however.
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Post by Jim on Dec 14, 2012 16:04:30 GMT -5
I haven't chosen a sub. My speakers, a pair of Canton bookshelves are 8ohms. But, I've always understood it to be that a powered sub does not present any load to my amplifier. As for the crossover, I can't answer that as I haven't bought picked a sub yet. Several I've looked at have a 80hz filter when using the high level output however. Why not just use a Y cable? Feed the line output to the UPA2-speakers, and the other line level to your sub? If you're using the amp of a powered sub - you need to give it a line level input (not high level). If you're feeding a sub with high level inputs - that is definitely a load to the amp (and the internal sub amp isn't being used). |
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efjay
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Post by efjay on Dec 14, 2012 16:25:30 GMT -5
If you're using the amp of a powered sub - you need to give it a line level input (not high level). If you're feeding a sub with high level inputs - that is definitely a load to the amp (and the internal sub amp isn't being used). With all due respect, I'm not certain that is entirely accurate. First, the subwoofer, assuming it is a powered version, will certainly use its own amplifier even when receiving a signal via speaker level connection. Second, as the amp is not powering the subwoofer, I'm not sure why there would be any change in overall impedance. My concern is largely with grounding issues. Some amp manufacturers, Musical Fidelity for example, make explicit mention of not connecting specific amps of theirs directly to the speaker level input of a powered sub. As the UPA-2 is not a class D design, and that have been the only companies I've seen make such warning (Nu-Force being another), I assumed that there would be no issue connecting the Emotiva in this manner. As to why I wouldn't use a y-cable, it's simply due to the fact that the sub is closer to my speakers than it would be to my electronics. Also, I've seen it argued that there are advantages to using a high level input. |
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Post by AudioHTIT on Dec 14, 2012 16:40:43 GMT -5
There would be some complexity added to the load with the sub crossover, but there should not be a significant change in impedance. I haven't seen mention of sub manufactures recommending you avoid certain amps, but there are many subs out there. As you say some find the high level inputs preferable, I have a friend with Quads and RELs who won't run them any other way.
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efjay
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Post by efjay on Dec 14, 2012 16:43:03 GMT -5
There would be some complexity added to the load with the sub crossover, but there should not be a significant change in impedance. I haven't seen mention of sub manufactures recommending you avoid certain amps, but there are many subs out there. As you say some find the high level inputs preferable, I have a friend with Quads and RELs who won't run them any other way. I've always understood it to be that the impedance of the crossover, which is what the signal is fed to, is usually so high as to have no affect at all. Also, the sub amp is not using any power at all from the amp it is connected to; rather, it is just taking the signal. Also, just to be clear, it was amp manufacturers that stated that their amp should be connected to a subwoofer via the high level input. |
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Post by AudioHTIT on Dec 14, 2012 16:54:16 GMT -5
There would be some complexity added to the load with the sub crossover, but there should not be a significant change in impedance. I haven't seen mention of sub manufactures recommending you avoid certain amps, but there are many subs out there. As you say some find the high level inputs preferable, I have a friend with Quads and RELs who won't run them any other way. I've always understood it to be that the impedance of the crossover, which is what the signal is fed to, is usually so high as to have no affect at all. Also, just to be clear, it was amp manufacturers that stated that their amp should be connected to a subwoofer via the high level input. I think that's true for the subwoofer portion of the crossover, little or no effect; but the speaker portion should have an added high pass filter, which would be seen by the amp. OK, makes sense if they've seen some combinations that don't like each other. |
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Post by roadrunner on Dec 14, 2012 16:58:03 GMT -5
efjay
The problem is you haven't given us sufficient information of what equipment is being used and how you have them wired. There are many different approaches for driving a sub woofer depending on the sub its self and the pre/pro or receiver. Typically, when using a self powered sub when your pre/pro has no defined output for the sub is to use a Y-adaptor on the Left channel output and run one leg to your speaker and the other leg to your sub woofer's low level input.
In the old days, there was no such thing as sub woofer outputs and the best way to add a sub was to use the Y-adaptor on the Left channel output to furnish your feed to the sub woofer. The bass content in LPs and CDs contained all of the bass frequencies in the Left channel.
How long would the cable need to be to run an RCA cable from your pre/pro to your sub? If it is less than 30 feet you need not worry about any signal degradation or noise. If the cable run is longer than 30 feet it would be best to use XLR cable to feed the sub, assuming you have XLR connectors on your sub and pre/pro. I fed my audio systems like this for better than 20 years and it worked flawlessly.
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efjay
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Posts: 11
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Post by efjay on Dec 14, 2012 17:22:30 GMT -5
My pre-amplifier is a Woo Audio 2 ( www.wooaudio.com/products/wa2.html). It has one set of out-puts. My speakers are Canton Vento 802. ( www.canton.de/en/archiv/produkt/vento802.htm). The speakers are on stands less than 20' from my electronics. The connections are pre-amp to amp, amp to speakers. The likely placement of the sub would be close to the speakers and would add no more than 5 additional feet of distance. It would be inconvenient to run an additional rca connection. (I did consider adding a wireless subwoofer kit www.soundcastsystems.com/_subCast_description.html and that remains a possibility. The UPA-2 has rca outputs for each channel. But wiring would be cheaper and future amps may not have rca outputs.) I hope this extra information helps. The class d amps have all mentioned that they cannot be hooked up to a subwoofer's high level input due to grounding issues. Absent such a warning, I cannot think of a good reason the UPA-2 cannot be hooked up to a sub's high level inputs. |
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Post by garbulky on Dec 14, 2012 17:53:08 GMT -5
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Post by Jim on Dec 14, 2012 20:51:21 GMT -5
With all due respect, I'm not certain that is entirely accurate. First, the subwoofer, assuming it is a powered version, will certainly use its own amplifier even when receiving a signal via speaker level connection. Second, as the amp is not powering the subwoofer, I'm not sure why there would be any change in overall impedance. Not all subs take the speaker level signal, attenuate it, and then feed it to the amplifier. Some use that signal and go to the driver - bypassing amplification....... Thus the impedance change. Before I said "that is definitely a load to the amp (and the internal sub amp isn't being used).". Key being *internal sub amp isn't being used*. But there is NO reason to use a speaker level signal, if you have a line level signal to begin with. Amplifying it... to attenuate it.... to amplify it again is asinine. I think the crossover isn't a big factor in impedance... it's really the driver that is the key player. So, either use cheap Y cables........ Or get a preamp that has a real LFE output. |
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efjay
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Post by efjay on Dec 14, 2012 23:27:47 GMT -5
I'm not trying to be difficult but numerous manufactures that make powered subwoofers utilize the option of high level inputs. For instance, SVS and Sunfire, just to name two, both offer the option on some of their subwoofers. I've yet to see one, while looking at subs, that mentions or implies that use of such an input would bypass their own internal amplifier. Some have recommended such an input over line level inputs. To be clear, this is an accepted and oft-recommended method for connecting a subwoofer, particularly to a system that that does not offer a line-level option. My sole concern is whether the amplifier cannot be connected directly to a high level input. As the Sunfire manual makes clear: The subwoofer’s two negative posts are joined internally (common-grounded). Your receiver/power amplifer must also be internally common-grounded or you cannot use this connection. Contact the manufacturer of your receiver to make
sure its outputs are common grounded.
If the UPA-2 meets this requirement, I can use the high level connection. If it does not, I can't. So, either use cheap Y cables........ Or get a preamp that has a real LFE output. I appreciate the desire to assist but that is substantially less than helpful. |
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