If you mean a conventional 2-way speaker with a passive crossover inside be sure to remove it/bypass it first when using an external crossover....
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Marchand XM44 Analog Active Crossover Review
- Thread starter amirm
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If you mean a conventional 2-way speaker with a passive crossover inside be sure to remove it/bypass it first when using an external crossover....
To post the obvious; far too many products have slid by for so many years based on just claims by manufacturers, subjective reviews, owner bias and group-think. Hopefully measurements will greatly improve this unacceptable situation.
D
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Do you believe your unit is malfunctioning in some way??
I suggest everybody take a breath here regards their evaluations of this product based on the objective measurements.
As an example: the frequency response graph showing the three response curves is incorrect. And the conclusion regarding stop-band attenuation of -30db invalid.
Distortion performance here isn't stellar, but it's not too bad.
There are some issues here, but nothing I would consider show-stopping for potential users interested in a non-DSP crossover.
Phil has been building these things for many years now, and there are numerous units in the field providing good performance.
Dave.
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OP
- Thread Starter
- #45
What makes them invalid?
D
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The actual response of the filters do not level off in the stop-band at -30db like that.
The response should continue to decrease at the defined roll-off rate all the way to the noise floor. And you certainly should not see a rising response well outside of the low-pass filter range. Your results depict a high-order shelving action.
The result looks correct regarding the pass-band portion of the responses (absolute level not withstanding) but there's an anomaly in the AP testing scheme somehow causing the confusing results in the out of band plotting. I'm not sure what the exact issue is, but some of these testing systems can plot confusing results depending upon the sampling scheme...differential mode....excitation....etc, etc.
If the owner is amenable, you could forward the unit to me and I'll test on my (completely different) system that I use for active crossover design/characterization.
Dave.
OP
- Thread Starter
- #47
That is what they should do. It is not what they are doing. The test is a simple sweep. The output is the output. As such, there is nothing invalid about the tests.
Perhaps the natural roll off of the driver helps in practice.
The rising response could be parasitic loads causing resonances higher up in frequency.
It is up to him. FYI he contacted the designer when I post the review. I would think we would hear from him and see his measurements.
D
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I'm sorry, but the topology of the circuitry won't allow it to exhibit that response.
This is some sort of testing anomaly, or an improper plotting technique of the AP interface, or something along those lines.
If the high-pass network was truly exhibiting that response, a user would most likely have some destroyed tweeters.
Dave.
Unless a part or two were defective. Checking the other channel to see if the low pass has that same anomaly would be useful.
Amir, was this done in continuous sweep mode?
D
Deleted member 2944
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If this particular XM-44 is loaded with standard filter modules and no specialized filters like notch, LT, shelve, etc, it should not exhibit the response Amir measured. Checking the other channel would probably be no different. I suspect this unit is working okay.
I'm almost 100% sure this is a measuring anomaly.
As I said, if the owner is amenable, I could also measure it. I use a completely different setup that I'm fairly confident with.
I measured one of these XM-44 units many years ago.........but it was a two-way unit. It did not exhibit that "shelving" action and measured as expected.
Phil does make schematic diagrams available for all his products. There's nothing in the (generic) configuration for this unit to create a shelving action like that.
https://www.marchandelec.com/ftp/xm44man.pdf
Dave.
I'm almost 100% sure this is a measuring anomaly.
As I said, if the owner is amenable, I could also measure it. I use a completely different setup that I'm fairly confident with.
I measured one of these XM-44 units many years ago.........but it was a two-way unit. It did not exhibit that "shelving" action and measured as expected.
Phil does make schematic diagrams available for all his products. There's nothing in the (generic) configuration for this unit to create a shelving action like that.
https://www.marchandelec.com/ftp/xm44man.pdf
Dave.
If it's a measurement issue, there indeed will be no difference. If it's a design issue, ditto.
If something is broken- and that DOES happen- the two channels will likely be different. So we narrow the possibilities down.
John1959
Member
BTW, I am not an electrical engineer, just an engineer, so I can't comment on the ongoing discussion about measurement fault/technical failure but that manual is something special, especially for the more technical oriented. All those details about the design! You know what you purchased after reading. It gives confidence. I hope the issue will be resolved soon and kudos for Marchand Electronics!
John.
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dbx active crossovers have a nice fit 'n finish compared to this. And are about 10x less in price. However, one should buy from a dealer who will take the item back, no questions asked, if there is a problem. I recently sent back a 223xs because the 40Hz high pass switches (on both channels) were defective. Also, you have to choose either TRS or XLR plugs, as they don't have both.
The question I have with crossovers is S/N. I'm not sure the benefit of having very low noise digital sources and amplifier (such as Benchmark) but throwing in an active crossover with 80-90 dB noise into the mix.
essence
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I also returned a 223xs because of transformer hum.
I was considering something like this when I was looking at options of integrating my sub but its very cost prohibitive.
There's not much point to a passive crossover when you can buy another DAC and do everything via software with zero signal degradation...
The Marchand was mentioned with quite a few others in the paper below.
by Barry Ober (JL Audio) ............... almost everything you ever wanted to know about subwoofers
http://soundoctor.com/whitepapers/subs.htm
by Barry Ober (JL Audio) ............... almost everything you ever wanted to know about subwoofers
http://soundoctor.com/whitepapers/subs.htm
You are correct.
That's why back then i also got a behringer ultradrive pro 2496 for my active speaker setup.
I am going to forward this to Mr. Marchand, who is an engineer himself. Would like to hear his input.
Looking forward to the reply, if you could please keep me updated. Even if you have to private message me. I have the XM66 and was always waiting for it or one of Marchands products to be tested. As Amir always says everything is item specific but in saying that, its still a disappointment.
I have not contacted him yet. Will update you guys when I do and get his response.
I bought the XM66 which is the variable version for Sub woofer crossover duties. I thought this would be the best option as my DSP is software controlled from my PC. Either I was going with a digital crossover with DSP or to choose a analogue active crossover and using DSP via the PC. I wanted to use Audiolense so I chose the active analouge option and Marchand products were marketed towards high end and not PA use.
I will say that even without DSP activated, the XM66 timing is perfect perhaps someone can chime in and tell us what this could be due to, is the supposed 4th order crossover which switches the phase 180 degrees and time aligns the mains with the sub woofer. No lag whatsoever, DSP only adds a little more smoother and tighter bass but nothing more to the timing.
Now, I will note that upon receiving the crossover there was a hiss through the speakers so it wasn't completely quiet, a huge disappointment for that price. I sent it back for a check up, and upon its return no noise or hiss at all, I have no idea what he did to get rid of it. Perhaps someone could explain this as well.
Personally, I love the ability to vary the crossover actively and use DSP via PC. I am a big fan of this.
I will say that even without DSP activated, the XM66 timing is perfect perhaps someone can chime in and tell us what this could be due to, is the supposed 4th order crossover which switches the phase 180 degrees and time aligns the mains with the sub woofer. No lag whatsoever, DSP only adds a little more smoother and tighter bass but nothing more to the timing.
Now, I will note that upon receiving the crossover there was a hiss through the speakers so it wasn't completely quiet, a huge disappointment for that price. I sent it back for a check up, and upon its return no noise or hiss at all, I have no idea what he did to get rid of it. Perhaps someone could explain this as well.
Personally, I love the ability to vary the crossover actively and use DSP via PC. I am a big fan of this.
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