Planar Speaker Asylum: RE: Tube - Solid State Mags-ML (on topic

Hi Timm -

In my recent Q&A with Roger Sanders He touched upon two subjects which maybe helpful in your search :

My Tube Preamp @ 600oh compatibility with the Magtech Stereo Amp : Quote:

roger@sanderssoundsystems.com
Feb 21

Hi Will,

I designed my amplifiers so that they are compatible with all preamps. Tube preamps often present a problem when driving solid state amplifiers because tubes are inherently high impedance devices. The laws of physics dictate that the impedance of the source (the preamp in this case) must be lower than the load impedance (the amplifier). Ideally, there should be at least a 1:10 ratio between the two, so the amp should have an input resistance that is at least 10x higher than the preamp.

Transistors typically have low impedance while tubes have high impedance. As a result, there is often an impedance mismatch between tube preamps and solid state amps.

To solve this problem, I use FETs (Field Effect Transistors) at the input of my amps. FETs have very high input impedance similar to tubes (about 10 megohm). I stabilize the input impedance with a precision resistor to 100 Kohm. That way, even a very high output impedance tube preamp will have no trouble driving my amp.

I make this high input impedance available through the unbalanced RCA input in my amps. The balanced input has a much lower input impedance of only 1 Kohm, which would be unsuitable for most tube preamps. The balanced input will still work with the 600 ohm output impedance of your ARC preamp, but it is not ideal. You would get much better results using the unbalanced input with its 100 Kohm input impedance.

- Question, Magtech driving my 3.7i and, 2 each DWM :

Hi Will,

Based on the schematic drawings you provided, I would expect that the first configuration would be the best for am amplifier. This is because the impedance will be higher than in the second configuration where you have the two speakers wired in parallel.

Maggie speakers are 4 ohm (actually closer to 3 ohms). When you wire them in parallel, the impedance is halved to slightly less than 2 ohms. That will require a huge amount of current from the amplifier and will stress its output transistors and power supply quite severely.

My Magtech amplifier is able to drive a 2 ohm load. In fact, it can drive a 1/2 ohm load. But it would prefer a higher impedance if that is an option.

In short, you can wire your DWM panels either way. I suggest you try it both ways and see what sounds best to you. If there is no significant difference between the two, I would recommend using the first configuration. But if you like the sound of the second configuration the best, then you can use it as the Magtech will be able to handle the more difficult load this presents.

Great listening,
-Roger

I finally have a system that yes, it's true , I/C choices and Speaker cables do in fact dramatically change the presentation owning to it being neutral rather than warm (which I previously thought I prefered ), starting with the Magtech - Oh the lovely, finer , entertaining details within the arrangements.

Thin sounding - Look to the associated gear or choose wisely down to the wires - I enjoy and could be satisfied with this Aurender A-10 alone as source / pre , and not for once think the system sounds thin without this ARC preamp available .

Planar Speaker Asylum

RE: Tube - Solid State Mags-ML (on topic - LONG)