Meet Your Maker: Pete Thomas, PMC loudspeakers

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Categories:
Audio,
Floorstanding,
Stand-mount,
Subwoofers,
Integrated amplifiers

How do you design loudspeakers?

The BBC had been designing loudspeakers for 40 years by the time I worked there, and it evolved this procedure that I think is brilliant and we use it today. That is they recognise that a loudspeaker design has to be fifty per cent measurement and fifty per cent listening – you can’t do it ALL listening or ALL measurement. What the BBC does is build a prototype, put it in a studio, and get all the ‘golden ears’ recording engineers to use them for about three months, logging their findings in a book. I can tell you, the first comments we got on our early designs were brutal! These guys are pretty fussy. 

It’s a great process because you get the comments, then redesign the product based on those comments. You still measure the speakers to make sure you are making something that is accurate, which means you end up with a speaker that measures well and also sounds good. 

The other interesting part is the speakers are designed up to almost the finished product on speech and in mono. We then test on music and in stereo at the end of the development stage, but because we listen to speech every day of our lives and are so focused on it, we know when speech sounds right or wrong. We actually use a 1958 BBC recording of speech all the time. We’ve very lucky to have that background because it gives us a reference point to this day. 

How did Fenestria come about?

Fenestria has been something we’ve wanted to do for a long time to be honest. Our high-end pro range was restyled and remodelled for the domestic market, but Fenestria is different. The birth of the fact range was intended to take the performance of those big studio monitors and reformat it into a long, tall, thin speakers. The fact range was the start of the development process to make a really high-end product, especially as a lot of new ideas were coming out of the R&D department. 

We’ve got both a product development team and pure R&D, who may or may not come up with ideas that are useful for future projects. However, the two or three things they did come up with wwas creating a chamber behind the dome midrange we’ve been using for the last 28 years, which lowered distortion significantly.

The next big development was the Laminair vents. This was Ollie’s big work, and improving the airflow in a transmission line makes a big difference to performance because there are surprisingly high velocities involved. We also recognised a lot of people are trying to make the cabinet more inert, but the weight of the panels involved makes such systems prohibitive. So, they came up with mass damping panels on anti-vibration mounts on critical points on the sides of the speaker. These act as an out-of-phase vibration to kill vibration, a bit like the counterweight in earthquake-proof skyscrapers.

The most important thing is we passed on to that R&D team the idea that you should trust these two things on the sides of your head! In engineering, you can get very carried away with the technology, but it has to give a benefit in performance, and I think that can get lost. 

But it’s also about measurement! Modern measurement systems are so advanced you can now measure more things and explore things you didn’t have the time to do in the past because the measurement process was so slow. You couldn’t have afforded to bring Fenestria to market 10 or 20 years ago – it would cost half a million pounds because of the investment in R&D!

This also means at the other extreme, a fairly inexpensive loudspeaker now has the performance of a speaker that would have cost three or four times more back in the day.

Tell us more about the museum!

It’s grown randomly over the last 40 years. I’m a bit of a collectaholic (the polite term for ‘hoarder’) and people started giving me stuff. It started - naturally enough - with a collection of all the early transmission lines (because there weren’t that many to collect) and it expanded from there. First to classic speakers, then amplifiers, turntables, tape machines... everything. We try to find classic or landmark designs, but then it got filled in with not-so-classic designs we acquired.. The goal is to create a 50’s, 60s, 70s, 80s, and 90s room with a working classic system of that era. Like a visitors centre!

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