Biamping option on a 3way

[augerpro]

Say I had built those Dayton 3way speakers and used one of those biamping jacks where you can biamp or run normally. Will running biamped screw up the functioning of the crossover? From what little I've learned so far the components in a 3way (particularily) "react" with each other quite a bit. This has an effect on impedence mostly correct? So if you biamp the woofer lowpass would no longer be "feeling" the effect of the bandpass and highpass. What would happen?

Or am I just thinking too hard too late at night with too little coffee? :P

[dynamowhum]

I too would like to know. I would also like to know what your impediances would be. Thanks

[BobEllis]

For most designs, such as the three ways presented in this forum, you can split the crossover and send the woofer section to one set of terminals and the M/T to another. You could even split the Mid and tweeters and triamp. Some crossovers are series designs that cannot be split. As long as you can clearly see each section connected to both terminals you should be fine.

Impedances depend on the particulars. In the case of the RS225/RS150/RS28 3 way, the woofer section would see approximately 4 ohms nominal and the top end would see approximately 8. Not that it really matters with most solid state amps these days.

However, biamping and using the passive crossovers is of little benefit, IMHO. To really get the benefits of biamping (or triamping) you should go with active crossovers and eliminate the passive bits completely. There are plenty of options from pro-sound units to kits to raw boards to building it yourself on prototype board.

Using the RS225/RS150/RS28 as an example, you'll want second order high and low pass filters, baffle step compensation and a phase correction/delay stage. All of this could be done with as few as 2 dual op amps per channel. If you don't have measurement capabilities, you wouldn't be too far off if you went with just straight 2nd order filters and boosted the woofer level to approximate baffle step correction.

I've got my triamped WT/MW center channel almost ready for test and tweaking. I'll post results when I finish. (public announcement helps pressure me into finishing )

[ThomasW]

Bob covered most of the important stuff.

I always use bi-amping terminals with jumpers on any big system. Makes diagnosing problems easier. And it means the systems is ready for true active bi-amping if I decide later on that's something I want to do.

[chasw98]

However, biamping and using the passive crossovers is of little benefit, IMHO. To really get the benefits of biamping (or triamping) you should go with active crossovers and eliminate the passive bits completely. There are plenty of options from pro-sound units to kits to raw boards to building it yourself on prototype board.

Question #1 - If a person were to biamp the RS 3 ways, would you run the LF by itself from one amplifier and then run the second amp straight to the MF driver with the HF XO in place?

Question #2 - I am assuming a Behringer DCX2496 would work well for this application, if not, what would you recommend short of building your own?

Thanks!

[BobEllis]

Chas,

1 - is correct, sort of. You have to have an active crossover before the amps and remove the high pass portions of the midrange XO. For example in Curt's TMWW XO (http://www.htguide.com/forum/attachm...achmentid=6319) it is C2011), in Dennis' it would be C2011, L2021R2021 and R2031

2. The Behringer would work and allow triamping. I've seen reviews ranging from "I wouldn't even recommend it to my ex wife" to "Sounds just as good as my gazillion dollar crossover". Guess you'll have to decide if it's OK for your system.

[mrogowski]

If what you want is a good basic electronic crossover, spending the extra money on a Behringer would be a waste, not to mention having to put up with all the gender changes and level matching.

Apart from building your own from scratch, scope out what's available for car audio. Decent quality, low noise units can be had for cheap and all you would need is a 12 volt power supply.

Then take the money you saved and get yourself some amplification...

Best,
Mark

[dynamowhum]

Mark what would you recommend from car audio then?

[ThomasW]

I don't think there's any advantage to a car unit when the Behringer CX2310 is so reasonbly priced

[chasw98]

"Using the RS225/RS150/RS28 as an example, you'll want second order high and low pass filters, baffle step compensation and a phase correction/delay stage. All of this could be done with as few as 2 dual op amps per channel. If you don't have measurement capabilities, you wouldn't be too far off if you went with just straight 2nd order filters and boosted the woofer level to approximate baffle step correction."

Thomas:
Will the CX2310 do BSC and Phase correction/Time delay? If not, will the 2496 do it? What would you recommend?

[BobEllis]

looking at the owner's manual http://cachepe.zzounds.com/media/CX2...cbc31438bc.pdf it appears to be a straight 24 db/octave LR. If you set the crossover to approximate the low end of the baffle step you'll be pretty darned close. Use "The Edge" from www.tolvan.com to find out what that frequency is.

Fourth order is OK, I just offered second order as being closer to the original design transfer function and easier to build if you were doing on a prototype board.

As for phase adjustment, although not ideal to do without, IMHO it isn't so critical at low frequencies. IIRC, Thomas uses one in his system and is rather happy with it.

