Magnepan MG10/QR DSP crossover

[HAL]

Since the dspNexus 2x8 can be used for either new speaker designs or reworking old speaker designs, decided to give it a try with a pair of Magnepan MG10QR planars I found.  Had a pair of Magnepan MGIIB's back in the '80s, so a good place to start.  At 10.5in wide about half the width of my old MGIIB's, so that should improve imaging.  Mechanically time aligned, but adding a servo sub will time align them for the room setup.

These are the original Quasi-Ribbon model of the speaker, a two way crossover design with single pole filters.  The response is reported as 80Hz to 22KHz for the speakers, so a good subwoofer is needed for first octave sound reproduction.  I know how to do that!

Speaker measurements are needed to see what will be the new DSP crossover design.

A few surprises along the way, so will see what happens.

[GDHAL]

Since the dspNexus 2x8 can be used for either new speaker designs or reworking old speaker designs, decided to give it a try with a pair of Magnepan MG10QR planars I found.  Had a pair of Magnepan MGIIB's back in the '80s, so a good place to start.  At 10.5in wide about half the width of my old MGIIB's, so that should improve imaging.  Mechanically time aligned, but adding a servo sub will time align them for the room setup.

These are the original Quasi-Ribbon model of the speaker, a two way crossover design with single pole filters.  The response is reported as 80Hz to 22KHz for the speakers, so a good subwoofer is needed for first octave sound reproduction.  I know how to do that!

Speaker measurements are needed to see what will be the new DSP crossover design.

A few surprises along the way, so will see what happens.

The only commentary I have is that my GoldenEar Triton Reference speakers use DSP, and they are the best speakers I've ever had. The bass integration with sub and mids is exactly perfect.

[HAL]

To me, DSP has completely surpassed the sound quality of passive crossovers when it is a competent design.  I will not go back.

[GDHAL]

To me, DSP has completely surpassed the sound quality of passive crossovers when it is a competent design.  I will not go back.

I agree. So please allow me to seek your opinion. Given that you're a friend (done business with?) Greg of GTAW, if I'm not mistaken his design approach is the best crossover is no crossover. Hence I believe his speakers don't use any (or I recall hearing something about a capacitor used for some kind of "protection", not sure though). Can you opine on the benefits (or lack thereof) of no crossover?

As a side, I've heard other (boxed) single driver full range speakers besides Greg's. They sound fine  but honestly I cannot hear anything advantageous versus multiple drivers with crossovers.

Thank you.

Hal

[HAL]

Greg's planar/ribbon combinations did not use a crossover on the woofer/mid panel, but had a cap on the direct drive ribbons.  The new ribbons he said are transformer coupled, so probably also has a cap to remove LF energy from the tweeter ribbon depending on the transformer.

I have heard them play very loud without strain, so his system is robust from the driver material and magnetic field strength components of the design.  Every generation of his planars sounded better.  He also uses them with a sub array.  In the past servo subs, now standard subwoofer designs.  Probably for the same reason everyone else is for lack of servo amps from Rythmik Audio.

I prefer using high rate XO's to remove more energy from the woofer and tweeter drivers to let them play loud and clean. I also like using high rate acoustic L-R style crossovers for all the crossover points.  I will be doing exactly that with the MG10QR's.  No linear phase filter crossovers will ever be used for speakers from HAL. 

When you can make a pair of LM10n planars play 180Hz to 20KHz flat and have plenty of acoustical output using a high rate L-R crossover, and sound this good, why bother with other types.  The MG10QR's should be a lot of fun since the bass panels go to 80Hz.  The servo subs will have a simple job to do. 

I am not a fan of boxed full range cone drivers other than for electric guitar and amp use.  That is a different animal than for music reproduction.

[HAL]

To drive the MG10QR's bass panels, will be using Pizza Box Amp v2.1 with the new 1kW SMPS and capacitor filter.  Those will be tested soon.  The QR tweeter amp will be the Orchard Audio Starkrimson monoblocks with 300W GaN SMPS.

