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Surround subwoofer setup

conqueeftador

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I've always read at XX frequency you can't tell where the bass is coming from. I don't know about anyone else, but the sense of feel alone rules that out.

Got a bit of an oddball setup where the surround and rear surround (both sides) are also used as 2 office systems for stereo listening via another preamp and a second dolby atmos system for the office. Each of those spaces need a sub as the speakers only go down to 80hz (Mission E80 85db) The preamps running those have a preout, so I can feed the stereo out from that amp to the subs. Works ok for stereo, which bypasses the Denon 3700H. The subs here have frequency control.

I have some slim custom peerless subs from a failed under sofa sub project which in turn out to be nothing but a mild and inconvenient tickle of my arsehole, I'll be using a pair of those under the center speaker. The front speakers are quite large (Mission E83) but I have a sub with twin 8"s that seems fairly good quality I'm going to try (Mission cube subwoofer). These are fairly cheap now so I can get a matched pair for the fronts easy enough but these do not have an adjustable crossover on the sub although I'm weighing up an SVS upgrade. I 'd rather stereo subs for the front.

The question is does that sounds the best way to hook all these up to the 3700H. Each speaker is running from a separate power amp and my initial thought was to set all speakers to large and use the preouts for the subs which would get me surround sound bass, but how would that affect the smaller speakers? Would they distort at higher volumes or does the speaker crossover cut out the lower frequencies it can't deal with?

Another concern with this setup would be the front preouts from the Denon would be split 4 times. Once for the 2 office systems and the main system for biamping and the subs.
 

alex-z

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Bass being omni-directional is true, but there are certain limitations. If the crossover point is too high, the slope too shallow, or strong resonances exist, then you can locate the subwoofer.

Your current setup is flawed because you are feeding both the speakers and subwoofers a full-range signal. Set the speakers to small, and hook your subwoofers up to the LFE output. There is no such thing as surround sound bass, or stereo bass. Yes, you are giving yourself additional distortion and reduced power handling for zero reason.

It sounds like you should consider adding a miniDSP 2x4HD for your offices, so that you can feed it the Zone 2 output, and then have it act as the crossover between your subs and speakers in each office.
 
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conqueeftador

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Thanks for the response. Anytime I've tried one sub, My body told me it was coming "from over there". Does this omni directional theory only apply to volumes which do not cause any sense of feel? I don't understand how that doesn't sour this theory for everyone.

I'd like to disagree on the stereo bass at least. I have seen enough people refer to stereo subs as very much worth it and I like a bit of symmetry vs one sub offset somewhere. What do you mean by surround bass isn't a thing? Are you saying no bass comes from the center and surrounds by design? What kind of frequency ranges are we talking about if so? We have the option to set the speakers to large and no sub, although on most AVRs, you set the LFE to come from the fronts, so it seems a bit strange? Are you saying it is a waste having full range speakers for anything but the fronts?

"Yes, you are giving yourself additional distortion and reduced power handling for zero reason."

Does the internal crossover on the speaker not roll the low frequencies it can't deal with off? Most speakers are designed to be used with a stereo amp which usually does not have any of these features. I figured the crossover would deal with that?

I hear you on the lack of control on the front subs, so aiming to pick up a pair of SVS for those. They have a DSP.

Below is the old response graph for the slim subs, I've converted it to sealed and updated the driver so that will likely be a bit different. They do have a crossover with high and low pass filters, it just isn't adjustable. Sound pretty good to my ears. Obviously they don't go massively low, but below 50hz will be where the SVS will take over.

1647422827502.png
 

alex-z

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If you can feel the direction your subwoofer is coming from at any volume, you have a setup issue. I have never experienced this except when using a 120Hz second order low-pass filter. Or on low quality subwoofers with severe cabinet resonances.

Plenty of people refer to stereo bass, none of them have a decent understanding of room acoustics. If each subwoofer is only playing the content from one channel, you are not experiencing the benefit of multi-sub, which is reducing the influence of room modes on your frequency response. Unless your listening room doubles as an airplane hanger, you have room modes.


Bass might come from the surrounds and centre channel, but it gets redirected into the LFE channel by your AV receiver, when the speakers are set to small. It is highly unusual to set any of your speakers to large, because that wastes the benefit of your subwoofers. Even in a full sized cinema where room modes are not a concern, stereo or surround bass is not a thing. There is less distortion and more power handling by using subs.

The crossover inside your speaker only handles the transition between the drivers inside the speaker. It has zero impact on low frequency behaviour. Stereo amps mostly don't have integrated high-pass filters, because most people buying stereo amps aren't using subs, and saves manufacturing costs to exclude them.

You should really buy a cheap measurement mic like a miniDSP UMIK-1 and actually do some system tuning. You have the potential for good sound but just need to properly integrate everything.
 
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conqueeftador

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I had a fairly large ported twin 10" Polk set to 60/70hz before, didn't matter where it was put, my body (not my ears) told where it was coming from, one side vibrated, the other did not. Looking forward to trying the SVS's.

