Two subwoofers for two channel music listening

Best is speaker hook up. Just run from speaker to sub. Place subs forward firing and inside of your mains.

I think you will find the same results from both options you have. Most guys with two channel use the speaker connection because a lot of two channel setups lack the connections needed. 
To take it to the next level adding and active crossover between your pre and amp (pre amp to sub, sub to amp) is best but more expensive and requires extra interconnects.

Right. No difference. Sub bass is mono. Line level or speaker level, same result. Running from one to he next is fine too. I've done all three. No difference. Use whichever is most convenient.

Audio Alchemy says NOT to hook subs up from their speaker binding posts, whereas Paul McGowan (PS Audio) did a video on speaker to sub


hth

Based on the OP's name, only more conflicting information has been provided-PERFECT

Audio Alchemy says NOT to hook subs up from their speaker binding posts, whereas Paul McGowan (PS Audio) did a video on speaker to sub

Right, but the OP specifically stated his subs have BOTH line level AND high level inputs.  

There is an interesting thing about connections, they are all designed such that if the plug fits, it is safe to use. Check it out. Works for everything.  

Technically, both line level and speaker level are the same. The only difference is the voltage. What do resistors do? Resist voltage. So any speaker level anything can be converted to line level voltage by simply putting a resistor in line. A sub that accepts speaker level, this is exactly what they do. Look at the circuit diagram, the first thing is a 20k or maybe 50k Ohm resistor. Or look at a Line Out Converter, this simple box is nothing more than a resistor with an RCA and terminals making it easy to hook up. Or you can do the same with solder in a few minutes. What I did to my amp, which didn't even have line out. So I modded it. https://systems.audiogon.com/systems/8367 Look at picture #26 to see just how simple this is to do.

To everyone - thanks for chiming in. I just do not want to localize sub bass in either left or right side. If the recording has something coming from left/right, that is fine with me.

@tablejockey - now you know why my user's name is chosen :)))

I have had my stereo subs set up in two ways:  in both methods I have no crossover and the subs serve as bass augmentation.  At first I had my speaker wire running from the amp through the speaker level inputs of two Dayton plate amps (left and right) which have their own binding posts that went to the subs. The speaker cable from the main amp then continued on to the main speakers. So it was kind of like a stop off at the speaker inputs of the plate amps. But without going through any of the crossover in the plate amp. (Blumenstein audio has an illustration of this method). The second method which is what I use now involves the output of my DAC which has both a preamp function and a line level output. I use the standard line level out to my main amp which has a volume control which drives my main speakers. Then I simply run the preamp out from the DAC using RCA to each plate amp which power the subs. The speakers run full range direct from the main amp. The subs are controlled by the preamp output. I suppose this is the same as bi amping but with a low pass filter in the plate amps rather than a crossover. I can control the level of bass using the preamp volume. And because I don’t change volume very often I can pretty much set and forget. Because I can separate left and right with the preamp and the two plate amps I can get true stereo bass augmentation. 

OP:  please see this old thread from about 7 years ago in which I asked a very similar questions. Perhaps there will be some value in it for you:

https://forum.audiogon.com/discussions/setting-up-dual-subwoofers-to-a-two-channel-amp

To everyone - thanks for chiming in. I just do not want to localize sub bass in either left or right side. - confuse_upgraditis

Your name is apt. 

Sub bass cannot be localized. Nothing you can do in the way of hooking them up or locating them on your room will ever change the fact we cannot tell where such low bass frequencies are coming from.

Not all subs have speaker hook ups , Svs has rca as well as other .
I use level level  with very good line out adapters from amplifier
 binding posts to line out adapters, that have rca  sub outs to subwoofer in, noticably more accurate then preamp out.

Why? I'd sell the speakers and buy one that does bass. Why ruin a speaker by adding bloated bass from subs. They are relegated to the home theater in this castle!

@millercarbon OP is unintentionally referring to being able to locate a sub by either having the xover set too high on the sub or having the volume/ gain set too high. Subs can do an excellent job @audioguy85 of augmenting speakers low end which when done correctly can take the pressure of your mains to produce those lows and free them up for mids and highs.

audioguy85541 posts01-30-2021 7:43pm"Why? I'd sell the speakers and buy one that does bass. Why ruin a speaker by adding bloated bass from subs. They are relegated to the home theater in this castle!"

With small stand-mount speakers and sub(s), you can locate the stand-mounts for best imaging/soundstaging and locate the sub(s) for best bass. With large speakers w/o sub(s) you don't have that option.

