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Quad 33 & 303 queries

one thing for sure if upgrade zener to 16v and 3 x 1000uF it improves the quality 33 , making sure you replace snubber 100nf 47 ohm.
 
303 fail one channel down humming/loud . any direction to correct it please ,assume its a cap.. thanks Al
 
Do you have just a hum or is there hum on top of the music?
What were you doing when it started?
Do you have the schematic, plenty on the web (look for Quad 303 Service Data if not).
Open it up and look for obvious damaged / burnt parts.
Then check voltages. The service data has most marked, but start with making sure there is no voltage across the speaker terminals. Next the 67 volt line then the positive of C1 should be about half that 33v ish. And so on...
 
hum alone/one channel present with out 33 connected ie 303 powered up to speakers also.... powered up with 33, THANKS hum on left channel music ok on left channel
 
If I understand correctly, the left channel hums and still plays music ( so is working OK apart from the hum ) then the electrolytic capacitors associated with the left side would be a good place to start. Just as you surmised.
 
Still not clear to me whether hum and music present etc. The crucial thing is if it is just hum. Need much more info from op on this really.
 
output caps micro values are very low, input are little swelled ,waiting for new caps on their way, thanks
 
Very unlikely to be the problem. No more help from me as you can't /wont even answer simple questions to allow us to diagnose it.
 
Nic Robinson said:
Have you tried it with a passive pre? Would be interested in your conclusions.
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Dragging this thread back to life following my passive experiment with my 303.

Having freed up a bit of cash by selling something else a while back, I bought a Khozmo passive to have a play with (bog standard, none of the upgrade options). It definitely cleans up the sound and reveals a fair bit of detail that's lost via the 33, and feels like a good match to the 303.

Listened via the Khozmo for 3 weeks and then yesterday swapped back to the 33. Immediately I can detect that the 33 is a little less revealing in comparison but you know what, it also adds some 'body' to the music that I really like. It's a shame that it's such a palaver swapping between the two preamps what with the different cables required, but I'm certainly in no massive hurry to swap back to the Khozmo. I shall keep both.
 
Calorgas,

Any further thoughts? When I get to the holiday place next week I'm tempted to pop the 33 back in to see if it beats the Tisbury that's currently there.
 
Nic Robinson said:
Any further thoughts? When I get to the holiday place next week I'm tempted to pop the 33 back in to see if it beats the Tisbury that's currently there.
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I don't suppose I have an awful lot more to add to what I said previously, and the reality is that (at the moment) I'm still using the 33.

I think the 303 + passive definitely sounds more 'hifi' than when using the 33, so if accuracy is the priority then the passive easily wins out. However I gotta say I enjoy the benefits of tone controls to enhance the bass a weeny bit, the ease of turning the system on and off via the 33 and the overall look and feel of the 33. It still sounds very good to me and right now I can enjoy listening to it despite knowing that it's possibly not the last word in fidelity.

You don't have anything to lose by giving the 33 another go if you have a bit of time to kill, even if in the end you decide that you prefer using the Tisbury. I expect that I'll swap back between the 33 and Khozmo at least a couple more times over the summer, driving myself and my family further round the twist :confused:.
 
Listened via the Khozmo for 3 weeks and then yesterday swapped back to the 33. Immediately I can detect that the 33 is a little less revealing in comparison but you know what, it also adds some 'body' to the music that I really like. It's a shame that it's such a palaver swapping between the two preamps what with the different cables required, but I'm certainly in no massive hurry to swap back to the Khozmo. I shall keep both.
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Agree completely. I found the same. Standard passives with pot, box and wire were generally more 'hifi' sounding than the 33, the degree to which largely depends on materials used ie silver, copper, different pot types. The sound didn't have as much slam/ oomph as an active preamp and majored on detail rather than flow. The active 33 was not as detailed, with a more general sound, but had more oomph and was more airy.
The MFA transformer coupled passive had the audiophile sound and the oomph, even as a passive, but at a premium.
Ive moved away from bog standard passives when Im using Quad power amps.
 
The 303 seems very happy with a valve preamp too, it sounds excellent with my Verdier and I’ve had great results eith Croft in the past. The Croft Basic being exceptional value IMHO.
 
regafan said:
Agree completely. I found the same. Standard passives with pot, box and wire were generally more 'hifi' sounding than the 33, the degree to which largely depends on materials used ie silver, copper, different pot types. The sound didn't have as much slam/ oomph as an active preamp and majored on detail rather than flow. The active 33 was not as detailed, with a more general sound, but had more oomph and was more airy.
The MFA transformer coupled passive had the audiophile sound and the oomph, even as a passive, but at a premium.
Ive moved away from bog standard passives when Im using Quad power amps.
Click to expand...

I’ve found that a Quad amp sounds absolutely fantastic when using a passive pre. In the context of my system all I need is a simple volume knob, there’s only one input, and in theory I could plug it directly into the power amp, using the Chord Mojo’s own volume control. I just like having a knob though. I suspect ultimately it comes down to having the right control, with the right impedance.
 
The Quad 303 input impedance is set by R101 22k in parallel with R100 220k, so about 20k. Most passive preamps will be high enough resistance at mid volume potentiometer range to be loaded by this.
 
Tony L said:
For cleaning Servisol Foam Cleanser 30. It is truly amazing stuff! Just strip the 33 down as far as you can, e.g. unscrew the knobs, remove the front panel etc, and clean the parts individually. Be very careful indeed with the illuminated logo, that part is exceptionally fragile. I'd be inclined not to clean it as it is very easy to accidentally remove the paint (it just pulls out from behind, so you can remove it when cleaning the rest of the facia). The Servisol is safe on all other parts of the case (I know this as I've cleaned a couple of 33s up, in fact I've got one in the classifieds room somewhere). I've no idea how the back panel comes off, I couldn't figure it out and didn't want to break it. It looks very fragile. For cables I use Gotham GAC of eBay, e.g. this DIN to phono lead. They do custom lengths if you ask.
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Tony, I have a 33/303 combination sans cables. does this cable recommendation still stand? not looking to spend large mounts.

Thanks,

Simon
 
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darkmatter said:
Tony, I have a 33/303 combination sans cables. does this cable recommendation still stand? not looking to spend large mounts.
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Yes, very much so. The GAC-1 stuff is superb IMHO, better than many very expensive ‘high-end’ cables to my ears. A real bargain and they are very well made indeed. I use a lot of it across my various systems.
 
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