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Setting sub up correctly

Discussion in 'Subwoofers' started by SOUNDSTYLE, Oct 10, 2002.

  1. SOUNDSTYLE

    SOUNDSTYLE
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    This thread is in advance of me getting either the CHT-12 or 15.

    My system:
    Denon 2700 processor
    Monitor Audio (MA) 703 PMC (which can produce 80Hz easily)
    MA Silver 3 rears
    MA 750CC centre

    I haven't a clue how to go about it correctly.
    Will I need a SPL meter to get the correct settings?

    I have a Denon 2700 processor and have all speakers set to small and all bass going to the sub.
    The db for the subwoofer can be adjusted through the processor but I don't know how to use it properly.
    At the moment it's at 0db (connected to a REL Q100E) and if I change the setting to -1 onwards the sub gets quieter which is what I don't want and that's why I leave it at 0.

    What routine should I go through once the hi and low level connections are connected, step by step?

    As the Denon has a dedicated subwoofer output and the sub has a red and white connection for low level which one should I use, or does it not make any difference?

    On a slightly different subject:
    Does anyone know if the Vivanco prowire (which I have connected to the REL for low level) is shielded, or should I get a better make?

    If I should get a better make where should I get?
    I'll need to get speaker cable for the hi-level aswell. I'm using Sonic link AST 200 bi-wire. Should I go for the same (if it's still made). I'll need 6-7 metres worth.

    I haven't got any cable for the hi-level at the moment because I'm using the neutrik connection which comes with the REL.

    Thanks




    :)
     
  2. Lowrider

    Lowrider
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    You don´t need high level connection if you set all the speakers as small.

    Your Prowire will probably work fine... but it doesn´t hurt to get something better, I have Audioquest G-Snake...
     
  3. SOUNDSTYLE

    SOUNDSTYLE
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    What I forgot to say, is that I have a Arcam 8R amp and Arcam 8P pre amp controlling the main speakers and the Denon controlling the rear and centre.

    This is because the Denon did not produce a good enough sound for my music.

    That's why I need to connect the hi-level connection from my Arcam.

    Hope that makes sense?

    Any answers to the rest of my questions?

    Thanks
     
  4. Lowrider

    Lowrider
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    Again, if you connect the Arcam pre to the pre-out of the Denon and the front speakers are set to small, you still don´t need high level...

    Unless you use direct mode... still the impedance on the sub is very high, so only a "low" level signal travels through, see the cables supplied with the REL...
     
  5. MikeK

    MikeK
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    Lowrider

    I think what Soundstyle is saying (I'm sure he'll correct me if not) is that he wants the high level connection so he can use the sub with stereo sources, such as CD, which are connected directly to the Arcam stereo amp, not the Denon AV receiver.

    For DD etc, as you say, he doesn't really need it.


    Soundstyle

    I wouldn't bother about an SPL meter for setting up the sub - the cheap ones are known to be pretty inaccurate at low frequencies.
    The Tandy/RS meter is common, and even has correction figures available on the web - personally I'm highly dubious that every meter will need the same amount of correction though.
    It's just not a high precision instrument - no surprise at £30 either though!

    From your description, the sub control on the Denon sounds like it's simply a level control - much the same as the level dial on the sub.

    Cable - personally I'd stick with the one you have. My opinion is that a more expensive lead won't make any discernible difference at all.
    Others think it will though, so it's up to you in the end!
    As for the high level connection, again, it's up to you, but bear in mind what Lowrider said - the input to the sub is relatively high impedance, so it'll be carrying very little current UNLESS you also then connect the main front speakers to the subwoofer's high level out posts - but personally I wouldn't do that!

