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Lamm M2.2 Monoblock Hybrid (Tube/Solid State) Power Amplifier

Part I

May, 2006

John E. Johnson, Jr.

 

Specifications:

 

● Hybrid Monoblock, Two Gain Stages, Buffer, and Output
    Stage, Triode Tube (6922) in Second Stage; Operates in
    Pure Class A to 41 Watts at 8 Ohms and 20.5 Watts at 4
    Ohms

● Power Output: 220 Watts RMS into 8 Ohms, 440 Watts RMS
    into 4 Ohms

● THD: 0.3%

● MFR: 4 Hz - 155 kHz, +0, - 3 dB

● S/N: 96 dB, 22 Hz - 22 kHz, 41.95 Volts RMS Output

● Sensitivity: 1.076 Volts for 220 Watts Output into 8 Ohms

● Input Impedance: 41 kOhms

● Dimensions: 8.25" H x 17" W x 19.5" D

● Weight: 71 Pounds

● MSRP: $21,090/Pair USA


Lamm Industries

www.lammindustries.com

Introduction

At one CES years ago, I wandered into the Lamm Industries exhibit at the Alexis Park hotel where all the high end audio companies displayed their products.

Lamm had two monoblock power amplifiers on the floor, each rated at  110 watts in pure Class A.

The monoblocks were huge, but, as I said, rated at "only" 110 watts each.

The entire room was shaking from the powerful sound that these amplifiers were producing.

Readers who have heard Lamm amplifiers are probably nodding their heads, "Yup. Been there, done that."

Ever since then, I have always made a point to go by the Lamm exhibits when I attend audio conventions.

I subsequently interviewed Vladimir Lamm at a show in San Francisco. He is a very interesting fellow. From Russia originally, and immigrated to the US a long time ago. He had designed audio equipment there.

After coming to the USA, he, of course, continued to design audio equipment and started Lamm Industries.

Although tubes started disappearing from electronic components in the US decades ago, tubes continued to be a part of the electronics industry in Russia. So, when Lamm came to the US, he incorporated tubes in his designs, and he still does that now. Every preamplifier and power amplifier that Lamm manufactures, has at least one tube in it.

M2.2

The Lamm M2.2 is a monoblock hybrid (mixture of tubes and transistors) power amplifier. It uses one tube (6922 triode) as the second stage. The input stage and output stage are solid state.

Power output is specified at 220 watts RMS into 8 ohms and 440 watts RMS into 4 ohms, but it is also rated into 2 ohms and 1 ohm.

On the rear panel, besides the XLR and RCA input jacks, and two pairs of five-way speaker binding posts, there is a toggle (seen in the photo above the fuse) that lets you select whether you are driving speakers rated at 1 to 6 ohms, or 8 to 16 ohms. The toggle limits the supply voltage and increases the idle current of the output stage when driving low impedance speakers.

You can also see the massive heat sinks. Remember, this is "just" a 220 watt monoblock. So, why all the heat sinks? (There are multi-channel amplifiers on the market with 5 x 200 watts or 7 x 200 watts that have less heat sinks than the M2.2.)

The reason is that the M2.2 is biased at 41 watts Pure Class A when driving 8 ohm speakers, and 21.5 watts Pure Class A with 4 ohm loads.

When an amplifier is biased into Class A, about four to six times that amount is dissipated as heat when at idle. So, the M2.2 puts out about 280 watts in heat, even at idle (no music playing). That can warm the room up pretty good, not to mention make the wheel on your electric meter spin like a Frizbee. Indeed, the heat sinks on the M2.2s get very hot during use.

To bias a power amplifier so high, means a big power supply, so that is why this thing weighs 71 pounds. That is as much as some big receivers that are rated at more than 100 watts per channel x 7. The difference is that the receivers are not biased into Class A (well, maybe a watt or two).

What's the big deal with Class A? Biasing into Class A means that current is flowing in the output stage at all times, enough to deliver the rated amount of watts at Class A. So, with the M2.2 biased to 41 watts of Class A power, the current to the speakers is instantly available, up to 41 watts output. This contrasts with other amplifiers that are not biased into Class A, where the current has to be turned on when it is needed (this is Class B). This slight delay in time between the demand and the actual current becoming available, is the difference, and it results in cleaner sound when the current does not have to be turned on before being delivered.

Now, the difference in sound quality between Class A and Class A/B (such as a receiver that has a watt or two in Class A) is not huge. If it were, consumers would never accept Class A/B products. Class A just gives the aficionado that last bit of audio nirvana. Of course, you have to be willing to pay for it, because those big power supplies are really expensive, especially when they consist of the parts quality you find in a Lamm product.

Click Here to Go to Part II.

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