Quad 909 Review?

[DSJR]

The Australian offshott serviced my 606 about 15 years back.... good service.

Good to know.

The 606 family of amps (more similar than different as the models evolved) are, in my book, good and safe used buys with a proven track record and relative ease of servicing. This family of amps had easy four ohm drive too, unlike earlier models such as the 405mk2, which tops out at 6 ohm and limits while getting rather warm below this (not so sure about the low powered 306 which shares some design similarities).

 

[dlaloum]

Good to know.

The 606 family of amps (more similar than different as the models evolved) are, in my book, good and safe used buys with a proven track record and relative ease of servicing. This family of amps had easy four ohm drive too, unlike earlier models such as the 405mk2, which tops out at 6 ohm and limits while getting rather warm below this (not so sure about the low powered 306 which shares some design similarities).

It's not exactly a powerhouse into lower impedance loads... but it handles them without strain, and without increase in distortion, making it an excellent choice for difficult speakers.

 

[DSJR]

Funny that. Fifty years ago, the Crown/Amcron DC300A was regarded as an 'animal' of an amp - 180WPC or so at 8 ohms and 260+ WPC at 4 ohms from memory (I believe these are conservative figures, as was the custom back then). These days, it's a softie compared to what's around now. The 606 when launched in the late 80s, also came with cautions as regards the output available

Times do change and amps along with them, it seems The latest Artera Stereo power amp, has had its bandwidths increased a little further apparently, but I very much doubt it's a subjective thing really, as any sonic change if there is one, could be in the redesigned? balanced input stage, now the Quadbus is no more.



P.S. Dada.au do have a record of all the product updates the EU shop used to supply kits for. Here's the one for the 606 family. Most of it may not be of any use to a later version such as the 909, but if any reader here finds a 606 at a good price and bearing in mind that UK sourced supply caps may not last as those in some US and a lot of far eastern amps do, the list of parts may be useful now the kit itself isn't available -

https://dadaelectronics.com.au/doc/Audio/Quad/Quad%20606/Quad-606-MK-I-II-707-and-909-Upgrade-Revision-Manual-V2.6.pdf

 

[john11]

£550 is an excellent price for a FULLY SERVICEABLE power amp which is happy with 4 ohm loads. Quad's service dept now do updates to older stuff (a pal had his 34/FM4/405-2 fully 'done' in Huntingdon recently and they realy went to town on them, surprisingly so, upping the FM4 to extra presets as well as the usual memory battery and recapping the 34 (can't remember what was done to the 405-2 but it was similarly refreshed!

Quad 606/707/909 family of amps are great and now traditional type models. HiFi World (now defunct), which was a valve/vinyl/Tannoy speaker kind of place for years, tested some power amps and were very pleasantly surprised by the bench tests and also of course the 'sonics' of this model. When I can, I'll dig the review/measurements out and scan them.

The very first 606s took a couple of hours to 'warm up' and lose a little 'grain' we all heard up top, but this was soon sorted and the later breeze-block 606s were pretty much 'there' right from cold starts. late 606s and the chamferred 606mk2, had a toroidal mains transformer and a 50% increase in supply capacity (twin 10,000uF became twin 15,000uF) which I believe were longer lasting than the leaky 405 supply caps.

The 707 had then deeply unfashionable and unknown in domestic audio 'Speakon' connectors, which have lately been shown to be superior to 4mm plugs or spade connectors. Superb amp, but no idea if anything was changed in the circuit.

The 909 had the Quadbus input and here may be a subject for discussion. Early Chinese made models had sub-standard caps, but these should have been dealt with by now. All subsequent production were fine, as was the QSP and the superb and still reasonably priced (compared to the overpriced bling-tat some of our high end dealers sell) Artera Stereo I love so much - the Artera preamp's nice too and superbly built and presented I think. The Artyera pair on dem at my local audio salon all but disappeared in a display system sat alongside acres of 'Fraimed Naim boxes' and they now don't seem to sell the brand, which obviously isn't as profitable as the other stuff they promote at multiples the price (but I'd suggest not multiples the performance).

Does that help? Once my 'Linn/Naim-chip' had been extracted in the late 80s and I woke up and started looking around with fresh eyes and 'ears,' I was amazed how capable this Quad block of a thing actually is, as it'll drive 230WPC or so into 4 ohms without current limiting or cooking to death as the 405s do. Sure the modern whizz-BANG chip amps raved over here will do better on the bench and Class D has finally come of age, but the 606 family of Quad power amps will be running I suspect, long after the others are in landfill!

When you said Fully Servicable you were not kidding. Just changed all the film caps to wimas, replaced the electros with new quality ones, new mogami input cable, van damme speaker cable. Now the 909 blows the topping pa5 II away in every department
Before the mods the topping was slightly better with more detail

 

[DSJR]

When you said Fully Servicable you were not kidding. Just changed all the film caps to wimas, replaced the electros with new quality ones, new mogami input cable, van damme speaker cable. Now the 909 blows the topping pa5 II away in every department
Before the mods the topping was slightly better with more detail

I'd obviously suggest the wiring and film cap change probably wouldn't be necessary, but the electrolytics maybe A couple of inches of wire compared to what's in there? Well, you know the 'ASR' response to that

Early Chinese made 909s were tricky due to the electrolytic caps not being as good as they should be (it was around the time of the 'issues' that affected many electronic items then), but this was sorted. The main issues I gather *could have been* the Quadbus input, but you'd need to check the dada.au site and the Dada blogspot for any info (not owning one of these, I can't remember exactly where I read it). The current Artera Stereo doesn't need any mods at all in my opinion, it's so good at the job!