    You can use either red or white phono - it shouldn't really matter.
    The sub may say on it which one to use though.
    A better idea is to use both by using a Y splitter from the single sub cable to both phonos - this gives a higher input to the sub's amp (it will sum left and right), which in turn means the sub's amp won't have to work quite as hard etc


    I think you are going to run into problems connecting the way you intend to though.
    For DD, if your AV amp filters at say 100Hz (don't know the actual figure) and you set all your speakers to SMALL, then everything below 100Hz will be sent to the sub via the low level connection.
    You'll no doubt either set the sub's crossover to max, or at least above 100Hz. This will probably work fine.
    However, if you then turn off the AV amp, and play a CD through the Arcam amp, the crossover on the sub will now be set incorrectly - your main speakers will play down to what, say 45Hz??, so the crossover really needs to be set around that as well or you'll get double bass. The sub will be doing 20-100 while at the same time the main front speakers are doing 45-20000 - so between 45-100, you'll efectively get double output, which probably won't sound too good (although I'm sure there are some who'd like it :) )
    You could adjust the crossover every time (a bit of a pain in the ass though), but the crossover, level and phase adjustments aren't mutually exclusive - usually you adjust one and the others need a tweak too!
    You could set all your speakers to LARGE on the AV amp, and set the sub's crossover to 45Hz for instance, and this will get round this problem - but now the only thing going down the low level connection would be the LFE channel info. You may lose a bit of that if the sub's crossover is set to 45Hz, and you'll also lose some centre and rear channel bass, due to the fact that they are now being asked to play full range and they may only be able to get down to say 60Hz or so.
    Setting the centre and rears to SMALL won't help either, as then all their bass below the amps filter freq will be sent down the low-level connection to the sub, which is now crossed over at 45Hz, so you'll lose all the bass for those channels between 45-100Hz.
    Some amps allow you to send any cut bass to both the sub and the main fronts though, and this may well get you round the problem to a degree, if yours offers this option.


    What would probably be better is to keep the REL for music, connected high level to the Arcam, and use the Velodyne for AV, connected low level to the Denon (with all speakers set to SMALL)
    This may not be feasible though!


    There are a few other alternatives which may be a reasonable compromise though.

    You could connect the Velodyne just with the low-level connection, and just not use it for music at all, relying on your main speakers alone.

    Or you could dispense altogether with the low-level connection.
    Set the Denon for no subwoofer, and fronts to LARGE.
    The Denon will then send the LFE channel to the front speakers, along with any cut bass from the centre and rears, if you set them to SMALL.
    Your fronts will then play all bass content for all channels from 100-45Hz, with the sub kicking in for 45Hz downwards.
    For CD, the fronts would just do their usual 45-20000, with the sub taking care of everything below 45Hz.
     
  6. Lowrider

    Lowrider
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    Or you can get a sub with separate xover and level controls for low and high inputs, REL, for instance...

    This way you wont have setup problems with your gear...
     
  7. Geoffrey Shrek

    Geoffrey Shrek
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    Somebody wake me up when this is over
     
  8. bob007

    bob007
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    I think he already owns a REL. :rolleyes:
     
  9. Lowrider

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    I ear he is upgrading it, there are better RELs than the Q100E, do you know... :eek:
     
  10. bob007

    bob007
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    I ear e is 2. :)

    Hopefully he will be owning a CHT15 shortly, what he is wanting to know is can the CHT15 be connected in the same way as the Rel Q100 he has now, via high/low level for music and movies, to which I think the answer has been given a few times in various threads.
     
  11. Lowrider

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    OK, I am a little edgy with the green thing, sorry I snapped... :blush:

    As he said "in advance of me getting either the CHT-12 or 15" I assumed he hadn´t decided yet...
     
