How does a subwoofer high-level input work?
Subscribe to Ask Paul Ask a QuestionThe proper connection for a subwoofer is from the speaker output connectors of a power amplifier. But, how does this circuit work on the subwoofer itself?
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Can’t see video.. shows a “private”
I got the same message.
But I replied to the email, and told Paul about it.
But if you really want to know how the high level inputs on a subwoofer works, that’s plane and cemple.
The high level output signal that’s coming in from the power amp to the subwoofer, is being broken down, to line level.
Because, any amp, is gonna be looking for a line level anyway.
The signal that comes from any power amp, is strong enough to drive a loud speaker.
Sure the input of the amp is gonna be looking for voltage, but it won’t be looking for currant.
That’s why some subwoofers, use resistors to brake down the voltage and currant, to line level.
That’s pretty much how that system works.
Thank you for that information. I do enjoying listening to Paul explain, but you did a good job.
You’re welcome Lurkerweb!
In spite of the fact that I’m without eye sight, I still keep up with both speaker and amplifier techknallagee.
I got a REL sub mostly from Paul’s praises of them. I of course tried others side-by-side. The response is so much better with the Hi-Level inputs.
Those are excellent subwoofers man!
I wish I had a pare with 15 inch drivers in them, with perhaps 1500 to 3000 watt class AB amps in them.
Perhaps 2021 will be a good year for me, as far as making and saving more money to do the things I want to do.
That is how I keep my husband out of trouble. He builds his speakers and tinkers with them. Sadly, they are enormous. But, the subwoofer he built is also used as a corner table with a lamp on top. It has a Class D amp and is used to test the house for earthquake safety.
I’m not too keen on class D amplifiers.
Just not sure about them.
But my go to amplifiers, are either class A, AB, H, and G operation.
But my favored amps are tube amps.
Hi Paul… Does using the high-level connection bypasses the built-in power-amp of the sub-woofer? And does it mean one cannot use the high-level connection when using a bridged power-amp? I am a little lost on this one. Thanks.
Leo
Hi Leo. No worries. No, the high level input does not bypass the subwoofer’s internal power supply/amplifier. All it does is attenuate the input signal from your power amplifier to match the low level input of the subwoofer’s internal amplifier.
Think of it this way. Imagine your subwoofer in blocks: Input preamp/crossover, power amplifier, woofer driver. The system is designed around a maximum 2 volt input at the sub’s preamp input. This allows users to connect the output of their main preamplifier to the subwoofer and all is good. It is the same input level as your stereo system’s main power amplifier. In this way, an output signal from your main preamplifier feeds both the stereo main power amp and the subwoofer’s amp and everything matches.
Now, people like me and John Hunter of REL want to include the audible signature of our main power amplifier into the subwoofer. We want this because our goal is to not hear the subwoofer. We want the sub to disappear (as if the main speakers have magically gained extended bass).
The easiest way to get the sonic signature of the main amp into our subwoofer is to take the main amplifier’s output and put it into our subwoofer as its input. The problem with this is the main power amplifier’s output is 30X higher than what we want (to match the sub’s low level input requirements – because that’s where we’re going to put that signal, into the sub’s low level input).
This is exactly the same thing we did at Genesis Technologies with our speaker’s built in subwoofer. On Genesis speakers, your main power amplifier fed our speakers through the input speaker binding posts just like any speaker. Our built in subwoofer tapped off the input binding posts and fed our subwoofer crossover/amplifier. All we needed was a couple of resistors to attenuate the main amp’s output.
Hope that helps.
Hi Paul…
Thank you for getting back to me so quickly. Right now, I am connecting my sub to the power amp’s speaker outputs. And my main speakers are in turn connected from the binding posts of the sub. The system seems to be working fine. Should I connect the main speakers from the power amp instead? I can do so either way.
I know it is the Holidays so please don’t go out of your way to respond right away. Happy Christmas and wish you and your family the best in 2021.
Likewise…
I don’t know if you heard but Tim de Paravicini died, and he was one of the most brilliant audio designers who ever lived, Very Sad!
