Quad 909 service life

[naimnut]

How long do you all think a Quad 909 power Amp would last before requiring a service?

 

[evand]

Eons

 

[Mike P]

When production moved to China Quad unfortunately started using cheaper lower quality capacitors from Capxon. These are known to be a bit unreliable compared to better quality parts.

I've just recapped mine and it was ready for it. Some of the original Capxon capacitors measured as having high ESR.

Recapping with new high quality parts brought out quite a lot more crispness and detail in the sound.

 

[camverton]

Both mine needed attention within five years fwiw.

 

[stevec67]

Both mine needed attention within five years fwiw.

That's poor. Should be 10 years minimum and generally 20 years for well designed kit.

 

[kernow]

Mine was fine after about 8 or so years before I sold it on

 

[davidsrsb]

That's poor. Should be 10 years minimum and generally 20 years for well designed kit.

With a normal power cycle, not left on 24x7

 

[camverton]

That's poor. Should be 10 years minimum and generally 20 years for well designed kit.

That’s what I thought! Both were exdem and iirc early chinese manufactured. Both used for extra channels in an AV setup and not left on when not in use. On the other hand I still have an old 303 and 606 that were still going strong when I last used them.

 

[stevec67]

That’s what I thought! Both were exdem and iirc early chinese manufactured. Both used for extra channels in an AV setup and not left on when not in use. On the other hand I still have an old 303 and 606 that were still going strong when I last used them.

Me too a 405 and a 303. I really like the 606, and the 520/510 that are the pro versions and pretty much bulletproof.

 

[davidsrsb]

Both were exdem and iirc early chinese manufactured. Both used for extra channels in an AV setup and not left on when not in use

Exdem could mean switched on in the shop for years

 

[camverton]

Exdem could mean switched on in the shop for years

Not impossible although they iirc they hadn’t been out long and one of the dealers I knew quite well and they didn’t normally leave kit powered up which is not surprising in that they had 7-9 dem rooms; would have been a fair old power bill if everything left powered up!

 

[davidsrsb]

The other possibility is that these Chinese capacitors were from the same origins as the PC motherboard electrolytic disaster. These self destructed after a few years due to a bad chemistry choice.
There are plenty of good quality Chinese capacitors these days.

 

[Tony L]

The other possibility is that these Chinese capacitors were from the same origins as the PC motherboard electrolytic disaster. These self destructed after a few years due to a bad chemistry choice.

This is a known issue with some 909s. The design is good, so if rebuilt with better caps it will last a very long time. Same with some other IAG kit, e.g. MDACs were plagued with capacitor issues at one period.

 

[naimnut]

How does one know if their amp has this problem?

 

[Tony L]

How does one know if their amp has this problem?

I’d check manufacturing date, capacitor brands etc against reports of failed amps. IIRC there is a fair bit of 909 content on the Dada Electronics Quad Spot blog if you hunt through. I certainly remember skipping past a good bit of 909 content when reading up on the 303 and 34. Some 909s certainly have bad caps. That much I remember!

 

[davidsrsb]

The bad years seem to be 1999-2003
https://en.wikipedia.org/wiki/Capacitor_plague
Some bad stock must have been in the supply chain after that.
Edit The timing does seem about right, I see a review of the 909 in 1999