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MiniDSP DDRC-88A / 88BM Dirac Series vs Marchand Electronics XM44 3-way crossover noise measurements

gags11

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#1
First, want to apologize if I am posting in the wrong thread. In my previous thread, where I was comparing Matrix Sabre DAC to Mytek DAC+, there was a suggestion that MiniDSP can replace and likely perform better than the analog active crossover I had from Marchand. I couldn’t resist and pulled the trigger on the fully loaded MiniDSP DDRC-88A/88BM with Dirac live.

Before going any further, here is my setup.
Mini PC running Roon Core kit, to Mytek DAC, to Marchand Electronics active crossover, to 3 Amps (W4S ST 1000 20-300hz, Hypex NC 400 monoblocks 300-3500 hz, and McIntosh MC275 mk6 tube amp above 3.5k hz). Speaker drivers are the original Klipsch RF7ii 10” woofers, Scanspeak 12MU midrange and Pioneer/TAD PT-R7Y beryllium ribbon tweeters.

I had no complaints, but decided to try the MiniDSP instead of the Marchand. When I got the MiniDSP unit, I went through all the set up procedures and calibrations using the Umik-1.

now back to the reason for this thread. My Pioneer tweeters have 96db sensitivity. As such, in my system, I can hear a faint hiss from the tweeters when my ear is about 0.5 ft away from them. Not an issue when listening to music. Interestingly, when MiniDSP was introduced into the chain this hiss got significantly louder and annoying. I could hear it within 2-3 ft. So I decided to do some basic crude measurements. I do not have the fancy equipment Amir possesses, but the simple microphone measurements confirm what I hear.

When measuring full bandwidth (20-20000 hz) dB levels, no difference could be seen. I had to narrow the bandwidth to 3-30khz to see the difference. First, mic is about 4ft away, showing the background noise, next Marchand in the chain and the mic about 2-3 inches from the driver, and next is the MiniDSP in the chain. Kind of disappointed, to say the least. Also not impressed by Dirac, but that is another topic altogether.
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gags11

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Thread Starter #2
To clarify, the measurements were done with DAC being off, and the volume on the MiniDSP turned all the way down.
 
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gags11

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Thread Starter #3
Another thing I learned from this test is that my ear is way more sensitive than the umik-1. Also, most of the background noise I could see is below 3khz. So any noise and likely distortion above that frequency can be a major annoyance, even at very low levels, at least to my ears.
 

pozz

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DonH56

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#6
The limitations of miniDSP's analog outputs are pretty well known and Amir has even tested one of their units. I am not surprised that Marchand's noise level is lower. It would be interesting to compare THD. The advantages of using a miniDSP are much greater flexibility in filter designs, better matching and stability by using digital filters (I would assume), and in this case the addition of room correction. If the standard analog filters are good enough, and room correction is not desired, then no real reason for a miniDSP IMO. I waffled on getting a miniDSP but never got around to it; I used a little analog dbx unit for my crossover when I needed it.
 

TimoJ

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#7
Have you tried changing DDRC's output gain via the internal DIPs? If that is not enough, you might need to add an extra attenuator between the DDRC and your amplifier. Read DDRC's user manual: part 8 Gain structure.
 
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gags11

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Thread Starter #10
Have you tried changing DDRC's output gain via the internal DIPs? If that is not enough, you might need to add an extra attenuator between the DDRC and your amplifier. Read DDRC's user manual: part 8 Gain structure.
thanks for the tip, will try.
 
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gags11

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Thread Starter #11

pozz

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#12
I don’t mind at all to send in the Marchand crossover to get some measurements, so long as the turn around time is not too long. If Amir would like to measure it, I will send it in!
@amirm are you game?
 

FrantzM

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#14
Another thing I learned from this test is that my ear is way more sensitive than the umik-1. Also, most of the background noise I could see is below 3khz. So any noise and likely distortion above that frequency can be a major annoyance, even at very low levels, at least to my ears.

Really ???
I am surprised this didn't raise any raucous ...
 

rvsixer

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#15
The limitations of miniDSP's analog outputs are pretty well known and Amir has even tested one of their units...
And also according to Amir's testing...its also known the miniDSP's SHD analog output is entirely acceptable (what measurements do have lesser values than DAC's exceeding its performance, are inaudible).
 
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