Quad Revision FAQ's: Part II: The Quad 33
The 33 has a very beautiful design (to be discussed ;-) but also electronics from the 6-ties. Can it be upgraded to modern high-end standards?
Personally I love the 6-ties for the design in furniture, fashion, wall-paper and for the music. The fact I was 2 years old in 1960 & 11 years old in '69 must have something to do with it ;-).
6-ties design has come back in today's fashion as an icon of the best design of the previous century, beside Art Deco.
The Quad 33 was one of the best examples of 6-ties design. It was the first hifi-design to show that the highest quality does not mean the most buttons, a large size and impressive meters, lamps & switches on the front-panel.
But can the 33 be adapted to modern high-end standards?
Sure, it can.
The 33 is completely transistor-based. Later pre-amps used Opamps. Quad used them from the 34 on.
There is nothing wrong with Opamps. Only, the first opamps made in the 7-ties (like the LM301) did not match the specs of a well-designed transistor pre-amp. In the 34 the sound passes throught (at least) 4 Opamps, each containing (at least) 24 transistors. Later it got worse...
Less is more is the design rule for the best pre-amps designed today.The 33 respects this principle in a great way.
What can be done to upgrade my 33 to high-end standards?
Ruud Janssen's website is the best advice on the 33 (and the 303) - see the links on the left. Unfortunately it is only in Dutch.
What has to be done in any way is:
- Replace all capacitors > 1 mF with new ones. They have dried out after more than 20 years.
- Increase the powersupply-line from 12 Volt to 16 Volt (the reason it was 12 Volt is because modern capacitors would have been too big to fit in).
These are the basic things.
How about the Volume-attunator potentiometer of 50KOhm with a switch on it?
The potentiometer is 50K Ohm Log with a switch. This one is no longer available. A company in the UK sent me an offer on my request, but I had to order a minimum of 1.000 of them to start a production-line "for a small quantity".
The best alternative is a DACT-attenuator (a switch with 24 positions, stereo, logaritmic) that is applied in most modern high-end.
Anyway, count >100 Euro for this one (see http://www.dact.com/html/attenuators.html) and you will have to add an external switch. That's what I did.
To be continued...