How do I check if I damaged my RCF Art 312A's?

[akillj]

I had a gig yesterday in which we pushed them very hard. ( Just below limiting ). I'm aware I needed more sound to give my current tops headroom but I don't have enough money yet. Anyway, I played the song "Teach Me How To Dougie" during a "dance off". For those unfamiliar with the song it has very high bass notes (I'm assuming over 150hz because a few times it limited my tops, even though on my two LS720P's I had the crossover at 150). About two or three times during those "high notes" I heard this loud rattling sound, and i'm pretty sure it was coming from my 312A's. If I were to guess I would think the speaker was over-flexing (Sorry I can't remember the word).

I played them at a low volume while taking down and they sounded fine, but I worry I may of damaged them. How do I check?

- Thanks!

[Finnish_Fox]

Turn it up to 11? :shrug:

[sss18734]

You're referring to over-excursion. Rarely a problem for mains used with a subwoofer and crossed over properly. Also, I believe the crossover on your sub ONLY affects the low pass filter on the sub, not the high pass filter on your mains. Your RCF's should have their own crossover.

Luckily, the on-board processing in those cabs is very good, so you probably didn't damage anything. Just crank them up to full volume and listen for anything unusual.

The rattling probably either came from the grille or cab at its resonant frequency, or from another object entirely.

[Gjhowe1]

Turn it up to 11? :shrug:

^LOL. Turn them on and have a listen. If they sound broken, they probably are. If you really want to get technical run a frequency sweep to see if they reproduce whats there supposed to.

[audiopyle]

I had a gig yesterday in which we pushed them very hard. ( Just below limiting ).

Although the ART312As roll off hard below 80 Hz, IF you are going to run them that hard use a crossover. Running your LS720P up to 150 Hz does nothing for your tops in this case, as they are still running full range. Probably makes it worse in fact, as the response in the overlap region will be muddy or cancelled. Your tops could have been working hard from 80-150 Hz and you might not know it.

[akillj]

I always thought the crossover on my Ls720P (Elite Series one) killed the bass to my tops and took over those frequency's. Was I incorrect?

And sorry I forgot to mention, I live in an apartment so turning them up isn't really an option. Is that the only way to tell if they're messed up? I was wondering if I could take the grill off or something and look for something wrong on the driver itself. I can listen to them at low-volumes but that's about it as far as output.

[ampnation]

yes, I am pretty sure you're right that the LS720P does a true crossover function feeding your tops the proper signal.

The easy way to tell is to install a free signal generator (http://3d2f.com/programs/14-027-sigjenny-download.shtml).

Hook up just your tops and find the lowest signal you can hear on your tops.

Now hook up sub + top and set the crossover low and your sub level down to make sure you can still hear it. If not, slowly bump up the frequency and/or level that is being fed until you can.

Now turn up your crossover frequency on the sub and if the top stops reproducing the signal, it works as you (and I) believe it does.

Besides confirming who the sub should work, this could potentially find a flaw/defect or a user error problem.

Keep in mind that a 120Hz crossover will send some signal under 120Hz to your tops and some signal over 120Hz to your subs. In fact, at the 120Hz point, both should already be declining so the combined output from the tops and the sub sums to be the full strength signal. Each drops off and the rapidity with which it drops off is determined by the slope. e.g. 6db/octave decrease, vs. 24db/octave decrease would be slow vs.rapid.

[audiopyle]

No, the "output" XLR of the LS720P is paralleled to the input, just passes the fullrange signal through.

[ampnation]

I always thought the crossover on my Ls720P (Elite Series one) killed the bass to my tops and took over those frequency's. Was I incorrect?



No, the "output" XLR of the LS720P is paralleled to the input, just passes the fullrange signal through.

In which case, you would definitely benefit from having an external crossover. For a little bit more than the cost of a crossover, you can get a DSP unit with a crossover and a lot of added features. A popular one here seems to be the BBE DS24.

