LH Labs S100 and M200 class a ss speaker amps

new pics just came out. 100 watt class a monoblocks, 50 watt class a stereo amp. Thought I'd create a thread since I'm down for a stereo amp and they are supposed to ship jan 31st..

 

Good looking heatsinks - looking forward to impressions. Any shots of the rear hookup available yet, or just promo shots?

 

Just drawn diagrams on the preorder page. Stereo amp has rca in, monoblocks have both rca and xlr in

 

Candide, ou l'Optimisme

More updates and pictures available here: https://www.indiegogo.com/projects/pulse-analog-audio-components-pre-order-headphones#/updates

 

Wow thanks Grahad I didn't notice the update, I ordered on lh labs web site instead of the indiegogo

 

I believe it's a mix of A and AB than pure A. There's a wee bit of marketing speak:

 

I think it's a form of dynamic bias but it's always kept in class a. Maybe someone smarter than me can say

 

It *sounds like* a form of class G/H rail manipulation, but that's a blind guess based on the single blurb.

 

I'll be slightly annoyed if it ends up being class AB. I'm fairly sure it uses a system like krell's ibias to track output and it dynamically sets the bias to keep it from crossing over to ab but being no higher than needed.. so there's less heat. I don't really know how bias works but this is how I imagine it

 

Given the size of the heatsinks, if they're pure Class A, with 50+50 continuous output on the lowest model, that's >100W of heat dissipation (assuming maximum theoretical efficiencies of 50%, actual efficiencies are like <35%), yeaaah I highly doubt that.

 

I feel like you guys are not even reading my descriptions of their bias system the output transistors don't need to constantly output full power for it to stay in class A, as I understand it
edit: bah, I'm probably wrong. I asked them to clarify this months ago on their forum but they never did

 

I don't see where they ever use the term "Class A" without a qualifier: Multi-Zone Class A (MCA).

Or this statement which says Class A without really saying that the amp is Class A: "It's a classic with typical class-A amp feel."

I think I see what you are saying, @uncola , like when it says "M200 will include 3 level MCA (Multi-Zone Class A) amplification to efficiently amplify to your listening level." it seems like the intended impression is that it goes from one level of Class A to another level of Class A to a third level of Class A. (That would be something new.)

When a company comes up with their own term, in this case "MCA (Multi-Zone Class A)", the Class A part does not have to be used literally.

Could be a great amplifier, regardless.

 

Nope. That sounds pretty much like a Class-G amp which has been around a while.
Google even found me a nice article talking about class G headphone amps: http://www.ti.com/lit/an/snaa128/snaa128.pdf

 

(As a form of TL;DR: )
What Class G does, is reduce nominal power usage when playing back music, because of the dynamic range of music enabling the usage of lower voltage rails when output is low, and switching over to the higher rails when there is a large swing in input voltage such that the output transistor, given the LOW voltage rails, will clip. Lower voltage levels cause less heat dissipation than higher voltages, saving power.

Given multi zone class A descriptions, it does sound likely that something similar is used to save power with normal music loads.

Larry Ho is a believer of First Watt principles (can't quite remember where I read it, somewhere in the LHLabs forums about the amps I believe), so I won't be surprised if they act like emotiva amps such that the first XX W is pure class A, but switch over when the heat dissipation becomes an issue.

At continuous output levels I'm not sure how much heat class G topology will save wrt normal class A, since the 50% maximum is well, maximum. I'd be surprised if LHLabs managed to pull it off with purely passive cooling.

 

I learnt something new. Thanks @Armaegis

@Grahad He mentions "I agree with Nelson. First watt is the most important. ;-)" here.

 

And then Class H is just an extension of Class G, where instead of multiple rails you have a variable one and ideally track the rails just ahead/above the music.

 

so these turned out to use multiple lm3886 chipamp chips not what I wanted at all. cancelled order.

 

Glad that you found out that this was not what you wanted and was able to cancel, @uncola .