ML Quest Z Speakers, amplifier build for these

william86

Member
2018-05-01 8:41 pm
Hello, I am new to the forum, I have been looking at building and amplifier for a while for my Martin Logan Quest Z. These are power hungry and drop below 2 ohms while playing. Looking for a decent amplifier Class A, Class A/AB to run these bad boys while playing. Looking for 400 watts.

I have basic electrical knowledge and can source the component for the build. I just need to be pushed in the right direction on the PCB or type of amp to build.

Thanks and look forward to some help.
 
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Hello, I am new to the forum, I have been looking at building and amplifier for a while for my Martin Logan Quest Z. These are power hungry and drop below 2 ohms while playing. Looking for a decent amplifier Class A, Class A/AB to run these bad boys while playing. Looking for 400 watts.

I have basic electrical knowledge and can source the component for the build. I just need to be pushed in the right direction on the PCB or type of amp to build.

Thanks and look forward to some help.

No guarantees, because I haven't looked them up yet... but the ICE modules now available from Parts Express might turn the trick for you.

ICEpower - Intelligent, Compact & Efficient Sound Made Powerful
 
...Martin Logan Quest Z. These are power hungry and drop below 2 ohms

Mlqfig01.jpg


While the low impedance is something you need to design for, the hugrly caacitive load is a much harder issue to deal with. Being able to supply sufficient power — power = V x A x cos (phase angle). That last term (about 45°) gets to 0.7 at the worst phase angles. As it approaches closer to 90° that number approaches zero —which it might well do under dynamic conditions.

From my experience with Dayton Wright XG8 being able to drive the capacitive load 8s much more important to deal with.

The best amp (of the day) that we ever used XG8 (including a stacked pair in parallel) was the 70w NAIM 250. Much higher rated bryston, dynacos, marntz, ampzillla, Phase Linear fell flat on their face.

Now, amplifiers are much better these days, but do look to the right goals. Huge power is not the 1st measure you need to look for.

dave
 

william86

Member
2018-05-01 8:41 pm
Mlqfig01.jpg


While the low impedance is something you need to design for, the hugrly caacitive load is a much harder issue to deal with. Being able to supply sufficient power — power = V x A x cos (phase angle). That last term (about 45°) gets to 0.7 at the worst phase angles. As it approaches closer to 90° that number approaches zero —which it might well do under dynamic conditions.

From my experience with Dayton Wright XG8 being able to drive the capacitive load 8s much more important to deal with.

I did not even think about the 8's when looking at an amp for these, i will need to look into this further as this is a valid point. Thanks for the input. I know that i can drive in low volume no problem, but was thinking it was the low ohms on the drive that was causing the protect circuit on the amps to enable. I am thinking it is the high ohms causing it now.
 
Ah, its highly capacitive at the high end. Hmmm, that's interesting - highly reactive loads like this are typically what triggers secondary breakdown in output transistors, so I'd be inclined to say go for lots of output devices in parallel or something using lateral MOSFETs (no secondary breakdown).

However in practice theres seldom much power at those high frequencies so it may be less difficult than it looks (anything that loud in the top octave is going to damage your ears!!).
 
Hi,

I agree with Planet10. A amp for ESLs doesn't require that much wattage but utter stability into complex loads. MLs panels have always been quite efficient ... 20-50W should suffice .... if stable.
As for amp modules I've made excellent experiences with LJM's L12-2 (at ebay from china, look for originals!).
The performance of these modules into non-segmented ESL panels is absolutely fantastic even when not considering their almost ridiculously low price tag.
Regarding class D I can't recommend them for ESL purposes.
The output inductance resonates with the panels capacitance.
If it's a design with the inductance not included into the feedback loop this resonance peaks at hf and can reach more than +10dB.
If the resonance is tamed they drive ESLs extremely stable .... but sonic performance hasn't convinced me yet .... quite impressive with rock and pop as they have a firm grip on the panel, but sucking blood and life from music, sounding anaemic on classics.
Class D has merits for subwoofers only imho.

jauu
Calvin