Would the subs still be missing the details if the fronts were set to large? That's how I wanted to set the SVS up, using the front pre outs and the subs DSP.

With the rest of the speakers, would it work to set them to small with a 50 or 60hz crossover? The slim subs will then do everything 50+ and the SVS everything 50 and below? Fronts could likely be moved to 40hz which I believe is the lowest I can set it to if also set to small using the LFE out. Although I'd like to try a set in stereo.

That link is massively detailed, thank you, I have saved it and will try and go through it when I have some more time.

I do actually have an MiniDSP I wanted to investigate for the office, older non HD one though, don't think it measures well. Will invest in a mic.
 

Andysu

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I do actually have an MiniDSP I wanted to investigate for the office, older non HD one though, don't think it measures well. Will invest in a mic.
may want to get two or four microphones as it isn't as easy with a single microphone you can place the four microphones around the room stuck in corners laying on the floor on attached to the ceiling or elsewhere with long xlr cables and simple six channel audio mixer with phantom power and mics connected to each mic input and output connected to pc computer , this way you can freely experiment or bigger audio mixer with more mic inputs and more mics .

mixer.jpg
 
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conqueeftador

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Sound interesting, I'm just venturing into all this, need to do alot more research and finish the basic setup before I get there. Still buying cables in various lengths and reading up on acoustic treatment.

A flaw in the Minidsp idea is it can only be put between one set of RCAs, ie one input on one of the rear integrated amps. They are Musical Fidelity X-A1s and Aux 1 is fed from the DAC for music, Aux 2 for office surround (One amp does front, one does rear) and Aux 3 for home theatre rear and rear surrounds (One does left, one does right). Only Aux 2 and 3 use the Denon as a preamp otherwise it is off.
 

alex-z

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I had a fairly large ported twin 10" Polk set to 60/70hz before, didn't matter where it was put, my body (not my ears) told where it was coming from, one side vibrated, the other did not. Looking forward to trying the SVS's.

Would the subs still be missing the details if the fronts were set to large? That's how I wanted to set the SVS up, using the front pre outs and the subs DSP.

With the rest of the speakers, would it work to set them to small with a 50 or 60hz crossover? The slim subs will then do everything 50+ and the SVS everything 50 and below? Fronts could likely be moved to 40hz which I believe is the lowest I can set it to if also set to small using the LFE out. Although I'd like to try a set in stereo.

That link is massively detailed, thank you, I have saved it and will try and go through it when I have some more time.

I do actually have an MiniDSP I wanted to investigate for the office, older non HD one though, don't think it measures well. Will invest in a mic.

Which 10" Polk? The PSW10 in particular is known for low quality bass, with a peaky response and port noise. The HTS10 is considerably better but almost 3x the price.

Don't set your fronts to large, there is no reason. Set to small, so that your speakers have a proper high-pass filter applied. Then hook all your subs up to the LFE outputs of the receiver, and then apply DSP on the subwoofers themselves, or with the miniDSP. For your office setups, hook them up to the Zone 2 output of the receiver, and then potentially into a second miniDSP unit. This results in a no compromises setup.

50 or 60Hz is possible, it depends on the size of the speakers. Most bookshelf speakers perform best with an 80Hz crossover.

When it comes to blending different sub models, the miniDSP is essential, and I would highly the HD model. Not only because of the lower noise floor, but also because it has more processing power, allowing for more filters.
 
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conqueeftador

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I have no idea to be honest, it was a while back. It was US spec, had 2x 10" in one box with a strange port on the back which had a square piece over the port. Pretty sure this was a good sub as the volume went to 11, which is better than the 10 we'd see on all the others.

Found this about using a 350watt 10" sub with the E83 - "The E83s actually produce 3dB more SPL at 28Hz and 6dB more at 31.5Hz than the E8AS1"

Hence I'm hesitant in removing frequencies the speakers do seem to be able to deal with? 40hz is the lowest I can set it to. Shame we can't set the roll off slope.

I wanted to avoid using the Denon for stereo (in the offices at least) if possible, initial testing indicates it does not sound too good being used as a preamp. I've just added 2x small Monitor Audio 8" for each of the rears and these have frequency control. So I can set that to 80hz, but that doesn't stop the rear speakers getting a full range signal.

The problem I can see with the minidsp is I've got integrated's on the rears, so I could only run it between one input, likely the stereo source unless I get a pre/pro for each of the rear setups which starts to add up.
 
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conqueeftador

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Got the pair of SVS setup, plugged into the LFE. Sound ok on a quick test. First issue is the LFE only goes down to 80hz on the Denon, so I'm having to use the crossover on the subs anyway. Set to 50hz on a 12db slope. Sounds alright.

Next issue, is on preset 2 for the office surround, I am unable to set all speakers to small and not use a sub, one pair of speakers has to be large if there is no sub set. I don't want to use the SVS for the office as they are quite far away.

Think the way around this is set preset 2 to use 1 sub, and use lfe1 output, and preset 1 to use both with the SVS both plugged into LFE 2, but then I'm stuck using the Denon for stereo.
 
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