Subwoofer crossovers
You shouldn't connect the subs to two different preamps without an A/B switch. You can get an auto switch from Niles Audio that works well. The Velodyne SMS-1 will let you do what you want to do plus give you room EQ. It has multiple settings also. Velodyne SMS-1 |
I am using 2 JL 113 in an mixed 2 channel / multi channel system with my Parsifal Encores, using an external Xover and a bass EQ unit (the SVS). An important consideration in how you want to do this is whether or not you want to run your mains at full range along with the subs on 2 channel, or if you want to use the high pass from the Xover. Can you elaborate? I presume for multi channel you will do all the bass managment and EQ in the Meridian SSP? I think your best bet is indeed to use a switch and an analog cross over and some form of bass EQ for the subs in stereo mode. Also, rather than summing the stereo signal I would run full discrete 2 channel stereo subs. You can split the mono LFE signal into a L/R signal into a stereo switch, and have a second stereo signal come in for use in 2 channel mode. |
I should being this by saying I am from the pro side. Pros feel the best way is always to run the mains full range, use a Low Pass filter on the sub that's being fed the same full range signal. However, for movies, the correct movie set up uses a dedicated Low Frequency Effects channel, with the caveat being different studios have used different LFE crossover freq's in their mixes. The correct one is 120Hz for THX style but some have used 80Hz. This is also a summed mono channel. This whole area of LFE and crossovers etc is what's called "bass management", which many of us hate for lack of a universal standard. The idea of rolling off mains sucks! Inserting a crossover into mains at such an audible point leaves a good sized "hole" to sort out, a artifact you cannot fix. Obviously this is a common problem so there is an entire class of product out there for it. Being that this 5.1, 7.1 processing is typically all digital, there will be a wide range of performance differences between processors. The main point to make is DO NOT rolloff the mains or insert any type of crossover on the mains for anything but movies. It makes a big [audio] mess. Brad |
Brad, glad there is professional confirmation for what my amateur intuition told me. I am running mains at full range and use a low pass filter for my discrete stereo sub signal. For MCH 5.1 I also sum the unfiltered LFE channel to the discrete stereo signal of my 2 subs. The only (non-pro, and non custom made) device I found that can do this is the NHT-X2 Xover. Now discontinued. You mention cross-over frequency for LFE channel, but I presume this is only relevant is you cross over mains, center of surround to the LFE channel. If you don't you will simply get on the LFE channel what was mixed to that channel in the studio. |
Hi Edorr Yes the crossover applies to the mains and a lot of speaker manufacturers (like ATC) dislike the idea. Others do it out of compliance if they plan to sell a lot of small 5.1 systems in post-the customers (in this case post production engineers) need to hear exactly what the 5.1 mix will sound like. Brad |
The posts in this thread suggest you folks are knowledgable about bass management. It seems as though SACD discs output as DSD from my Sony XA5400ES or Oppo BDP-93 to my Cary Cinema 11a lack bass management. The subs are not invoked. OTOH, HDCD discs from the BDP-93 do invoke the subs. I read one of Kal Rubinson's remarks to suggest DSD might not carry bass management information. Do I need to output LPCM to get the subs to fire? Is it endemic to DSD or is it a problem with the Cinema 11a? I'm trying to understand this. db |
You cannot apply bass management in either the Oppo or the Cary when playing in DSD Direct mode. However, when you play a 5.1 SACD you should still get information on your subs (this is the .1 channel), because this information is present on your source and does not require bass management to reproduce. When playing a stereo SACD (or a 4.0 or 5.0 SACD), you will not get any bass on the sub and need to convert to PCM if you want to use the subs. Try both modes and see if the benefits of bass management outweigh the loss in resolution of converting to DSD. Some have reporting no such loss exists, in which case PCM conversion is always preferable. To my ears the loss is substantial. IF you play a 5.1 SACD and you get no output on the subs something is wrong in your setup. |
I'll take the other side of Brad's argument. Unless you're using full-range room EQ (ala Audyssey), the most audible of the passive-treatment resistive, room induced, problems occur between +/- 60hz and +/- 110hz in most rooms (IME, anyway). Bassbusters are great, but their effectiveness starts to diminish below 100hz, and is generally, entirely gone by +/- 70hz, IME. If you're using subs, you can address these thorny problems with careful placement of the subs and/or deciated subwoofer EQ (SVS or Velodyne). Either way, the subs need to be the source of the output in this mid/upper bass range if they're going to the tool used to fix the problem. This means the subs need to roll off fairly high: somewhere north of 75hz in every room I've set up. This usually makes a good "hand-off" to unfiltered mains impossible, unless the mains have no bass at all. Something like the Sunfire Ribbon Monitor might work, but most high-end mains have sufficient bass to relegate the sub-woofer to deepest bass only. You can't run the subs high enough to fix the nasty problem that subs are best suited to fix - unless you low cut the main speakers. That's a mistake IMO. I know many, many folks prefer to eliminate an active x-over, but at 80hz, I find that even a modest cost unit like the NHT x-2 is very, very hard to detect. Of course, this "undetectability" depends both on the system in question and the listener in question, but I've A/B'd the X-2 in some very high end chains and, with suitable program material (i.e. no bass at all), I can't hear the difference. Also, of course, YMMV, on that one. It's entirely possible that a truly crappy low cut for the mains like that in the Velodyne SMS-1 may be a different story. I'd agree that decent active x-over is important. But, shy of that, I believe that any deterioration introduced by a decent active x-over is (IMHO) likely to be swamped by the benefits of crossing the subs out higher in frequency than is usually possible when the mains are run full-range. A lot of people note that there are also benefits to relieving certain mains of the heavy lifting in the mid/upper bass, as well, but - IMO- that's just a little icing on the cake. Just the other side of the coin. Marty |
