Bass management with MC-1 and B&Ws

[Rob]

Hello again,
I just recently set my bass management to 40Hz (about 10 days ago). My question is will this setting damage my B&Ws? I have the 804s, 805s, HTM1, and 601s2 for sides. I just now changed the 601s2 to 80Hz, I hope they were not damaged. Is there anyone who can answer my questions?
So far this forum has been excellant to me, and I am very appreciative.
Thanks, Rob

[Doug]

Rob, glad your enjoying the forum. We strive to please most of the people most of the time. Sometimes we hit our target, and well, occasionally, we might miss.

There are many factors of whether your speakers are damaged. At lower SPLs, your likely very safe running them full range. That doesn't mean they will transduce the entire soundfield they are served though.

However, there are situations where a speaker is designed to handle 40 and up, where the speaker could potentially be damaged. I am not intimately familiar with your speakers, so I cannot comment much on their range. But I can tell you that with my Sonus faber Grand Pianos crossed over at 40, that they can make a horrible sound when driven to higher SPLs. The sound is because they are passive radiator based speakers, and honestly, there's just more air trying to escape the speaker than can safely travel through the passive radiator. That is the only exit for air as they are not ported. For me, the solution is to cross them over at 80 for home theater and I have no problems. So, I recommend listening closely to your speakers for strain, and at the first point it occurs, cut them back immediately, increase the crossover, or lower the SPLs. Hope that helps...

Doug (Lex)





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[MRWILLL]

Rob...


What sets Lexicon's line of pre-pros's from others is that whether your spks are large/small, the bass management (Bass Enhance) can still be set. If you are running small spks with BE, the pre-pro limits the right amount of LF to your spks. With the spks set to large, the max amount of BE is implemented.




STOP!!...LOOK!!...LISTEN!!
DVD...Hear it from the people who
mixed and mastered it "LEXICON".

[WMG]

Bass Enhance is a great feature, but your side speakers need to be able to handle the rerouted bass or you do risk the chance of damage. Your other option is to add side subwoofers if your side speakers are not capable of at least 40 Hz. The subject has been greatly cussed and discussed. If you have not done so, I would recommend you reading the excellent presentation on Bass Enhance by Philip Brandes at the SMR site. Check out the enclosed link and go to Bass Enhance FAQ by Philip Brandes. http://www.smr-home-theatre.org/Lexicon/index.html

Good luck,
Will

[MRWILLL]

WMG...


The only way you can cause damage to your spks is to have your (small spks/that do not play down to 40Hz or below) spks set as large with the BE engaged. You can set your spks to small with the BE engaged for the smaller type spk. BE works for small/large type spks.




STOP!!...LOOK!!...LISTEN!!
DVD...Hear it from the people who
mixed and mastered it "LEXICON".

[ukexpat]

Not quite correct -- you may get some BE effect with speakers set to SMALL but the higher the crosover the less effect you will get -- it will hardly be noticeable with an 80Hz crossover.

Check the BE FAQ for full details, available at:

http://www.smr-group.co.uk/brandes.html




Nigel Pond
SMR Group (http://www.smr-group.co.uk)

[MRWILLL]

Same words...Please tell us how one can ruin his/her spks using BE?




STOP!!...LOOK!!...LISTEN!!
DVD...Hear it from the people who
mixed and mastered it "LEXICON".

[ukexpat]

BE sends full range information to the side speakers and it only works with that info going directly to the sides -- 30Hz and lower I think -- so your side spkrs need to be able to handle that either on their own or with the aid of a sub at each side. If they cannot, then you can damage your speakers. As the effectiveness of BE relies upon such low freq info being fed to the sides, the higher you raise the side xover, the less effective it is.




Nigel Pond
SMR Group (http://www.smr-group.co.uk)

[Rob]

Hi again
Im a little confused. I was told by my A/V salesman that if I have the "bass enhance" on and everything set to large except the sides (which I have at small standard and the "side highpass at 80Hz) and the bass management set at 40Hz that I should have no problem damaging my speakers.
It would break my heart if I damaged my B&Ws.
Thanks, Rob

[ukexpat]

Rob

Your dealer obviously does not understand how Bass Enhance works. For best results you have to use full range sides or smaller sides supplemented by a subwoofer on each side. His suggestions about speaker size settings are also completely wrong (for BE to work as intended). Lexicon does recommend some settings as a starting point (either in the manual or in the theory and design booklet). Philip Brandes' paper at the SMR group site (at the link I provided before) is probably the most authoritative description of BE outside the head of the inventor, David Greisinger. You should direct your dealer's attention to it or print it out for him!!

Let me repeat again, if your engage BE and set your sides to full range, and if they are not able to handle the prodigious amounts of low frequency info they will receive as a result, you run a very high risk of damaging your speakers. Raising the side crossover may prevent damage but raising it above 40 will prevent BE from working at all.




Nigel Pond
SMR Group (http://www.smr-group.co.uk)