XPA-2 v Two XPA-2's

[tsruha]

What are the advantages of using two XPA-2's as monoblocks v one XPA-2 as a stereo amp?

What are the disadvantages (if any)?

[garbulky]

XPA-2 monoblock is rated for 8 ohm loads only.

[jhob]

If I remember correctly, I think they only can be used in Monoblock mode with speakers that are 8ohms.

[jhob]

And if you're considering monoblocks, for about the same price as a new XPA-2 (or even a little less) you can probably find a pair of used XPA-1L's.

[tsruha]

Thanks for the responses. My speakers are 8ohm. I already have an XPA-2 and there are some used for sale that are very reasonably priced that would be cheaper than picking up the XPA-1L's until I can afford them.

[garbulky]

I preferred the XPA-2 gen 2's to the XPA-1 L with Axiom towers.

[teaman]

Personally I prefer the Gen 1 XPA-2's to the Gen 2 as the gain structure was higher. 32db vs 29db

[repeetavx]

If you're talking about bridging an XPA-2 to make it a mono-block, then these are the things to consider.

It won't handle low impedances as well as an unbridged XPA-2. This will result in overheating and maybe signal distortion.
You raise your noise floor in the signal to noise ratio.
You lower your Damping factor. (Lose the ability for your amp to control bass frequencies as well.)

XPA-2s do ok when bridged, but they are really designed to be used as two channel amps.
But, if your talking about Vertical Bi-Amping, then that is another story.

[tsruha]

This is precisely what I want to do, vertical biamp each speaker to its own XPA-2.

Feb 1, 2017 15:31:50 GMT -5 repeetavx said:

If you're talking about bridging an XPA-2 to make it a mono-block, then these are the things to consider.

It won't handle low impedances as well as an unbridged XPA-2. This will result in overheating and maybe signal distortion.
You raise your noise floor in the signal to noise ratio.
You lower your Damping factor. (Lose the ability for your amp to control bass frequencies as well.)

XPA-2s do ok when bridged, but they are really designed to be used as two channel amps.
But, if your talking about Vertical Bi-Amping, then that is another story.

[vcautokid]

Absolutely the best course. Vertically Bi-amping is going to give the best results. The XPA-2 is an amazing amplifier. Loved mine allot when I had it. Now my Brother continues the love. So yes 2 XPA-2 in a Bi-amplified solution would be very cool.

[tsruha]

Thank you guys for all your help!

[leonski]

Bridged amps RARELY are thought of to have the sonic virtues of the UnBridged amp.

If you even consider the biamp approach, keep in mind that to reap All the benefits, you need to do some speaker surgery and bypass the crossove while going to
a crossover between preamp and the XPA-2s.
Duplicating the stock crossover using something like MiniDSP is an easy approach and still leaves lots of room for experiment down the road.
You will Also reap as much as a 3db boost depending on the crossover frequency.

www.minidsp.com/applications

They are inexpensive but very Capable. You program them with your Confuser. Some of the MiniDSP units will hold several 'programs' so you can easily experiment.

[tsruha]

Feb 2, 2017 3:12:09 GMT -5 leonski said:

Bridged amps RARELY are thought of to have the sonic virtues of the UnBridged amp.

If you even consider the biamp approach, keep in mind that to reap All the benefits, you need to do some speaker surgery and bypass the crossove while going to
a crossover between preamp and the XPA-2s.
Duplicating the stock crossover using something like MiniDSP is an easy approach and still leaves lots of room for experiment down the road.
You will Also reap as much as a 3db boost depending on the crossover frequency.

www.minidsp.com/applications

They are inexpensive but very Capable. You program them with your Confuser. Some of the MiniDSP units will hold several 'programs' so you can easily experiment.

Do I need to remove the crossovers from my speakers or simply use an external crossover at line level and keep the crossovers in the speakers?  How would this affect the crossover once it reaches the speakers if the crossovers in the speakers are still there?

[leonski]

Never EVER run a crossover into a crossover. With Rare Exception.
You need to disconnect but not necessarily 'remove' the crossover in-speaker.

If it's a 3-way speaker, you may need to Keep the mid to high crossover. This would be if you do not want to
go to a TRIamp system which both adds another channel of amp to each speaker but additional complexity.