Marty, not an unreasonable argument, but keep in mind that by crossing over to your subs at say 100Hz in order to get typical room modes in range of the EQ you apply on the subs, you are not only running the mains through an active filter. You are also turning your full range system into a satellite sub system. I had a dialogue with a guy who was doing just that (basically using Avalon Eidolons as satellites!), and advised against it. He has since gone another direction I believe. It all depends on your room. If you have some horrific boomy modes the satellite + EQ'ed sub approach may sound better, but in a half decent room it probably won't. There are a few alternatives though. Use the Rives Parc 3 band analog EQ unit (<300Hz) in the mains signal part. I had one of those for a while but never used it. The second option is to get a speaker with separate woofer cabinet and monitor, get an external cross-over, bi-amp them and apply EQ only to the woofer cabinet. In fact, the Vandersteens do just that out of the box. Their woofer cabinet is active and has build in EQ. The Salk Soundscapes would allow you to do that to, as do verity audios (you need to get the external cross-over). I toyed with this idea, but after measuring my room in REW and finding out my mode aroun 100 hz was less than 10db I decided not to bother. |
I cross at 75 hz in my current room, because that's as low as I can go and make it work. I have gotten below 70hz in a previous room, but never down to 60hz. My point is that full range speakers in free space start to exhibit really difficult behavior somewhere not too, too far below 100hz in most rooms. Wherever that point is, that's where I feel that you're best off crossing to subs (if you're using subs), because the subs will almost certainly allow better behavior. Whether that makes your system a sat/sub or not isn't really that important to me. Not to me, anyway, tho others might be more concerned. Marty BTW, Have you ever crossed your Verity Parsifal mains straight to the JL subs without the Verity bass cabs? I also have P/Es and tried it once with my Rythmik subs. I know that it's odd (and might not be appropriate for a long term configuration), but it was both interesting and educational, (and reasonably easy with the SMS), if nothing else. I'd be curious to see how it flew with your JLs. |
Edorr, Sorry for the loooong delay in replying to you. I saw no reply's after 2 week and thought this was a dead thread. I am using my Sarastro II's full range. They have an 11 inch bass driver but I like how the JL's load the room and with Floyd music they add that very low fast bass. I crossover the JL's at 35Hz since they are being used with 2 channel. I would not want them at a much higher crossover since the Sarastro's sound great in full range. I have tried a few subs and for 2 channel I prefer the JL's they are the fastest sub I have found I just wish it had an LFE input. Yes I want the Meridian to handle the subs crossover & EQ's when in theater mode. Martykl, The NHT x-2 sound very interesting and the cost is minimal but is there a better unit available. I like the fact it has an LFE input. Do you know if it overrides the stereo input? This thread is getting interesting. Thanks for the reply's |
Hevac1, we have a very similar approach in that I cross over at 35Hz and run mains at full range. I am also using the NHT crossover (as low pass filter only) and it works like a charm. It sums the LFE to the stereo signal. Obvioulsy, it does NOT apply the Xover settings to the LFE channel but adds the "full range" LFE signal (which is typically up to 80-120Hz). Marchand will custom build you a Crossover that sums LFE and stereo as well. I believe it was Marty who mentioned he preferred the cheaper NHT though. Funny you sould mention Floyd music. Blew up my midrange drivers listening to shine on you crazy diamond last month. |
Hevac, the LFE channel on the NHT is summed to the stereo channels. It does not override it. Works like a charm. It was the only device I could find that could so this. Marchand offered to custom build me a 3 in 2 out Xover for a lot more money. Unfortunately NHT no longer makes the x2 but they show up used occasionally. |
Re: Marchand x-over. I just want to clarify my experience. I bought a used Marchand that had been re-tubed by the dealer, but it was still noisy. I returned it and bought an X2 for interim use while I decided how to proceed with a permanent x-over solution. The X2 turned out to be good enough to keep - so I did. However, this shouldn't be taken as a thumbs down on the Marchand. It's entirely posible (maybe even likely) that the issues I had were with that particular unit, especially given that it was used. I don't think anyone should extend my experience with that unit to an evaluation of that model. I certainly don't. Marty |
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Sure, but to suggest Hevac should cut off his $40,000 speakers with 11" woofers at 80Hz and reproduce this range with two EQ'ed subs instead makes no sense. Now, if you believe a sub / satellite system has big inherent advantages that is a different discussion. But once you have sunk a lot of cash in a full range speaker, you might as well use it. Keep in mind that going up the foodchain in a speaker lineup usually involves getting bigger cabinets and woofers. If you opt for a sub / satellite configuration, get a cheaper model and deploy the savings towards subs. |