[Al Poulin]

Just to recap : no, the 720P does not have a filter that sends a hi passed signal to the tops. It has thru jacks that send the exact same signal as the one that came in. Set the low pass filter on your sub at its lowest point (90hz I believe) so that you do not have so many overlapping frequencies. Listening to your speakers at low level can at least confirm that your horns were not damaged. IF you were running below clipping all night, you should be fine. That's why powered speakers have built-in limiters/protection. I usually do not recommend using a dedicated crossover with RCF tops simply because their response naturally drops quite significantly below 80hz. I suggest you run them as you are BUT make sure not to boost the low frequecies on your mixer (or eq). If you feel you need more bottom end, turn up the gains on the subs a little. The RCFs genrally require less signal than the Yorkvilles (at a given gain position) so adjust them accordginly.Try setting the gains on the tops and subs so that your sound is well balanced without needing any eq boosts from your mixer. (start with everything flat and adjust your tops/subs gains to achieve a balanced sound). Very little EQ is actually needed to get the 312As sounding great.

With my 310As/LS720P I keep everything flat, but will add a little top end (+3DB high frequency on my mixer channel eqs to sweeten up the top end)


Al - Party-Time! DJ Services

[Evil Steve]

I usually do not recommend using a dedicated crossover with RCF tops simply because their response naturally drops quite significantly below 80hz.

Al, You keep saying that because the response of the speaker (from an audio standpoint) rolls off below 80hz, a crossover is not necessary.
The spec sheet on the 312a says the speaker is good to 50hz.
Regardless of whether the speaker is ABLE to produce a solid 50hz, I contend it is TRYING to.
If it's trying to produce below 80hz, regardless of whether it's successful, the cone is still moving in & out. Over-excursion becomes a clear and real possibility. The amplifier is still sending the woofer as much signal as the limiters will allow. If there is some form of dsp on the RCF cabinet, then there might be a high-pass filter kicking in when the demand for bass goes high enough. The specifications that I've seen on the RCF product don't mention this. That doesn't mean it's not there.
Your application might not require significant sound pressure levels. Your subs may compensate for a lack of response from your tops. That does not mean your top speakers aren't trying to reproduce frequencies they are not capable of.
A loudspeaker is not a smart device. If you ask it to do perform a task it is not capable of, it will try to perform that task until it is destroyed, or you stop asking.

[Al Poulin]

The RCF 312A's response is down almost -20DBs at 50hz, so the RCF spec sheet is simply incorrect, as is the case with many of their powered speaker spec sheets (when it comes to frequency response). They indicate -/+3DB 50hz or 45 hz response for almost all of their powered 10,12'' and 15'' cabs when this is almost never the case... :mad:

On the right, under documentation, open en_art 312A specsheet PDF and look at the graph. That should tell you all you need to know. You would need to add a shitload of boost in the low frequencies to get these speakers to produce audible 50hz content.

http://www.rcf.it/products/pro-speaker-systems/art-series/art-312-a

I'm not saying a proper crossover isn't ideal, I just feel it isn't worth the cost and the added noise of adding it in your signal path when it comes to these particular speakers. Keeping you EQ flat (or simply not boosting the low frequencies at all) will assure the speakers aren't forced to try to reproduce too much of the deep stuff. I suggest this method because it works just fine with most RCF speakers, saves money and saves the user from having to carry an extra piece of gear that will do very little to improve performance. A sub (or subs) with built-in crossovers (such as RCF's) would be great, but as mentionned performance will only be slightly improved.

Where you would see noticeable improvement (and significantly less stress on the tops) is with live (band) use, where an uncompressed mic'd kick drum was being put through the PA. In this case, I would say a proper crossover is necessary to protect the woofer in the tops. In the case of a DJ using mostly already ultra compressed source material, the crossover becomes something good to have, but far from necessary IMO.


Al

[ampnation]

That seems like a solid plan Al. I didn't realize those FR graphs were available for the RCF's - glad to know where they are.

