Category Archives: General

A positive review from an audio journalist, and the end of ATRAD Audio

First up – the review. 
Around Feb 2019 I was contacted by Richard Varey, from Witchdoctor magazine – about supplying an amplifier for review. He’d see the old ATRAD-Audio website and wanted to know more.

So I built an amp for him – a Matariki EL84 integrated – making some improvements on the original prototype (which remains as my Daily Driver)
I sent the amp and he did a review: https://witchdoctor.co.nz/index.php/2019/08/atrad-audio-matariki-valve-amplifier-review/

During the month he had it, a buyer expressed interest in taking it after the review was finished. So it was sold to him and he is reportedly happy with it.

The end of ATRAD Audio (well, not quite, but a bit of a change)
Shortly after this point, it was brought to my attention that my operation looked too much like a commercial endeavour, and taking commissioned builds meant I’d need to comply with various regulations both for the product and my own qualifications. Additionally, to comply with these electrical regulations, I’d need to sumbit a sample to a laboratory for expensive destructive testing.

Clearly this was out of reach for a hobbyist so I decided reluctantly to cease operation. The ATRAD Audio site was repurposed into what you see now.

However this is not quite the end. It turns out if I build things for myself and then sell them as used, the restrictions don’t apply, because when buying a used appliance, all risk passes to the buyer.

So this is how I will continue.

Which is the way most vacuum tube amp hobbyists run anyway.

When suppliers go the extra mile

Since I started building amplifiers, I’ve been reliant on one supplier in particular, for my chassis and casework.

Most suppliers of parts can be replaced – however when you’re sourcing outwork services you enter into a relationship with your supplier that goes beyond a straight customer / supplier dynamic.

Introducing Embrace Design who have provided all the CNC and laser cutting and engraving services for the cases for my amplifiers.
The service doesn’t stop there however. Henri has been a rich source of suggestions and ideas and has been completely cooperative in working with me to get exactly the look and aesthetics I have been looking for, as well as a good emergency weekend source of fasteners and other necessities.
Much of the exterior appearance of my amplifiers is down to Henri’s skill with translating the designs into reality.
Worth acknowledging here.

A tale of two products

… in which I make myself unwelcome at a high-end hi-fi store.
This is a personal experience which happened over a decade ago, but I decided to put it here because it’s still relevant.
These are the two products in question

Audio Alchemy Digital Transmission Interface, US$ 1600

Generic 10/100 8-port auto-sensing ethernet hub, around US$ 40 – 60 (at the time) depending on brand.

On the day in question, I walked into a hi-fi shop and the proprietor greeted me with a wide smile. This was a real high-end place where the demo systems are set up with speaker cables as thick as fire hoses, and just the rack that the system is sitting on has a five-figure price ticket.
We got talking (this was years before I started designing and building gear myself, I was just looking at buying a new pair of speakers which is what drew me into the shop). Pretty soon he had figured out my system and had decided that it would be improved by the addition of the top product, above.
While extolling its many and varied virtues, he inadvertently tripped himself up by completely inaccurately describing the phenomenon of jitter … seems he hadn’t read up enough on the technical manual that accompanied the product.
After a little while, I attempted to summarise my understanding of this product back to him, to show him I’d been listening. He was all ready to sell me one until I started asking some questions which led me to explain the function of the second pictured device…

Conversation went something like this:
“So, this machine will take a PCM data stream at 1.4 megabits per second (Red Book CD standard), store and buffer it, then output an identical data stream according to its own internal clock, which is carefully designed to be high-accuracy and not susceptible to disruption, correct?”


“Yes, and [long spiel about how that makes it sound better, yada yada]”


“And it’s $2200.” [That was the $NZ price at the time]


“Yes, possibly the best value enhancement you can make to a digital system…..”


“OK, so what then would you say about a device that does this at around 70 times the data rate, and not for one but eight separate inputs?”


“Well the DTI represents the cutting edge of digital transmission design, so perhaps in the future something might be designed that could do what you say, but it would be a very high-end piece of equipment, so only the most serious audiophiles would require it, and that’s assuming there’d ever be a digital recording standard that would utilise such a bit rate”


“So you’re saying it’d be expensive then?”


“Something with over 500 times the processing capacity of this machine? Very!”


At which point I explained the functionality of the 10/100 ethernet hub, and then its price.
He wasn’t smiling any more.

In fact, I got the distinct sense I’d outstayed my welcome in that establishment.

– This is why I don’t go into high-end hi-fi stores any more. –

Advice comes at a cost

This post is a bit of a rant, and also a warning to those embarking on this craft and seeking the advice of experienced or expert designers and builders.


No pictures in this one sorry.


I’ve debated whether to post this for a while, but recent events have compelled me to.
When I started this blog, I was completely new to designing and building amplifiers and valve gear in general. I was delighted to see all of the resources available on the internet, and I joined one or two of the more popular forums. After sitting and watching for a while, and reading as much as I could, I started posting up a few questions, and a couple of schematics I’d designed, to get some input and opinion from the wise and experienced folks.


The input and opinion I got was not quite what I was expecting or hoping for. In my mind I’d imagined that the experienced folks would be tolerant of – or even welcoming – to the newbie, and take time to give explanations or point to resources to further my understanding.


Instead I was the recipient of sarcasm, scorn and ridicule. Both on the boards, and in private messages. It became quickly apparent to me that the prevailing attitude seemed to be that unless you know all of the common topologies by heart, you have no business even picking up a soldering iron. 


My particular approach has been that I don’t want to just find a schematic and build it, I want to understand how it works. I’ll only build something I can describe the working of to another person. So I’m gonna ask questions… that’s how you learn.
Besides the condescending remarks, another thing I had to contend with was opinion stated as fact. Some examples:

  • “Hammond Sucks. Edcor all the way”
  • “No audio circuit has any business using the 12AU7, it’s so non-linear.”

So one of the first skills I had to pick up was the ability to discern fact from strongly-held and expressed beliefs.


The next problem I encountered was a peculiar way of offering recommendations. The most recent example was concerning the use of a Constant-Current Source for preamp tubes. This particular recommendation was given to me in an email by another old-timer in a way that implied that any amplifier without a CCS is some kind of useless toy. When I questioned this, my question was taken as a challenge, and I received an insulting and profanity-laden email in return.


Here’s the thing, though. If someone tells me I need a CCS – or any other such recommendation – they should expect me to ask why. This is not to challenge or disagree – but rather because I want to know the reasoning. I need to know if this is another opinion-stated-as-fact, or whether there is some basis for the recommendation. I want to know:

  • Why would I need a CCS?
  • What problem does it solve?
  • How bad is that problem?

This helps me build understanding and further my knowledge. I did not profess to be an expert in this area – it remains a hobby which I fit around a career and a family. I do strive to learn something from each project, and make each one better than the last.


To that effect, I have made a decision which I should have made back in 2016 and this is the reason for this longwinded post. From now on, I am receiving my knowledge from books, or the small number of personal sources I trust, and I recommend anyone else starting out do likewise. 


Either that or develop a thick skin against the attitude you’re likely to encounter.
For my part, if anyone asks me for my knowledge, I’ll happily share it without condescension, such as it is.

Follow the heat waves

Big thanks to a friend who lent me their Flir E4 Thermal Imaging camera

After warming up the amp, I used the camera to measure the envelope temperature of the big KT88 valves.

From the KT88 Datasheet:

Phew!

The question you may be asking: what was playing through the amplifier during this photo session? Glad you asked. Icehouse… Man of Colours.