Keld Ampworks’ Fluffy Green Policy

I write this post with some trepidation. As public and government figures finally start to take heed of the dangers around climate change and linked environmental issues, some have started to view what is essentially a scientific theory, backed up by decades of real world evidence and proven hypotheses, as a political issue. As a very small business, it’s very risky to engage in political discourse and risk alienating customers. So let me be clear, this is isn’t a political post. I’m an engineer, and Keld Ampworks is an engineering company. Climate change is a problem. The problem was (and continues to be) created by the actions of engineering industries. The problem is identified and rigorously quantified by scientists. With a growing human population, the problem is one of efficiency. Efficiency is the engineer’s domain. The solutions lie within engineering.

With that in mind, all of my fluffy green policies are about Keld Ampworks’ commitment to making the rational engineering efficiency choice, they’re not about economic efficiency.

What can Keld Ampworks do about it? At the end of the day, I’m a tiny tiny company with very little financial power. Only little things.

Repairs are the ‘Green’ choice.

The core of the Keld business is in repairs. Every unit that’s repaired here and at all the other repair shops across the world is a unit that does not need to be scrapped and replaced. Landfill is reduced, waste is reduced.

Repair is nearly always the choice of best engineering efficiency, however it’s frequently not the choice of best economic efficiency. Unlike many repairers, I don’t have a ‘no cheap amps’ policy. I’ll offer a quote even on a cheap 90s solid state amp where the cost of repair is equal to the economic value of the amp. I’ll always be honest with the customer about the economic side of things. I’m not trying to dupe anyone.

WEEE, RoHS and Solder

All components removed from amplifiers are disposed of through the WEEE scheme. All CE marked products are repaired with RoHS components. All CE units are repaired with Pb-Free solder. As well as being a legal requirement, this is also the choice of best engineering efficiency: a mix of Lead and lead free causes a solder joint that is weaker than either a Pb or Pb free joint, resulting in a less reliable amp. A less reliable amp is not an efficient engineering outcome. I expand upon this here. But there’s a big caveat here…

RoHS and Pb-Free exceptions.

HOWEVER in units that predate RoHS regulations I use lead solder exclusively. Using Pb-free has no environmental advantage in a unit that is already non-RoHS and the solder mix reduces the reliability as described here. I will also use non-RoHS components in non RoHS units. It would be a poor engineering efficiency choice to scrap a unit, rather than use a non-RoHS component.


All customer communications are paperless. This is the most efficient way of communication.


Keld Ampworks uses a paperless bank with a commitment not to invest in fossil fuel based energy. Fossil fuels may be an economically efficient way to generate electricity, but it’s not an efficient engineering choice.

Component reuse

In general, it’s a poor engineering choice to reuse old components. However there are some exceptions. I routinely save transformers and knobs, heatsinks and obsolete components from amplifiers that weren’t repairable. These are then used in other repairs.

Packaging reuse

I get several component orders every week as well as getting repair work in by post. All packaging is re-used for items that are posted out to customers. Packaging that I can’t make use of is donated to another Newark based business for reuse. Any remainder is recycled.

Design for longevity

Much of Keld Ampworks design work is done with Class D amplifiers. In this, we again have to think about engineering efficiency, not just in use, but over the lifetime of a product. Class D products are often designed using monolithic chips that are unrepairable and go obsolete. My Class D designs use discrete MOSFET devices – replacement parts will always be available, meaning that the amps will always be repairable.