The Croft Acoustics QUAD II KT88 Amplifiers - Review 2011

Discover the classic QUAD 2 Power Monoblock Amplifiers upgraded by the late Glenn Croft

The Croft modified QUAD II monoblock amplifiers in conjunction with my Tannoy Monitor Gold loudspeakers. A classic combination.

Croft QUAD 2 Monoblock Amplifiers

After using many transistorised amplifiers, I wanted to create a real vintage, circa 1960s system, so with that itch to scratch, a pair of QUAD II's were a perfect match together with my Tannoy Monitor Gold loudspeakers in Lancaster cabinets and my Thorens TD124 MKII turntable.

But, before we get to the QUAD II's, in my search for a perfect set of vintage monoblock amplifiers I first bought a pair of LEAK TL12+ mono's together with a LEAK Point One preamplifier. The Point One was actually converted to a passive unit and using it with several amplifiers afterwards, it sounded really nice indeed.

LEAK TL-12 Monoblock Amplifiers

The TL12+ monoblocks looked smashing, but I found that they just didn't seem to drive the Tannoys as well as I wished. 

On low volume with none complicated music, they sounded really lush but, try to fire them up with some dance or heavy rock, well, forget it. The sound stage simply fell apart at the seams.

I was a little surprised by this as the Tannoys are really easy to drive but, unfortunately, it wasn't to be.

LEAK TL-12 Monoblock Amplifiers

LEAK Point One Preamplifier

So, in steps the QUAD II's.

These beautiful QUAD II monoblocks were converted from using KT66's to KT88's by Glenn Croft. Unfortunately, when they were converted was unknown to me but Glenn Croft was nicely surprised to get them back for a service so my guess was early to mid-1990s.

Croft QUAD II Monoblock Amplifiers and Thorens TD124 MKII

Croft QUAD II Monoblock Amplifiers and Thorens TD124 MKII

When I bought them, they were using the Gold Lion KT88 valves accompanied with Brimar and Mullard signal and regulator valves. The casework was at some point re-sprayed to a brighter grey/blue colour which updated their look nicely.

When they were being serviced, Glenn checked everything out and replaced some parts for good measure. I was very pleased to know that they were still in perfect working order.

Inside the Croft QUAD II Monoblock Amplifiers

The QUAD II amplifiers were created by Peter Walker in 1953 and the build quality of these old Quads is simply wonderful, but they do need some space around them, they can get very warm. I was told they were manufactured back in the early 1960s which was nice to know.

When I got them back from Glenn, I powered them up and sat down to listen, I couldn't believe how much bloom and life the Tannoys gave with these little things in charge. After about 30 mins of warm-up, it was time to really try them out and give them some 'V'. This is the point where the LEAK TL12's really fell apart, they didn't like demanding music at higher volumes so with that in mind I started with some Spiritualized, Deep Purple, and Wolfmother.

Croft QUAD II Monoblock Amplifiers and Thorens TD124 MKII

Wow... straight away, the tannoys sang, pushing out a full range of psychedelic dynamic goodness. Powerful and authoritative, I was a very happy bunny indeed. Playing ambient, Goa and dance also brought a smile to my face. The bass was great, not as focussed as I would have liked but still very nice.

The next step was to set out to buy some top-notch vintage valves.

My first choices were Genelex or Brimar but I finally fell on some original 1950s GEC KT88s and signal valves.

Croft QUAD II Monoblock Amplifiers

Croft QUAD II Monoblock Amplifiers

Croft QUAD II Monoblock Amplifiers

GEC KT88 valves for the Croft QUAD II Monoblock Amplifiers

Once the GECs were in the amplifiers, things improved even more. I was so surprised. The bass was now more focused and had more authority whilst the mid were slightly leaned back, this wasn't a bad thing as it brought out everything with more ambience.

Another thing I found with the QUADs was that given a 1hr+ of operation, things really started to boogie.

Another worthwhile upgrade was using the Mark Grant interconnects together with some Van Den Hull The Wind MKII Hybrid speaker cable. I found Mark Grant cables really gave the QUADs a more natural sound, highly recommended.

To my knowledge, these QUAD II's were a one-off custom job from Croft Acoustics. But I would recommend having the same modifications done to any old and tired QUAD II's. You will certainly fall in love with these little anvil-like wonders again.

Tannoyista vintage system