The difference between 60hz and 80z?

[inbox4]

Hi all,

I have been experimenting with the set up of my cinema system. I have changed the crossover on the front three speakers from 80hz to 60hz and prefer the sound. My speakers are: B&W 685 (fronts) and B&W HTM62 (centre).

Am I more likely to damage the speakers on this setting? I like to listen to bassy action films at high volumes and don't wont to risk damaging my speakers. Does the extra 20hz bass I am now sending to my speakers make much difference and pose anymore risk?

I would like to keep these settings as I prefer them. I don't want to compromise on volume levels though or run an increased risk of damaging my speakers.

Any comments/ reassurance would be appreciated.

Thanks.

 

[Frank Harvey]

At 80Hz, you're more or less safe to push almost any speaker to high volumes, but smaller speakers set to 60Hz will be more prone to damage.

 

[inbox4]

At 80Hz, you're more or less safe to push almost any speaker to high volumes, but smaller speakers set to 60Hz will be more prone to damage.

Thanks David.

Would you advise against having my B&Ws set to 60Hz then?

- I do like films like Hulk and The Avengers etc!

 

[Frank Harvey]

At 80Hz, you're more or less safe to push almost any speaker to high volumes, but smaller speakers set to 60Hz will be more prone to damage.

Thanks David.

Would you advise against having my B&Ws set to 60Hz then?

- I do like films like Hulk and The Avengers etc!

50/50. Using a higher crossover point does need a more capable subwoofer. With a PV1, it's a shame you can't choose 70Hz and split the difference! I personally would select 80Hz.

 

[inbox4]

Thanks David. I appreciate your expertise and advice as always.

 

[Big Chris]

... About 20hz.:rofl:

 

[moreseric]

I think so too. Pushing small speaker to work with low frequency is not good idea. I don't think that you will kill speaker,

but sound will be worse for sure. It is better to use only subwoofer for low frequencies.

 

[inbox4]

I think so too. Pushing small speaker to work with low frequency is not good idea. I don't think that you will kill speaker,

but sound will be worse for sure. It is better to use only subwoofer for low frequencies.

I prefer the sound of my system with the front speakers crossing over at 60Hz. My concern and question was purely around whether this is likely to damage them when playing high volume, deep bass, action films.

Based on David's comments, I don't think I'll take the risk. Perhaps I should consider updating the 685s to 684s at some point in e future. Then perhaps I can get away with running a lower crossover more safely?

 

[Son_of_SJ]

With large (just over a metre tall) front speakers, the automatic speaker calibration by the receivers designates the front speakers as full-range and so I don't have to worry about crossover frequencies at all (from a previous thread, I know that David at Frank Harvey would still choose a crossover frequency of 80 Hz even when using floorstanding speakers). It's a personal choice, but I certainly prefer having large front (and in my rooms, large rear speakers also) to having smaller speakers and having to consider crossover frequencies. Of course, restricted space in some households may force the choice of smaller speakers.

 

[inbox4]

Just because a speaker is over a meter tall doesn't mean it isn't susceptible to damage surely? A loud, very deep bass note that over stretches a drive unit is bad news full stop.

I know large speakers go deeper so have a greater ability to play deeper notes, but the sort of sub sonic bass that is on some blu-ray discs is beyond the majority.

I mentioned changing my B&W 685 bookshelves for the 684 floorstanders earlier. Although I fancy doing this, I cant see that the 684 would be any more resilient. I believe it uses the same drive units as mine, it just has two bass drives rather than one. How would this make them anymore resilient to a lower crossover?

 

[bigboss]

I don't think your speakers will struggle or get damaged by 60Hz. By definition, sub sonic is below 20Hz. If your speaker isn't capable of handling it, you simply won't hear that lower frequencies. But the speakers won't get damaged.

 

[inbox4]

I don't think your speakers will struggle or get damaged by 60Hz. By definition, sub sonic is below 20Hz. If your speaker isn't capable of handling it, you simply won't hear that lower frequencies. But the speakers won't get damaged.

That's a very good point. More specifically, if the crossover is set at 60Hz, the speakers wont be receiving bass any lower than 60Hz as those signals will be sent to the sub.

