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Sanders Preamplifier Review

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A transistor is really just a triode in a solid state. Specifically, its emitter is like a tube’s cathode (heater) in that it is the source of electrons that produce the current through the device. The collector is like a tube’s anode (plate) in that the electrons are gathered there and the current flows out of the transistor from that point. The base is like a triode tube’s grid in that it controls the number of electrons that flow through the transistor.

In a discrete transistor, the junction where all the activity occurs is microscopic. The vast majority of what comprises the visual transistor is just the package that holds the junction. The junction is built on a silicon wafer.

In an IC, transistor junctions are laid down on a silicon wafer, just like in a discrete transistor. The only difference between an IC and a discrete transistor is that an IC usually has many transistor junctions, it has circuit traces that connect those transistors. Additionally the resistors and capacitors that are required for the circuit are also produced on the same chip. As a result, you can have a miniature version of a PCB that contains many components.

There is inherently no difference between a PCB circuit and an IC, as all the same parts and circuit is used. However, the IC will be vastly smaller, usually better designed, and it will be absolutely consistent. As a result, it will generally out-perform discrete circuit designs. And an IC is a whole lot cheaper than building a discrete circuit — especially if that circuit uses tubes.”

One thing to remember is this: All ICs are not created equal. Every manufacturer makes chips for specific applications, though many use the similar circuits and architecture, like differential inputs, cascodes, even folded cascodes, long-tailed-pairs, etc.. Most circuits are direct coupled, so no lossy coupling capacitors. The difference from one chip to another is how they are “tuned” for a specific application.

Some applications like “down hole” applications, which are for the oil and gas industry, require “bullet proof” chipsets. You don’t want to pull one mile of pipe out of the ground because a $1.50 chip burned out. So, the manufacturer compromises some aspects of performance to give much higher reliability. Think of it like this: Ford makes trucks and they make cars. Trucks don’t handle like cars and cars can’t carry as much cargo as a truck. It’s the same thing with chips.

Once you look at premium chip sets from manufacturers like Texas Instruments, you realize that some are not cheap. The truly high performance chips are manufactured to very tight tolerances in clean-room environments. To get very low levels of noise, high gain, and bandwidth up to the gigahertz region, the complimentary transistors on an IC must be as closely matched as possible. This kind of quality costs significant money (ten to twenty times the cost of most “so-so” op-amps). Some of these chipsets cost over $15 each, in orders of 1,000. That means the cost for a few dozen will be significantly higher. Manufacturers have spent billions creating the technology, processes, and manufacturing facilities to make nearly perfect chips. So, chips aren’t created equal. Even the exact same circuit, built by different manufacturers, will give different results. It pays to buy quality parts, even if they are integrated circuits.

One thing Roger didn’t mention is this: If you take ten transistors and pack them on an IC, you are avoiding the inductance of the individual legs, the noise and distortion added when you solder a leg to a circuit board (because solder is a poor conductor compared to copper), just for the signal to be forced down a PCB trace, through another glob of solder, up the leg of another transistor, and into the transistor body. Just imagine you are an electron, trying to jump through all those different materials. It adds up to audible noise and distortion. Miniaturization eliminates losses by directly connecting one transistor to another, all in the same package. The result is lower distortion, higher bandwidth, higher slew rate, and inaudible noise. I’ve seen noise figures of 0.85nV/√(Hz), which is below the noise floor of all but the most extreme test setups, using equipment that costs as much as a modest house.

Find me a discreet circuit with 0.85nV noise figures, large signal bandwidth of 1.2 Gigahertz, and 3rd-order Intermodulation Distortion at -102dB; I don’t think you can. If you go back forty years and look at early op-amps, they don’t compare at all. It’s like comparing a Model T to a Ferrari 458 Italia.

Am I sold on the efficacy of modern integrated circuits? Yes. Just remember that it’s up to the designer to pick the correct chip for the job, and that a great chip can’t make up for other problems in the product. I might add that some of the chips and resistors are made in the US, if I am correct (I might be wrong).

The break-in period of the preamp lasted about a week. Roger and I disagreed about this. He feels that break-in is mostly in my imagination, but electrolytic capacitors do change some during the first few hours. To me, it sounded like the ESR of the capacitors gradually improved during the first three or four days, then stopped changing within the week. After that first week, I heard no further changes in sound. The improvements were a lower noise floor and better micro-dynamics. In other words, details were more obvious after the break-in period. It wasn’t a dramatic change, though.”

5 Responses to Sanders Preamplifier Review


  1. Excellent, I already bought the Sanders amp and have a used pair of Magneplanars 20.1, It took me loans to afford those two, but since nirvana is near I decided to be in debt by making a deposit on the Sanders preamp, the review has made me realized that when all of them will be together I will not be leaving my living room at all for quite some time. I was convinced that tubes will give you pure sound but after listening to the Sanders amp with my unbalanced YBA preamp, I disagree, totally! Thanks!!

  2. phillip holmes says:

    It takes a lot of power to make the Maggies sing, so I’m glad you got the big amp. The Sanders preamp is a commendably neutral piece, with none of the traditional transistor limitations (dark sound, lots of IM, etc..).

  3. Deaghlan says:

    Amp/preamp on early 2016 buy list. Can’t wait!!!

  4. buddyboy says:

    I’ve had a Coda windows 4 pre, for 9 yrs, give or take. No phono. I couldn’t be happier.

  5. Declan S. says:

    Never, have I heard such clarity, and “straight wire design” as this amazing little preamp.
    Crystal clear, clean, does not color anything, it’s just a switching box which sends the signal with out any colorization, or house sound, or masking with added lows, or anything else.

    This is the cleanest preamplifier I have ever used. Took a bit of getting used to, as do all new products.
    I could not be happier, and am looking forward to the power amplifier (Magtech) soon, I hope, I get getting these darn property tax bills which sucks the saved funds for the Magtech.

    I do soon hope to be able to call Roger, and say “IM READY”

    This preamp is simply amazing. This is one of the only preamps I’ve listened to which is colorless and simply sends the signal as it is from the source.
    I love this preamp! It is flawless!
    Thank you Roger!

    Declan.

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