Amplifiers for dynamic headphones

Here is a rundown of any products I have in stock at any given time.  Given the demands of my day job I do not accept orders ahead of time, I just sell what I’ve built.  This also works better with the more experimental nature of what I do as we are always coming up with new designs and/or changing older ones. Feel free to contact me at if you are interested in any item here.  I will reply to every mail so if you haven’t received a reply within 24 hours then feel free to send me another email.  Email gets lost all the time, it is flagged as spam or something like that.  All prices in US dollars (USD).

Here is something I’ve been working on for a while, the Pure BiPolar or Dynalo Mk2.  The Dynalo circuit has been used in a lot of amps over the years but as parts have been obsolete it was time to finally update it.  The biggest difference is the input stage which is now “super symmetry” as Nelson Pass called it but it means it can take a single ended signal (RCA) and converts it to balanced without any extra circuitry.  That’s why the amp has only one balanced output socket, it is always balanced.  Other changes are higher rail voltages and higher Class A bias for more power.  To power the amplifier modules it has my own version of the ultra stable GRLV (Gold Reference Low Voltage) power supply which is just about the best power supply we can design fed by an oversized transformer.  The end result of this is one of the best dynamic amps we’ve ever designed.  It’s highly transparent and able to cope with even the most demanding loads.

Price: 2100$ plus shipping

This should make some happy, I had some spare boards sitting around and made three new Squarewave amps.  This is a play on an old SinglePower design but with the added benefit of it actually working as it should.  Such a neat feature…  😉  Anyway, these were very well received when I built a batch of them more than a year ago and these are essentially identical except I’ve upgraded a few components as I had ran out of the ones used in the last batch.  It’s a warm and pleasant sounding dynamic amp but with plenty of power for any reasonable load.  Fully discrete design with matched jfet inputs and the rest are all bipolar.  Fully DC coupled as well with a servo on the output to keep it all in check.

Price: 590$ plus shipping

After a lot of requests for an unbalanced dynamic amp I decided to draw up a new version of the classic Dynalo circuit.  This has been my favorite dynamic circuit for well over a decade and today, it’s hard to beat.  It is the basis of the PureBipolar circuit and fully discrete.  Each channel has two pairs of matched complementary Jfet input transistors with bipolar parts for the rest of the way.  This circuit uses the original parts as I managed to find a small stock of them.  Gain is fixed at 7.5 which is a good middle point for most dynamic phones.  The back has a single RCA input with a loop output so the signal can be passed on further down the chain.  Volume attenuation is by a GoldPoint stepped attenuator.

Price:  765$ plus shipping for the stepped attenuator version

Also up for sale is a new version of the Dynalo with the RK27 volume control.  It’s the same as the one above but now the case has been marked on both ends and I’ve switched to the new LSK489/LSJ689 input fets.  Otherwise it is identical.

Price: 655$ plus shipping


Page updated 28.12.2017