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Thread: Vintage amps from Quad -70's/80's

  1. #21
    Join Date: Jun 2011

    Location: NW England

    Posts: 42
    I'm Peter.

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    I am also considering a 33/303/ combo. I do like the 'iconc' design look of the 33/303 series. However I understand that they do need an upgrade for improved performance due to the lower grade components used in the original design.
    A fully serviced pair of 33/303 from Quad or other specialist - will they out performed the later 45/405?

  2. #22
    Join Date: May 2008

    Location: A Strangely Isolated Place in Suffolk with Far Away Trains Passing By...

    Posts: 14,535
    I'm David.

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    Dada do some excellent upgrade kits if you feel up to servicing yourself.

    The 33 can be totally transformed IMO with the power supply revision and recapping elsewhere. I also found that replacing C400 (I think it was) on the output board with a 1uF cap (.68 fitted IIRC) takes the bass down to below 10Hz instead of brickwalling it at 30Hz and this opened up the sound no end on digital sources and allowed the sonics to "breathe," the results as big as the power supply upgrade IMO.

    The thing with the 33, is that good original boards are available for not much money, so comparisons before and after are easy to do. I like my ton-up 33 and certainly am not looking for a 44. If the preamp is for a main system though, as said before, a LATE 44 will be fine...

    The 303 is very much a triumph of its time, but the capacitor coupling and needed current limiting to 4A (to prevent the early ouput trannies from cooking themselves) can be a severe issue with modern 4 Ohm "Euro-Boxes." Give a fettled 303 a speaker it likes however, and it becomes an utterly charming little amp with a lovely midrange. I'm one of those who doesn't necessarily agree with souping the thing up to within an inch of its life with new boards, output transistors and front panel, but there are so many around still, that the choice is yours. The basic amp in good order is still a fine and charming, if small sounding thing.
    Tear down these walls; Cut the ties that held me
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  3. #23
    Join Date: Jun 2011

    Location: NW England

    Posts: 42
    I'm Peter.

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    Ok guys after a good few weeks break from the hi-fi trail. My search for a vintage amp from the QUAD camp starts again.

    I have decided to go for a 34 or 44 with the 405-2 combo. Can someone here explain the main difference betwen the 34 (grey version) and the later 44 pre amp?

    I know the 34 has 3 inputs and the 44 has 4. The facia design is slightly different but from a musical perspective which one is a better sounding amp?

  4. #24
    Join Date: May 2008

    Location: A Strangely Isolated Place in Suffolk with Far Away Trains Passing By...

    Posts: 14,535
    I'm David.

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    The 34 has leaky-capacitor issues which affect the sonics and in worst case can damage the circuit board. I never liked the thing to be honest, much preferring the 44.

    The 44 preamp went through something of a major revision later in life and the sonics benefitted much from the change I thought, especially in reproduction of jazz, rock and percussive music in general, somthing neither the stock 34 and 306 seemed very good at IMO (ugh!). The way you identify the later 44 is by the filter/tone cancel switch and (I think) the omission of the LED showing tone-defeat - HELP BARRY

    The 405-2 needs several hours to fully sweeten up, a slightly steely sting being evident on the two I used extensively at home. The power hungry ATC's I used with the later one shortened this "warm-up" time to around an hour or so, by which time the case was luvverly and hot, but some of the later mods may eliminate this altogether.

    P.S. What bothers me about the Net Audio boards is that they are mk3 for the 303. How much "better" are the mk3 ones over the mk1's, let alone the originals, which weren't cr@p by any standards? Andr'e, have a look at -

    http://richardbrice.net/quad33&303.htm

    Good luck with your Quad hunt. Prices are rising, so tread carefully and factor in an amount for servicing.
    Tear down these walls; Cut the ties that held me
    Crying out at the top of my voice; Tell me now if you can hear me

  5. #25
    Join Date: May 2008

    Location: A Strangely Isolated Place in Suffolk with Far Away Trains Passing By...

    Posts: 14,535
    I'm David.

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    Quote Originally Posted by Andre View Post
    I love '303's infact i'm working on one now but the '33'! nay thanks
    THIS is the sodding page I was looking for regarding the 35Hz filter on the 33, which IMO constricts the bass and makes it "boppy" rather than "breathy."

    http://www.vinylengine.com/phpBB2/vi...c.php?p=190581

    Yep, C400, change from 0.068uF to 1uF (Wima's in my case). In conjunction with the dada power supply update (logically argued for on their site), the sound is transformed for the better IMO, making the 33 far more transparent to the signal it's fed with, certainly on the line stages.
    Tear down these walls; Cut the ties that held me
    Crying out at the top of my voice; Tell me now if you can hear me

  6. #26
    Join Date: Jun 2011

    Location: NW England

    Posts: 42
    I'm Peter.

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    The differences in performance between a serviced 34 and the 44 is likely to be negliable. I would therefore factor in the cost of servicing when considering the varying prices of these amps being offered for sale.

    Thanks for the advice DSJR.

  7. #27
    Join Date: May 2008

    Location: A Strangely Isolated Place in Suffolk with Far Away Trains Passing By...

    Posts: 14,535
    I'm David.

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    Have you ever compared the 34 and 44 when they were NEW? I did, on many occasions and over many individual samples. On music with any percussion, the differences in dynamic contrasts were sadly easy to hear. Adding a 306 to a 34 made it even worse, IMO.

    A LATE 44/405-2, if these can be got in good order for under £500 (tricky I suspect), would be good value today. The only thing is, the Rega Brio R is too good to ignore for a decently designed MODERN solid-state amp.

    P.S. I understand that the Current Dumping circuit was really only truly relevant in the 70's when output devices weren't supposedly as good/capable as they are these days. My Crown amps use an earlier derivative? of this idea I think, with an individually regulated Class AB stage driving equally regulated Class B output devices. The regulation on each transistor stage maintains reliability and circuit safety in a 19" rack and may just have a bearing on the sonics too.....
    Tear down these walls; Cut the ties that held me
    Crying out at the top of my voice; Tell me now if you can hear me

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