The idea of monitors and subs is appealing, but I wonder about the dynamic range of monitors. I think they might be great for most of the music I enjoy, small jazz and chamber groups, but what about the occasional excursion into large orchestrations, e.g. Mahler's 2nd. I admit that I haven't listened to many of the newer monitors. db |
I think Edorr may have misunderstood my question. I use a pair of 15" subs with room correction, and I agree they are important for portraying small jazz groups. I was asking about the ability of monitors to handle the dynamic range of a large orchestration in the frequency regions not handled by subs. db |
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Edorr, Pink Floyd and some other music is why I upgraded from the Verity Ovation to the Sarastro's. I bottomed out the bass drivers of the Ovations with music from The Wall album. I prefer the sound of Verity speakers so I stayed with the line and the fit and finish of them is awesome. If I did not push 90 - 100 db with Floyd and some other music I would not have run into the issue. BTW I could not make them bottom out with the CD version of The Wall. Vinyl is my preference SW when I listen to 2 channel music. The only thing I miss most after the upgrade was not being able to rotate the bass cabinet but the size of the Sarastro's bass driver more than makes up for the inability to rotate the bass driver forward. I am looking into the NHTx2. It looks like it does more than really need. I will set the front panel EQ to match what I have the JL's front panel setup for, so the 2 channel system will have no change. Then when the LFE input gets info it will over ride the 2 channel settings to the LFE crossover setting. I will set the LFE crossover to 110 Hz and allow the Meridian to set the actual crossover point. As long as the crossover point is at or lower than 110Hz there should be no problem. |
I did an in house shootout between the Avalons Eidolon Visions and my Verity Parsifals and prefered the former. Highs of Verity were a bit smoother, but I prefed mid and in particular high bass in the Avalons. I blew up the Avalon midrange playing Floyd at 95db (105 peak) at 12ft distance. To my knowledge the NHT does not apply any crossover filtering to the LFE channel, and there is no 110Hz setting you can apply. It (correctly) assumes LFE is always crossed over in the SSP or source player. It passes on signal and sums it to the 2 channel information. If you set the NHT to the same setting as the JLs you are applying two low pass filters (not sure slopes would match). You would get less signal degradation if you bypassed the filter in the JL (flip the switch) and just applied the crossover of the NHT, not sure the difference would be audible, but philosophically this would be preferable. How are you planning to score a used NHT if I may ask? |
Hevac - other thought. If you have set cross-over on your JL's for stereo mode (at say 35Hz), the JL's will cut of your LFE input at that frequency as well, and you would lose most of your LFE information. The only way around this is to use the NHT crossover as intended and as I described in my previous post, and switch off the JL's Xover. |
Edoor, I stand corrected, the Feq. switch I was talking about is for " the High Pass Filter determines the range of frequencies that the main speakers ("satellites") will reproduce" my mistake and I will not be using that option at all. I will be using one of the 2 main outputs from my Ref3 for my Sarastro's and the other to the NHT x2 Yes when I get the X2 I will switch off the JL's crossover. As for where I will a NHT x2 I am not sure. I am good at finding items I need so I will search around a bit. Jarad from Goodwins say's he can make it all work without an additional crossover. I may try that also. I really wish they added a remote to the crossover. I have not been able to stress any of the Sarastro's drives so far, all that happens is the speakers get so load it is not comfortable to be in the room with them. The sound is still very clear at that point also. |
Should work. Very similar to what I am doing. Only thing to keep in mind is that if you apply cross over to your mains in the meridian in MCH mode, AND you run a set of outputs from your preamp (I presume with HT bypass) through the NHT, you will get low pass information from your mains twice. First on the LFE channel (crossed over in the Meridian), and once more from the stereo inputs in the NHT. This is certainly the case if you cross over in the Meridian while still running the mains at full range. But even if you apply a high pass filter to the mains in the Meridian, quite a bit of LF information will still be there (because of the slope of the filter) for the NHT to send to the subs (adding it to the LFE channel information). The way around this would be to not use the Meridian crossover for the mains, but let the NHT do the work through the stereo inputs, even in MCH mode. |
My Ref 3 has three stereo outputs, 2 that are adjusted by the volume control in all modes but HTpassthrough and/or processor input and one at a fixed output for recording. I plan on using the NHTx2 on one of the outputs from the Ref3 and the other is going straight to the amps for the Sarastro's. I will also be connecting the LFE output from the Meridian directly to the NHT x2's LFE input. I know I will have to adjustments but I should be able to make these adjustments in the Meridian setup for MCH mode. I will also setup the NHT crossover to duplicate the current setting I have set on the JL's front panal then defeat the JL's settings. I must make the adjustment in HT mode because making any other adjustment in 2 channel mode is unacceptable. The NHT x2 will only be conncted to the subs and not to the main speakers. BTW are you having any issues with any type of noise when using the x2 or drop in fidelity. |