 

[john11]

The first thing i did was to take out the quad bus, then fitted in new rca sockets.
The mogami input cable i felt was necessary. The cable is perfect because it is heavily sheilded and needs to be because it is near that huge transformer which is chucking out tons of EMF radiation
I remember my old quad 405-2, i took out the transformer and placed it in an external abs enclosure one metre away which really helped to clear up the sound, so i can corroborate that this EMF interference mod does work.
The film caps made a minor improvement, but wima's are cheap and i had already stripped the amp down so a few seconds shoving in a few caps made sense
The speaker cable made a minor improvement over the cheap steel cable
I also soldered polypropylene's onto the back of all of the electros, this made a big difference. I read in a post on another forum someone substituted c7 for a 47uf film cap

 

[mdunjic]

I'd obviously suggest the wiring and film cap change probably wouldn't be necessary, but the electrolytics maybe A couple of inches of wire compared to what's in there? Well, you know the 'ASR' response to that

Early Chinese made 909s were tricky due to the electrolytic caps not being as good as they should be (it was around the time of the 'issues' that affected many electronic items then), but this was sorted. The main issues I gather *could have been* the Quadbus input, but you'd need to check the dada.au site and the Dada blogspot for any info (not owning one of these, I can't remember exactly where I read it). The current Artera Stereo doesn't need any mods at all in my opinion, it's so good at the job!

I serviced mine, Chinese made Quad 909, with local Dada Electronics North America here in Oakville, Canada (North American partners of Dada Europe) and of course Quadbus was gone he he ... I never used the Quadbus anyway in my 15 years of 909 usage.

 

[john11]

I serviced mine, Chinese made Quad 909, with local Dada Electronics North America here in Oakville, Canada (North American partners of Dada Europe) and of course Quadbus was gone he he ... I never used the Quadbus anyway in my 15 years of 909 usage.

Good point. The quad bus was a failure. And there was such small improvements between the 606 707 and 909 that it seemed like quad were just going around in circles, it's no wonder the company closed down with so many poor decisions being made.

And I've compared my fully modded quad with my topping pa5 II and the quad does sound better, but i'm in the territory of diminshing returns, that i will have to spend a lot of money to get very little improvement. I would have stuck to the topping but the only reason i moved away to the quad is to get more power. I have to run the topping at full blast to get the sound pressure levels i am after

 

[Spurs27]

Some prefer the Quadbus/Ampbus input phono connection. The signal just runs through one OPA275 opamp.

 

[john11]

How do you think the 909 would feel about a one ohm load. Some of my amps are happy with a 2 ohm load but struggle with anything lower. My old 405-2 seemed to get along quite happily with one ohm drivers

 

[Spurs27]

How do you think the 909 would feel about a one ohm load. Some of my amps are happy with a 2 ohm load but struggle with anything lower. My old 405-2 seemed to get along quite happily with one ohm drivers

You mean that you will connect a 1 ohm resistance to the amp?

 

[john11]

You mean that you will connect a 1 ohm resistance to the amp?

Well it will be more like one ohm impedance rather than resistance, but some amps I’ve owned don’t mind, some do grumble though

A driver with a 4 ohm nominal impedance will likely have a minimum impedance of about two ohms. A dual voice coil driver has a nominal impedance of 2 ohms and a minimum impedance of approximately one ohm

 

[Spurs27]

Well it will be more like one ohm impedance rather than resistance, but some amps I’ve owned don’t mind, some do grumble though

A driver with a 4 ohm nominal impedance will likely have a minimum impedance of about two ohms. A dual voice coil driver has a nominal impedance of 2 ohms and a minimum impedance of approximately one ohm

If the 405 managed, 909 will probably too...

 

[john11]

If the 405 managed, 909 will probably too...

Thanks ! I'm looking to purchase an inductor to make a crossover, which will be put into a speaker to use with the quad 909.
The inductor has the following specs :



Do you know what is meant by internal resistance in the specs. I thought the inductor's resistance is always changing with frequency and is usually called inductive reactance rather than resistance

 

[Spurs27]

Thanks ! I'm looking to purchase an inductor to make a crossover, which will be put into a speaker to use with the quad 909.
The inductor has the following specs :

View attachment 398515

Do you know what is meant by internal resistance in the specs. I thought the inductor's resistance is always changing with frequency and is usually called inductive reactance rather than resistance

It's DC resistance, AC resistance is impedance. Generally very low impedance in higher frequencies isn't that problematic, but at lower frequencies it might be.

 

[dlaloum]

How do you think the 909 would feel about a one ohm load. Some of my amps are happy with a 2 ohm load but struggle with anything lower. My old 405-2 seemed to get along quite happily with one ohm drivers

The 909 will handle it fine - the specs do state "unconditionally stable into any load".

The gotcha is that the performance is then current limited, you will only get about 40W continuous into 1ohm. (around 90W peak into 1Ohm) - this is plenty for most domestic circumstances.... but may be a limiting factor in some situations.

 

[john11]

It's DC resistance, AC resistance is impedance. Generally very low impedance in higher frequencies isn't that problematic, but at lower frequencies it might be.

Thanks ! Does that mean the inductor will add 0.6 ohm resistance at all frequencies

 

[john11]

Do you know if 63 volts caps can be safely used in the 909 power supply. The stock caps in my 909 are 80 volt 15,000uf. But dada say they use 63 volts. I think the 909 power supply is 57 volts but am not sure

 

[Spurs27]

Thanks ! Does that mean the inductor will add 0.6 ohm resistance at all frequencies

Isn't it DC resistance? It also depends on where the coil is in the circuit.

 

[john11]

Isn't it DC resistance? It also depends on where the coil is in the circuit.

Okay, but if 0.6 ohms is the resistance of the wire used to make the inductor then that 0.6 ohms should be at all frequencies ?