The specs of my speakers suggest that they go slightly lower than 60Hz so a setting of 60Hz should be well within their capabilities. I wonder why David at Frank Harvey was recommending 80Hz as safer?

Any ideas?

 

[bigboss]

Only he can answer that!

I wouldn't call your speakers small.

 

[Frank Harvey]

The specs of my speakers suggest that they go slightly lower than 60Hz so a setting of 60Hz should be well within their capabilities. I wonder why David at Frank Harvey was recommending 80Hz as safer?

Any ideas?

There's nothing wrong in setting the crossover point to the +/-3dB frequency response figures stated by most manufacturers - in this case, 49Hz. For the most part, a 60Hz setting will work fine, but bear in mind that the 685 mid/bass driver has to cover a range of almost 4000Hz. If that driver has to reproduce a number of frequencies at the same time, as well as producing some loudly, some quietly - this will put a lot of strain on the speaker, especially if it is nearing its maximum output, or some of those frequencies are lower than it can comfortably produce. If all speakers could do this, there'd be no market for high end ones.

Suffice to say, playing a full range signal from a Bluray - which can have very energetic content right down to 10Hz or lower, can damage a hi-fi speaker if it is set to large. A speaker will try and recreate what it is given.

Upping the crossover point eases the workload on the mid/bass driver, and leaves much of the hard work to the subwoofer - which lets face it, has been designed to work up to at least 80Hz, with some having been designed to work right up to 150Hz or even 200Hz should it be needed. The result is that because the driver has less to do, it can do what it does more cleanly.

There are a few different ways you can set up a 5.1 system, and having been demonstrating and selling AV systems for over 20 years (yes, back to VHS and Laserdisc days and the birth of Dolby Surround), I feel that THX's guidelines generally produce a better sound, and produces a more predictable result in almost any room, regardless of the issues that awkward rooms can throw up.

There are instances when using floorstanders in a hi-fi based 5.1 system will produce better sounding results than what I would normally recommend, but this would rely on the room being acoustically good, and the floorstanders being particularly capable, which would normally mean higher end ranges.

 

[inbox4]

Thanks again David.

Would you consider that changing my 685s for 684s would be an upgrade (in a system used exclusively for home cinema/ tv)?

Or, am I right in thinking that there would be no benefit whatsoever if the crossover is set to 80Hz or 60Hz. I assume with one of these crossovers set, I would get exacly the same out of either speaker (which I think use the same drivers anyway) and I would not benefit from the larger cabinet or additional drive unit in the 684 as all the lower frequencies on going to the sub?

Based on my rational above, why would anyone use floorstanders in an AV system if they wanted to follow THX's recommended 80Hz crossover?

 

[moreseric]

I don't think your speakers will struggle or get damaged by 60Hz. By definition, sub sonic is below 20Hz. If your speaker isn't capable of handling it, you simply won't hear that lower frequencies. But the speakers won't get damaged.

That's a very good point. More specifically, if the crossover is set at 60Hz, the speakers wont be receiving bass any lower than 60Hz as those signals will be sent to the sub.

That is right. But remember that crossover doesn't cut signal like on/off switch. It all depends on the crossover and its characteristics
The best way is, to check speaker characteristics. If it shows that the speaker works well at 60hz, than everything should be fine.
I prefer to use sub for low frequencies beacuse it was made specially ​​for it.

 

[inbox4]

I don't think your speakers will struggle or get damaged by 60Hz. By definition, sub sonic is below 20Hz. If your speaker isn't capable of handling it, you simply won't hear that lower frequencies. But the speakers won't get damaged.

That's a very good point. More specifically, if the crossover is set at 60Hz, the speakers wont be receiving bass any lower than 60Hz as those signals will be sent to the sub.

That is right. But remember that crossover doesn't cut signal like on/off switch. It all depends on the crossover and its characteristics
The best way is, to check speaker characteristics. If it shows that the speaker works well at 60hz, than everything should be fine.
I prefer to use sub for low frequencies beacuse it was made specially ​​for it.

60Hz isn't a particularly low frequency though is it?

That still leaves the sub a 40Hz range to handle.

 

[Frank Harvey]

Thanks again David.