  12. bob007

    bob007
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    I knew the CHT12 was not an option on the power buy, and saw this post yesterday.
    ;)
     
  13. SOUNDSTYLE

    SOUNDSTYLE
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    MikeK
    Thanks for the long post. There's quite a bit of information there, some of which I don't understand completely due to my inexperience with subwoofers and surround processors etc.
    I don't know the difference between 'crossover', 'level' and 'phase' for instance, and if I did I would be able to connect the sub up knowing exactly what would happen if I did this or that.
    You understand my dilemma exactly, by the way.
    I have asked about this problem a couple of times in other threads and Jase[/B} posted this (I don't know how to quote):

    SOUNDSTYLE

    If you have the processor set to all speakers small, all bass to sub then you don´t need the high level connection. The low level will handle everything i.e all bass below the cutoff frequency (80hz). For music just listen in Stereo mode.

    If you are using any DIRECT mode then, Yes, you´ll need the High Level connection and you would switch OFF the SW channel for low level, assuming your Denon processor allows this. I assume you´re using the Arcam for any analogue source, CD etc? You´d still need the High Level connection in this case as well.

    The way to do this on the Velodyne would be have them both connected but you would have to make a note/mark on the volume level, one for music, one for movies and also switch in or out the subs internal crossover.

    For Movies I would leave the crossover ignored on the sub (controlled by your processor, all speakers small etc) and when you want music just flick the switch and it will use the subs crossover at whatever setting you have it. Then just adjust the volume to the relevant mark and thats it.

    What Jase says makes sense but do you think it will work?
    I really want to connect as explained above: hi-level from the Arcam and low-level from the Denon.
    It looks like I will have to find a setting for each and remember what they are, then adjust the sub whenever I listen to one or the other.
    If I know that it will work this way then I can buy the CHT-15 with confidence and not worry that I won't be able to connect it up the way I want.


    Thanks to Bob007 and lowrider aswell.

    Geoffrey Shrek - If you have no worthwhile comments why don't you bugger off and stop reading my thread.

    Thanks again
     
  14. Geoffrey Shrek

    Geoffrey Shrek
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    Thats not nice. My opinion is just as valid as the next mans. At least I don't make up storys like some other members.
    I'll leave it at that this time :mad:
     
  15. SOUNDSTYLE

    SOUNDSTYLE
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    What opinion is that. You didn't say anything.
    What stories (correct spelling) am I making up??
     
  16. Lowrider

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    Don´t worry Sound, he is teasing me... I am through answering to him, just ignore IT...

    Monkeee, Ian,

    I apologise, you are right, it takes two, but it is forgotten and forgiven, just business as usual... :cool:
     
  17. MikeK

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    It might, but you'd have to try it!
    I think you may have problems though!

    For movies, the Arcam stereo amp will be sending an 80-20000Hz signal to the subwoofer (it can't avoid doing this as the sub is connected to it's speaker outputs), and the subwoofer would now be without a crossover (you've switched it out).
    Fair enough, it won't reproduce the high stuff, but it will produce a few hundred Hz, say 200 or more, usually without a problem.
    So, while only the sub is producing sound between 20-80Hz, both the sub and the fronts will be producing it from 80-200Hz or so, effectively doubling the output between those frequencies - not good IMO.

    You can get round this by aways having the sub's crossover switched in, and adjusting it between music and movie sessions.
    Say 45Hz for music, and 80Hz for movies.
    A bit of a pain though (as it will usually entail adjusting the level and phase too).
    It also means that the low-level signal gets double filtered, once by the Denon, and again by the subwoofer.


    Subwoofer level = overall subwoofer volume
    Subwoofer crossover is the frequency at which the subwoofer will start to reduce it's output (or more accurately it's input).
    Phase is the control which enables you to get the subwoofer output and the main speaker output "in phase" at the crossover frequency. In phase signals will sum together (known as constructive interference), while out of phase signals will cancel each other out (known, not surprisingly, as destructive interference).
    Usually you can't make a change to one of these without changing the others, as they are all interdependent, but small tweaks may be OK. Eg, adjusting the crossover upwards will mean you may have to reduce the level a bit, adjusting the phase so that the two sources are in phase will appear to increase the level as well, so you may have to turn the level down again, and so on...
    Then there's room interaction, where certain frequencies are boosted by the room, while others are attenuated......more fiddling!


