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Direct mode and subwoofer

Discussion in 'Arcam Owners' Forum' started by Jim_R, Mar 16, 2005.

  1. Jim_R

    Jim_R
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    Is there any way to use a powered subwoofer with the AVR300 in Direct mode?
     
  2. steeled

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    From my understanding of the AVR300 in direct mode no signal is passed to the subwofer output unless you are using a 7.1 source.

    To use your sub you will need to use the speaker level inputs on the sub.

    Hope this helps.

    Regards
     
  3. misfit_toy

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    Yes Jim, there is a way. Albeit an unconventional one. I have my Arcam set with the subwoofer setting to None. And then I have two identical subwoofer cables running out of the Front Left and Right Pre-amp outputs straight into my L/R RCA inputs on my subwoofer. This runs all the low end signal from your left and right channels PLUS your subwoofer signal directly to your subwoofer.

    There are several things to keep in mind while doing this though. First off is the benefit of having your subwoofer for all music, even in Direct Mode. Second, you remove one entire layer of crossover from the signal path for the sound (i.e. - cleaner sound).

    There are things that you will need to do to compensate for this though. Because your receiver is no longer doing the crossover work for you, you'll need to enable the crossover on your subwoofer. I recommend between 60-80 Hz. But you can set it to whatever you like. Also, you will most certainly need to have your front speakers to be full range towers as bookshelves will not be able to handle the discrete LFE signal you will be sending it. And you will certainly need to calibrate the phase on your subwoofer and may need to fiddle with placement as to not have any major boosts and drops in low Hz signals.

    Also keep in mind that any low end signals your Fronts main speakers can't handle it will be picked up by your subwoofer. That goes for both L/R and subwoofer signal.

    If you do all things properly you should have the cleanest signal you've ever heard out of your Arcam and lotsa bass for all occasions. Good luck!
     
  4. ANDY_DUTTON

    ANDY_DUTTON
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    Whilst the post above by misfit_toy is correct, you should keep in mind that if you do this there is NO crossover on the front speakers so full range signals will be going to front Left and right.

    This is OK so long as these speakers can cope with the energy. i.e they are not satelite speakers, if you use satelite speakers in this configuration you are likely to damage them.

    To get the base level in the room correct you need to match the xover on your sub to the natural roll of of your front speakers. If they are stand mounts this is likely to be arround 60Hz and for floor mounts probably about 40Hz, but you will need to experiment to get a smooth xover.

    Regards,
    Andrew
     
  5. Jim_R

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    Gee, I must not have been paying attention. I never saw the replies from misfit_toy and Andy_Dutton until this morning. Thank you for your replies. Since my original post, I have purchased my center and surround speakers. Oddly enough, Magnepan (my speaker manufacturer) recommends the very wiring scenario suggested by misfit_toy for a cleaner sound. I was actually excited about trying the suggestion, but after further thought, I do not think that my Quad ESL-57s (front L and R speakers) would be able to handle the LFE signal found in some movies. I think that it would work great for most music, but movies would be a problem.
     
  6. Crustyloafer

    Crustyloafer
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    There is a very simple way to use a subwoofer in direct mode, all you need is a subwoofer that can connect to the amp with a high level connection. Any of the REL or MJ Acoustics models will do this. You then just connect the subwoofer to the same speaker terminals as your main speakers.
     
  7. Jim_R

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    Can channels 6 and 7 be used to drive the subwoofer - for direct mode stereo operation?
     
  8. Shaka

    Shaka
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    If you're talking about the high level input connection then I think that in direct stereo mode, only channel 1 & 2 are ever used, so attaching the sub to speaker terminals 6 & 7 wouldn't have any benefit. If you connect it to terminals 1 & 2 as Crusty's suggestion above, you can use the sub in stereo direct mode. I'm assuming your sub has a high level connection?

    I have my REL connected to the dedicated LFE terminal via the low level connection and also to speaker terminals 1 & 2 (as described in the manual) using the high level connection. The crossover during multichannel playback is determined by AVR300. During stereo playback, the subs frequency rollover setting determines the crossover.
     
  9. Crustyloafer

    Crustyloafer
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    That's exactly the way I have mine setup too, only the high level is connected to a dedicated stereo power amp and not the AVR300.
     
  10. SMCC

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    I'd advocate this method of connection too. I have a DV27A configured with subwoofer:none and front L&R:large
    which feeds an A85 with multichannel board. The A85 powers the front L&R speakers which seem to cope very nicely with the full-range signal (ATC SCM7) and the sub receives the same signal from the A85's FL/FR pre-outs via a P85 power amp.

    I tried using the pre-outs direct into the sub's line level inputs but the pre-out signal voltage is so small (compared to a typical line level signal) that my sub would never be loud enough.

    It's really nice to always have the sub always on, regardless of source, especially if like me you have bookshelf speakers without a great deal of bass extension.
     
  11. Jim_R

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    I apologize for my limited knowledge, but I do have a couple of questions. First, what is a high level connection? Also, if I run bass cables from the front right and left pre-outs on the AVR300 to my subwoofer, will LFE channel information be sent to the subwoofer as well? If so, how does that happen?
     
  12. mrkeeling

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    I am not sure that feeding the full range signal to the speakers that are not (really) full range is the best possible solution. At least it was not for me. I have small towers for fronts that go down to 50Hz.

