You'ce got to have some old Quad in the mix !

[nutteronthebus]

Hi I have a surplus of Quads at the moment 2 X 303 4 x 405-1 and 2 x405-2 8 x 33 preamps 2 x 44 preamps and 5 x FM4 tuners ( 2 need repairing 2 have the later chip that removes the battery ) most of the 33 preamps have been upgraded to the DADA style 16v power supply and new caps etc . I have yet to get round to 3 of the 33 a these were a trade in for upgraded ones . The 405-1 also need new caps and R7 and R8 feed zener diodes to power the input op-amp. They are underrated for power. They dissipate at least 0.37W and the resistors are 0.25W. So at some point one burns out, puts the op-amp hard to one rail, pegs one dumper at the power rail, the crowbar fires and blows the dumper, the driver and then the crowbar. Then the rail fuse blows. The resistors should be replaced with 1W resistors, spaced away from the board by a few millimetres to allow air to circulate . Electrolytic capacitors associated with the protection circuits are directly above R30 and R31 (560 ohm power resistors). These run hot, and cook the electrolytic. These are ROE epoxy potted caps, and will be badly discoloured and cracked. When replacing, the caps should be soldered to the track side of the board to keep them away from the heat and of course the RIFA caps on the power switch
( the advice on the 405-1 is thanks to Craig Sawyers from the https://www.vintage-radio.net/forum/...569#post986569 )

Dave

PS I do like the 303 sound it is very mellow

[jandl100]

AVI Lab Series.
Nice - and a bit upfront, taut and 'exciting' compared to the average, imo.
Quad 303 - on the laidback and mellow side, as has been said.
Big difference in presentation, in my view.

As I understand it (from AOS posts!) the 303 was the direct successor to the snoozy but tonally rich (imo) Quad II valve monoblocks. and that lineage is readily audible. With the 303 I think Quad tried (and largely succeeded) in producing a solid state Quad II.

Later Quad amps headed for a more dynamic presentation but lost the tonal magic of the Quad II. Maybe the Quad II overdid the tonal richness, but cor lummy it sounded good!
I had a Quad 405 as my very first 'proper hifi' amp, I then upped to the 405-2 and that was a real eye/ear opener! Much more dynamic and, to me, interesting sounding.
I had a 606 for a short while - a fine amp just missing a layer or so of detail resolution to call it great, imo.
I'd like to try a 306 one day.

[IHP]

snoozy but tonally rich

I have never come across that term in any review article but my word it's on the money !

[agk]

I enjoyed my time some years ago with a 303 fed direct from a Denon cdp.
A nice sound as I recall if like me you don't like overly bright treble.
The only real problem I had was speaker cables interfering with my tv picture.

[IHP]

Here's the Amplabs one........

[Andy831]

Here's the Amplabs one........

Now that looks the business. If it sounds half as good as it looks then it will be stunning

[spendorman]

Nice, I always thought that an on-off switch could be useful. I have fitted one to my 405-2. There are already some convenient holes in the rear panel that can be used to mount a miniature switch.

Strange that they quote 40/220 W on the amp as consumption, mine consume around 12-13 Watts at idle.

[smithie]

hi guys
thanks for all the input and views.
i may now have to wait till after christmas where i can dedicate some more funds towards the quad appraisal/buying thing,but i will certainly be giving one of them ago...ive just got to know now

"jandl100
AVI Lab Series.
Nice - and a bit upfront, taut and 'exciting' compared to the average, imo.
Quad 303 - on the laidback and mellow side, as has been said.
Big difference in presentation, in my view.

As I understand it (from AOS posts!) the 303 was the direct successor to the snoozy but tonally rich (imo) Quad II valve monoblocks. and that lineage is readily audible. With the 303 I think Quad tried (and largely succeeded) in producing a solid state Quad II.

Later Quad amps headed for a more dynamic presentation but lost the tonal magic of the Quad II. Maybe the Quad II overdid the tonal richness, but cor lummy it sounded good!
I had a Quad 405 as my very first 'proper hifi' amp, I then upped to the 405-2 and that was a real eye/ear opener! Much more dynamic and, to me, interesting sounding.
I had a 606 for a short while - a fine amp just missing a layer or so of detail resolution to call it great, imo.
I'd like to try a 306 one day."

great post and thanks for your take on my avi compared to a quad,i think you've described the avi labs amplifier pretty spot on.

great thread by the way guys.

regards
paul