Running amps as biamp and continueing to use the speaker level crossover does not gain you Much.

Read THIS and see if it makes much sense to you.

sound.whsites.net/bi-amp.htm

This is part ONE of a Two-Parter, so you've got some reading to do to see if you want to give this a try.
The good news? Changes proposed are 'reversible' but you must work carefully and keep track of everything.

[KeithL]

There is a lot of confusion about bi-amping.

In simplest terms there's "real bi-amping" and what people today call "vertical bi-amping" (or sometimes they just call it bi-amping).

What many people currently refer to as "bi-amping", and what the dual terminals on many speakers enable you to do,  is really something else. By removing the jumpers, you are allowed separate access to each section of the speaker, WITH ITS PART OF THE CROSSOVER STILL IN THE CIRCUIT. You can then use two different amplifiers to drive each section of the speaker. Each amplifier is fed the same full range signal, and amplifies the same audio signal, and it is still the speaker's passive crossover components that route each frequency range to the appropriate driver. The benefit of doing this is that, because each amplifier is only powering part of the frequency spectrum, each amplifier is doing less work, and there is less interaction between the bass and upper frequencies. (Note that, in a speaker with three or more drivers, the woofer is generally considered to be one section, and the midrange and tweeter or tweeters the other.) 

In REAL bi-amping (or multi-amping), each speaker driver has its own amplifier, which is connected directly to the driver. A line level electronic crossover is then used to divide the content up so that each frequency range goes to the amplifier that is connected to the correct driver. This is the version that has the most benefits; it's also the one that requires the most effort. Because each amplifier must be connected directly to the speaker driver, the crossover inside the speaker must be removed or bypassed. (This is desirable because it eliminates the power and damping losses due to the crossover components being in circuit. This allows the amplifier to deliver more power, and to control the speaker more precisely. Also, while passive crossover components are chosen to select a specific crossover frequency and slope, by removing them, you can then adjust the crossover by changing the settings on your active crossover. Most active crossovers can be configured to various crossover frequencies and filter slopes.) In order to do it this way, each driver must be connected directly to the amplifier.

Since commercial speakers are NOT wired to allow this, it is most commonly used in high end DIY systems, or by people willing to make serious modifications to their speakers. Of course, if you're building your own speakers, this adds the cost of the electronic crossover, and the extra amplifier channels, but you can save some money by NOT designing or building the passive crossovers used in most other speaker designs. The benefits of doing this sort of bi-amping are more power to each driver, better amplifier control over each driver, and the ability to fully optimize each amplifier to the driver it powers. The main drawback is that you need a separate amplifier channel for each driver, and an electronic crossover component.

NOTE: Our powered Airmotiv 4s, 5s, and 6s, and Stealth 8 monitors feature TRUE ACTIVE CROSSOVERS and TRUE BI-AMPING. Each speaker has two separate amplifiers inside, one connected directly to each driver, and a precision active electronic crossover.

NOTE: The "bi-amp" option on preamp/processors is intended for "vertical bi-amping. It simply serves the purpose of a pair of signal splitters or "y cables" by sending duplicates of the front left and front right output signals to another set of output connectors. (Usually the rear surrounds are repurposed for this.) You then have two outputs for each main channel, which you can connect to two amplifier channels, providing the two amplifier channels needed to vertically bi-amp each speaker. Both outputs receive the entire main speaker signal; there is no electronic crossover involved; simply a signal splitter. In contrast, when you use something like a miniDSP as an "electronic crossover", it actually does split the audio signal into multiple frequency ranges, and route each to a separate output.

HOWEVER, the short answer to your question is that, in order to use a TRUE electronic crossover with your speakers, you really DO have to modify them and bypass the internal crossovers. Trying to use an electronic crossover with the internal passive crossover still connected is going to nullify most of the benefits of bi-amping (and will be difficult to get to work satisfactorily at all). You'd be better off to simply do vertical bi-amping and not bother with the miniDSP.

Feb 2, 2017 16:09:33 GMT -5 tsruha said:

Feb 2, 2017 3:12:09 GMT -5 leonski said:

Bridged amps RARELY are thought of to have the sonic virtues of the UnBridged amp.

