Advice for speaker/sub setup - amp crossover and speaker size settings

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jase250

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#30195 1-Feb-2009 11:56

Hi folks,

I am looking for some advice regarding the amp settings for speakers in my modest surround system.

I have read a couple of articles which recommend setting all your speakers to "small" so that the lower frequency sounds are handled by the sub, allowing the rest of the speakers to use all their power to reproduce the rest of the sound more accurately.

This makes sense to me, but not, it seems, to the tech that programmed my amp: when using the setup mic, it sets all my speakers to large. I can understand this for my Xandus 5000 fronts, but my centre and surrounds are only Valdus 100s.

This begs the question: how much (blind?) faith should I put in the amp manufacturer to obtain the correct settings?

I am running an Onkyo TX-SR603, Wharfedale speakers as above and a Powercube 12+ sub connected via single channel preout.

Also I would like some advice regarding the crossover frequency settings. The the sub settings go up in 10 Hz increments from 35 to 85, while my amp has 20 Hz incs from 60 to 120, then 150. Considering the lower frequency capabilities of my fronts, should I set the crossover to 60 and match this with the sub? Or would it be better to match it with the surround speakers lower limit? This seems a bit dodgy, as I daresay some sounds in the directional range would be fed to the sub, but do I want to be sending low frequencies to those smaller surrounds?

My instincts say that I should let the amp do all the settings, apart from the surrounds and centre, which I should change to "small" so the crossover only affects these.

Any input would be greatly appreciated.

Cheers, Jason.

Jaxson

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#193342 2-Feb-2009 09:19

I have been quite impressed with the auto setup on the Onkyo receivers. I used to own a powercube at one stage too, and I quite liked it for home theatre. I found there was a pretty clear frequency above which the sub resonated/buzzed/distorted etc, so I always set the sub crossover frequency just before this point. To find this point, you'd need to feed the sub with a signal/music that is not being adjusted by an amp. Start with the crossover as low as it will go and increase it until you find the point I'm talking about, but it's up to you if you want to do this.

Personally I'd set the sub volume to roughly 50% and the crossover to say 80hz or so and then re run the auto setup program. This should give the amp enough 'room' to work with to merge the two. The benefit of the mic setup is it will auto boost or reduce the signals at certain frequency ranges to suit the gear you have, and this gives a more linear response from your gear.

Hope that might help? Good luck, but take the time to enjoy the movies/music as well!

stevenz

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#193347 2-Feb-2009 09:48

I'd set the crossover on the amp to 80Hz and the one on the sub itself as high as it'll go. The amp will probably have a harder digital cutoff than the sub which probably uses a capacitive rolloff. Generally the bigger the driver in the sub, the lower the crossover should be. 80Hz should be good for a 12" as long as your main speakers will handle down to around 60Hz ok (most smaller ones I've seen similar to the Valdus 100's generally stop being useful at about that mark).

I've got a Yamaha unit which has the same sort of autosetup, uses an external microphone that measures speaker size etc. and it seems to be pretty accurate. Basically any speaker that will reproduce lower frequencies at a good volume is deemed to be "large" (as small drivers can't produce lower frequencies very loudly as they can't generate enough pressure). If the YPAO (Yamaha Parametric Acoustic Optimisation) says the speakers are small/large, then that's generally what they are. I've got pretty good faith in the auto-setup systems on modern amps so you'll probably be ok with it.

I work on the principle that in most cases you shouldn't notice the sub until it's turned off. Which generally means having the crossover as low as you can without leaving a frequency-gap, and not having it set too loud.

richms

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#193431 2-Feb-2009 15:33

The issue I have seen with the auto setup when it did it on a friends system is that it doesnt really take into account that some speakers have a response out low, but only at low levels - at the higher levels that you operate it on compared to the test mode they just flap and bang around and are quite bad sounding, yet at under 80ish dB they have loads of bass response and are great.

Richard rich.ms

Jaxson

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#193456 2-Feb-2009 16:50

Actually that's a really good point, in that the output/response of speakers does vary at different volumes.

My current Onkyo receiver replaced my Pioneer system and my speakers sound better now than they did before. However, I did have to up the centre volume to hear the vocals.

Really though you need to ensure you have the hardware to produce the full range of frequencies, and most of the time there will initially be an overlap between the lower end of your main speakers, and the top end of your subwoofer. The receiver auto tune should sort this out nicely. You can tweak the levels once the auto setup has finished if you find the response is not to your liking at different volumes.

Setting the sub physical cross over too low will leave you a hole in the middle low frequency range, so better to allow these frequencies and have the receiver handle the cut off points in my opinion. I found the powercube more earthquake ish than the replacement newer wharfedale offering. You felt it, whereas the replacement one, the sw150? was quite the opposite.

jase250

90 posts

Master Geek

#193510 2-Feb-2009 19:54

Thanks for the input, folks.

stevenz:
I work on the principle that in most cases you shouldn't notice the sub until it's turned off.

Well, I must be doing ok, then: My wife said "I don't hear anything different" until I switched it off on the first day we had it...

Have a bit more experimenting to do.

Thanks again to all who responded. BTW, my mains are Xarus 5000s, not Xandus

The amp sets all my speakers to large and swtiches on double bass - which means if I go with this, there should be no gaps at all, considering that all speakers are being delivered full range and my sub cutoff is higher than the crossover. Still can't bring myself to believe this to be correct on my little surrounds, even though they are 6" with a little tweeter in there as well, so will have to set these to small...

Again, thanks to everybody who had input.

richms

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#193569 2-Feb-2009 23:59

I found after much messing with mine, that the sound I _like_ is far from what you would think is ideal.

Low pass on the sub at about 60, highpass on the amp for the mains at 100 - if the sub is any higher - its obvious where it is, and if the mains are any lower they sound like crap at decent volumes - dont really notice the missing part on movies - music I think sounds cleaner and still has some weight behind the bass unlike with it all going to the mains where there is that horrible drone coming thru all the time.

if its backed down to flatmate friendly levels then it is clearly better with full range going to the mains, but they cant handle any decent volumes like that - might be the amp since I am using the one in a rather craptacular reciever tho.

Richard rich.ms

Jaxson

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#193635 3-Feb-2009 10:15

The Onkyo double bass feature sends bass sounds to both the speakers and the sub woofer.
If you find you have any distortion at higher levels, you could turn this off and it will redirect the bass to just the subwoofer and free up your possibly smaller speakers from these lower frequency ranges.

There's no guaranteeing that the crossover is very definite about the sub cut off point, on both the actual sub setpoint adjustment, or inside the receiver. In practise there is a roll off after this frequency, which means some sounds are still reproduced above the cut off point. The setup richms has suggested might actually allow a smooth transition between the subs upper end and your speakers lower end, so really it's a try and see job sorry.

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bazzer

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#193643 3-Feb-2009 10:40

Are you sure the filter on your sub is used? My sub bypasses its own filter when fed via the LFE input and relies on the signal already being filtered. I don't know about yours.