If you want to replace your internal passive crossover with an external crossover, then you need separate wires to your tweeters, midrange, and woofer from the crossover.
I looked up the Mc901. It is a hybrid amp that wants to drive your woofers with solid state and your mids and tweeter with tube. To do this your speakers have to be set up for biwiring.
If you speakers are set up for biwiring then you could remove the internal crossover from your woofer if you want. I don't think this is the intention, but it probably would be good to have the amp crossover set about the same frequency as the internal crossover.
You still need to upper crossover to separate the mid frequencies from the tweeters.
If your speakers aren't set up for bi-amping, I don't know if the mc901 will accommodate that or not.
... the Mc901. It is a hybrid amp that wants to drive your woofers with solid state and your mids and tweeter with tube. To do this your speakers have to be set up for biwiring ...
No, the speakers need to be made for biamplifying. Biwiring and biamping are two different things. If you connect both MC901 outputs to a biwired speaker, you'll blow the amp.
@cleeds Biamping is technically correct. Biamping is what I meant to say.
However, a speaker truly set up for biwiring should be the same as one set up for biamping. Some speaker manufacturers have the biwires connected on the inside, so they are really just a placebo.
If you connect both MC901 outputs to a biwired speaker, you'll blow the amp.
Usually not. Sometimes yes. Depends on exactly how the speaker inputs were wired and whether or not your amp outs are balanced or not.
A properly wired speaker for bi-wiring separates out the crossover sections entirely internally. Some however short the grounds together, by design or by oversight.
It is not ideal to use both an active and passive crossover, but it is still workable.
I own these amps, and they are all you think they would be. Extremely versatile and easy to work with. When I purchased them, I ran Infinity IRS Betas. The mid/high panels with the tube section, and the bass towers with the solid state. I did not use the internal crossover since the Betas have a servo box for the Woofers and adjustable level crossovers on the mid/high panels. These amps sounded much better than a half a dozen or more previous arrangements with the Betas.
Now they are running a set of Analysis Audio Orion Mid/High panels using the internal crossover on the amps, with no passive crossover in line to the speakers. This is the best way to run these amps and sounds incredible. Another option is to run the monos as two separate amps for two separate types of speakers if you’d like to change up your flavor. You can run a more sensitive pair of speakers off of the tube section, and drive more power-hungry speakers with the solid-state section switching between based on your mood, but this will need two outputs from your preamp.
Can’t say enough good about the MC901’s. I watch the used market daily and have yet to see a used set for sale since their introduction.
A biwirable speaker provides a separate path for lo and hi frequencies, but they are still joined electrically at the xover. A biamplified speaker provides electrically isolated paths for the two frequency bands. That's the difference between the two.
A biwirable speaker provides a separate path for lo and hi frequencies, but they are still joined electrically at the xover.
@Cleeds In my experience that’s’ almost never the case, but I have seen it happen. Almost all speakers I’ve seen with 2 sets of inputs and external jumpers separate the crossovers internally. Otherwise, why have jumpers??
You can easily check this in a couple of ways. Remove the jumpers and plug in the woofers. See if anything comes out of the tweeter.
Next, do an impedance check between hot to hot and ground to ground. Should be infinite.
The one case I remember being posted about the speaker only had ground shorted internally. Normally this would be OK unless your amp was fully balanced.
Almost all speakers I’ve seen with 2 sets of inputs and external jumpers separate the crossovers internally. Otherwise, why have jumpers??
Agreed, biwiring doesn't make much sense and neither do the jumpers. When you biwire, you do not send the full amplifier output to the tweeter, do you? Of course not, you'd blow the bugger out. It still goes through the speaker's x-over. It's easy to verify with a DMM - just check for continuity. Spendors used to be wired that way, IIRC, and it always puzzled me.
What you are missing in your understanding is that the filter sections for each driver are independent in the classic, parallel crossover.
When the external straps are removed the individual high and low pass sections remain in place but the crossovers should not (and usually are not) have any be connected internally.
An external crossover would of course be additive to the internal crossover so it's not quite as good as having a purely external crossover, but it's workable.
Still, the risk of connecting two amps to the same bi-wire speaker is only present in rare cases when they join the grounds internally, and a balanced amp is used.
There's a lot of info here that may be relevant to your question. If you own or are looking to own these amps and are looking for info based on the specifics of these amplifiers, I can help. These are a significant investment and VERY rare in topic discussion here, so want to make sure you receive the info and perspective based on experience that will help.
@erik_squireswhat you're essentially claiming is that any speaker that can be biwired can also be biamplified - that the two terms are interchangeable. That's simply mistaken and, as I noted, easily tested with a DMM or VOM.
When you biwire, you do not send the full amplifier output to the tweeter, do you? Of course not, you’d blow the bugger out. It still goes through the speaker’s x-over. It’s easy to verify with a DMM - just check for continuity. Spendors used to be wired that way, IIRC, and it always puzzled me.
I agree that you should check for continuity before bi-amping, Check hot to hot and ground to ground. I’ve seen all 3 cases:
Infinite impedance
Both internally shorted (0 Ohms)
Ground only shorted
In the case of 1, bi-amping is fully safe.
In the case of 2, no bi-amping at all is safe
In the case of 3, only unbalanced amps with 1 hot output are safe.
In all cases listed the internal crossover remains in place. It's really a manufacturing choice whether or not the filters are joined internally.
Want to point out that there’s a number of A’goners who are successfully passively bi-amping. 1 and 3 seem to be the most common situation.
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