This will be 500W into the planar 4 Ohm load, so should have plenty of dynamics even with the 86dB/1w/1m sensitivity to 113dBSPL.  The QR's should be good to 108dBSPL.
The fuses will remain after the crossover upgrade.

The dspNexus 2x8 DSP crossover design is done for testing. 

Now to mod the speaker crossovers to allow access to the two drivers directly.

[HAL]

Removed the connector panel on the MG10QR and this is the passive crossover and wiring to the drivers.  They are fast-on connectors so easy to disconnect the original crossover, remove the original connectors and use 5-way binding posts and new wiring directly to the drivers to biamp the speakers.  Will use the Pizza Box Amp v2.1 on the woofer panels and the Starkrimson monoblocks on the Quasi-ribbons. 

The EA dspNexus 2x8 will be the DSP crossover to replace the passive crossovers and add the servo subs below the 80Hz rolloff of the woofer panels. 

With the nominal crossover will be able to make measurements to see what will improve the response of the system.  Using higher order Linkwitz-Reily crossovers will improve power handling for the drivers and the amps. 

This is Deja-Vu as I did this to my MGIIB's back in the 1980's, since the capacitors at the time were Mylar and Polypropylene caps were then available.  A bit bigger, but sounded a lot better.  Now to bypass all the passive components and see what the MG10QR's are fully capable of sounding like.

[P.I.]

The EA dspNexus 2x8 will be the DSP crossover to replace the passive crossovers and add the servo subs below the 80Hz rolloff of the woofer panels. 

With the nominal crossover will be able to make measurements to see what will improve the response of the system.  Using higher order Linkwitz-Reily crossovers will improve power handling for the drivers and the amps. 

By using the higher order filters, you can pull that mid/tweet fuse and replace it with a short piece of 1/4" copper tubing.  This greatly helps the dynamics of small Maggies.

[HAL]

Dave,
That is a good idea. 

I know my old MGIIB's sound better every few years replacing the fuses and cleaning contacts. 

Rich

[P.I.]

Dave,
That is a good idea. 

I know my old MGIIB's sound better every few years replacing the fuses and cleaning contacts. 

Rich

Polish up that copper tube first.

Yeah.  I'm still me 

[GDHAL]

Dave,
That is a good idea. 

I know my old MGIIB's sound better every few years replacing the fuses and cleaning contacts. 

Rich

Rich, what are you using to clean contacts? I'm attaching a PDF of what is supposedly best, but I cannot order this unless in bulk (i.e. I cannot find it retail).

Thanks.

[HAL]

I use Caig Deoxit for contact cleaning.  There is also Deoxit Gold for those contacts.  Used it for many years and very happy with it.

One or two cans will probably last me a lifetime for contact cleaning.  Easy to find.

[HAL]

Dave,
That is a good idea. 

I know my old MGIIB's sound better every few years replacing the fuses and cleaning contacts. 

Rich

Polish up that copper tube first.

Yeah.  I'm still me 

Dave,
I would expect nothing less!

[P.I.]

Dave,
That is a good idea. 

I know my old MGIIB's sound better every few years replacing the fuses and cleaning contacts. 

Rich

Polish up that copper tube first.

Yeah.  I'm still me 

Dave,
I would expect nothing less!

https://www.mcmaster.com/products/tubing/general-purpose-copper-tubing/?s=copper+tubing

I've used this for lots of things in different diameters.  Good stuff.

General disclaimer:  Bypass fuses at your own risk.  Be smart.  Enjoy the music!

[HAL]

Dave,
Understand.

I will start with the tweeter fuse and see how it goes.  Should be easy to see what it can take. 

More worried about power off transients if I forget to first turn off the amps.  I need a timer startup system like Parasound has in the JC preamp and JC poweramps.  The Starkrimson Ultra DIY 250W modules have 12V triggers for power up/down.  On the list of things to do.  Until then a line strip with a switch.