If you even consider the biamp approach, keep in mind that to reap All the benefits, you need to do some speaker surgery and bypass the crossove while going to
a crossover between preamp and the XPA-2s.
Duplicating the stock crossover using something like MiniDSP is an easy approach and still leaves lots of room for experiment down the road.
You will Also reap as much as a 3db boost depending on the crossover frequency.

www.minidsp.com/applications

They are inexpensive but very Capable. You program them with your Confuser. Some of the MiniDSP units will hold several 'programs' so you can easily experiment.

Do I need to remove the crossovers from my speakers or simply use an external crossover at line level and keep the crossovers in the speakers?  How would this affect the crossover once it reaches the speakers if the crossovers in the speakers are still there?

[leonski]

You don't gain much or anything leaving the speakers crossover in-place. Each amp still has to amplifiy the full range signal.

REad the article from Elliot Sound Products. This is clear and will allow the OP to ask better questions going forward.

Lots of ink has been spent on 'vertical' vs 'horizontal' biamping.

[repeetavx]

I'm a big fan of passive vertical biamping. Not that active vertical biamping isn't better, because it is. It's just that first you have to modify your speakers. Then figure out the proper crossover frequencies. Then make sure your treble / Bass balance is correct.

That's a lot of personal engineering you have to go through, when you can get ninety percent of the sound by using the speakers crossover.

If you want a project then fine. But if you're just looking for great sound. ..

[leonski]

Faikrly true, repeetvx, it isn't a drop-dead plug in to go to real biamping. It is quite the 'Project'.
But the new DSP based solutions help a LOT. Coupled with a SPL meter, you can dial in pretty good.
The place to start would be with the manufacturers specs for the crossover. Frequency, slope and alignment
If the highs or lows end up a little 'hot' you can always shelve it down a couple db and try again.

At the higher levels, it gets to be more trouble to get that little Extra. But bridging XPA-2s into 90 db sensitive speakers ain't it.

[KeithL]

Exactly; full-on bi-amping is a lot of work.

Another thing to remember is that speaker drivers themselves are rarely perfect. Therefore, with most speakers, the passive crossovers in the speaker actually do more than just divide the frequency ranges - they provide correction for the characteristics of the drivers, and compensation for things like the time alignment of the drivers and the tuning of the box. In other words, if you switch to an electronic crossover, it doesn't have to just do a great job of dividing the frequencies, it often ALSO has to replace the various corrections and adjustments that were previously being done by the original passive crossover. (The value proposition is different when you're building a DIY speaker from scratch; when you have a properly designed speaker that works well most of that work has already been done for you. When you do "passive bi-amping", since the original passive crossover remains in place, any corrections or adjustments that were carefully designed into it also remain in place... which can be important. Otherwise you're going to have to re-engineer those corrections into the electronic crossover.)

Feb 2, 2017 21:24:07 GMT -5 repeetavx said:

I'm a big fan of passive vertical biamping. Not that active vertical biamping isn't better, because it is. It's just that first you have to modify your speakers. Then figure out the proper crossover frequencies. Then make sure your treble / Bass balance is correct.

That's a lot of personal engineering you have to go through, when you can get ninety percent of the sound by using the speakers crossover.

If you want a project then fine. But if you're just looking for great sound. ..

[leonski]

This should keep the dedicated DIY guy busy for a while:

www.minidsp.com/applications/advanced-tools/rephase-fir-tool

FIR Filters in the digital domain allow the time and phase alignment of multi-driver speakers.

This is an Advanced project NOT for the faint of heart or if you are not willing to do the work.
And invest in the rest of the stuff needed to make it work.

usr.audioasylum.com/images/2/26701/Horizontal_and_Vertical_Biamping.jpg

Here is a picture of Vertical V horizontal biamping, just to get everyone on the same page.


the Decision to go vertical or horizontal is partly based on crosssover frequency.    If you cross at 5000hz,
you only need a fraction of the power Above V Below that frequency.   It wouldn't make sense to me, in that case
to have a pair of kilowatt monoblocks.  But if you cross somewhere near the 50:50 point of power needed, than,
by all means, run a pair of same - amps.   Gain Matching is important, too, but with DSP, you can easily add or
subtract a few db per 'way' as needed.