"Bloated bass from subs" doesn't exist if they're set up properly. Test tones and SPL meter is the method I chose.

Are you using bookshelf speakers that only reach to 200hz? Hooking up L R stereo subs may help the soundstage. Subs integrating at 20hz, probably not much, but I'm not convinced there's no difference with all recordings. Not everything is mixed to mono. 

No way full range speakers give you LF at proper DB. Also, placement of full range is not optimum for LF.  Bloated or thin LF is improper integration/placement/phase. At a minimum use a test tone sweep of low frequency. Hook up both ways and experiment w placement. 

confuse_upgraditis OP
Method one - Lets say the subs have high/speaker level inputs. So do you hook up the left sub from the left amplifier out and similarly right speaker out from the amp to right sub high level in? This set up is just like the stereo pair of speakers.

Method two - The alternate is from a preamp hook up the RCA line in of one subwoofer then daisy chain i.e. RCA out from the first sub to the RCA in of the second subwoofer. Not using a Y splitter from the preamp. Trying to use both red and white RCA from preamp to red and white RCA in of the first sub.

The very best way is, Method Three!! below. (proper stereo subs) I’ve tried them all.

I use two actives in my second system (<40hz), each sub one sits behind each main speaker, and driven from left or right line outs.
The left sub is run from left line out. And same goes for the the right sub with the right line out.
Just experiment with the 180’ phase switch if you have them on the subs, as one way will be louder at the xover point you’ve used (where your mains roll off) and louder is the right phase, the other way will null out (dip) at the xover point.
Then set your levels, so you can "just detect" them working on the lowest notes (if your mains are large ones like mine)

Cheers George

@georgehifi 

I do very similar, except I connect both my subwoofers directly from the amp to my subs via the high level speaker inputs, in stereo. Both my subs sit behind my Vandersteen’s. Yes, I’m aware that you don’t get a true stereo sub effect at those db levels, but it works to simply augment the Vandy’s and supply a bit more ‘grunt’. Then, obviously, set the crossover and gain at the subs so that they are integrated sound-wise and not noticeable as separate subs. Interestingly, in my room, the gain in one side is higher than the other for the integration, simply because of the room loading. I was able to adjust for that using Vandertones and a db meter at each frequency.

Works for me. I got rid if the whole LFE connections quite a long time ago.

You will get a cleaner signal (bass) from the line level, as an amps speaker output, is far dirtier.
Also this is what happens inside a sub, follow the speaker level input and it goes through a "dropping opamp" IC11A and then goes to the "line level rca input opamp" IC11B then to the rest of the subs amps, so by using line level you also use one less opamp as well. https://ibb.co/3cmCWC8


Cheers George

@georgehifi 

Unfortunately, my vintage Belles 400A amp has no line outs.

You take them from your pre/source, you can stick these on the pre’s output or the Belle’s input to get a line level to each of the subs.
https://www.ebay.com.au/itm/1pcs-1-RCA-Male-Plug-To-Dual-2-RCA-Female-Jack-T-Adapter-Connector-Gold-...

https://www.ebay.com.au/itm/Gold-1-RCA-Male-Plug-To-Dual-2-RCA-Female-Jack-Right-Angle-F-Adapter-Con...

Cheers George

@georgehifi

Yes, I could, for 2 channel. But I then lose my subs when in HT mode via my Parasound ZPre3 pass-through. I can double check, but although that pre has a sub line-out, it does not transmit the sub signal while using pass-through. Which means I would have to use the AV receiver line-outs with a splitter.

The RCA adapter might work though.

Seriously, not sure it is worth the hassle, but could consider it.

Seriously, not sure it is worth the hassle, but could consider it.

You get cleaner tighter lows, using the line level. 

Cheers George

@georgehifi

Do those adapters both transfer the signal into the amp, while also feeding out to the sub? For  some reason, I thought they only went to the input path. Or, are you saying use the spitter at the pre via the bi-pass connections?

If so, $10 and an additional cable (have one long length I am not using) could be a consideration.

@georgehifi. 
You will get a cleaner signal (bass) from the line level, as an amps speaker output, is far dirtier. 

Then why is REL recommend using speaker out?

I am more inclined to believe REL.

I am more inclined to believe REL.

Go with what you like

Did you see and comprehend the circuit link I posted that all subs do similar to.And any tech will tell you line level has less distortions noise ect than speaker level will have.

Cheers George

As an MME yes I can read and understand your schematic @georgehifi though it has been 40 years since I took the required circuits course.

Still I will stick what REL is telling me over you.

