Mid-range vocal-only PA speaker

[ampnation]

As I go forward with my PA biz, one of the things I want to try to do is focus on corporate/conference/press conference type gigs where the music if any is minimal. I currently do some gigs of this type, pro bono for non-profits I belong to. My small setup includes Kustom KSC10M 10" 2-way monitors powered by a Peavey PV4BI powered mixer. This setup works okay, but I would like to improve it in a couple of ways.

1. I notice that feedback, while not a huge problem, does occur. I won't be there to set up properly or monitor rentals of the equipment usually, so I want to minimize feedback without a feedback suppressor which a novice probably wouldn't operate correctly anyway.

2. The Kustoms are some of the cheapest PA speakers you can find. They have decent cabs, but the components are tinny sounding, have a bad rep on reliability, and don't handle a lot of power (60w RMS, 120w peak). I would want to improve on these weaknesses.

So I thought about making a custom PA speaker for such events. My concept would be a single-driver mid-range speaker cab. The frequency range would cover roughly the vocal range. Power handling would be much higher and could be paired with the Peavey for small rooms or something larger for something like an outdoor press conference or large conference room.

I figure it is usually the HF that causes feedback and not needed for vocals. These would be simple square face traps with a speaker pole mount, Speakon connector, spray-on coating, corner guards and feet. No need for a crossover, passive or active.

To keep weight down (I want even weaklings to be able to pole mount these), I'm thinking of using Eminence Deltalite II 2512 or 2510's (250w RMS ea.). I figure a pair of these powered by a Crown XTi 1000 (275w per. ch.) would fill a pretty big room with vocals.

Ideas?

[Paul O]

Feedback can happen at any frequency and a speaker system that has peaky response will be more feedback prone so your design should have as flat a response as possible. It's pretty much a given you will need some corrective EQ somewhere in the chain to achieve this either in a passive filter inside the speakers or via a rackmounted piece of equipment, but that depends how good the drivers are of course. For what would be considered good quality vocal reproduction you need extenson up to 5khz or so but there's no real need for anyting below 200hz so a stack of 3" or 4" fullrange drivers lends itself very well to this type application. The added benefits of a column speaker like this is wide horizontal dispersion through the vocal range and relatively low feedback sensitivity so talkers don't have to be as careful about where they go with an open mic.

Another thing you absolutely do not want anywhere near inexperienced users is an omnidirectional microphone, I have seen these feedback when standing behind the speakers, so supply only cardoid wired or wireless mics with your rental.

[Randy L]

Agreed on the mic. But to dummy-proof it even more, maybe consider a super-cardioid pickup which has even greater off-axis feedback rejection.

I would also include a laminated instruction sheet with the gear showing how to properly set the system up, paying close attention to feedback avoidance through speaker placement and mic proximity to the speaker's mouth.

[nj_ray]

Have you considered this amp, build it into one of your cabs, no need to keep track of a separate mixer and amp. You could even build the mic receiver into the cab for a nice minimal setup rental solution. Just a thought, though I realize this may start to get heavy, but you would not need to worry about explaining the connections from mic to mixer to amp to speaker etc.


http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-797

[jeff_free69]

As I go forward with my PA biz, one of the things I want to try to do is focus on corporate/conference/press conference type gigs where the music if any is minimal.So I thought about making a custom PA speaker for such events. My concept would be a single-driver mid-range speaker cab. The frequency range would cover roughly the vocal range. Power handling would be much higher and could be paired with the Peavey for small rooms or something larger for something like an outdoor press conference or large conference room.
ideas?

I built some mini vocal monitors for my band using eminence CX8 coax with the screw in tweeter. It fit perfectly into some small monitor style cabs PE had on closeout last year (I think they were originally made for behind the seats of pickup trucks). 2 of em fit into a milk crate for easy transport.

I don't agree with the assement that you can get by without a tweeter:
a) you need the inteligiblity, or it will be mud
b) you can get feedback anyway because a 10" or 12" almost always has a huge resonance peak around ~2 - 3 K. check out the specs... So you need to roll off the hi's on the woofer by at least 12 db /octave. I put Lpads on the tweeters to keep them balanced and under control.
Since these were dedicated for vocals (not music) I cheated a bit and crossed over the tweeters a little higher than I rolled off the woofer, giving a bit of a net dip around 2k , which is prime feedback territory.

I've got nothing against the idea of using a line array of smaller (3-4") drivers l, but there are no pro level entries here. So you need a LOT OF EM a) compensate for very low efficiency and b) to handle the power. also I don't agree with the comment that below 200HZ won't matter. In practice I think it will sound thin.

I've used Eminence Alpha 6 with instruments, but crossed over with woofer at 150Hz. These could get you down to 100 - 150 Hz without blowing.

Check out my build
http://techtalk.parts-express.com/showthread.php?t=209278

[meep]

vocal intelligibility ends at 5khz but if your business is to develop a good following you don't want to give the impression of running 1950's gear. I'm all for a tried and true 12" 2-way with some sort of horn-loaded tweeter, I prefer the constant-directivity horns for smaller rooms.

