Hi-

I have an HK AVR 520 with a pair of M22ti's for front
speakers and an EP175 subwoofer. When I play DTS encoded
DVD's, I have heard that the LFE channel is 10dB lower
than it should be and that the receiver needs to boost
it separately. However, my HK AVR 520 receiver is only
able to amplify the LFE when the front speakers are
set to LARGE. I typically set the front speakers to
SMALL and then direct the bass+LFE to the subwoofer.
This works fine but not for DTS movie DVD's.

Would setting my M22ti's to LARGE and directing the
bass to them and only the LFE to my EP175 damage my
front speakers at all?

Does anybody with similar equipment have any suggestions
for dealing with this?

In the long run when I am able to upgrade my front
speakers to something that is more obviously LARGE,
would the M60's be clearly considered to be LARGE?

Thanks!

Bruce

Bruce, what you report hearing about a 10db boost in the LFE channel(for certain technical reasons)when processed by the receiver is essentially correct. However, the 520 and all other HT receivers are designed to do this, whether in DD or DTS and whether speakers are set "large" or "small". Why do you say that your 520 "..is only able to amplify the LFE when the front speakers are set to LARGE"? Unless your 520 has a defect on DTS only which I've never heard of before I don't understand the problem.

You have a good sub and it's good procedure to set all speakers as "small"(regardless of how big they are)and the 520 crossover at probably 80hz. The crossover on the sub would then be turned up to the max to get it out of the way of the 520 crossover. This reduces the strain on both the main speakers and the amps in the receiver which drive them.

Hi JohnK-

Thanks for the response!

I had read about a problem with the H/K 520's ability to deal with a DTS LFE problem where the LFE track is 10dB too low on hometheaterforum:

(The thread is titled "DTS LFE problem and H/K 520")
http://www.hometheaterforum.com/htforum/showthread.php?s=ddd9053d100d4a74d76b44f029b27970&threadid=95640&highlight=DTS+AND+LFE+AND+520

In that thread, people speak of how only the LFE track requires a 10dB boost. Apparently the 520 has limited bass management capabilities and is only able to specifically boost the LFE track when the front speakers are set to LARGE. When set to SMALL, the 520 only allows the user to direct both the LFE and the bass to the sub. Boosting the bass (by boosting the sub output) would then end up increasing both the LFE and the bass (below the xover) when the speakers are set to SMALL.

This is all based on readings I've done. I have not been able to measure the system's LFE output on DTS DVD's to confirm that there is this problem. But, it's always fun to keep tweaking these things...

Thanks again!

Bruce

JohnK:
What is the reason to set your floorstanders to "small" and have the sub do the duty for LFE? Is it bad for the speakers to actually play the lower frequencies? If the speakers can play down to 35Hz why not let it play it? The reason for these questions are when I set my speakers to "small" it send all frequencies to what I set it to "60Hz" or lower to the sub. The speakers "seem" to sound better with the setting to "large". Thats why when I listen to music I set my speakers to "large" with the Sub off and no crossover. I like driving my speakers with full range in music mode. Is this bad? I just hate the fact that when I pop in a movie I enable the sub and re-setup the crossover to 60hz and then disable it when I play music.

In reply to:

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If the speakers can play down to 35Hz why not let it play it?

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First you have to realize not all the low bass is in the LFE channel, many times there will be low bass (as low as 20hz) mixed into the main channels too. So if your towers are set to large and they only go down to 35hz you're missing out on that bass. I just cringe when I hear people talking about setting their VP150's or bookshelves to large, because they're definitely missing out on bass that is there in those channels.

Second, you have to realize that the crossover is not a "brick wall", but actually a slope. In fact, the ideal recommendation is that your speakers should be able to play a full octave below the crossover point, since they will still be receiving a signal at those frequencies. That means that for a tower that can play down to 35hz the ideal crossover would be 70hz. Your speaker is still getting a signal well below 70hz, it's just rolled-off as you get lower. So it's not like you're wasting the capabilities of your speakers.

