JBL Master Reference Monitor

[iansr]

Not enough taps for the LF section, so it has to be assisted with a few biquads.
miniDSP uses proportional Q EQs, and you also have the possibility to load your own biquad coefficients.
It should be pretty accurate, but again...

https://www.minidsp.com/forum/opendr...start=45#24625
It would probably be a better idea to convert to proportional Q the modified constant Q values found in the new rePhase settings for those 8 EQ points.

I *hate* IIR crossovers and their noisy/unreliable/capricious biquad implementations
FIR is the future, for sure, and not only for linear-phase crossovers.

I'm looking at getting a pair of M2s. As luck would have it, I already own a 4x10HD unit. I'm a novice at DSP so forgive the question but is the 4x10HD FIR capable ?

[johanwholst]

No IIR only on Minidsp 4x10.
I have tested 2x4HD on M2, and it sounds good with a combined IIR/FIR filter. A pad is recommended on the tweeter to supress noise, but it is not too bad using an amplifier with around 20dB gain. 4x10 is more quiet, and you can probably run the compression driver "bare backed" with very little hiss using a rather low gain amp. The crowns will most likelly need a big pad like the original network.

[iansr]

No IIR only on Minidsp 4x10.
I have tested 2x4HD on M2, and it sounds good with a combined IIR/FIR filter. A pad is recommended on the tweeter to supress noise, but it is not too bad using an amplifier with around 20dB gain. 4x10 is more quiet, and you can probably run the compression driver "bare backed" with very little hiss using a rather low gain amp. The crowns will most likelly need a big pad like the original network.

OK Thanks. Sounds like my 4x10 would provide a decent crossover solution. I already own very quiet amps that would be suitable so I won't be using the Crowns.

[dprice]

4x10 is more quiet, and you can probably run the compression driver "bare backed" with very little hiss using a rather low gain amp. The crowns will most likelly need a big pad like the original network.

The M2 passive "crossover" also provides some protection to the HF driver by rolling off the lower frequencies. I would strongly consider keeping it since mistakes do happen and it will be an expensive one if the worst happens.

Enjoy!

[iansr]

The M2 passive "crossover" also provides some protection to the HF driver by rolling off the lower frequencies. I would strongly consider keeping it since mistakes do happen and it will be an expensive one if the worst happens.

Enjoy!

Well I'll be buying the M2s not DIYing them and I'm certainly not going to mess with them.

Having done more reading I've concluded that rather than use my 4x10 I'd be better using the FIR capable openDRC DI units

[ivica]

Well I'll be buying the M2s not DIYing them and I'm certainly not going to mess with them.

Having done more reading I've concluded that rather than use my 4x10 I'd be better using the FIR capable openDRC DI units

Hi,

Using FIR or IIR is, I think less important, then the level of possible hiss or wide frequency noise, that are sometime on some digital network solutions evident, especially when high sensitive , wide frequency drivers are present, and power amps of over 26dB gain applied.

regards
ivica

[iansr]

I'm trying to find out the sensitivity and minimum impedance of the D2. Not been able to find this info anywhere. I'll be using different amps for the woofers and the D2s and I'm trying to work out how powerful the D2 amp will need to be.

[ivica]

I'm trying to find out the sensitivity and minimum impedance of the D2. Not been able to find this info anywhere. I'll be using different amps for the woofers and the D2s and I'm trying to work out how powerful the D2 amp will need to be.

Hi iansr,

As D2 driver has TWO diaphragms, each of 16 Ohms nominal, and if used in 'series' that would be 32 Ohms, so I would not expect that minimum would be less then 16 Ohms.
As the sum of surfaces of both diaphragms is almost equal to 4" dome diaphragm, I would expect that D2 driver would have almost the same efficiency, so about 110dB/1W/1m, but if voltage driven by 2.83Veff, that would be -6dB, so to say 104dB/(2.83Veff)/1m.
Depending on the horn type applied, if, say, CD ("constant directivity" horn such M2) is used the FR roll-off about -6db/oct from 3kHz can be expected up to say 10~12kHz, but it would be the best to apply FR measurements to make proper EQ.

reagrds
ivica

[pos]

The lpad and cap in the M2 passive network is aimed at a 20 ohm load, so that is probably the average load of the unit in the frequency range of interest.
Also note that this lpad eats 9dB so you cannot go away with a low power amp and you will basically divide its 20 ohm max output power by 10.

[iansr]

The lpad and cap in the M2 passive network is aimed at a 10 ohm load, so that is probably the average load of the unit in the frequency range of interest.
Also note that this lpad eats 9dB so you cannot go away with a low power amp and you will basically divide its 10 ohm max output power by 10.

Ok thanks. That's a shame. Looks like I'll be using my Ncore 400s on the D2 and a Crown K2 for the woofers.

[pos]

I am using a pair of ncores sharing one power supply per side myself, with the passive network in place.
Works pretty well, but I am sure a ton of other amps would work just as well.

[pos]

Oups just realized I wrote 10 ohm instead of 20 ohm in the above post #1494.
Edited...

[ivica]

Oups just realized I wrote 10 ohm instead of 20 ohm in the above post #1494.
Edited...

Hi,

Hmmm, now undestandable... :=))

regards
ivica

[iansr]

I've generated the file in rephase and am trying to work out what I do next. I've read the miniDSP guidance note and it says, load the file into FIR Channel 1 and Channel 2 in the 2x2 plugin, but it doesn't tell you how to do that. Where can I find guidance on how to load the file?

[pos]

This is probably described somewhere in the manual, but basically you have to click on each FIR bloc, click on "browse" and select the bin file, then click the "send to DSP" button.
You need to redo this for all the presets you want to use.

Also make sure the "FIR bypass" button is not activated!