Category Archives: Amplification

Circuit topology, why less is more

Any quick look under the hood of truly high end audio components immediately reveals their design philosophy:  the highest quality of pure, simple, short signal paths w/o tone controls or other things screwing it up. One look at the above photo of the Nakamichi CA-5A preamplifier (The Nakamichi CA-5A preamplifier) illustrates this completely, and also shows off the build quality.  Witness the isolated transformer, simple high quality components, and exemplary design.  No more, no less…

As for the rest of the components?…  I want them to amplify the signal as accurately as possible and other than that get out of the way of the original integrity of the (minuscule!) analog signal path created by my 103R phono cartridge (The formidable Denon 103 vs. 103R low output moving coil phono cartridges – is there really a difference?…) or the (albeit more robust) signal from my very carefully chosen outboard DAC (Marantz DSD DAC)


Why it’s not about watts per channel (wpc)

missed the link before.  good read.

this is very true, and mentioned by Haley as well:

“much more important to limit higher order harmonic distortion than it is to seek artificially low overall distortion levels.”

that’s why THD tell you nothing.  that, along with WPC, are used to sell amplifiers.  ignore these ratings.  or, if anything, look for a amp with higher THD which means they didn’t use negative feedback or other things to get a low THD thereby screwing up it’s sonic qualities.  and… you now know what to look for in a high current amp, which is something very significant, especially with your speakers!

A very good example of why its not about watts per channel.  This is one of the best sounding amps ever made and only 50 wpc (class a).  Was looking for one of their preamps though.  Always wanted one.  I had Audionics of Oregon, a main competitor at the time but lower cost.

Self Powered Speakers

PurityToIPODwho better to design an amp perfectly to drive their speakers than the speaker manufacture themselves.  i had some self-powered bookshelf speakers back in the day that were simply amazing!  the beauty would be simplicity and cost savings, the down side if if the amp blows or the speaker element blows, you gotta fix it or you loose both your speakers and your amps at the same time.

More on self powered speakers later…

Horizontal bi-amping with non-matching amplifiers

Wiring for horizontal bi-amplification
Wiring for horizontal bi-amplification

Horizontal Passive Bi-Amplification
Horizontal bi-amping allows you to use two different types,
models or brands of amplifiers (i.e. tubes on top, transistor
on the bottom). However, we recommend that you use
two identical amplifiers (i.e. same brand and model).
If you must use two different amplifiers, it is essential that
they have the same gain or that one of the two have adjustable
gain so that you can match their gain characteristics.
If the amplifiers of choice do not have the same gain
characteristics, then a sonic imbalance will occur.

For non-matching amplifiers:

since the loads your adcoms present to the Onkyo are 50K ohm and 100K ohm, which should present a load 33.333K ohm load to your pre-amp, which should be easily driven by it, assuming the output impedance of 470 ohms specified in the manual for your record outputs (rec out) on your Onkyo is also put out on your pre-outs.  It doesn’t specify for the pre-out, so fingers crossed that it’s about the same as your record outs.  the quality of tour interconnect cables and splitters will likely have a great effect on impedance than your mismatched amps.

see this link for how to calculate impudence for dissimilar loads wired in parallel (this is in a perfect world. it’s actually WAY more complicated than that, but this is good enough for what we are up to):


ohms and calculations aside.  think of it in these simple terms…

you will be splitting the signal from your Onkyo L and R front pre outputs and sending it to two amps instead of just one.  so think of it as now “driving” two amps instead of just one.  this puts a far greater load on your pre-amp.  most audiophile quality pre-amps are designed with this in mind.  but AVR receivers with pre-outs as an add-on or even an after-thought…  not so much.  don’t get me wrong, i think your Onkyo will drive your amps just fine.  but we want to do everything we can to make it easier.  this includes:

– high quality splitters
– high quality and as short as possible interconnects (that’s why i like the stubby splitters, why add more cable into the equation if you don’t need to)

to insure against any hum, you will want to place your pre-amp (Onkyo) at least 6” away from your adcoms, preferably on a different shelf.  if you can still get away with 3’ interconnects, that would be best.

More later…

Why bi-amping isn’t always what you may think


Bi-amping used to be the sole providence of high end audio.  I’m therefore suprized that many modern mid-fi speakers have the ability at all.  But, as long as it’s there why not play around with  and see if it makes any difference.  Most modern, higher end 7.1 AVRs also have the ability to utilize the “surround back” speakers to another zone or to bi-amping your front speakers if you like.

That said, we are still talking about a very different version of bi-amping from what i knew it to be in the 1970s, i.e. passive rather than active.  The good news is that passively bi-amping just requires removing jumpers (or “bridging plate”) and hooking up directly to the binding posts on the speakers and let’s the speaker manufacturer decide what happens from there.  Less control, but also less ways to screw it up if the listener doesn’t have knowledge of speaker crossover networks.

Active crossovers (XOs) require some basic knowledge of speaker design, crossover designs, and the limitations of the individual drivers.  I built up a small pair of speakers in the 70s with Kef B110 bass drivers and T27 tweeters.  I was building off a schematic but tweaked the parts of the passive crossover network with better quality than what the manufacturer (they were Rodger’s LS35A’s) provided and they sounded AMAZING and i saved a ton of $$$ by buying the drivers separately and building them myself.  As a side note, those 70s speakers (from the manufacturer, not my home-made version) have become highly collectable and I’ve seen them advertised for up to 10 times their original selling price of $400, which was high  at the time.