Would you consider that changing my 685s for 684s would be an upgrade (in a system used exclusively for home cinema/ tv)?

Yes and no.

Yes, because obviously the 684's are going to be more capable in that they will handle higher SPL's with less distortion as you'll have two mid/bass drivers sharing the load that one would be dealing with on the 685's.

No, because big floorstanders aren't needed for AV systems. Using a sub to cover up to 80Hz means that only small speakers are needed, in which case, the 685's will do fine. I tend to find that floorstanders (when used in the traditional way of being allowed to utilise their entire useful frequency range before asking the sub to join in) can sound "heavy" and bloated in an AV system, which smothers detail. A standmount or satellite speaker sounds "faster" in comparison.

Or, am I right in thinking that there would be no benefit whatsoever if the crossover is set to 80Hz or 60Hz. I assume with one of these crossovers set, I would get exacly the same out of either speaker (which I think use the same drivers anyway) and I would not benefit from the larger cabinet or additional drive unit in the 684 as all the lower frequencies on going to the sub?

It would be sensible to assume you'll get the same from a standmount speaker and a floorstander if they're both set to an 80Hz crossover point, although this isn't true. You will get a slightly different sound from the two. The floorstander, due to its larger cabinet volume, will sound a little fuller than the standmount, but again, a fuller sound is smothering detail. The floorstander will also deal with a 60Hz crossover better, as its dual mid/bass drivers and cabinet volume will allow it to reach deeper more effortlessly.

Based on my rational above, why would anyone use floorstanders in an AV system if they wanted to follow THX's recommended 80Hz crossover?

There would be no real need for a floorstander if THX guidelines were being followed. Many people will though, mainly if they prefer their music reproduction via the more conventional 2.0 type speaker system.

 

[Frank Harvey]

60Hz isn't a particularly low frequency though is it?

That still leaves the sub a 40Hz range to handle.

60Hz isn't particularly low, but remember that the lower the frequency goes, the more cone movement is needed to reproduce that frequency at the same level as the higher bass frequencies (hence why hi-fi speakers can't do sub frequencies). During movies that have a lot of bass, there could be very strong 60Hz energy going on, and played at higher volumes, this could become an issue for some speakers. I've used smaller satellite speakers (which were designed to roll off at 80Hz that have had their mid/bass drivers bottom out when set as they should do, basically because the volume was too high fr them to handle. Setting the crossover point higher at something like 100Hz cures this, so crossover points for speakers are all based on the speaker's capabilities. The size of the speaker isn't really an issue, its what the drive units are capable of.

 

[inbox4]

Thanks David, your posts have helped to improving my understanding.

I've been experimenting with different crossovers and have found that a consistent crossover all round really improves integration too. I had previously experimented with the fronts at 60Hz and 80Hz whilst keeping the rears (B&W DS3s) at 90Hz. Having them all at 80Hz makes the system sound more open and coherent.

I think I will stick with 80Hz all round.

My system is sounding great.

Cheers for your help and advice.

 

[Son_of_SJ]

Based on my rational above, why would anyone use floorstanders in an AV system if they wanted to follow THX's recommended 80Hz crossover?

There would be no real need for a floorstander if THX guidelines were being followed. Many people will though, mainly if they prefer their music reproduction via the more conventional 2.0 type speaker system.

My "floorstanders" (which are all actually on stands or on raised surfaces), both front and surround pairs, are designated as "Large" by the receiver calibration in all my rooms. I have tried setting them as "Small" with a crossover frequency of 80Hz, as the THX guidlines and David recommend. However, I personally prefer the sound, for both 2.0 inputs like most TV and 5.1 Blu-Rays, with the speakers set as Large (with no crossover frequency and thus handling the full range of frequencies), supported by the LFE effects being sent to the subwoofer when playing Blu-Rays. If others prefer to set speakers to "Small" with a crossover frequency of 80Hz when playing Blu-Rays, I'm happy with that, for them. But certainly for 2.0 inputs, like the television, I can't believe that putting that through a full-range speaker is not better than using a smaller speaker, all other things being equal, of course. Last night, for instance, I was quite struck by some of the deep noises that were broadcast during CSI on channel 5 USA, which surely a smaller loudspeaker would not do as well, no?