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Quad 909 upgrade/mod list

Discussion in 'classic' started by Chris88, May 7, 2017.

  1. Barrymagrec

    Barrymagrec pfm Member

    Yes, luckily not much SMD on older kit.

    Those 0402s are right b*stards to solder, if you have many to do.
  2. russel

    russel ./_dazed_and_confused

    I wouldn't use a wirewound on the bridge components it may cause it to go out of balance.
  3. Chris88

    Chris88 pfm Member

    Quad originally used wirewound for R16 & R17, are you saying regular type metal film would be better? What would be best to use here?

    I know those resistor generate a lot of heat thats for sure.
  4. Chris88

    Chris88 pfm Member

    A basic question that i'm not sure about;

    When i refer to the 909 manual, why are some resistors listed with "R" (560R 1/4W 1%), and some with "K" (22K 1/4W 1%)?

    Do the letters "R" and "K" indicate different values or something else maybe?

    Is this of any significance?

    Cheers again : )
  5. Barrymagrec

    Barrymagrec pfm Member

    It`s the multiplier.

    R is 1 so 560R is 560 ohms.

    K is 1000 so 22k is 22000 ohms

    M is 1000000 ( you don`t find so many of those in transistor kit
  6. Chris88

    Chris88 pfm Member

    Cheers Barry that's much appreciated.

    I would also like to ask would it be ideal for the volts to match/be the same for R1/R2? For example 300V for both?

    As oppose to say 300V for R1, and 350V for R2?

    Does this effect stability or anything else?

    Is it ideal to have same volts for these?
  7. Julf

    Julf Evil brother of Mark V Shaney

    No, the voltage rating does not matter, but you do want to use the same type of resistors, with similar termal coefficients etc.
  8. Chris88

    Chris88 pfm Member

    So if i found a good resistor for R2 that was say 100 PPM/C, it would be a bad idea to use 25 PPM/C for R1?

    Ideally i would want to use 100 PPM/C for both (R1 & R2) right?
  9. cjyosemite

    cjyosemite pfm Member

    I am coming in a bit late on this thread but as it is still active I thought I would add my two-penneth. If improved sound quality is your aim then I would suggest getting hold of a pair of Quad 99 mono amps as in my opinion they are better than the 909. That it also the opinion shared by a few dealers when the subject has come up in casual conversation...... and I don't know whether I should say this.......but it is also the opinion of the Quad sales manager. When I asked him why they did not demo & advertise the 99 mono a bit more his reply was that people associated Quad amps with the "current dumping" design & the 909 is the one that sells.

    Being a tight-fisted Yorkshireman the other advantage is that despite being as rare as hen's teeth, a pair of 99 mono's used to sell for around £400 at the time when a 909 was £500. If your real purpose is to tinker then you could tinker with two 99's for every 909.
  10. Chris88

    Chris88 pfm Member

    Interesting, wish i'd been aware of that years ago while they were still making them new. I actually use two 909 stereo amps, bi-amped vertically (one amp for each speaker), which i find far superior to a traditional horizontal setup, and someone indicated to me that in regards to using x2 stereo amps bi-amped vertically, it's actually very similar to having mono amps, but the tech stuff is beyond me. It certainly sounds superior to my ears over the traditional horizontal method.
  11. Chris88

    Chris88 pfm Member

    Random question, if capacitors kept in storage for long periods can go off over time, how about;

    resistors, opamps and fuses, do they also go off or they are not effected?
  12. Julf

    Julf Evil brother of Mark V Shaney

    Capacitors suffer mainly from heat. Resistors do as well, but to a very much smaller degree, nothing to worry about unless they have been stored 50 years or something. Opamps no prob, and fuses only suffer from surface corrosion.
  13. Barrymagrec

    Barrymagrec pfm Member

    Yes, I have a NOS, completely unused wire ended 68k 10% resistor (Dubilier I think) which is about seventy years old and now measures 90k, it is a type often seen on vintage Quad and Leak amps so.....
  14. rich46

    rich46 quad rules

    leave alone, except like for like replacement that design hit the market in 1980 and is still in current range without any major changes. poorly modded 606/909 go back to quad for repair. it keeps service guys in work says rob in service at quad.
  15. cjyosemite

    cjyosemite pfm Member

    I have a faint recollection of using a pair of 909's in vertical bi-amping mode in the days when I had five 909's & 2 pairs of 99 mono's. Cannot remember what I used them all for but I did have 2 AV systems. The modern version of the 99 mono is the Elite mono which i think is still in the range but only available in black.
  16. rich46

    rich46 quad rules

    the only non current dumper is the platinum range which didn't sell well. quad have gone back to mid range antera which uses current dumping..the platinum range took 4 years at great cost. the new range will have same spec. as the 909 that drives all their speakers so why have complicated ranges.
  17. Zombie

    Zombie pfm Member

    Platinum, what a stupid name for kit in the internet search age...almost as stupid as Elite...
  18. cjyosemite

    cjyosemite pfm Member

    Yes you are right, the Elite mono is no longer shown in the range & the 2 power amps appear to be renamed/revamped versions of the 909 stereo & the 909 mono although I am not certain the 909 mono existed for long as I think there were heat problems with it which also occurred initially with the 99 mono in the early days of manufacturing in China.
  19. Chris88

    Chris88 pfm Member

    A couple of years ago I purchased x3 brand new Quad QSP amps (the successor to the 909) and i was not happy with how they sounded
    Last edited: Dec 29, 2017
  20. cjyosemite

    cjyosemite pfm Member

    Interesting comment about the lower quality components as that happened when they started making them in China. I remember it well because you could not get a 909 for life or money & Quad did not even know when the ship was due in, so I decided to opt for a pair of 99 monos. The component quality problem occurred on those as well & one got too hot to touch - better for frying eggs than playing music - so back they went to Quad & they sent replacements. Unbelievably the same problem occurred so back went the second pair. Still no sign of any 909's so they did me a special deal on the demo one used by Ken Kessler so I possible had the last UK made 909. I think Quad UK read the riot act to China stressing they would ruin the brand if they used lower quality components again. Some years later I bought a 99 mono for the centre channel of an AV system & subsequently a second one for a second AV system. These subsequently became a hi-fi pair when I moved from AV processors with multiple power amps to AV receivers & I have never had a problem with them or a subsequent pair I bought & still use. I sold the first pair about 5 years ago.

    The concern is that the overheating problem I had was many years ago but you bought your 909's only a few years ago so it may be that standards have slipped again unless it is from an early China batch.

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