[mrogowski]

You're right, the CX2310 is cheap. The only shortcomings is the gender and level problems. Chas, if you can live with a basic setup get the CX2310. To achieve everything Bob mentioned, you would be looking at the CX3400 at minimum - still not a bad price negating the above issues I mentioned.

The 2496 is, well, just plain cool, and will do anything and everything you want. An excellent unit if you plan to "grow" your speaker design/designing. If you got the cash, bite the bullet and get the 2496. Oh, and don't worry about the degraded sound bit...

Best,
Mark

Ha, Bob beat me to the post....

[chasw98]

Hey, if a 2496 will do it with good fidelity, I will start looking. I already found them for $250.00 just doing a quick search. Balanced, unbalanced, -10, +4, doesn't bother me. I can build a pad or a gain circuit real quick and easy if the need arises. Thanks.

[ThomasW]

Thomas:
Will the CX2310 do BSC and Phase correction/Time delay? If not, will the 2496 do it? What would you recommend?

Nope it's a plain jane analog crossover.

The only shortcomings is the gender and level problems.

male or female? .....:wink:

Using one with consumer gear I haven't have any level matching problems. Neither have several others I know are using them.

With new the quick locking strain-relief XLRs, making a set of cables takes 10 minutes. Or one can just pick up some low buck mic cables.

[mrogowski]

Let me clarify a bit - you won't have level matching problems if you have level controls on your amps. It becomes probematic when they don't exist.

Best,
Mark

[ThomasW]

Let me clarify a bit - you won't have level matching problems if you have level controls on your amps. It becomes probematic when they don't exist.
Best,
Mark

Mark,

The Behringer analog crossovers (CX2310/CX3400) have individual input level controls for both channels. In addition they have a separate high and low output pots for both channels and a separate level control for the sub out.

The all digital DCX2496 is the unit that's problematic with regard to output level controls

[mrogowski]

Ok, got it. I hope Chas does too...

[rumatt]

The all digital DCX2496 is the unit that's problematic with regard to output level controls

From a quick look at the manual, it seems that the DCX2496 has both EQ and phase correction on all output channels.

It also looks like you can hook up a PC to program it. If someone figures out a setting that worked well to tri-amp the 3-ways, it might be easy to share. You'd still need a bunch of amps, but the cost of the DCX2496 would be offset by the fact that you don't need to buy the passive crossover parts.

In terms of the quality of the DAC, Scott Endler modifies Behringer 2496 units, upgrading the DAC's and other components, and says he prefers them to the Benchamrk DAC1 afterward.

[ThomasW]

From a quick look at the manual, it seems that the DCX2496 has both EQ and phase correction on all output channels.

It also looks like you can hook up a PC to program it. If someone figures out a setting that worked well to tri-amp the 3-ways, it might be easy to share. You'd still need a bunch of amps, but the cost of the DCX2496 would be offset by the fact that you don't need to buy the passive crossover parts.

One still needs level controls for each channel.

In terms of the quality of the DAC, Scott Endler modifies Behringer 2496 units, upgrading the DAC's and other components, and says he prefers them to the Benchamrk DAC1 afterward.

Not too surprising a statement given he's selling the product...

[rumatt]

One still needs level controls for each channel.

It's got a +/- 15 db gain on all input and output channels. See attache pic.

Not too surprising a statement given he's selling the product...

Yeah, I agree. Just saying that the DAC quality is potentially decent.

[kingpin]

Mark,
The all digital DCX2496 is the unit that's problematic with regard to output level controls

Thomas can you please expand on this. As this(dcx2496)is what I plan on using in my towers to control the dual 12" subs in each cabinet.

Do you have any other suggestions I should think about.

Thanks
Mike

P.S. Remember layman's terms please. :T

[BobEllis]

Some have found feeding the DCX2496 with an analog signal from a preamp it becomes noisy and a bit grainy at low volumes because the low signal only uses a few of the bits available. Some do not find the effect objectionable.

One way around this issue is to feed the 2496 a digital signal and control the volume with an attenuator AFTER the 2496. This would have to be a 6 channel attenuator for a three way stereo system - one per driver.

Six gang potentiometers are hard to find and do not track well between channels (as you change the volume the relative balance between drivers will change). A better solution is some kind of stepped attenuator. This can be either a multi gang switch, a series of relays or a digital switch.

A Google search will turn up suitable kits and ready made attenuators. Unfortunately, even the kits could end up costing as much as the DCX2496. That is the problem that Thomas was referring to, rather than adjusting the relative levels of each output.

[ThomasW]

A Google search will turn up suitable kits and ready made attenuators. Unfortunately, even the kits could end up costing as much as the DCX2496. That is the problem that Thomas was referring to, rather than adjusting the relative levels of each output.

Yep....