Video is private…lol.
Paul’s having second thoughts about subwoofer hook ups. Maybe Low Level RCA’s aren’t such a bad idea?! 🙂
Could it be that things aren’t that simple when room acoustics and taming of room modes come into the game? Simple enlargement (augmentation) of the bass performance of the main speakers might not be sufficient but room acoustics require equalization of both main speakers and subwoofers. Thus were is the real advantage of high level inputs? Not to mention the advantage of long balanced interconnects for the active sub’s input in contrast to long unshielded (?) unbalanced high level speaker cables for the optional high level input???? And please don’t answer: “The proof is in eating the pudding!” 🙂
paulsquirrel. I don’t find anything simple about using a sub for 2 channel music. While it does extend bass and when set properly, mine does disappear making my speakers sound better. But I’m frequently adjusting the sub depending on the source music, where I’m at in the room, how many people are in the room, etc. And adjusting my sub means reaching blindly behind it turning knobs then back to the sweet spot and repeat until satisfied. By that time, a new song starts and repeat again. I’m exaggerating some, but doesn’t this sub adjustment open the door wider for deviation from the original mix of the musicians?
I think Id be happier with better full range speakers and ditch the sub. Or maybe a sub with a remote control so I can make sonic adjustments from the sweet spot.
Indeed, it’s not simple and easy getting a subwoofer or a subwoofer array in best match with both the listening room and the main speakers. And it’s most astonishing that some subwoofer manufacturers recommend having the subwoofer placed near the side and/or rear walls while other recommend a position in close vicinity to the main speakers. And here we are in the middle of the core problem concerning deep bass: room acoustics! Precise measurement of the phase-delays and the low frequency room modes is mandatory as well as a great equalizer allowing the correct phase setting. Room treatment is highly recommended – I use active bass traps.
I can sort of understand that a high level connection from a tube amplifier might add some sonic signature to the sub. However, assuming both the sub and main speakers are driven by transistor amps and also that the crossover point is fairly low, and the cabling is of decent quality, I don’t know why there would be any sonic difference. After all, the internal network in the sub is reducing that high level input to the same low level input as fed directly by the preamp. Plus, you would avoid any potential problem with differential amplifiers feeding into an unbalanced circuit.
I don’t see the point of wanting the power amp’s sonic signature as an input to another power amplifier, unless the combined sonic signature of the external power amp and internal sub woofer amps is more pleasing than that of the internal amp alone. Maybe yes, maybe no. A more direct signal path from the preamp to the internal sub amp might be better. Probably splitting hairs here, but that’s what we all do, right?
I had submitted a question regarding this and I am still curious for an answer.
On commercial high-end receivers with surround sound, you can have two mono-out RCA terminals for subwoofers. A left and a separate right channel. The signal is mono on each subwoofer channel. However, on most powered subwoofers and mono block amplifiers (especially for subwoofers) there is a right (red) and left (black) RCA input. This would suggest a “stereo” configuration. Based on what you have stated here, that this is more likely a positive and ground situation?
Here is the quandary that I want explained. If I connect the mono subwoofer RCA output from the receiver to only ONE of the RCA connectors on the power amp of a subwoofer (it doesn’t matter which I choose), I get significantly reduced bass response. If I use an RCA Y-Splitter and plug into both RCA inputs on the subwoofer’s power amp, I get incredibly fantastic bass response.
What is happening here? Is it just that the signal is being doubled to the power amp by feeding a single mono signal twice? The idea that one is the actual signal and the other is a ground, doesn’t make sense to me. Or is this theory that the RCA mono output on the receiver is sending a 1 amp signal and by splitting it into two, it’s magically doubling to 2 amps?
I am very confused.
My system is running a Yamaha surround receiver with a left and right subwoofer output. I am using two AudioQuest Boxer cables (grounded) with AudioQuest’s RCA Y-Splitter to two different NHT mono block amps. The bass response is overwhelming and I have to reduce the volume. When I had connected these amps without the Y-Splitter, I had to max out the volume on both NHT mono block amps to get any bass response.
Can you explain?