The reason a 80hz x-over is recommended is because even though 70 might be ideal for your towers, it's probably too low for the other speakers in your system. Since most receivers and pre/pros don't support multiple x-over frequencies, it's best to just cross everything over at 80hz. This probably means you're breaking the octave rule mentioned above for your center/surround speakers, but you really don't want to have your x-over any higher than 80hz because bass will start to become directional as you go higher.

Another thing to consider is that even though your speakers might be able to go down to 35hz, that doesn't necessarily mean they can play those frequencies as cleanly as a good subwoofer, especially at loud volumes. You would also be demanding more power from the receiver/amp for you mains, which may or may not be a problem. Factor this two things together and you can see that if you like to play at really loud levels (say, reference level DD/DTS or very loud music), you might be more likely to hit the limits of your system when your mains are set to large.

jKohn: Your explaination definitely make sense.
But this is what I noticed. Correct me at anytime if I'm wrong. I set my Rotel to Large. This gives the full range of sound to my speakers which can handle down to at least 35-38db. I do not get a "brick wall" when I set the crossover to none because what I read is that when I set the crossover to none in the Rotel it sends the full range of sound also to the sub. I then set my subs crossover to what I feel sounds the best which I think hovers in the 65hz and then raise the level of the sub to the same level as all the speakers with the sound meter. (A little overkill but it does level it off nice and cleanly). If I used the crossover built into the reciver and used the bypass on the sub and I forgot to turn on the sub then definitely my front speakers would have "hit that wall" to whatever I set it on the crossover if I set it to "small".

The other question I have is why your recommendation of having my receiver set crossover at 70Hz or 80Hz for speakers that go down to 35Hz which is like the Axiom M60. As I said above I noticed my crossover on the sub is around 65hz.
I can tell that going with DD/DTS the system is able to handle it but going from 2 stereo with no sub to all 5.1 channels running I noticed a drop of my volume running 53 to about 65 to get the same level with all speakers driven. Which leaves me to believe I might be purchasing an Anthem power amp to drive my 2 fronts by itself through pre-outs.

Rotel SX-1065 2 x 120w 8ohm / 5 x 100w 8ohm
Fronts: Monitor Audio Silver S6 6 ohm 35 - 30k handling 40 - 120W
Center: B&W CC6 8 ohm 78 - 20k handling 25W-120W
Surrounds: Axiom M22Ti 8 ohm 50 - 22k handling 10W - 200W
Sub: Mirage Bipolar BPS150 22 - 100 150W

In reply to:

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First you have to realize not all the low bass is in the LFE channel, many times there will be low bass (as low as 20hz) mixed into the main channels too. So if your towers are set to large and they only go down to 35hz you're missing out on that bass. I just cringe when I hear people talking about setting their VP150's or bookshelves to large, because they're definitely missing out on bass that is there in those channels.

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And what of receivers that can direct Bass to both the fronts and the sub?

Bruce, if I read your second message correctly, you haven't noticed any problem, just read about one that supposedly exists. I read the 42 posts on the other thread and thought that much of it was confused comment by those who didn't even recognize the difference between LFE and overall bass. Darryl and Lewis seemed more knowledgeable. I suspect that the reason you didn't notice this problem is that it doesn't exist. As I said, as far as I know all HT receivers, including the 520, have the required LFE boost. Some receivers have a LFE REDUCTION control, primarily to compensate for some early DTS productions which had the LFE too hot. Continue to set your speakers "small",get the sub cross out of the way, and don't worry about it.

Sat, I pretty much agree with Jeff's replies to you. If your Rotel allows you to bypass the receiver crossover(I'm not familiar with its bass management options)then yes, a full-range signal would be sent to both the sub and speakers and you'd have to use the sub cross to just reinforce the lowest octave or so. Again, both theory and personal experience tells me that if you have a good sub(and you do)let it have primary responsibility for what it does best(even when the mains have pretty good bass).Take part of the burden off of the speakers and the receiver amp sections driving them by setting everything "small".