    All things considered, I'd at least try the setup without the low-level connection. As you already have a subwoofer, you can try it with that before you buy anything.
    Whichever way you connect up, it's going to involve some sort of compromise - you may find that this way is the least!
     
  18. bjd

    bjd
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    Shrek, if you have a personal problem with Lowrider, maybe you should sort it out in private. I don't really see the point in following him around the forum, interjecting inane rubbish in other peoples threads. Like someone said earlier, if you have nothing useful to contribute, don't bother.

    Brian
     
  19. Lowrider

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    You have two "permanent" solutions (no fidling around when changing sources):

    First, as Mike said, no sub, all bass to front speakers, high level connection using sub´s xover...

    Second, forget the Arcam pre, connect all your sources to the Denon, just use the Arcam power for the front channels, and use low level and the receiver´s xover...

    If you choose the "complicated" solution, I don´t think you have to adjust phase differently for the two setups, it depends mainly of the location of the sub and the speakers, so it should be the same whatever input you use...
     
  20. Lowrider

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    I thought a little more about it, (is it the smoke detector I ear)... :rolleyes:

    All speakers small, low level from the receiver, high level from speaker outputs of the Arcam...

    Set the sub for the high level, sub´s xover around 45hz, (whatever sounds better, under the front speakers -3db freq), phase the way you get more, and tighter, bass from the sub, volume to your taste, use a CD with good bass, lots of it...

    Next, just change the xover on the sub to max, leave the volume control set of the sub as you set it for high level, adjust bass level on the receiver to your liking, with a DVD with lots of bass, I would pick a concert, Sting´s "all this time" has loads of it...

    Now, all you have to change is the xover setting on the sub, max for any source connected to the receiver, 45hz, (whatever), for sources connected to the pre...

    Mike, feel free to correct me if I am wrong... ;)
     
  21. MikeK

    MikeK
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    All of these methods will "work", and you may get an overall sound which is acceptable.

    However, the problem still remains with the high level connection.
    Set the sub's crossover to max (120 Hz) and the following will happen for movies:
    The Denon will cut the bass to the front channels (as the speakers are set to small - I'm guessing it's cut frequency for doing this is around 80Hz), so only 80-20000Hz will be sent to the Arcam, which will amplify and feed this signal to both the main speakers and the subwoofer.
    Ignoring filter slopes for a moment, the front speakers will reproduce the lot, 80-20000Hz, but the sub will also produce sound as well, from 80-120Hz. This will give you a raised overall output between 80-120Hz. The real question is whether the listener finds this acceptable - if so, problem solved.
    Unless you actually hear it in room, it's very hard to say.
    If the Denon cuts at 120Hz, this might well work OK, subject to subwoofer positioning. Personally I don't like sending frequencies that high to the sub, but it doesn't seem to bother other people.

    While striving for perfectly flat response across the entire 20-20000Hz spectrum is the goal, in reality, you simply aren't going to get it, no matter how carefully you set up your equipment.
    On paper a +3dB rise at certain frequency levels may not look good, but in practice it may well be of little concern in the overall scheme of things.

    I guess what I'm saying is that whether you set the crossover for movies to 80Hz or to the max 120Hz, may in reality not make a great deal of difference.
    Everyone is different, but personally I would soon get tired of constantly switching between two different settings, whether it be 45+80 or 45+120.

    Incidentally, I suspect Soundstyle may well have these "problems" already, but is able to mask the effects somewhat due to the REL having the dual level settings - it still only has a single crossover I believe. As I said though, while it may not look that good on paper, in reality it may not make that much of a difference. Depends on the listener as well as I suppose - while I don't know Soundstyle at all, I'm guessing that from his eqpt (and the fact that he wanted the Arcam for music), that he pretty much knows what sound he likes and what he doesn't.