Cheers.

skypunk292 posts01-31-2021 12:10pm
"....Then why is REL recommend using speaker out?"

REL has long maintained that Speaker Level connections to their subs provides better (and easier) integration because the same signal feeding the main speakers is also fed to the subs. As such, the sound characteristics of the main power amp are accounted for.

In general, I've always found it best to heed the advice of equipment designers, who know far more about their products than Internet "experts". 

Still I will stick what REL is telling me over you. 

Like I said, go with what you want, maybe Rel has got a sus low level input on their subs, who knows, show us a circuit diagram for some clarity.

I have a couple of REL subs and love them.  The manufacturer is very specific about setup. The ideal setup (from their point of view) is the subs connected at high level (to the speakers .... they have slightly different ways to do this depending on the type of amp you have.  Connection to the preamp is verboten :) Their ideal position depended on the room you have outside of the main speakers is the option for my long room, second choice inside main speakers for other shapes.  I have the impression from this and others responses that there are a few ways to do the setup.  If I were you I would call SVS and ask them what in their experience is best for you particular situation.

^^^ REL recs are nonsense. Subs are 100% room and main dependent.

Right. No difference. Sub bass is mono. Line level or speaker level, same result. Running from one to he next is fine too. I've done all three. No difference. Use whichever is most convenient.

Unless you have mains that play well to 30Hz or lower, the subs are going to have significant output into the mid-bass which is easily localizable.

Mains with smallish woofers - [less than 10"] - will benefit from rolling the lows from the mains

Line level is the ONLY way to do it properly. Hi-Level inputs are a compromise to the amp, the mains and the subs.

See  ieLogical SubterraneanHomesickBlues for some useful information on sub integration.

I think only advantage REL offers with high-level is convenience factor.
I agree using line-level direct to subwoofer is probably a better approach.
Pre-amp (or using DAC direct line-level) to amp -> High-Level connection to Subwoofer -> Drop voltage to match internal line-level of subwoofer.
For sure line-level is more direct, but who knows if you can really hear any difference unless using long runs of RCA cable is having issues with RFI. Line-level using XLR will have advantage over RCA.

I got in touch with SVS and they suggested not mixing high level and line level. That we all can agree on:))

I will get a measurement mic in next couple of months or so and measure these things for my own learning and also for fun. I want to place the subs in their optimal location in the room - not necessarily symmetrically inside or outside of the main speakers. Nothing wrong with the symmetrical positioning though. Aesthetically they look really nice. Right now they are outside of the main speakers. 

I am also planning to do a DSP based crossover to distribute low frequency, say 50 - 60 Hz, to the dual subs. I used to have external 80 Hz high pass filter with my large bookshelf speakers and the dual sub crossover set appropriately. I really liked the sound. The imaging and soundstage were great. I had a pair of Maggies with the same set up. Now I have a pair of Thiel CS2.4 (and I am already looking for CS3.7 or 7.2 model ...... my never ending itch for upgrades - sigh) that go down to mid 30s, I guess. Adequate for most music I listen to. I still want the occasional 20 Hz bass if it is present in the music, as I like to feel that bass more than I hear it :)))  Heck at some point I will go for distributed bass array with 4 subwoofers! My room is a dedicated listening room, 17 X 24 ft in size. So I got space for that.

Before the mic and third party DSP ask SVS if one of their DSP/App equipped models could act as a master controller for your 1000 series. Remote control volume, customizable EQ presets, and the very useful adjustable Q = interactive low frequency.

I'm not sure if the SVS version is similar to the Velodyne Plus' Q which is a simple visual and audible drag and drop adjustment for individual bandwidth parametric filter frequency and level.
When used in conjunction with its discrete mutiband gain settings allow for a much higher crossover beginning with tone that closely matches the mains presentation from the crossover region on.



I'm in agreement with georgehifi and ieales descriptions. Comparisons with an owners REL $9K Studio III and two different amplifiers the low level inputs were our obvious preference. I wouldn't recommend the product.  

Richard Edmund Lord may have been the first to offer high level inputs intended as a connection of convenience for systems that lack low level outputs. Remarketing the same circuit for a different reason?
I would add that I've never encountered speaker level connectivity in any professional reinforcement or studio system.  

You want your subs to be the deepest, tightest and driest they can be, the last thing you want is an amp driving another amp, that’s just wrong and gives one note bass, that’s why line level drive the best for them.
The last thing you would want is to drive them from say a tube amps etc speaker output.
Probably the only amp driven output that could compete with line level, would come from an amp like a Krells or similar, that have absolutely no ? on bass performance.

