Bronze MemberUsername: Blazer
Post Number: 41
Some receivers and processors do not send a signal to the sub out jack when in the stereo mode. That means when you listen to music in stereo, you lose the benefit of the subwoofer. Not good. Additionally, in the vast majority of receivers and processors, the subwoofer output jack is low-pass filtered. That means that there is a filter (sometimes mistakenly referred to as a crossover) that blocks sounds above a given frequency from getting out of the sub out jack. Usually that filter is in the 100Hz-150Hz, range . Why is that so bad?
1. Your powered subwoofer also has a built-in low pass filter, and when the two filters combine their interaction can cause irregularities in the frequency response. In plain English, you get lower performance.
2. In the case of many systems, especially sub/sat systems, the low pass filter that's built-in to a receiver or processor may be set to the wrong frequency.
3. The variable low-pass filter (crossover) adjustment is one of the most useful tools for adjusting your subwoofer to "blend" with the rest of the system. By using a pre-filtered signal, you are defeating this excellent and useful feature. Using the sub out jack is sometimes the right thing to do. Some high-end separate component processors like those from Adcom, B&K, Parasound, Proceed and others, allow you to defeat the built-in low pass filter or select the frequency. Check your electronics manual to learn how. Some processors and receivers have unfiltered subwoofer output jacks-so it's OK to connect the line in of your subwoofer to the sub out jack.
Unfortunately electronics manufacturers rarely specify the filter characteristics of the sub out jack in their manuals. Carefully check the electronics' specs or contact the manufacturer to find out whether or not your receiver's subwoofer output jack is filtered.
4. When using the sub out jack with palm-of-hand sized satellite speakers, you are forced to use the Small setting on the front left and right speakers. The Small setting introduces a high pass filter on the satellites in addition to the one that is built into the satellite's crossover. Bottom line, this arrangement severely degrades the sound of the satellite speakers and exacerbates the hole-in-the midrange effect. Sub/sat users should follow our hook up and bass management advice.
Some subwoofers have "LFE" line inputs that bypass the subwoofer's built-in low-pass filter This feature is great for avoiding the double-filter effect when using a filtered sub out jack.
Many people are worried that if they don't use the subwoofer output jack, they'll miss the Low Frequency Effects (LFE) channel on 5.1 channel DVDs. Not true. We'll tell you the secret to getting every last bit of bass, regardless of which hook up you use, in the "Setting Bass Management" section below.
So What's The Alternative?
For the most people, the easiest and best sounding thing to do is connect the subwoofer to the Front Left and Right speaker outputs. You can either connect your front main speakers to the subwoofer's speaker output terminals or you can "parallel wire" them to the same terminals.
You may get some performance advantages by using low level (line level) connections from the Front Left and Right preamp outputs instead, if your receiver has them. If you have only one set of preamp outputs and they are being used to feed the power amp input, use a "Y" type connector.
Digital surround sound receivers, preamps, or processors must be configured properly to get the best performance from the other important part of your home theater system: your speakers. You must "tell" the surround processor where to send each channel's bass information. This is known as "Bass Management" or "Speaker Set-Up." Most processors and receivers allow you to adjust these functions using an "on-screen" display. (Check the user's manual of your electronics to learn how to access these functions.) Bass management can be confusing. Good news is that once you've selected the bass management modes that you're happy with, all receivers remember your settings allowing you to forget about it and just enjoy your system.
When-in your receiver's bass management function-a channel is selected as "Large," it means all of that channel's sounds, the whole spectrum of frequencies including the bass information, will be directed to that speaker. When "Small" is selected, the deep bass sounds (usually below 150Hz) are filtered out of that speaker and directed to either the subwoofer output jack or to the Left and Right channels (depending on whether the subwoofer is selected as "On" or "Off"). For example, if you select the center channel speaker as "Large," the center channel bass will go to the center speaker. If you select "Small," the center bass will be filtered out by the receiver and sent elsewhere.
When you select the subwoofer as "On" (sometimes it's "Yes/No" rather than "On/Off"), the LFE channel will be directed to the sub out jack along with any bass information from channels you selected as "Small." When the subwoofer is selected as "Off," the LFE channel and bass from "Small" channels will be directed to the Front Left and Right outputs (speaker level and line level). OK, enough theory.
Hope this finally clears things up for everyone. Happy listening...
I have 2 nos. Quam 250mm woofers. I am thnking of building a active sub for my yamaha rxv 630 amp.
The amp has filtered sub output at 90hz.
The speakers are of 8 ohms.Can handle 10hz - 250hz.
At the present position the amp can work 8-16 ohms.
My quary is-
1.Is it ok if I connect the 2 speakers in series?
2.I hope no separate filter will be nessesory as the amp is providing frequency below 90 hz.
3.Only a sub amp is required to be connected.
4.I prefer infinite baffle, due to simple design and tight bass... kindly comment.