Quad II Monoblock Valve Power Amp

Quad II Monoblock Valve Power Amp


The word "classic" is used far too often to describe hi-fi equipment and indeed is sometimes placed on equipment that is sometimes undeserving. However there can be few people who can argue with the Quad II Monoblock Valve Power Amp's status a true classic in every respect.

The Quad II Monoblock Valve Power Amp were first launched by Quad in 1953 adn really established Quad as a company of some clout that really had something special to offer. The Quad II Monoblock Valve Power Amp's circuit was designed by Quad's founder Peter Walker and was revolutionary because of it's simplicity which made for a highly efficient yet low distortion output valve amp. In all the Quad II Monoblock Valve Power Amp circuit contains just thirteen resistors and six capacitors per channel to complement the output transformers and 5 valves per channel.

Because of the simplicity of the circuit, there is no circuit board in the Quad II Monoblock Valve Power Amp just a solder tag board and all the components are hard wired very neatly under the case.

Although the design of the Quad II Monoblock Valve Power Amp is over 50 years old it is a testament to Peter Walker's design that the new owners of Quad, IAG relaunched the Quad II in 2005 and made sure it was a faithful reproduction of the original design keeping the same circuit intact . The only thing different with the new Quad II Monoblock Valve Power Amp is that it now has a power switch and valve protection grilled for safety reasons, the original six pin "jones" connector has been replace with two gold plated phono sockets and the name plate has been replaced at the front, which is a bit of a shame as the plate added something to the design of the original Quad II Monoblock Valve Power Amp.

When the Quad II Monoblock Valve Power Amp is powered up it is able to supply about 15 watts which is perfectly adequate for normal room listening and produces a lovely warm valve sound that can only be described as natural, emotional and very enjoyable.

The current Quad II Monoblock Valve Power Amp are available in pairs priced £2000 from Quad dealers and the orignal valve amps do not come cheap either. Providing you are buying an unmodified pair with close matching serial numbers and original valves you can expect to pay anything up to £1000. This fact also highlights the esteem the Quad II Monoblock Valve Power Amp has in hi-fi circles - one of the very best. The original Quad II Monoblock Valve Power Amp stayed in production until 1970 by which time 96,000 had been made making it one of Quad's best selling products ever.

This entry was posted on Saturday January 6th, 2007 at 9:33 PM and is filed under Amplifiers. You can follow any responses to this entry through the RSS 2.0 feed. Comments are now closed.

10 Responses to Quad II Monoblock Valve Power Amp

Nigel from beds Says:
October 29th, 2007 at 1:29 PM

Hi...I have just purchased a pair of Quad II's and a 22 preamp with the rectangular push buttons. The serial numbersd ar460** and 482** and both were last serviced in October 1987 together so I would imagine they are a matched pair? Apparently they were stored in their original boxes since that last service Judging by your photo they look identical with the same make and number valves as per original. The only thing I have noticed on one of them is a black instead of silver choke? I'm obviously unsure what Quad did at that service but the smaller of the 3 cube-like 'towers' that rise from the base, which I think is the choke, is in black and not silver. It does not look like a respray but a factory made choke in black.
I am about to fire them up and the only lead that is missing is the mains lead which is just a two pin socket that fits onto the 2 pins at the back of the pre-amp I would imagine? I have an old 2 pin socket which is probably from the same era and looks the part and there is no right/wrong way to wire them is there?
Is there anything I should do before powering them up? I have checked that all the valves are properly inserted and there is nothing visible to show anything anywhere inside or out has blown or got hot. All the valves look as good as new.
I hope that is enough information for you...Thank you

Hi-fi insight Says:
October 29th, 2007 at 1:39 PM


Your best bet if you are unsure about anything is to contact Quad/IAG.

Your first point of contact should be Rob Flain, IAG Group Service Manager who is an extremely helpful person and should be able to answer your query.

Ian Says:
January 18th, 2008 at 1:29 PM

Hello There,
I just wondered if it was possible to date these amps from the serial no ?

Reiss Says:
April 3rd, 2009 at 9:29 PM

i want 2 know how 2 go about sellin my Quad II Monoblock Valve Power Amp & pre amp & radios, there all in fantastic workin order. could u tell me a guide price if u can? thanks

David Says:
February 9th, 2010 at 1:49 AM

I am interested in a vintage pair of Quad II.

Thanking you in advance.


Dave Says:
March 22nd, 2010 at 9:18 PM

Have a pair of Quad II monoblocks. The original input jack has been replaced with RCA's. Don't really know a fair asking price. Dave H

Matt Says:
March 29th, 2010 at 4:58 AM

Hi dave email me please

Adrian Says:
July 6th, 2011 at 9:26 AM

I also have a pair of vintage Quad II if anyone interested. Many thanks

Mike the parrot guy Says:
May 27th, 2012 at 8:20 PM


I was an audio dealer in another life. I have in the closet some old QUAD gear. I have a valve stereo preamp with one tube-type power amplifier. They worked when retired to the closet, but I suspect the electrolytic capacitors will have to be replaced,

I am willing to entertain offers. I prefer not to ship them, but I will if needed. I am in Tampa Bay area.


Gary ashwell Says:
October 10th, 2013 at 10:53 AM

has anybody a pair of Quad 11 power amplifiers for sale, prefer nice condition pair.

Subscribe to RSS feed