    Another issue is that if you sent 10 of us into a room to set this up, the chances are that we'd all come up with a slightly different way of doing it, and quite a few of those would in reality sound little different from each other.
    But as is common among people like us, there's always that nagging feeling that you might be able to get things just that little bit better - and these symptoms usually lead to full infection with upgraditis :)
     
  22. Lowrider

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    Mike,

    Hmmm... You are right, I keep forgetting there is only one control... :blush:

    So if he wants to use the sub for stereo as well, he really only has the two options I mention in the first post...

    I also wouldn´t choose the other option, even if I had to fiddle just with the xover control, I am sure I would forget it most times...

    Well Sound,

    If you give more importance to music pick option 1 (you will strain a bit the Arcam, with movies, as it has to amplify even the LFE), otherwise movies option 2... :(

    As your speakers go down to 30hz, and the Arcam only has 50 watts, I would just use the subwoofer for DVDs, you can play your CDs there when you want more slam, less accuracy, and forget the high level connection completely, music doesn´t have much bass under 30hz, (I know, a sub makes it sound better), but maybe you cannot have the best of both worlds, yet... :rolleyes:
     
  23. gringottsdirect

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    Antonio, I see you are playing safe with your crash helmet...:)

    I suppose it depends on what music is played, but a lot of stuff I like has lots of bass under 30hz, I do agree with you that music sounds better with a good sub .
     
  24. Lowrider

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    Sure, I have two subs... It is funny when I have audiophile friends asking me to switch off the subs, (my mains go down to 35hz)... They always ask me to turn them back on... :D
     
  25. SOUNDSTYLE

    SOUNDSTYLE
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    What about disconnecting the speaker cable from the sub's high-level connection when watching a movie?
    Would that cure the problem?
    I can then have a setting for hi-level and another setting for low and adjust it depending if I listening to music or watching a film?

    What do you guys think?
    Thanks again.
     
  26. Jase

    Jase
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    SOUNDSTYLE

    Are you using the Denon for any other source other than movies?
     
  27. Lowrider

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    That would work, plus just changing the xover frequency, as I mentioned before, but it is a pain, at least for me it would be...
     
  28. SOUNDSTYLE

    SOUNDSTYLE
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    No.
     
  29. Jase

    Jase
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    Then I can´t see why should have a problem. The Denon will handle the movie side of things, all speakers set to small, all bass to sub. Sub connected via low level phono. On the CHT15 you have a subwoofer direct switch which switches in & out the internal crossover (bit like the Rel modes 2 & 4). Just set it to ignore the subs crossover for movies then when you want to listen to music with the Arcam and via the high level connection, switch it back in and it will use whatever crossover frequency setting you have selected.

    The only thing you should have to change will be the actual volume on the sub and maybe the phase, both easily done as they are marked clearly (volume 0-10, Phase 0-180, in steps).

    You won´t need to unplug any cables or anything. Just remember that you´ll need extra speaker cables for the high level connection as you need a run from the arcam to the sub and then another run back from the sub to the arcam. This is where its different to the Rel High level connection cable.

    All the best
     
  30. SOUNDSTYLE

    SOUNDSTYLE
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    Thanks Jase
    I don't know if this makes a difference and you've taken it into consideration but I have the system connected so that when watching a movie the Denon is only controlling the centre and rears, and the Arcam is controlling the main speakers.
    Did you know this already?

    I thought I would only need cable going from the Arcam to the sub?

    Why is cable needed from the sub back to the Arcam?

    What would be the best way to connect to the sub/arcam: Bare wire or banana?

    Could you please tell me the process you would go through when setting the sub for low level and then again for hi-level?

    Which would you start with first: low-level or high-level?
    I want to make sure I get it right because I haven't a clue really.
    I hope (and you guys awell I guess) that this will be the last of my question but I'm not promising anything ;)

    You've all been a great help in explaining things but it's still a lot to take in. :)
     

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