Tubes and less sensitive speakers


I love the sound of tube amps but I use Maggie 3.7's.  I have tried  an 45 watt tube amp  and while I loved the clarity of midrange, I missed the low end slam, even with a sub.  Is there a tube amp out there that matches well with Magnepans?  I am using the Hegel H360 and a friend recommended Coda high current amps but I still am thinking tubes.

boxcarman

Showing 2 responses by bdp24

 

Regarding the poet by @blisshifi: Mating subs with Maggies (in fact any and all dipole loudspeakers) is indeed a challenge. The solution is a dipole subwoofer, which Magnepan has been working on a for a few years now.

There is already a real good one available, the Rythmik Audio/GR Research Open Baffle Servo-Feedback Subwoofer. It employs two or three (your choice) 12" servo-feedback-controlled 12" woofers in an open baffle frame, and works splendidly with dipole loudspeakers. Check the GR Research website for details.

 

 

One thing to consider is installing a high pass filter on the input jacks of the power amp (inside the amp)---or in a little box containing the filter plugged into the input jacks (as the video below will explain)---feeding the Maggies, to remove low bass frequencies from entering the amp and therefore the Maggies. The "corner" frequency of the filter is determined by the value of the capacitor used and the input impedance of the amp. There are formulas available on the internet for determining the cap value required for different amplifier input frequencies and the desired x/o frequency. Removing the low bass from the input signal to the amp will significantly decrease the power required to run the Maggies, and improve the sound of the amp and speakers as well (decreased power amp distortion produced, less excursion of the Maggie Mylar diaphragms). Removing the bottom octave (20-40 Hz) cuts the amplifier power required in half!

One amp to consider is the no-longer-in production Music Reference RM-200 MK.2 (review by Michael Fremer and John Atkinson available for reading on the Stereophile website), available used for around $2500 (one just sold at that price yesterday on USAM). The RM-200 was designed specifically to work well with low impedance loudspeakers, and puts out 125 watts into 4 and 8 ohm loads (the amp also includes 2 ohm and 1 ohm taps!). It uses only a single pair of KT88 (or 6550) tubes to produce those 125 watts, yet the tubes last around 10,000 hours.

Then add a pair of subwoofers to reproduce the low bass. Planar devotees have employed this tactic for decades, all the way back to the QUAD ESL of the 1950’s. I’ll post below a video Danny Richie of GR Research made on the subject of high pass filtering loudspeakers and adding subs:

 

https://youtu.be/65eFr2rKy3M?si=rftln4L2ryHM_yvf