Canuck Audio Mart

I've got a set of very large speakers I picked up mostly because my street is having a block party. They are custom made with electrovoice horn mids and tweeters with what looks like older eminence drivers which are 15 inch. I took them apart to fix cabinet issues and they sound quite good considering what they were built for. My issue is that due to not having any specs for these other than the ohm's rating from my meter at 6.1 . I haven't really looked too hard at the crossover though they look to be in good shape and use quality components.

I've hooked them to the most powerfull amp I have at the ready (not going to subject my good stuff to these lol) an onkyo with 80wpc at 8 ohms 155wpc into 4 ohms and they start to get distorted at about 10 oclock on the volume. This amp has no issues pushing hard to drive speakers to party level yet these things don't seem to like it. I 've never owned at set of speakers of this size before any thoughts on what I'll need amp wise to get these things to light up with breaking up lol? Do I have to go PA style amp for these? I would like to be the block party hero over here not the distortion king. Thanks for any advice you can offer.

The only thing a PA amp will give you is the ability to run for hours at high volume without overheating. You can typically run large, PA type speakers off pretty small amps (I ran several pairs of Dynaco ST-80 amps for hours at a time back in the 70s and they were only rated at 35 or 40WPC IIRC) and typically have high power handling capabilities so I will have to assume that you are not overpowering them with your Onkyo. What sources are you using to drive the Onkyo? Are you using a mixer or console of some sort? If so, you may be overdriving the inputs on the Onkyo which is what could be causing the distortion (I've seen this several times before with older amps being used with newer mixers, consoles and CDPs)

PA type speakers usually use fairly simple crossovers with few components (2 coils and 2 capacitors is fairly common) to ensure reliability, so a look at the crossovers is definitely in order. First thing is to determine the value of the blocking capacitors as they control how much bass energy is blocked from the mids and tweeters. Then get the model numbers for the horn drivers to check out the crossover requirements. Do the woofers also sound distorted? If so, you may have an entirely different problem (see the end of trhe first paragraph).

Please get back to us with those capacitor values and horn model numbers.

The highs and mids seem to be holding up better it's the driver that is more outta control, I guess I should have put that in my post. Oddly enough one amp I tried out was 25 watt and it seemed to produce about the same stable spl level as the more powerfull unit. From what I'm thinking now it could be these drivers although seeming to be in good shape have probley been beaten on pretty hard over the years. I was using a yamaha cd player as a source.

I'll try to post the crossover values but these are a bear to take apart due to the woofers being sealed in due to some problems with the cabinets.

Yeah, abuse over the years is also a very real possibility that I didn't want to to bring up. Moisture can cause bass drivers (BTW, tweeters and midranges that are not mounted in cabinets are also drivers) to flex and distort, so can loose voice coils which can sometimes play fine at lower volumes but get distorted fast as volume rises above a certain point. There are a few other causes for bass distortion including something loose in the cabinet or coming into intermittent contact with the back side of the cone (think internal interconnect wire or the driver's own tinsel leads to the cone), torn or worn spiders or suspensions.

An Older Bryston 4B could be had very reasonable if your willing to ignore cosmetic issues(I've seen em in the 500 dollar range). If the drivers are shot take a look at the Peavy Black Widows (I used to run 6 of them as passive subs with a 4B). They are not the last word in drivers but good bang for the buck. Cheers

Thanks for your thoughts guys, as for the woofers the spiders, coils and cloth surrounds are in great shape and they deffo don't have any cone or coil rubbing or anything. the cabinet work I did took care of any rattling there could be as I caulked all seems installed new batting and crossover mounts. It could just be these things take a BIG amp to keep the woofers from fluttering all over the place. I guess I'll have to keep it reasonable on block party day or hook up my infinity's on a second amp for a little boost. I think some Cerwin Vega 15" drivers and crossover swap would make them far easier to power. cheers all

If the woofers are the problem then I'd take a second look at the cabinet repairs as well. Any leaks there will change the tuning of the enclosure, upsetting the distortion and power handling of the system. Has everything been sealed properly and is airtight? Is there the right amount of stuffing in the box?

Well put it this way these things are so airtight other than the port I would take them into orbit lol I just replaced the ratty insulation with some acoustic matting. When I stuck my head in the woofer holes and yelled it was dead as hell in there which was what I was after.

Maybe I'll remove some of batting and see if that changes anything.

You say that the woofers are fluttering? By that I assume that you mean that they are having very large excursions and coming close to bottoming out. This is DEFINATELY NOT normal behaviour for any speaker. The only way I know of doing that with a relatively low power amp is either by having some sort of acoustic feedback, having the bass and loudness controls cranked way upo to maximum boost or that the amp is having some sort of low frequency oscillation. 15" Eminence drivers should barely be visibly moving even with an 80WPC amp; I have seen them take the full output of a 350WPC amp with no problems whatsoever. At this point I'd be suspecting a problem with your amp rather than the speakers.

Does your amp have a low or subsonic filter? If so, engage it and see if that cures the overexcursion problem. If it does, have the amp checked out ASAP as a low frequency oscillation problem can destroy just about any speaker, not just a high efficiency PA type speaker. Also, check the amp out with another set of speaekrs at lower volumes to see if you get the same sort of behaviour.

On a side note, if you are thinking about using your Infinitys for outdoor sound re-enforcemennt use; DON'T DO IT!!!! They are made for residential use in a closed room and would take at least 4 to 10X the power the horn cabs would just to keep up which would drive them way beyond the point of damage. Another thing to considerf is that your Onkyo amp is also designed for hiome music use and will be under a whole lot of stress when driven at the kinds of volume levels necessary for a block party. A pair of 4" muffin fans extracting the heat out of the amp casing would be a minimum precaution to slow down the probablility of blowing the amp.

At this point, I'm going to make another assumption that you have never done any pro type sound re-enforcement. If I were you, I'd look into renting a pro amp for the day to be on the safe side; the cost should be fairly minimal and you run far less risk of everything blowing upo after an hour and you looking like the bad guy. While you are there checking into things, you might want to spend $20 andhave them have a look at your speakers to see if they play OK with the amp you choose. At least you'll know that nothing will blow up and be the hero you hope to be!

I did pro sound re-enforcement and mobile disco for almost a decade in my youth and learned my lessons the hard way, blowing up half a dozen residential amps (some very powerful ones too) in the process. Same thing with residential speakers. Can't tell you how many weddings I've attended where the residential equipment used blew up right in the middle of the party; even managed to save a couple of those because I just happened to have one of my mobile rigs still in the back of my van that I loaned them to continue the festivities.

Did you play the friggin' piano too, Marc? haha

thanks ob156 I'll look into a rental amp might be a good alternative

Unfortunately not yournamehere. My daughter at least has the ability to play a little bit, but I have not got a music playing bone in my body; heck I can barely sing in the shower!!!

rental AMPS with a board or equilizer and cables. If you want to be remembered rent a few more cabinets and stands to raise the monitors up over their heads. Cheaper than a band. My apologies to the musicians.

-- 30 Jul 2010 11:46 --

rental AMPS with a board or equilizer and cables. If you want to be remembered rent a few more cabinets and stands to raise the monitors up over their heads. Cheaper than a band. My apologies to the musicians.

Hey Marc, bring back the old avatar, that one's just not you.

You mean this one André???