IIRC, you use an almost identical setup to the OP... 310's over 720's. I don't imagine the 312's have so much more output so as to make that difference in setup much more than academic (<= 3db) . And I am pretty sure I'm heard you commenting such that I feel comfortable that the 310/312 + 720 matchup is good meaning one doesn't overpower the other. And further that if you need some extra bass, you add a 2nd 720. Right so far?

Assuming all that, I like your suggestion for the OP. For others who might be viewing the thread I would like to add that if one were using more powerful subs with the 310's or 312's they might be leaving a substantial amount of potential in reserve using this method. To regain that reserve, using a crossover set at 100Hz or 120Hz will allow the sub to take over more duty within the overall range allowing the tops to get louder before limiting in addition to adding extra energy to the sub's performance.

And that brings up something that was touched on earlier the OP should be sure not to scan past without taking note... If he sets the crossover right near 80 Hz (I don't think you can set 80Hz exact with that pot knob on the 720, right?) instead of 120Hz the will avoid the problems that come with having two very different cabs producing the same frequency range. Those problems can include cancelation that occurs when a valley from one cab's audio waveform hits the listener at the same time as peak from the other. A variation on this principle is used in noise cancelation headphones. The result in both cases is no sound or reduced sound vs. louder sound. So it is highly possible that by running the 720 at a 120Hz LPF setting, that 80 to 120 Hz portion of the spectrum was suffering from mediocre to lousy reproduction that only got worse as the volume was increased.

[Al Poulin]

I usually use a pair of 310As with my single 720P (corner loaded) and the sub definitely limits before the tops - which is to be expected given the high output of the RCFs. (I should have more subs, but honestly, a single corner loaded one gives me enough low frequencies for the types of events that I do)

A pair of 720Ps is a better match (output wise) for a pair of either 310As or 312As which BTW have almost identical SPL capability. (the 312A simply has more beef below 100hz because of the bigger woofer and significantly bigger cabinet).

If you really want to maximize output as much as possible while keeping as much bass out of your tops, then yes a crossover is the ideal solution (set at somewhere around 100hz) BUT in typical DJ applications I just don't feel it will make that much of a difference and worth the cost/hassle.

Al

[akillj]

Thank you everyone! Especially Al, great information being passed in this thread. Thanks a bunch guys.

[Evolved]

You're referring to over-excursion. Rarely a problem for mains used with a subwoofer and crossed over properly. Also, I believe the crossover on your sub ONLY affects the low pass filter on the sub, not the high pass filter on your mains. Your RCF's should have their own crossover.

Luckily, the on-board processing in those cabs is very good, so you probably didn't damage anything. Just crank them up to full volume and listen for anything unusual.

The rattling probably either came from the grille or cab at its resonant frequency, or from another object entirely.

Based on this response would you say that the 720P's isn't a real crossover in the sense that an RCF subwoofer would have?

And if you had the RCF sub with crossover - would this not happen to him? Just curious.

[Al Poulin]

Based on this response would you say that the 720P's isn't a real crossover in the sense that an RCF subwoofer would have?

And if you had the RCF sub with crossover - would this not happen to him? Just curious.

Yorkville powered subs have an internal adjustable low pass filter that does handle ONE part of a true crossover's function, but not the other. In the Yorkville, you CAN adjust up to which frequency the sub itself puts out (adjustable from 90 to 150hz) which is helpful to match it with the tops you will be using, BUT you can't choose which frequency the tops will be sent - or limit/filter these frequencies since the yorkville has THRU outputs only (which don't modify the original signal).

With the RCF subs, you are doing both by selecting a frequency. The sub sends the frequencies above your chosen crossover point to the tops via high passed outputs and sends everything below your chosen point internally to the sub.

The low pass filter on the Yorkville can be helpful when using really small tops for example. Say you are using 8'' tops that don't have much output below 120hz, you can set the Yorkville to handle everything 120hz and below. It would be a really good idea for Yorkville to include a built-in crossover in their subs, but they figure most people will be using Yorkville subs will Yorkville tops and using the user selectable 100hz hi pass button included on certain NX, Elite and Unity tops. I can't imagine a true crossover would be that expensive to add though AND this could definitely be useful to many users...

Al