    I do not have AVR300 but AVR200 (and a bunch of amps) :) and only one source that I care about – my DVD, DVD-a, SACD player. The solution for me was Outlaw ICBM (Integrated Controlled Bass Manager). This thing is analog active crossover with adjustable crossover points (from 40Hz to 120Hz) separately for each speaker group (one for fronts, one for centre, one for surrounds).

    I am bypassing any kind of bass management in my player, connecting its 5.1 output to 5.1 input on my AVR through ICBM.
    This way I have only one, pure DA conversion (no bass management, no delays, no nothing) :thumbsup: . ICBM takes all the LF from all the channels (at set crossover point – in my case different for each speaker group) ads it to LFE and feeds .1 input on AVR. 5.1 input on AVR can not be more direct – you can not apply any DSP even if you want to :D .

    I use this for whatever I play: CD’s, DVD’s, DVD-a’s, SACD’s. All DA conversions and decoding are done in the player (shortest path possible – no jitter, no clock sinc problems).

    This gave me the best sound by far :clap: . Running my fronts Large (before I got ICBM) did produce satisfactory bass, but my upper bass and lower mids were muddy. I guess stressing the speaker with full range signal took its tool on clarity.
    :beer:
     
  13. Crustyloafer

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    1. A high level connection is one that allows the subwoofer to be fed a signal directly from the main speaker terminals on the amplifier. Thus when using this connection in direct mode the subwofoer still gets the audio signal as it is conneted to the same sockets as your main speakers. All you then do is set the crossover on the subwoofer to a point where it just fills in for the frequencies your main speakers struggle to produce. Most high quality subwoofers should alow this method of connection. A good example is the REL Stentor 3 which I use myself.

    2. You do not need to run connections from the front left and right pre outs on your AVR300 if you have a subwoofer that has a high level input as it will be connected directly to the same terminals as your main speakers.
     
  14. Starkiller

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    Hi

    Would it be possible with the AVR300 to use a spare amp channel say 6or7 (as im running a 5.1 setup) to drive a non amp'ed sub, maybe linking the sub out phono to an input phono?

    this would save me a fortune in my budget as i have a nice 15" JBL sub sat idol. (and it would be fun building boxes again:) )
     
  15. Crustyloafer

    Crustyloafer
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    I guess if you had a DVD player with Dolby Digital and DTS decoding onobard it you could use the multi channel ouptuts on that to go into the multichannel inputs on the AVR300 but making sure that the subwoofer output from the DVD player was plugged into the Surround Back Left or Right inputs on the Multi Channel inputs on the AVR300. Doing this you are relying on the processing capabilities of the DVD player and wasting them on the AVR300 and is probably a very messy way of doing things. It is also likely to put a lot of strain on the amplifier in the AVR300 trying to drive a big 15" drive unit as well as the rest of the speakers. All in all, probably not a good idea.
     
  16. Starkiller

    Starkiller
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    thanks for your reply :D

    im looking at the 79dvd arcam as well, but I thought i could use the sub out on the AVR300, maybe with a splitter if i used a second sub like the cub2(but probably not as i would be testing)

    Im only thinking of a cheap way to boost a Sub sat set if needed, the current favorite SIB XL & Cub2 has a tiny sub, and no one seams to have any views on it.

    The Car sub is JBL 152, its only 150W rms but 4ohms, the idea is i could make a box to be hidden behind a couch, 3cuFt is recommended by JBL and is do-able.

    this would probably be temperary until i was happy with the box then id get a BK amp.
    ive also got pair of old mac audio 8" that could be played with :devil: .
     
  17. Crustyloafer

    Crustyloafer
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    I still think you'd be better off forgetting about wiring up a passive sub to the Arcam, you may have to change your name from 'Starkiller' to 'Ampkiller'
     
  18. Starkiller

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    Ampkiller, nice one

    but serously, wouldnt the amps internal protection kick in, plus i think you can limit the volume per speaker.
    I wont need high wattage, im thinking of a ported design and its in a corner right by me.

    4ohms may be the killer as the other speakers are 8ohms and i notice there is a 4-8ohm switch

    Maybe the Arcam man could advise us(me)
     
  19. ANDY_DUTTON

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    Ok I had a bit of a think about this. I agree with Crustyloafer that this is probably not a good idea as it will put alot of strain on the PSU and probably degrade the sound of the main channels. However if you really want to try it I think this will work. The amplifers will protect themselves so long as you don't short circuit them or wire them together.

    Set the system to 4 ohms (do not use 8 that really will make it all get too hot) the 8 ohm speakers will work fine on the 4ohm setting they will just have 3dB less volume before clipping (unlikely you would even notice this).

    Take the sub out of the AVR300 and feed it back to an unused audio source say AV use a splitter if you are going to use a dual voice coil speaker. Set Zone 2 up to use the AV input it will now feed this to channels 6+7. You will have to adjust the volume for the subwoofer independantly of the main speakers using the Z2 volume control once set it will track the volume as the signal goes through both volume controls. Only use both amplifers if you have a speaker with dual voice coils, DO NOT wire the two outputs together this will cause damage to the amplifers.

    My advice though would be to go to a second hand shop and pick up a cheap PA amp of 100 to 150W you should be able to get something for £30 or £40. And use this to drive the sub. Much simpler and better sound quality fom the main channels in the AVR300.

    Regards,
    Andrew
     
  20. Starkiller

    Starkiller
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    thanks alot too both of you :thumbsup:

    Andy its only a single coil, so ill just use the one amp
    unless im expermenting with the 8"s

    if it works fine, a power amp at £30-40 wouldnt be a problem, might even get a BK amp in the future.
     

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