Cheers George

Right. The only proper way to hook up subwoofers is with a dedicated two way subwoofer crossover preferably digital. The preamp outputs go to the crossover which will have dedicated main amp and sub amp outputs all line level. This rolls off the main speakers improving integration and lowering distortion in the main speakers. Good bass management systems will give you a wide choice of crossover point and slopes. The best will also automatically correct for phase and time and do room control.
Any other method is challenged one way or another. REL approach is just a cheap way to do it. Their insistence that is is the best is a rouge to sell more subwoofers. They know people who are buying their inexpensive subs do not want to spend more money and/or deal with more complexity. If they recommended the right way nobody would buy their subs. What you have here is a dysfunctional relationship between a manufacturer and it's clients destined to produce mediocrity, an interesting relationship common in the political world. The best subwoofer systems use passive subwoofers. You have to die laughing. You have all these audiophiles spending ridiculous money to keep their electronics isolated but they are fine jamming an amplifier into a earthquake replicating machine wherein the pressures vary from +- 30 PSI. So, why doesn't the industry produce passive subs? Passive subs in most cases are not much less expensive. Plate amps are dirt cheap and they make a lot of money selling them. People love all in one cheap solutions. It is the culture. JL Audio cuts it both ways. They make amplified subs with crossovers like everyone else but for people who want to do it right they make an analog subwoofer crossover to go between the preamp and amplifiers. The DEQX Premate has a wonderful bass management system with which you can set up a SOTA subwoofer system.

The only proper way to hook up subwoofers is with a dedicated two way subwoofer crossover preferably digital. The preamp outputs go to the crossover which will have dedicated main amp and sub amp outputs all line level. This rolls off the main speakers improving integration and lowering distortion in the main speakers.

I've had the best results using an external crossover as well. Back in my home theater days I purchased an Outlaw ICBM-1 for bass management in the analog domain, including integration of 2 subs. I kept only the ICBM-1 when I went back to 2-channel. It's been in/out of my systems for years and I still find it to be quite transparent and incredibly handy. OP .. these can still be found used on ebay in the $200-$250 range. Here's a review from back in the day if you'd like to know more about it.

http://www.soundstagenetwork.com/revequip/outlawaudio_icbm.htm

Each method will work but the first one would be prferable to me because the pre amp method would strongly depend on the features of the pre amp and the first method the features are usually on the sub like volume level and phase.

Designers at REL say to use the speaker output from your amplifier with your speakers hooked up to the same jack if you only have one set of outputs.

pre-sub-amp-mains

To make it easier for your amp, and for your mains: go preamp line out to self-powered sub.

then sub sends everything but low bass to the amp

then amp to mains.

amp does not have to amplify low bass signals (they are the biggest power need).

mains do not try to make low bass, also the hardest to do. this lets them do an easier and cleaner job of highs, mids, upper bass.

this allows a less powerful amp to be used, and that especially makes it easier to try tubes.

smaller amp = less: money; size; weight; heat. = more placement options.

Bass is STEREO, place front firing subs adjacent to mains, to achieve bass imaging.

It is not just the bass fundamentals, also the overtones that give localization.

The bulk of what you get (except organs/1812) will not be super low bass, A great deal of what you listen to will have low bass, discernable locations. Presumably you mains do not handle low bass as well as you would like.

I have two very powerful 15" in my speakers, you could think of them as subs. They definitely produce stereo bass.

I listen to a lot of Jazz trios, quartets, even bigger groups, with nice imaging of bass players.

IF piano is off center, and IF recorded/mixed properly, low notes are definitely discernable by location.

Yes, organ is Mono, but many other instruments locations are discernable

not complete, but a quickie find showing which (not that many) instruments get way down there into the 'mono bass' range

https://www.researchgate.net/figure/Frequency-ranges-of-several-musical-instruments-30_fig3_22844644...

More than 2 SUBS, SWARMS. Sacrifice Directionality for Extension?

People who want very/extremely lows produced cleanly will use more than 2 subs, sometimes multiple ’Swarms’ which has been discussed here. I’ve never heard that except a swarm of bees chasing me, and that is directional, i.e. run this way.

Swarms, more than 2 subs get super lows, however the results are MONO BASS, even the upper bass will be mono because the fundamentals and overtones emanate from too many locations, and reflect off too many surfaces..

Some use ported mains and/or ported subs. I recommend only front firing ports, again to retain directionality.

I much prefer decently low bass with imaging than a bit more bass.

In my exuberant youth, I, with help from Electro-Voice Engineering department, designed these enclosures with optional ports, to squeak more bass from these 15", which I measurably got.

