Archive for the ‘RW Audio’ Category

Amp1 v2.0

Amp1 was my first production headphone amplifier, in “upgrade” form it was highly regarded from audiophile customers, headphone newbies and even where it received an award.

Blue Moon Award

Enter Amp1 v2.0, what’s new?  Everything inside!  What’s the same?  Everything on the outside.  While working on designs for Amp8S and Amp4 I found that some of these new concepts and components could be scaled back slightly and fit in Amp1.  This all started when testing the IEM output of Amp8S which will have a dedicated IEM signal path for very low noise and appropriate gain so the volume control is actually usable.  This was the basis of Amp4 which took the basic topology added buffers for higher current output.  However with a less expensive buffer and only 2 channels (vs 4 in the balanced configuration of Amp4) it would fit both the physical size requirements and the price point of a revised Amp1.  This began as a few tweaks to the Amp1 design incorporating parts of the power supply from Amp8S and Amp4, along with the buffers and gain topology.  The further I went the less and less remained of the original design, and it finally hit a point where I started with a clean slate and only the input connectors, output connectors and volume potentiometer remained in the same location.  Everything else is new, the power supply is vastly improved because it was designed for IEM use in Amp8S, with an ultra low noise floor.  The output buffers have been optimised and stand alone vs being inside the negative feedback loop of the main gain stage.  This non feedback design has resulted in a much more open and natural sound while maintaining excellent measured performance by optimising the buffer circuitry independently.  The amp has socketed op-amps, however at this point I don’t recommend changing the buffers.  The amp won’t initially be available as a kit because I had to move to mostly surface mount parts.  The length of the signal path in the original Amp1 was a longer than ideal, because of this Amp1 v2.0 has been optimized for performance using mainly 0805 smd components.  Not crazy small like 0402’s or 0201’s but not the most friendly for someone new to smd soldering.  Of course reflow soldering is also a much better way to do smd and is the method I will be using to produce Amp1 v2.0.  If I can find a cost effective solder paste stencil I may release it as a kit including solder paste and the solder paste stencil.

thumb_i (1) thumb_i


Of course I think it sounds better, but it’s not just “better” it’s been improved on all levels.  The power supply is drastically better, the core topology is better, output current is higher,  output impedance is lower, the noise floor is much lower, detail and resolution are on a whole new level, the soundstage and instrument placement is wider and more stable.  Once I’m happy with the first prototypes they will go out to a few reviewers and I will start small scale production.  Introductory pricing will be $199US which is only $4 more than Amp1 Upgrade with a significant improvement in performance.  After the introductory period the price will be $229US.


Amp1 v2.0 will be available mid 2014.

RW blog

Welcome to the RW blog, over the past couple of years much of my time has been spent working on an electric car conversion project that brought together two of my biggest interests.  Cars and electronics have been a big part of my life for the past couple of decades, my electric car conversion dubbed 944HV is based on a 1986 Porsche 944 but has been relieved of it’s engine and all related components.  A large electric motor, controller and batteries have taken their place and serve as the propulsion system for the car.  This conversion provided a performance INCREASE and makes the car an even bigger pleasure to drive.

Water cooling3


This has been a very rewarding experience and I have learned a great deal this project.  Some of what I learned can be directly put into RW Audio, related to hardware and electrical design.  When building an electric car you learn a lot about batteries, they are the core of any electric car and can make or break a successful conversion.  A couple of years ago I had designed a NiMH battery pack for Amp1, it was very simple and effective, however after an upgrade to the AC power supply that I am currently providing with Amp1 the performance margin vanished and the only benefit to the battery system was portable or off grid use.  As anyone will quickly learn in an Electric Vehicle (EV) conversion is that Lithium Ion (Li-Ion) is the only battery type that makes a real car.  Lead acid, NiMH, Ni-CAD, can all be used, but the difference between these and Li-Ion is very significant in performance, weight, life span and practicality.  What does this have to do with headphone amplifiers?  Good quality low impedance Li-Ion cells make a very good low noise power supply for headphone amplifiers.  Part of the reason Portable1 sounds better than Amp1 is because of the Lithium battery, they share a similar core design however one of the significant improvements in Portable1 is the power supply.

I’m currently working on a Lithium Ion (Li-Battery) to power Amp1 and/or any other low power equipment that will operate on a 12-16.8v battery.  I’ve been testing this battery system on the bench with a balanced pair of Amp1 Upgrades.  The performance is clean, smooth and natural.  The battery will be configured to power one or two Amp1 headphone amplifiers.   Battery life is roughly 100 hours for a single Amp1 or about 60 hours for a pair.


The voltage display shown sitting on top will be mounted front and center and act as the power “on” LED as well as voltage indication.  Internal circuitry will turn off the battery when it is empty to eliminate the chance of over-discharge.  One of the other things I found while converting the 944 is the overwhelming theme that simple is better.  When I started to look at the practicality of a Lithium battery to power Amp1 I also had to look at the charger.  I designed a somewhat complicated 2 cell charging and monitoring system for Portable1 that both charges the battery and keeps it in the safe voltage range.  The battery for Amp1 is a 4 cell unit making the charger more complicated and costly, this starts to detract from the Value that all RW Audio products provide.  The solution is to piggyback on an industry that has the economy of scale to create an inexpensive reliable Lithium battery charger.  A small 4S RC charger designed for planes, helicopters and cars fits the bill nicely at a price point I couldn’t hope to replicate.  For this reason by default the battery will not include the charger, but I will provide the option for a cost effective version for those that don’t already have a small RC charger.  The battery itself will have built in protection circuitry to prevent over-discharge and the front voltage display will cover the indication for power and when it’s time to recharge.


I like this system because it will provide a significant performance increase at a price that compliments the value I strive for in all of my products.

Early on I created a blog for my 944 conversion to document and share the progress I was making on the car.  I really like this format and the type of information that can be shared without a complete website redesign or waiting for a complete and polished product before sharing it with others.  This blog will contain my idea’s, things I’m playing with on the bench and the direction and development of new products.  If you haven’t already noticed RW Audio bares little resemblance to other audio companies.  I don’t release new products to align with CES, I don’t market my products to people who don’t need them.  If you find my amp and feel it’s the best amp for your dollar I’m proud to share my hard work with you.  I’m not going to get rich doing this, I have a day job that pays the bills, however this is what I love to do.  I love meeting new people and sharing my love for audio with others.  The feedback from a customer who has never heard his or her headphones sound so good is what I strive to accomplish.  Success is not measured in the number of sales I make, it is in the enjoyment that a customer gets from their music library.

I’m not sure how often this blog will get updated, but check back and see what’s new.  The comments section will be open but tightly monitored, the spam that a blog attracts is unbelievable.

Happy New Year to all and I look forward to making progress on some new ideas in 2013!

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