quad 606 / 2

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chrisB1

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Sorry if this is a dumbass question, but is the 606 / 2 identified as such on the case somewhere ? Just asked a question of someone selling a 606 on fleabay & he says he can't say if it's a later 'mk2' or an earlier one. Cheers.

Chris
 
This is a 606 Mk1

Quad_606_Power_Amplifier.jpg



and this is a 606 Mk2


750848254_7BXrVROi_quad606.jpg



Chamfered edges and small orange 'Quad' on the later version.
 
As a matter of interest, what do you think would be a rasonable price for a 606 / II + 66 pre-amp & controller (good outward condition - dealer selling) ? I suppose I should be asking what is the most I should pay for this combo !?

Cheers,

Chris
 
Hi Chris,

Probably £250-350 for each unit if in good condition.
The Pre/controller seems more scarce so likely to be the more expensive of the pair.
I'm considering a 606 myself at the moment - the little 306 can run out of puff on certain speakers.
 
Beyond 'puff' is there much to choose between the various Quad current dumpers? I've just picked up a 405-2 for a goodish price, just as something ESL friendly that I can run round the clock without worrying about valve life.
 
Little difference John, certainly nothing to worry about.

The input stage on the 405 is different and based around an op amp.
The 306 and 606 lack this and apply the missing gain later in the circuit.
The way that the op amp input in configured means the 405 has a little more residual hiss but that will only be a concern if you use high sensitivity speakers such as horns.
You'll have no problem with ESLs.
 
Thanks again Rob. Again, as a matter of interest, what are the main differences in the later (ie 900 series) amps ? Would the 909 be a good match with my Gales do you think ? (still waiting for the fleabay result on the 606).

Chris
 
Okay another quickie about the 405 if anyone is reading. I've just bought one but one channel seems to be dead. It may be the fuses. However, having changed them, I now can't switch it on without blowing the main fuse (2.5 A/250V). Is this a common prblem when powering straight from the mains rather than via the pre? Can't see whay it should be and I didn't initially have this problem.
 
If the mains fuse is blowing when you replace the fuse on the pcb (for the dc line) it strongly suggests that the output stage has blown.
That is very difficult to do on a 405 given the protection circuits - assuming these haven't been removed or tampered with.
The duff board is pulling far too much current and so blowing the mains fuse.

Send it back John.
 
RobHolt said:
If the mains fuse is blowing when you replace the fuse on the pcb (for the dc line) it strongly suggests that the output stage has blown.
That is very difficult to do on a 405 given the protection circuits - assuming these haven't been removed or tampered with.

Send it back John.
Click to expand...

Thanks - The seller has already agreed to take it, no questions.
 
John, just one last thought.

The internal mains fuse should be 2.5A anti-surge type.
Worth checking that a standard fuse hasn't been fitted.
 
I think it should Mark.

Personally I'd recommend replacing even working fuses at service since most get stressed in use.

Another idea for John, as this 405 looks dud and is going back, try s 306 which along with the 606 is essentially a 405 with the benefit of an extra decade of development.
The current limiting is very different and less aggressive than the 405 - essentially you have a trip sitting in the AC line so that when the whole amplifier draws too much current the thing just turns off.

It's a small power amplifier - smaller than a Naim Nait 1 to give you some idea - so is no power house but you get a real 50w/8R and 75w/4R.
One benefit over earlier amplifiers is the omission of the OP amp input stage and something closer to dual mono PSU - each channel having its own smoothing caps, rectifier, and traffo winding.
Servicing is easy and cheap. Just four PSU electrolytics and four smaller caps on the main board. There is nothing else inside that should need replacing unless the amp has ben abused. You can usefully use slightly larger PSU caps and up the voltage rating with today's caps which are both smaller and superior to those available 20 years ago.
So a nice clean 306 including the cost of a DIY service comes in at under £200.
 
RobHolt said:
I think it should Mark.

Personally I'd recommend replacing even working fuses at service since most get stressed in use.

Another idea for John, as this 405 looks dud and is going back, try s 306 which along with the 606 is essentially a 405 with the benefit of an extra decade of development.
The current limiting is very different and less aggressive than the 405 - essentially you have a trip sitting in the AC line so that when the whole amplifier draws too much current the thing just turns off.

It's a small power amplifier - smaller than a Naim Nait 1 to give you some idea - so is no power house but you get a real 50w/8R and 75w/4R.
One benefit over earlier amplifiers is the omission of the OP amp input stage and something closer to dual mono PSU - each channel having its own smoothing caps, rectifier, and traffo winding.
Servicing is easy and cheap. Just four PSU electrolytics and four smaller caps on the main board. There is nothing else inside that should need replacing unless the amp has ben abused. You can usefully use slightly larger PSU caps and up the voltage rating with today's caps which are both smaller and superior to those available 20 years ago.
So a nice clean 306 including the cost of a DIY service comes in at under £200.
Click to expand...

I've been looking at both the 306 and 606 as alternatives. I wasn't entirely convinced that 50W was enough power - I don't want to overheat it - but the 606 is a bit of a monster and a lot more money. I notice that the 306, like the 405 omits a mains switch (not sure I like this) but then again the 606 has been criticised for major thunk on switch-on. Decisions decisions!
 
DrMartin said:
My 6 month old 909 does that so they haven't come very far. It 's the only thing I don't like about the amp.
Click to expand...

They are designed to be controlled from the Pre-amp!

I have the same problem. I switch it off at the wall! The DAC stays on.
 
Labarum said:
They are designed to be controlled from the Pre-amp!

I have the same problem. I switch it off at the wall! The DAC stays on.
Click to expand...


So they say, but the pre - amp does not actually turn the 909 power amp off - even when connected with the amp-bus. All it does is change the colour of the LED on the 909 from Blue to Red, when you switch the pre-amp to stand-by.

The pre-amp goes to stand-by but the 909 power stays powered up unless you switch it off with the power switch at the rear (which is a pain IMO).

I know it sounds daft but it's true and it is even spelt out in the instruction manual, which also tells you to switch the pre-amp off before switching off the 909 - which I always do.

After both have been switched off completely you get a nasty "scratch" sound from the speakers, after about 5 seconds. I don't like it.
 

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