Lab.Gruppen E 4:2 Pro Amplifier Review

[pozz]

I’d be happy to send one...but is it relevant? These are definitely designed for high performance installations!

Definitely. Good to know how all types peform.

 

[pauldavidthomas]

I've bought a few Lab Gruppen E4:2's for Atmos height duties initially. I can't hear any difference between them and either a Denon X3600h or Crown XLS 1502 or XLS 1002's. I've also tried them driving a centre channel MK Sound MP150's - work perfectly. The fan is a bit loud, swapped out for a Noctua fan. Set the attenuation on them right and also the on-level - you can make them so they will measure your Processor's idle level and will then power the channel up when 6db above that. So, no hiss from my Sensitive MK Sound 4 Ohm speakers or JBL 3677's.

You always find a lot of peoples 'opinions' without actually trying stuff for themselves. Go on, don't follow the crowd, use your ears and if you can't hear a difference, don't spend the crazy money on, let's say other class D amps. I'm currently paying about £120 a pop on these amps in the UK.

 

[Zinda]

This is a review and detailed measurements of the Lab.Gruppen E 4:2 "touring" pro amplifier. It was kindly sent to me by a member. The E42 costs US $899. If you don't know about the originally Swedish company they have been a fixture in pro amplification for many years. It has changed hands a few times and is now part of the same group as Behringer.

The E42 comes in a "1U" rackmount chassis:

View attachment 69945​

There are no VU meters as we see in competitor's amps with larger footprint. There is useful indicators for current limit and protection however.

The rear shows the connections which while typical in pro world, are foreign to consumer electronics:

View attachment 69946

The phoenix connectors are used for both inputs and outputs. They are large and easy to terminate but obviously need custom cabling.

There is variable gain. I set it to max which produced a gain of 27 dB, approximating the nominal 29 dB which is common with consumer amps.

There is an odd Lo-z and 70 volt switch. It is common to have 70 volt mode (for long speaker runs) but not the way it is implemented here:

View attachment 69948

As you see, for 8 ohm you are supposed to use the 70 volt mode even though that label has nothing to do with such loading.

For 4 ohm, you have to use Lo-Z which is what I used for most of my testing. As you shall see, this proved to be quite problematic.

In general, I am not fond of a product that requires the owner to bend to its needs. I mean this is not a tube amp. WHy does it have a switch setting for the load impedance? Speakers don't have constant impedance anyway so in reality there is no good way to know what setting to use.

The 1U chassis mandates tiny fans which are almost always very noisy and that is the case here. While I have heard much louder, this is still something that is not acceptable in a standard home audio system unless you can place the amp in a different room.

The design here is Class-D amplification by the way and hence the ability to squeeze it all in this small enclosure.

Amplifier Audio Measurements
As usual, we feed the amp a 1 kHz tone and ask it to produce 5 watts into a 4 ohm load to represent low level music listening:

View attachment 69950

We see pretty high harmonic distortion at multiples of our 1 kHz tone (2, 3, 4, etc. kHz). SINAD which is a sum of distortion+noise then is dominated by high distortion giving the E42 an average rating amount nearly 100 amplifiers tested so far:

View attachment 69951

Signal to noise ratio is "OK at 5 watts:
View attachment 69953

But not that great at full power. Spec is a whopping 112 dB.

Frequency response shows some load dependency due to necessary output filter in class D amplifiers to attenuate switching noise:
View attachment 69954

I am using simple resistive load and still getting some peaking. A real speaker with its more complex impedance may cause other frequency response variations.

32-tone test signal resembling "music" shows the same distortion profile we have already seen:
View attachment 69955

So far the measurements aren't that bad and fit the level of performance pro amps usually target so you may be wondering why it got the headless panther rating. This is why:

View attachment 69956

I am only getting 85 watts with both channels driven versus 200! This is in Lo-z mode as instructed. The limiter kicks in and stops the amp from producing more power (reason the graph seems to go backward). Maybe the amp is designed to only allow for peak excursions? I tried running my tests to find that peak but could not because the limiter would keep kicking in, confusing the analyzer.

Switching to 70 volt input and 8 ohm gets us the specified power:

View attachment 69957

So seems like the amp does not like low impedance of 4 ohm even though it is well within its spec.

Testing frequency sensitivity we get a very complex set of graphs as we change that factor and run the above sweep:

View attachment 69958

Class-D amplifiers have very complex distortion profiles as the circuit is not a simple analog amplifier. So this is not unusual for the type.

One shining performance aspect was crosstalk:

View attachment 69959

This is near state of the art!

