Different ohms drivers with one crossover?

[Altoman188]

Howdy,
I am looking a system in a new youth room and we already have some older Yamaha 15 in box's that are biamp only. I was thinking about building a internal passive crossover so simplify the install and cost of amps, but the drivers are very different ratings. The 15 is a 6 ohm and the 2" tweeter is a 16 ohm. I was what effect that would have on the overall of the box.
Thanks a ton.
Josh

[Chris Roemer]

Howdy,
I am looking a system in a new youth room and we already have some older Yamaha 15 in box's that are biamp only. I was thinking about building a internal passive crossover so simplify the install and cost of amps, but the drivers are very different ratings. The 15 is a 6 ohm and the 2" tweeter is a 16 ohm. I was what effect that would have on the overall of the box.
Thanks a ton.
Josh

I am looking (1) a system in a new youth room and we already have some older Yamaha 15 (2) in box's that are biamp only. I was thinking about building a internal passive crossover so (3) simplify the install and cost of amps, but the drivers are very different (4) ratings. The 15 is a 6 ohm and the 2" tweeter is a 16 ohm. I was (5) what effect that would have on the overall (6)of the box.

Please provide (fill-in) answers to the missing info in your post:

1 - a) "to buy", b) "to design", c) "to install"
2 - a) "inch woofers", b) "inch 2-way speaker systems"
3 - ? you think a passive XO will simplify your installation?
- ? you'd like to avoid buying extra amplification to actually bi-amp?
- ? If you're not currently bi-amping, how are these working for you now?
4 - a) impedance - I'm guessing this is correct?, b) power, c) passband
5 - wondering?
6 - a) impedance?, b) power handling, c) frequency response, d) expense

Chris

[bangleiii]

Howdy,
I am looking a system in a new youth room and we already have some older Yamaha 15 in box's that are biamp only. I was thinking about building a internal passive crossover so simplify the install and cost of amps, but the drivers are very different ratings. The 15 is a 6 ohm and the 2" tweeter is a 16 ohm. I was what effect that would have on the overall of the box.
Thanks a ton.
Josh

2" tweeter is mighty small for a 15"!. Put a 5uf on the tweeter and let the woofer run wild.

[billfitzmaurice]

I was what effect that would have on the overall of the box.

None, provided you calculate the correct component values based on the actual measured impedance of each driver at the crossover frequency.

[AMC]

Don't be a dick Chris, everyone knew exactly what the OP was saying.

To add a bit of detail to BFM's answer. YOU CAN NOT USE A OFF THE SHELF CROSSOVER! You could design a passive crossover and the impedance does not matter, in the sense that they do not have to be the same. I would caution you however, as this is not always an easy task, and takes considerable time and effort. In the end, it is much easier, and often cheaper, to bi-amp. Good quality and high power handling passive crossover components are not cheap, and you could easily go over $100 (each). And in the end, you would not be sure how well it is going to work, until you build it. For probably about $200 used, you could get an inexpensive X-over and extra amp. And it would offer more flexible use going forward.

[wg_ski]

2" tweeter is mighty small for a 15"!. Put a 5uf on the tweeter and let the woofer run wild.

Either a 2" voice coil driver on a 1" horn, or a 2" exit horn (with bigger driver), more than likely. An old bi-amp only system may very well have a 2" exit HF unit - which is not small by any means.

While the 5uF cap would probably work, the shrill upper midrange will send everyone screaming from the room. A pre-made crossover might sound better, but not optimum. Maybe good enough. What frequency depends on what the tweeter driver really is (a 1" or 2" exit). The best choices for those are over $100 each, and for that much you can buy an active crossover and a small (100W/side) used amp for the highs.

Building your own crossovers can be less expensive - but your first one(s) won't be. Most of us have already invested in test and measurement gear, and a stockpile of commonly used parts. Then (and only then) does it become cost effective.

[Altoman188]

So a little more info on it, it is in fact a 2" exit driver i cant remember horn dimentions. It calls for 165 watts if i can recall correctly, and the 15 wants 600 w. I had been running them bi-amped and they sounded fine i was just hoping to have a less complicated system for moving it around and also in case i am not the one who hooks it up. I also was planning on building the crossovers entirely myself being that it is an odd setup and off the shelf stuff will be hard to find i just have never used such varied ohms in drivers nor have i built a pro audio crossover just HT stuff. I will see if i can get more specs on the drivers themselves but it is hard to find info on these. I do know the reccomended Xover is 1250 hz which is low for an off the self Xover also part of why i planned on building it.
I may still end up just bi-amping it since i already have an active ashley wish all the settings diled in i just was thinking it might be a fun project

[AMC]

... i just was thinking it might be a fun project

No, it wont. There a bunch of fun things about this stuff, that is not one of them. If you already have the x-over, just get an amp and run it that way.

And please remember, those wattage ratings are absolute MAXIMUMS, not recommendations.

