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Effed up Quad 909 (UK made)

John W ,I thought Peter Comeau was in charge of the design ? If things are as bad as you say at Quad why has the Platignum series got such good reviews in HFN & RR & Hi-Fi World albeit I could not use the Platignum stereo amplifier due to the Hum I experienced through the speakers. Unfortunately Rob made no effort to solve the problem.
 
Interesting about the quadbus commands as I bought the Elite pre + Elite CD and found that the CD hangs with the commands for the digital inputs.
Switching to my 99pre and 99CD or combining Elite pre - 99CD or 99 pre - Elite CD there isn't any hangups...same with the "big" system remote. It works fine in CD mode but when using tune up/down for switching digital inputs it also hangs the system...weird.
 
Disbeliever said:
John W ,I thought Peter Comeau was in charge of the design ?
Click to expand...

Peters heads an acoustics design department - he has no in-depth electronics experience.

IAG China would like the outside world to believe that they are fronted by a Western designer - but its more about image, there's is so much politics involved... its China after all!
 
Zombie said:
Interesting about the quadbus commands as I bought the Elite pre + Elite CD and found that the CD hangs with the commands for the digital inputs.
Switching to my 99pre and 99CD or combining Elite pre - 99CD or 99 pre - Elite CD there isn't any hangups...same with the "big" system remote. It works fine in CD mode but when using tune up/down for switching digital inputs it also hangs the system...weird.
Click to expand...

Yes this is what happens when the legacy engineering experience and history is lost... I guess the Chinese software guys missed this one (not to blame them, as they where working blind without having the history and background info etc. to the legacy BUS command set).

They didn't even come to discuss with us (we had earlier reversed engineered the BUS and its command structure for the replacement Tuner).
 
JohnW said:
Peters heads an acoustics design department - he has no in-depth electrics experience.

IAG China would like the press and customers to believe that they are fronted by a Western designer - but its more about image, there's is so much politics involved... its China after all!
Click to expand...

so who designed the QSP without a proper relay & the Platignum ,the Chinese

Kessler liked the QSP but not WHF?
 
The Quad QSP is 99% the Quad 606/707/909 design, as nobody is left at Quad that has an even elementary understanding of Current dumping beyond the basic concept so don't expect to see any advances to this design...

The Quad Platinum was a legacy design from Quad UK operations, apparently they paid a consultant from somewhere on the English south coast truckloads of money for the designs - its just taken so many years to reach production.

6 years ago when I first met IAG they had the design "Complete" its anyone's guess why its taken so long to finally reach production - apparently halfway through the project the management in China decided that they didn't need the help of the original design team (consultants), and to avoid further expense they could take control of the project in China - the subsequent consequences of this decision are predictable.

Certainly I never met the original designer(s)? - the various nice looking prototype units sat for a few years in the offices of the head of the R&D Dept. in China with little seemly happening - in the end, certain components became obsolete and a stupidly highend ARM micro processor was designed out... Credit to the Chinese software guys who had to rewrite the software and UI basically from scratch... after such a convoluted history, the project was untidy and complex.... hence the delays. However, the amplifiers circuit originates and dates back to the UK based designers / consultants - it has no connection to Quads ealier designs (current dumping) etc.
 
Jeez, got info that they were at your door at 6:14 am...sorry. And Elvis has indeed left your building.
 
Got the Quad yesterday. Sounds very good. Thank you, John. Very kind of you to fix the problem and to improve the amp. Hope I can help you some day.
 
Thomas,

Glad its arrived safely - give it time to warm up - the new caps need time to settle in :)

I'd be interested to know if you have noticed any difference to Bass firmness or a more open treble? - I only ask as from past experience the modifications I made should help improve these areas.... but then the unit is now very different with the Quad Bus PCB removed so hard to make "direct" comparisons.
 
It is definitely more open and with "wider" image. Bass I can't say, but it gives the impression of being "faster".
What mods did you do?
I can print a schematic and add the changes to it for reference.
(I hope the caps and other components didn't cost too much. I can compensate you, if you like.)
 
Zombie said:
It is definitely more open and with "wider" image. Bass I can't say, but it gives the impression of being "faster".
What mods did you do?
I can print a schematic and add the changes to it for reference.
(I hope the caps and other components didn't cost too much. I can compensate you, if you like.)
Click to expand...

Thomas,

Dont worry about the components, nothing was ordered for your unit, I only used parts that where laying around the lab.

I'm weary of IAG China using my IP to improve the Quad QSP (which is basically the 909) - so I'd rather not reveal the circuit modifications, I detest the Chinese lack of respect for IP.

Sad really, as I'd be more then happy for others to be able to improve there own units (for personal use) - but as I've aged I recognise and now really despise Chinese IP theft. Personal use is Ok, but when someone else starts making money from my own work (without far compensation) then it upsets me.

Back in the early days of the massive MDAC thread here on PFM, an engineer from IAG China (masquerading as an air conditioning engineer or some such) posted here trying to understand our thinking behind some of the MDAC's designs more salient features - sometime later IAG released the QDAC that incorporates certain key section of the MDAC design (Clock circuit etc)...

While money has little meaning to me, I do value the results of my work as its basically what I live for...
 
Hi John,

I have the same problem with a slight hum in my 909 units. I'm sure it is earth loop problem because I changed all the resistor and caps. Can i send you photo and maybe you can tell me if something is out of the ordinary? My email is [email protected].
What is yours?

Thanks,
Dan
 
santodx5 said:
Hi John,

I have the same problem with a slight hum in my 909 units. I'm sure it is earth loop problem because I changed all the resistor and caps. Can i send you photo and maybe you can tell me if something is out of the ordinary?
What is yours?

Thanks,
Dan
Click to expand...

Dan,

I just Emailed you - I suggest you now can remove your Email from the message to avoid spam robots...
 
Hello
My Quad 909 have been modified and the ampbus have been removed. The sound has improved but unfortunately there's now a slight buzz coming from the speakers - even if there's no input. My other 909 is completely silent. I've tried changing wall sockets, cables and powercables and inverting the phase but nothing works. Any ideas please?
 
Check if the signal cables are correctly connected. Earth to signal and signal to earth might cause the buzz
 
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