chiily
PFM Special Builder
Recently, this week, I purchased a fabulous pair of Quad II amps from @John_73 of this parish. https://pinkfishmedia.net/forum/threads/pair-of-original-quad-ii-amplifiers.261545/#post-4543836
They really are in lovely condition and date from 1966 based on their serial numbers. One has a few marks on the paint, not scratches just blemishes. If I can find a blemish that is hidden away I may try either some Brasso on it, or maybe a little TCut, just to see if the blemish can be lifted.
These are the first Quad IIs I've seen in the flesh, and ain't they heavy for something so little! Their simplicity is quite astounding, such a long way from the SS amps I've previously built. I can't wait to get these up and running playing through my Quad ESL 57s (another PFM buy from @foxwelljsly)
John_73 was kind enough to throw in not just the Quad book, but also a box full of new cables, connector shells, Russian PIO capacitors, a huge assortment of both carbon and carbon film resistors, etc. And this afternoon I couldn't help myself but to plug in my soldering iron and start to put in to practice all the information I'd read over the week about servicing and maintaining Quad IIs.
The Plan
Working from this schematic:
Quad II cct by Garf Arf, on Flickr
The Plan was/is to refresh:
C2 and C3 with Russian military K40Y-9 0.1uF capacitors
C1 with a Mallory 150 series 0.1uf capacitor,
C5 with a Kemet/Rifa 22uF electrolytic capacitor
For C4/C6, they are in the grey box, tucked away underneath, I am going to use one of Keith Snook's replacement boxes to keep in the theme of the original Quads.
Resistors; I'm having an internal struggle over them. Most sites say that they have no bearing on the sound, so get those carbon comps out and get those metal film resistors in. And certainly from a reliability PoV then yes; but they don't quite look right. John's little box of stuff has a replacement set of Carbon Film resistors, but I'm tempted to try some Takman carbon films...hifi collective has them in stock...tempting...
The only resistor that needs something that Takman can't provide is a replacement for R12, which has to have a power handling of more than 5W. John's box held three Mills MRA12F 180R resistors and three Rifa 22uF caps for C5.
Valve-wise - for the moment I'm going to buy a set to get me going from Watford valves, but I have on my birthday list a quad of of Gold Lion KT66s
What's not in the Plan is cutting any metal work. I'll keep the two pin power connector and the Jones plugs. I think they suit the style and mark the era that these amps come from.
Progress
As I said above, John's box of stuff had components that needed fitting, I mean they were just itching to be soldered in to the amps. In went the Russian K40-Y, 0.1uF caps for C2 and C3, and the Mills resistor for R12 and the Rifa cap for C5.
PXL_20211211_180059541 by Garf Arf, on Flickr
What is interesting about these amps is that no one has been in them before. The three cheese slot screws I undid where Linn tight, and the heads were completely unmarked
They really are in lovely condition and date from 1966 based on their serial numbers. One has a few marks on the paint, not scratches just blemishes. If I can find a blemish that is hidden away I may try either some Brasso on it, or maybe a little TCut, just to see if the blemish can be lifted.
These are the first Quad IIs I've seen in the flesh, and ain't they heavy for something so little! Their simplicity is quite astounding, such a long way from the SS amps I've previously built. I can't wait to get these up and running playing through my Quad ESL 57s (another PFM buy from @foxwelljsly)
John_73 was kind enough to throw in not just the Quad book, but also a box full of new cables, connector shells, Russian PIO capacitors, a huge assortment of both carbon and carbon film resistors, etc. And this afternoon I couldn't help myself but to plug in my soldering iron and start to put in to practice all the information I'd read over the week about servicing and maintaining Quad IIs.
The Plan
Working from this schematic:
Quad II cct by Garf Arf, on Flickr
The Plan was/is to refresh:
C2 and C3 with Russian military K40Y-9 0.1uF capacitors
C1 with a Mallory 150 series 0.1uf capacitor,
C5 with a Kemet/Rifa 22uF electrolytic capacitor
For C4/C6, they are in the grey box, tucked away underneath, I am going to use one of Keith Snook's replacement boxes to keep in the theme of the original Quads.
Resistors; I'm having an internal struggle over them. Most sites say that they have no bearing on the sound, so get those carbon comps out and get those metal film resistors in. And certainly from a reliability PoV then yes; but they don't quite look right. John's little box of stuff has a replacement set of Carbon Film resistors, but I'm tempted to try some Takman carbon films...hifi collective has them in stock...tempting...
The only resistor that needs something that Takman can't provide is a replacement for R12, which has to have a power handling of more than 5W. John's box held three Mills MRA12F 180R resistors and three Rifa 22uF caps for C5.
Valve-wise - for the moment I'm going to buy a set to get me going from Watford valves, but I have on my birthday list a quad of of Gold Lion KT66s
What's not in the Plan is cutting any metal work. I'll keep the two pin power connector and the Jones plugs. I think they suit the style and mark the era that these amps come from.
Progress
As I said above, John's box of stuff had components that needed fitting, I mean they were just itching to be soldered in to the amps. In went the Russian K40-Y, 0.1uF caps for C2 and C3, and the Mills resistor for R12 and the Rifa cap for C5.
PXL_20211211_180059541 by Garf Arf, on Flickr
What is interesting about these amps is that no one has been in them before. The three cheese slot screws I undid where Linn tight, and the heads were completely unmarked