The hypercardioid mics are great for feedback rejection but even experienced vocalists have problems with them because they don't understand how to "work the mic." Look at what churches and other established PAs are using. The directional condensers are good for spoken words, and the good ole' 57, 58 for spoken or music vox.

Mic is critical--- speakers are to some degree secondary b/c feedback is a big component of the ROOM and the SETUP. A parametric EQ is better for tuning out FB than a graphic, and a graphic will likely get abused. OTOH a graphic with the little "feedback indicator" (can't recall the manufacturer terms) such as behringer and peavey *might* be useful for the amateur user.


I might suggest sourcing some used resin-cased 12" 2-ways for rental work. Eons, EV-SX100s, etc for rental durability.

Mike

[Randy L]

I don't agree with the assement that you can get by without a tweeter:
a) you need the inteligiblity, or it will be mud
b) you can get feedback anyway because a 10" or 12" almost always has a huge resonance peak around ~2 - 3 K. check out the specs...

Agreed. My work has a lecturn with an internal speaker system. 2 10" full range drivers and the sound is pretty flat. The feedback it is plagued by is the low end caused by turning the volume up too high to compensate for the speaker's mouth about 18" from the mic! The mic they use is the Shure PG48which is pretty cheap.

[ampnation]

Thanks for the feedback (pun intended) all.

This is why I ask questions first and act later when I can. I am back to my plan to build 12" 2-ways. I might put a passive crossover in them, but leaning toward bi-amp. Since I am an extreme novice, I'm taking my time but leaning toward using PE PA trap boxes, Delta Pro 12A's and Selenium D220Ti's with a Pyle Pro horn. This should be good for certain venues and paired with a sub will sound very good I think. I just need to do the modeling then try it out.

I downloaded WinISD and I've asked this elsewhere, but haven't heard back yet... The spec sheet for Delta Pro 12A doesn't list Pe, at least not as such nor Z. I know Pe is the power rating, but not sure which to use? RMS? Pgm? The number in the database for a regular Delta is 300w but the RMS is 400w on that one, so am I missing something? and Z is nominal impedence, right?

[Phil_RC_1]

Thanks for the feedback (pun intended) all.

using PE PA trap boxes, Delta Pro 12A's and Selenium D220Ti's
For durability and light weight you may want to look at these speaker cabs (http://www.erseaudio.com/Products/SPXProSpeakerCabinets) from ERSE.


I downloaded WinISD and I've asked this elsewhere, but haven't heard back yet... The spec sheet for Delta Pro 12A doesn't list Pe, at least not as such nor Z. I know Pe is the power rating, but not sure which to use? RMS? Pgm? The number in the database for a regular Delta is 300w but the RMS is 400w on that one, so am I missing something? and Z is nominal impedence, right?

One problem with WinISD (standard) is that it doesn't simulate cone excursion. Cone excursion is typically what actually limits the amount of power that can be applied to a woofer. The Pe, RMS or other power ratings from the manufacturer are thermal power limits of the voice coil, which are usually higher then the actual amount of power that the woofer can handle in the bass frequencies due to cone excursion.

[ampnation]

One problem with WinISD (standard) is that it doesn't simulate cone excursion.

I see WinISD pro is in alpha. Does unibox include cone excursion in it's model? Are any of the commercial products significantly better? I notice there are tools that come with the Loudspeaker Design Cookbook. What about that?

[Paul O]

Winsid Pro does cone excursion along with port air velocity and a bunch of other things. It's not perfect... I have noticed some glitches at times but it's hard to beat for the price.

[Paul O]

The spec sheet for Delta Pro 12A doesn't list Pe, at least not as such nor Z.

Yeah it does it's 400w and Z is nominal impedance. Download the Pro version and then read the help about entering the speaker parameters, when done in the right order the software will calculate missing values and then you'll get proper results for power handling and excursion and such.

[ampnation]

One problem with WinISD (standard) is that it doesn't simulate cone excursion. Cone excursion is typically what actually limits the amount of power that can be applied to a woofer. The Pe, RMS or other power ratings from the manufacturer are thermal power limits of the voice coil, which are usually higher then the actual amount of power that the woofer can handle in the bass frequencies due to cone excursion.

This doesn't sound right to me at all. I've never seen anyone suggest powering a driver at under RMS rating, or if they did, they got a ton of flack from people recommending RMS all the way up to peak as far as amp capacity with the general consensus that a good amp (i.e. conservatively rated) with a rating equal to driver program rating or slightly higher will be safe if you don't clip the amp. If speakers self destructed at RMS or even slightly above it, the recommendation would seem to be for amps lower than the RMS because, correct me if I'm wrong, but cone excursion can kill a speaker if the power is too much for just a brief period whereas thermal takes time to build up unless you're just overwhelming it.

[billfitzmaurice]

I've never seen anyone suggest powering a driver at under RMS rating.Then you haven't built any of my subwoofer designs. :)
The plans all list the maximum safe input voltage to set your limiter so that the driver won't exceed xmax, which only serves to generate excess heat that results in eventual driver failure.

[meep]

for rental-- go passive XO.

You don't need the high school drama club renting your hardware and swapping the lows and highs. >pop<

[Randy L]

^ Agreed.