Planar Speaker Asylum Welcome! Need support, you got it. Or share your ideas and experiences.

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Planar Speaker Asylum ]

---

[ Alert Moderator ]

---

My Magnepan 1.6QR DIY Upgrade II: Going Active!!

Posted by dumpingground (A) on January 30, 2012 at 09:46:57

Let me start with an acknowledgement---
This post would not have been possible without the enormous help from neolith:
http://db.audioasylum.com/mhtml/m.html?forum=mug&n=176456

Interested readers can view my Previous effort to update the passive crossover on my 1.6 with updated components:
http://db.audioasylum.com/mhtml/m.html?forum=mug&n=171078

I had been using 2 Parasound HCA-1000A power amps to biamp my magnepan speakers with my external crossover. Biamping with a passive crossover between the amps and the speakers is helpful but does not fully realize the potential of active biamping.

With the preliminaries out of the way, I would like to post my current progress in going Active! By that I mean, I have bypassed completely the internal as well as my updated passive crossover for my Magnepan 1.6QR speakers. I have the following setup:

Onkyo TX-SR707 Preouts -> minidsp 2x4 unbalanced -> 2 x Parasound HCA-1000A power amps -> Magnepan 1.6QR high and low panel speaker tabs.

This setup allows me to actively biamp with an active crossover my maggie speakers. The power amps are directly connected to the maggie panels allowing the amps to directly control and power the panels for maximum sound quality. The active crossover splits the high and low frequencies before the power amps so that the amps only see and amplify the signal going to each (low or high) panel. A much more efficient and potentially distortion free (for amp head room, etc) setup. Specifically, in my setup the Parasound amps are known as a "high bias Class A/AB amp". So if I can keep the load down especially on the high panel driving amp, I can operate these in Class A which is said to be better especially in the highs.

You can read about the neat little and relatively in expensive $145 minidsp here:
http://www.minidsp.com
I am also using the minidsp 2-way Advanced Crossover plugin.

In this initial post I will mainly speak to the configuration and initial listening tests.

After the upgrade I used the speaker calibration signal (pink/white noise) from my onkyo to level set the high and low panels by disconnecting the high panel and measuring the low and then repeating for the low panel on the magnepan to match the signal levels from before the update with the passive crossover.

My initial listening notes are as follows. The sound from going active was of course greatly improved! Specifically, the bass was much more refined and exact, by that I mean you could hear not only the start of the bass note but the end as well with very good sharp definition. The highs sounded much more detailed and 3D-like to me. There seemed to be a richness to the sound especially on vocals that was greatly improved.

Based on Neolith's previously acknowledged help, I was able to setup the minidsp crossover slopes and filters. See the attached screen shots for my config. Screen shots are for only one speaker, but the second front speaker is the same of course.

minidsp main screen:

minidsp crossover settings screen showing the HP and LP settings:

LP LR 12db/oct @ 400hz
HP BW 6db/oct @ 1475hz

minidsp delay/gain output screen:
After the going active, the high panel was about 2dB too hot as measured by a radio shack sound pressure meter. So I adjusted the high panel output gain down -2 on the minidsp controls for the channels going to the high panels. (hard to see in the channel 1 screen shot below)

I do have a measurement mic and REW software. So in the future I will take some frequency measurements of the setup with the passive crossover and compare it to the active configuration.

Also, note that I left the polarity of the high panel wiring the same as it was with the passive crossover, which is inverted I believe from the low panel. With the minidsp software it is easy to in realtime invert the polarity of the signal going to the high and low panel as well as to adjust the time alignment of the panels with respect to each other.

This post is made possible by the generous support of people like you and our sponsors:

Schiit Audio

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---