quad 606 / 2

I've a 405/2 and a 306 - both make only a mild 'plip-plop' at on/off.

BTW the 306 has a mains switch on the front - right hand side just beneath the logo.

My 34/FM4/306 are all connected via the switched IEC sockets on the back, so one switch can turn the lot on or off. Th 405 operates likewise if in use.

I wouldn't worry about the noise though as it won't do any harm.
its only a worry if using very high sensitivity speakers with limited excursion such as Lowthers.

 

£150 should bag you a nice clean 306.
They are reliable amps, and cheap to post due to the small size.
Have a punt - you can sell it on for no loss very easily.

I've serviced a few of these for people and slightly uprated the PSU in the process.
If you try one and it seems to drive your speakers without stress I'll happily give it a service and refresh for cost of parts. About £35 covers it.

306/606/707/909 all use the same circuit with only two differences. The 306 uses a smaller PSU commensurate with the 50wpc rating and smaller chassis.
The 306 has one pair of dumper transistors per channel whereas the others use multiple devices in parallel to give high current capability.

 

It'll be running ESL63s in a medium sized room and occasionally running Tannoy Monitor Golds. h latter shouldn't present a problem but is this enough grunt for 63s?

 

Quad said so in their product literature for both products at the time, though it depends how loudly you listen. If you are running them up near the limits then a 606 is preferable.
Mine copes fine with 57s.... and 63s will only play a little louder.

 

I've read in some places that some people are happily using passive preamps with Quad 405 amps. Are both the 405 mk1 and 2 sensitive??

 

More sensitive than the standard line input - from memory 300mV (330mv?)

I had mine adjusted to modern standard as it was refurbished.

 

Passive into a 405 is fine.

Given the 20k input impedance, and assuming the output stage on your sources is robust, try going with a 5k pot and <50cm low capacitance interconnects.

 

I just bought a 606 mk I for powering Proac Studio 100s monitors in my home recording studio. I paid £310 - I understand is not the best of deals, but thats what they seem to be going for on Ebay at the moment. I don't monitor at high volumes, however my speakers need plenty of juice and the 606 should be able to provide it. Hopefully it will arrive in one piece!

 

A 606 will toss Studio 100s around like a play thing.
Should work very well together.

 

Hello
Can anybody recommend some good tweaks to get the quad 606/2 to perform even better:
- powerchords
- fuses
- feet/ spikes
- platforms
- etc??

thanks a lot!

 

Hi,

None of the those things will make any difference to performance.

Powercords/fuses - The effect of the supplied items is negligible in terms of altering the mains impedance seen by the amplifier. The Quad is also well filtered and therefore any special filtered cables will also bring no improvement.

Feet/spikes/platforms - The 606 isn't microphonic and the performance will not change however you mount it. Just ensure it is ventilated.

As supplied it is transparent to what goes in, and you can't get more transparent than transparent

 

Thanks Rob!

 

There may be some electronics tweaks Rob can recommend, such as replacing the op-amps at the input section. It is worth understanding though, that even if the performance can be technically improved by such things, you may well not hear it! Noise floor dropping 10dB from inaudible to even more inaudible

 

A 606/2 is very well sorted as standard. It shares a circuit with the smaller 306 and omits the front end op amp used in the earlier 405.

The only things I'd do to the 606/306 are periodic recapping and perhaps adjust the input sensitivity (down) when used with some preamps.
These are very easy amps to maintain, as other than the 4 PSU caps there is only one other small electrolytic on the board IIRC. All the rest are film caps.

 

- and no bias setting to wander or adjust

 

I just got my 'new' 606 mk 2 - a refurbished piece with new nichicon caps, audio grade opamps and lowered sensitivity. It's as new in appearance - very beautiful!
I've matched it with a Music First Audio passive pre. I'm afraid it's not a very good match, as I feel that I really have to crank it up to get decent dynamics. Can you suggest any alternative preamps apart from the matching quad 44's and 66's?

 

Michell (or Trichord) Orca.

A bit rare, though. But very very good.

 

Why did you lower the sensitivity? Go and get that put back as it was and it will be a better match for the Music First. Also if it has been extensively refurbed it will need a few hours on it before you really appreciate what it can do. Finally leave the amp on for 24 hours straight before really critical listening. It might all be placebo, but I heard a 606 sound much better to my ears after being used for a while (it had been boxed and unused for an extensive period prior to being purchased by a friend).

 

Michell Orca.. Hmmm - interesting!
Thanks for the advice! I'll consider getting the sensitivity returned..
As to the running in issue it was burned in for 500 hours by the workshop, that ought to be enough ;o)