How does Active Martin Logans balance Active Low Frequency section and ELS panel?

[Pars]

Dear All, I am a user of ML Vantage speakers recently. I am wondering any one has an idea how ML processes speaker input? They do not accept Sub Pre-Out so they use speaker input. Which means you input already amplified signal to amplify again, which should increase the distorsion, No? Another thing is, we all know that Panels are very fast, and bass is slow... how does ML balances the speed difference? You can not speed up the bass, can only slow down the panel, right? Then there is bi-wire option, which makes things more complicated. If I use single wire, shall I connect the wires to Low Frequency binding posts rather than ESL side so save some speed? or am I thinking too much? I believe Active Martin Logans do process both signals and delivers them through process to balance the speed? Anyone?

 

[Tosh]

ALL bass is slow, so active bass is fast enough. But passive bass is just mangled out of control....

 

[Pars]

ALL bass is slow, so active bass is fast enough. But passive bass is just mangled out of control....

Thanks for your reply, I accept that ALL bass is slow... but amplifying once again should make it even slower, creating a lag because ESL is direct from the amp, and low frequency goes through internal amp. I believe there must be a system inside to cover that.. but anyways.. it shounds seamless so maybe I should stop questioning and enjoy

 

[Leporello]

I've always believed feeding an active woofer an already amplified to speaker level signal is sub-optimal. You are absolutely right. No matter how vanishingly low the distortion of your main power amp, your are further cascading it with the woofer driver and its distortion. Some audio gurus say this is the way to go, since you want the characteristics of your main amp matched to the woofer. I say this is nonsense. The advantage, though, is that the balance between the woofer and panel is baked in by the engineers so you don't have to worry your pretty little head over it.

As for the bass "speed", you are asking the wrong questions. Yes, a low frequency signal has a low rate of change. There is no such thing as a "fast" woofer. What you really want is a woofer free from peaks and "hangover". An ESL panel is highly damped by the air, so hangover is practically nonexistent. When paired with an underdamped woofer, it is perceived as poor panel/woofer integration. Martin Logan has come a really long way with their hybrid systems in that regard. I was listening to Ascents (not "i") for a few years and the woofer that came with it I considered mediocre at best. The newer active woofers allow negative feedback from the woofer itself. If the woofer cone can start and stop on a dime, which this "servo" arrangement enables, I suppose you could call that "fast". To some extent, you even get some feedback correction from the room.

Regarding further throughput delay through the woofer amplifier after already being delayed by the main amp: technically yes, but throughput delay of an audio amplifier is inconsequential. A signal could go through the amps a hundred times in the time either the woofer cone or panel is supposed to think about starting to move.

Unless you are up to doing some design work--at the very least figuring out how to match the levels-- I would stick with what you have. It is good enough for all practical purposes. The folks here discussing active woofers are mostly talking about converting from passive. You already have 99.9% of the advantage of an active woofer. The guys home-brewing active crossover (often with a favorite Crown amp featuring built-in crossover) are not getting servo control.

In looking up the Vantage on the ML Web site (they have produced quite a few models over the years) I was shocked to see that when I landed on the home page there was not an ESL in sight! This is a recent development. It was not so when rumors of ML phasing out ESL's was first a thread topic. Who knows?

 

[Pars]

I've always believed feeding an active woofer an already amplified to speaker level signal is sub-optimal. You are absolutely right. No matter how vanishingly low the distortion of your main power amp, your are further cascading it with the woofer driver and its distortion. Some audio gurus say this is the way to go, since you want the characteristics of your main amp matched to the woofer. I say this is nonsense. The advantage, though, is that the balance between the woofer and panel is baked in by the engineers so you don't have to worry your pretty little head over it.

As for the bass "speed", you are asking the wrong questions. Yes, a low frequency signal has a low rate of change. There is no such thing as a "fast" woofer. What you really want is a woofer free from peaks and "hangover". An ESL panel is highly damped by the air, so hangover is practically nonexistent. When paired with an underdamped woofer, it is perceived as poor panel/woofer integration. Martin Logan has come a really long way with their hybrid systems in that regard. I was listening to Ascents (not "i") for a few years and the woofer that came with it I considered mediocre at best. The newer active woofers allow negative feedback from the woofer itself. If the woofer cone can start and stop on a dime, which this "servo" arrangement enables, I suppose you could call that "fast". To some extent, you even get some feedback correction from the room.

Regarding further throughput delay through the woofer amplifier after already being delayed by the main amp: technically yes, but throughput delay of an audio amplifier is inconsequential. A signal could go through the amps a hundred times in the time either the woofer cone or panel is supposed to think about starting to move.

Unless you are up to doing some design work--at the very least figuring out how to match the levels-- I would stick with what you have. It is good enough for all practical purposes. The folks here discussing active woofers are mostly talking about converting from passive. You already have 99.9% of the advantage of an active woofer. The guys home-brewing active crossover (often with a favorite Crown amp featuring built-in crossover) are not getting servo control.

In looking up the Vantage on the ML Web site (they have produced quite a few models over the years) I was shocked to see that when I landed on the home page there was not an ESL in sight! This is a recent development. It was not so when rumors of ML phasing out ESL's was first a thread topic. Who knows?

Thanks a lot for your time to explain .... I also read that Servo arrangement is available with new ML actives, probably not with my Vantages but .. godd to know. I believe this is similar to Motional Feedback Woofers once used by Philips (545 MFB) and Sony (SA-S1 Hybrid). Then this is great if I understand it correctly. Hope Vantage had it too.

 

[Fidji99]

Re Distortion - lower in FR you go, less sensitive we are to distortion, in lowest frequencies THD below 10% is consider unaudible (search for some subwoofer test e.g. on audioholics or on erin’ s page. So any distortion added by amp will be magnitudes lower than combination of driver distortion and room modes.

On the other hand - active amp for woofers takes a lot of burden out of your main amp, so it has enough current to drive panels, thus it will play cleaner in the range where it is really important. This why you can drive active ESL with relatively modest amps, unlike old beast e.g. Prodigies.

 

[jtucker]

So far as i know, no ML ESLs use servo controlled woofers. The more recent speakers, stating with Montis, use DSP to control the phase response of the woofer(s) to match closely with the phase response of the panels around the crossover point. This results in smooth integration between panel and bass section.