[Altoman188]

Scratch that, its a 400W for 15 and 80 for highs. And that is rating not peak, so roughly double that is max thank you though. I found specs for it finally but i think i am just going to go with bi-amping for now unless someone wants to nerd out with me. And fun is many things to many people just because you dont find it fun doesn't mean i wont. Opinions are great but not universal.

[AMC]

And fun is many things to many people just because you dont find it fun doesn't mean i wont. Opinions are great but not universal.

Very true. For me, what can take all the fun out of it is the cost and time. If you build a nice passive x-over, and put it together, and it doesn't sound right, you have to order new caps and coils. And for what you are doing, a single 14ga air core inductor can run over $40.00. Then you have to wait for it to arrive etc, etc. I like instant gratification.

I think you are on the right track though.

[jefffluker]

Altoman188--you MOST DEFINITELY can build a passive crossover for this speaker, and yes, it will simplify the set-up. (one cable, one plug)

The 2" compression driver--Most 2" horn/driver duos work well up to about 5,000 Hz, above which they begin to exhibit a) rapid attenuation and b) increasingly narrow dispersion. (12dB down, 10 degrees horizontal at 16kHz) In my experience, you can EQ the response, but the "beaming" can't really be fixed. If you want or need sweet highs, add a super tweeter. Doesn't need to be mounted on the baffle-you can attach it to the top or side.

A well designed high-pass crossover will tame the considerable low-end response. Start at...IDK...1600Hz? Work your way up (or down?) and see what sounds good. Whatever the frequency, I recommend AT LEAST a second order slope. (I'd use a fourth order slope. Overkill...)

ALSO The 2" driver sensitivity is much higher that that of the woofer, and will require fixed-resistor attenuation of 15 dB or more. These resistors will take a beating, esp. the series unit. HIGH power resistors (50-100 watt) are needed--stuff PE doesn't carry. Try Digi-Key. They sell super-bad 100 watt Vishay-Dale units for about 8 bucks.

The woofer--Could possibly be left uncrossed, depending on it's response and natural roll-off.

Yes, I've omitted many details--The Complete Crossover 101 is too much for one post.

I've built/repaired/upgraded many pro-sound crossovers. Perhaps I can build or help you build yours--Do you live near the Gulf coast?

E-mail any time.

Jeff Fluker
jeff@hotwaxunlimited.com

[wg_ski]

Of course it *can* be done - it's just that the 'pros' are cautioning against getting in over his head and spending more money than just doing it the conventional and easier way. It can in fact be a 'fun project', but only if all the infrastructure is already in place to do such a thing. The principles are the same as building any speaker - measure, simulate, prototype, measure, repeat as necessary. Pro type drivers behave differently than what a HT speaker builder is used to - and it does help to know what to expect before ever getting out the mic (like the HF beaming or CD rolloff, +15dB woofer breakup peaks, etc.) For first-timers or if time is money, it's probably too much trouble. For an experienced speaker builder with all the tools, a big stash of caps, resistors, cores and magnet wire it can be done in a leisurely weekend.

[Djfive5six]

well if its a simple solution why not run it mono two way each tweeter on one channel of the amp and the two15" on the other channel use a electronic tunable crossover w limiter to be on the safe side and put a security panel over the crossover so kids dont take it out of adjustment and kill something

[kblackmore]

I was just thinking about your thoughts of someone else setting up the system. Years ago I had a second crew running my alternative system. They kept cooking the tweeters by hooking it up improperly. My solution was to replace the input connectors on the speakers and the output connectors on the amp rack. I used XLR connectors (male on speakers, female on amp racks). I wired the highs to use pins 2+3, bass on pins 1+3, and the mids on pins 1+2. For speaker wire, I cut the ends off some old extension cords I had laying around. By doing this, it made hooking the speakers wrong impossible. My tweeters were safe from them from then out. Perhaps this might give you an idea how to make your system safer to be in other's hands.....

[billfitzmaurice]

I was just thinking about your thoughts of someone else setting up the system. Years ago I had a second crew running my alternative system. They kept cooking the tweeters by hooking it up improperly. My solution was to replace the input connectors on the speakers and the output connectors on the amp rack. I used XLR connectors (male on speakers, female on amp racks). I wired the highs to use pins 2+3, bass on pins 1+3, and the mids on pins 1+2. For speaker wire, I cut the ends off some old extension cords I had laying around. By doing this, it made hooking the speakers wrong impossible. My tweeters were safe from them from then out. Perhaps this might give you an idea how to make your system safer to be in other's hands.....

That's where 4 pole Speakons come in. Typically pins 1+1- are wired to the lows, 2+2- to the highs. Four pole Speakons are used at the rack in a break-out box from the amps, a single 4 conductor cable goes from the rack to the speaker, and you can't mess it up. OTOH if you put XLRs on a rack sooner or later some idiot will plug a mic or board into the rack output.