However, they are rear facing ports. Less pressure in the enclosure, the front 15's go lower. Additional output from the tuned port and rear surface of the woofer, that gets to rear wall/corners. Even more extension, but they muddy the directionality of both the extended bas, also all it's output, fundamentals and overtones muddy everything else.

It's a trade off. I keep the ports closed. Why sacrifice directionality of a lot of low content for most of my music to get more bass infrequently or rarely?.

Martin Logan makes a couple of lines of subwoofers and they recommend the line level option over the high impedance connection where possible, though to be honest, I doubt that you or I  would ever be able to hear the difference.
I'm no audio engineer, but I did stay at a Hollywood Express last night :)

You want your subs to be the deepest, tightest and driest they can be, the last thing you want is an amp driving another amp, that’s just wrong and gives one note bass, that’s why line level drive the best for them.
The last thing you would want is to drive them from say a tube amps etc speaker output.
Probably the only amp driven output that could compete with line level, would come from an amp like a Krells or similar, that have absolutely no ? on bass performance.

Cheers George

I gave you more credit than that, guess I was wrong.

In this scenario, no amp is driving another amp. You are completely off the mark. The only thing that is happening is that the main amp is sending a low level signal to the sub amp. This works beautifully and makes it much easier to make the main speakers and sub(s) coherent.

Oz

It's interesting that the SVS 1000 has both line level and speaker level inputs.  I have the SVS SB 3000 and it only has line level.  But it does have a terrific Bluetooth app to manage volume, xover point, slope remotely. No more continuous getting out of your listening position to tweak the sub controls.  Really comes in handy for music that's recorded a bit this as the Bluetooth app also allows user preset settings.

@ozzy621 - thanks for commenting that the speaker level input doesn't result in an amp driving an amp. Inherently we all should know this can't be as the sound would be horrible. I still don't understand how 'the main amp sends a low level signal to the sub amp' and not full range signal as the main amp speaker terminals are designed to do.
Perhaps someone out there could explain how this main amp speaker output to sub amp speaker input works.

Remote Control of Sub(s) sounds terrific, initial setup from a few listening spots. After that, remote volume would be very nice.

A crossover has to exist somewhere, to separate low bass from everything else. Home theater receivers have built in, and the content coding has separate bass.

2 channel amps for music systems typically do not have crossovers built in. You can use a self powered sub’s built in crossover, that is the method that makes it easier for the amp and mains because they do not have to produce low bass.

A separate external crossover does the same thing, except you have more control of the quality of that device. And you do not need to get any signal back from the sub. Crossover sends lows to sub, everything else (easier job) to the amp(s) which send signals with no low bass (easier job) to the mains. 

http://www.acousticfrontiers.com/three-ways-to-add-a-subwoofer-crossover-to-your-two-channel-system/

Many subs have crossovers built in, some line in, some speaker wires in, some both. If via speaker wires, the amp is still producing low bass, then the sub filters that for itself, and sends speaker wires to your mains. This gives the mains a break, but does not give the amp a break.

Since my speakers are in a slightly recessed open room, and face a much bigger room,  I measuered and phase aligned my subs, with the towers on top.  This works side by side, too. Maybe human hearing is not very directional at low frequencies, but this phase alignment certainly decreases the interference between the subs and tower woofers.    

There is a diff btw stereo and mono subs, just try it and listen. Mono has more power and authority, but stereo sounds more natural, to me. You didnt tell us about your room? I've found that my 23x20ft room really needed a sub on the other side from the first sub and mains. Nothing else added the right sense of fullness. That's like a mini-swarm. Room treatments certainly helped, but not nearly as much as moving that 2nd sub away from mains.

If that's true for you (large room), then mono should be best. I use option 4, 2 -15 subs (xover 40) in stereo near the mains which are not xovered, and a single 10 driven mono and xovered a little higher (57hz) to help load the room with the mains. Someday I'll try a 4th and run it as two pairs in stereo.

Stereo vs mono can be done with speaker or preamp. All mine run on preamp. Main amp is driven xlr from dac, and use rca spltter for subs. Each 15 gets a single cable, and 10 get two for mono.
RELs disappear so well bc they use speaker outs which lends the main amp sound to the subs. It's a really nice effect, but I prefer the cleaner, tighter sound of the preamp outputs. As always, the quality of the interconnects and power matters a lot, and especially for the subs to xover to mains. That's the drawback of doing a swarm my way, you need more good cables. It's all tradeoffs, best of luck and let us know what you tried.