Quad 909 Modification

Hello guys,

I posted a thread in neighboring country forum, thought I should post it here as well.

I get influenced and acquired a Quad 909, for my new Harbeth P3ESR.

Reviews, discussions, revisions, modification of Quad 909 from internet makes me very itchy to get mine "upgraded".

Assuming IAG did a good job in main transformer, resistors, and transistors, I'll be replacing the mainland-made capacitors with BHC, Wima, Nichicon, Silvered Mica. I'll also be removing the Quadlink ampbus with phono RCA jacks, rewire all internal wire with MOGAMI cable, copper sheet tape the main trans to reduce possible EMI. Quad binding post are made by CLIFF UK, assumed it's good and will not touch it ;D

Gathered most of the components and materials ready, will start diy post CNY!!







Excited!

Internal Pic of my Quad 909:

Confirmed china-made. Capxon capacitors....


Quadlink must removed  ;D


+ve -ve DC supply and speaker output wiring will change & solder-on instead

Hello Guys,

Spent good 12hrs yesterday from 10am - 10pm to complete the mod ! Exhausted  
It may look simple, but it isn't, trust me  >

Naked Transformer


Copper Taped Shielded  ;D


Reservoir Capacitors


Replaced with BHC & Mounted AC Trans




MOGAMI Snake Speaker Cable, 2.5mmsq each core, used for internal wiring; very flexible & quality !


Quad Link removed, replaced RCA input with solid copper RCA jacks




Chassis, Rectifier Board Almost There


Original Quad Amp Board




Replace low-cost capacitors with quality ones


Both Amp Boards done, next to secure them on chassis & re-wire


That's it! Done!


Beautiful isn't it? I really like my workmanship. LOL  ;D


Powered up & measure the necessary with DMM:

Positive Rail to Virtual Ground Measured +58.4VDC (specs +57.8 )
Negative Rail to Virtual Ground Measured -54.6VDC (specs -53.4)

Supply voltage normal, pretty close to specs, likely due to higher AC incoming voltage in my place.

Right Speaker Output 0.05mVDC - Okay
Left Speaker Output 0.02mVDC - Okay

Safe to connect source & speakers! I didn't connect to my Harbeth yet of course, hooked up a pair of test (lousy full range) speakers, and it SINGs! 

Left overnight for 8hrs+, runs warm & still singing. Should stress test it couple of days & measure the parameters again before I connect my P3ESR! ;D

Wonderful!, Thanks for sharing. Yes I like you work too!

Nice work!
I'm sure you will like what's to come from your Harbeths when you hook them up together.

Thanks for the compliments :-)

great work & good details, helpful to quad 909/606 whom wishes to upgrade diy

Nice. Can write a review? It would b wholesome.