Net Audio’s Quad 33 redux
Posted in News on June 11th, 2010 by gkrakow
David Pritchard is one of the really good guys in the audio business today. First, he loves good sounding equipment – and second, he especially loves good-sounding, vintage transistor Quad component products.
I wrote about Net-Audio a few years back and David’s amazing upgrades for the Quad 33 (pre-amp) and 303 (power amp). The different pre-amp upgrade options consist of swapping out the original plug-in circuit boards for David’s modern designs. The power amp upgrades range from soldering in a new power supply board to a full, top-to-bottom re-design of the amp. Read my original write-up on MSNBC.com for full details.
I’ve listened to all of these options and can tell you that David really knows what he’s doing. In the past 3 years, I’ve tried other amps and pre-amps on my vintage Quad ESL speakers – but within weeks I always seem to come back to – and prefer listening to David’s upgraded components. A short while later, David had sent me an even newer Tape Adapter board. My 33 sounded great.
That brings us to the present. David let me know he had made further improvements to the Quad 33 output boards and wanted to know if I was interested in hearing what he accomplished with some new, MK2 series boards. If I could have reached through the computer screen and grabbed the boards right then and there it wouldn’t have been soon enough.
After waiting a few weeks (which seemed like an eternity) the plug-in boards arrived. I quickly replaced David’s “old” boards with the new ones – sat back and started listening. They sounded great – but I knew that if I followed David’s instructions – and let the new components “burn-in” for a few hundred hours I’d be rewarded with an even better listening experience.
That was an understatement. The new boards now have nearly 400 hours on them and the improvement over the last boards is amazing. Playing upon his circuits strengths, David has actually squeezed even more clarity and a wider/deeper sound-stage out of his designs.
To put it another way, an original, UN-modified Quad 33 sounds a bit dull and dated compared to modern-day hi-fi equipment. With David’s original upgraded circuit boards a modified Quad 33 could keep pace with most modern-day gear. With these new boards, a Net-Audio 33 can basically keep up with the rest of the stuff out there. Even with all the mods, David’s 33 reproduces music that sounds absolutely right.
Match the 33 with a Quad 303 (make sure the amp is working properly – they are 30-40 years old) and, at least, add David’s super-duper power supply board – and you have some spectacular gear to listen to.
Back when I was doing the original testing of Net-Audio modded gear, I brought my Quad 303 with David’s new power supply board to an amplifier shoot-out at my friend Robin’s house. He had arranged to have a number of very expensive power amplifiers to try on Robin’s Quad speakers. After a n hour or so, the other listener involved, a musician and fellow Quad ESL owner snapped his head around when Robin placed my 303 in the music playback chain. “What’s that?” “That’s a 35-year old Quad 303”, was our response. The expert was stunned. It sounded (and still sounds) THAT good.
Here’s the best part. Finding unmodified Quad 33s and Quad 303s is easy. Just look on eBay. They always seem to be at least one or two examples of each for sale. And usually even more are available from Great Britain. Prices are low – especially with the dollar being strong at the moment. Even with overseas shipping.
David’s original replacement output boards are still available ($94.50 at current exchange rates) and the new (and highly recommended) MK2 boards are $109. An entire Net-Audio upgrade (full boards swap) will set you back $269. That’s a bargain for what you get. You’ll need to add a 120v power supply (it plugs into your new Tape Adapter board and David will advise you on which one to get) also postage, handling and any taxes your government might add.
David reminds me that my 33 is currently, nearly, completely up-to-date. It now contains the following Net-Audio components:
You have the new output and tape adaptor boards plus you have an original disc board, not the new MK2. All signals go through the output boards. Tape and Radio signals pass through the Tape adaptor board as does the disc signal after being processed by the disc amplifier and disc adaptor cards.
There is a MK2 disc board which you do not have fitted to your 33.
I think it sounds amazing just the way it is.
These are top-quality component boards that are available now at near rock-bottom prices. Add some of David’s upgrade magic to classic Quad components and you’ll have an affordable and stupendously super-sounding system.
Very, very highly recommended.