Finally, here is our very wide band spectrum analysis:

View attachment 69960

We see the switching frequency of around 370 KHz peaking to nearly -10 dB. I like to see at least 20 dB of attenuation here.

Conclusions
Lab Gruppen is a trusted brand in pro amplifier industry. As such, I am surprised by the results I achieved here. Company is proud of the limiting circuit in this amp for reasons that I don't understand from their writing. Whatever it is, it appears to be more designed to keep the amplifier from getting damaged (a real concern in live sound) than being performant. Combined with the fan noise and quite high price for such modest power level, it is really not a fit for home use.

Needless to say, I can't recommend the Lab.Gruppen E 4:2 amplifier.

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As always, questions, comments, recommendations, etc. are welcome.

One of my pink panthers is getting frustrated with the state of the country and wants to run for a political office!!! Naturally he is looking to me to provide seed capital for his campaign. Heaven knows what little money I have won't be used to plaster signs on people's laws and power poles! But maybe you can make his desires come through by donating using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

I had the C8.10x commercial amp that they claimed to be a 2000 wattt 8 channel anp rated at 250 wpc* but it only drew 600W of power? That's like 62Wpc. Everything the make is rated in MAX watts. I traded it and other amps for a working song AVR. I got a working Niles 12 x 30wpc amp, a non-working Sony ES amp (every ES Sony piece I've ever seen was broken) a partially working LB Gruppen that had 2 channels that would fail the start check sequence. I took a look and found 2 burnt fuses mounted inside that other 6 were good i replaced those 2 fuses and still had nothing connected to it just trying to turn it on and see all channels pass the start up. The next time I powered it on it started the test and shut down and never started again.. it burnt its own self test check circuit! An area on the main board in the front of the unit (not in the amplifying section) had burnt copper traces and each component along the route burnt, everything is tiny DSM type crap, it took out what was supposed to be saving the amp from self destruction but it wasn't even worth fixing in my eyes, I can't use a 62wpc amp. That amp sold for nearly $4k back in 2017 and I couldnt figure out who would ever consider it? It to has that same useless 70v and 100v system with 20 DIP switches on the back and each switch had 3 or 4 settings. They actually have a class you can take to learn how to use it, it's no joke, they have certification courses set up for those who want to do lab gruppen pro installs. It's the same for some other junk I got over the years called BiAmp. I got the DSP unit and there again, no instructions available. Only on line courses to get certified. I finally was able to log on it and see what it did through a custom serial to lan cable after reading for days on how to gain access to the pieces last password used when it was shut down in case they didn't rest the pasword. All in DOS like commands with Internet addresses input. It will act as several different EQs, crossover, as many points you want, amp or multiple channels, but you had bays I'm the rear for each thing you want to use. It might only be an empty shell with a motherboard and bays for $4k. Mine has a few amps (10 or 20wpc) but trying to set it up using their impossible system was too much for me to put up with. I got to where I could start my custom set up in block chain mode on my computer with it showing input, dual 31band eq and a 3 way crossover but I couldn't connect the block chain to the amps. I didn't know what devices I had to list to get it done and after a week I was done with it. Just like you said, I hate it when companies try to make me relearn using a simple piece of audio gear making it so complex that you have to start a career in learning plus getting certification to go to the next component. I don't see how they can get installers to spend that much time to learn a 1 off type system that will just be changed to be more user friendly by another company in the near future.

There's really nothing that complex about setting up a system but when it's tied into a complete network of business phones and conference rooms, that's when you realize that this is not really ment for Audio hobbyists or even pro audio use. These are nothing more than fancy phone audio parts that have nothing in common with home or pro audio even when they make it seem like it has that exact purpose in mind. They hide the fact that these are phone line parts until you finally can find anything in print (and they will make sure it's not available) or pay to take their courses just to find out what you have isn't worth the trouble since it's never going to provide full range excellence but rather top of the line phone and conference audio. The 250wpc rating is explained as a max setting in a very professional way as they talk of slew rates and increased voltage swings that demand peaks of 4 times the steady current voltages. (BiAmps largest amp output was only 150wpc when I checked years ago, that was a 2U model that was priced similar to this one.) But nothing they say adds up to anything more than the power it draws from the mains, simply because that's what defines it's power output, you never put out more watts than you draw, I had to let a few manufacturers know this over time. Lab Gruppern is only selling to people who don't look at or actually use these products themselves, just the big companies that need things like fancy phone lines and run huge corporations and they just pay whatever lab gruppen says it will cost and they remind them that they'll need to have a guy training for certifications before they can even use it. Like a permanent phone "IT" guy on site.