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QUDOS - the brilliant new amplifier boards from Avondale

This finally is my dual mono Qudos which has taken a long time.
Runs off 44v and set up as per instructions 120mA.
The wiring isn't pretty and is fairly basic stuff apart from silver plated PTFE for signal output and Mogami Neglex microphone for signal input.
The big heatsink is internal but well vented top and bottom, still needs more height on the rack to keep it cool than the NCC200 Nap180 it replaces.
It is in a Mogami 8cm high case on Quadraspire with on 10cm uprights.
Sounds great though, all you could possible want. A bit lean on start up but after 20 mins is full sounding, detailed with great sound stage.
Will be my best amp I think.

https://www.dropbox.com/s/h6vjfxpytmf946k/QudosDM 1.JPG?dl=0
https://www.dropbox.com/s/ytt443wozubr8kp/QudosDM 2.JPG?dl=0

Chris
 
Very good Chris. Its a hell of a feeling when something you have put together yourself works and sounds killer to boot.
 
Taken delivery of these (I have a brace) this week ....nice touch and no mistaking what they are. :)

30957590388_05d0f03c59_k_d.jpg
 
laverda said:
Taken delivery of these (I have a brace) this week ....nice touch and no mistaking what they are. :)

30957590388_05d0f03c59_k_d.jpg
Click to expand...

Very sweet...

Can we have a shot from above please? I want to check the values of R4, R27 and R5, R26 and C9, C10. There are some changes to a few values between RichardH's cct diagram and the one I built to.

Details....

Location My build Richard's scan
R4, R27 100R 27R
C9, C10 470pf 100n
R5, R26 220R 15R

Ta.
 
chrisn said:
This finally is my dual mono Qudos which has taken a long time.
Runs off 44v and set up as per instructions 120mA.
The wiring isn't pretty and is fairly basic stuff apart from silver plated PTFE for signal output and Mogami Neglex microphone for signal input.
The big heatsink is internal but well vented top and bottom, still needs more height on the rack to keep it cool than the NCC200 Nap180 it replaces.
It is in a Mogami 8cm high case on Quadraspire with on 10cm uprights.
Sounds great though, all you could possible want. A bit lean on start up but after 20 mins is full sounding, detailed with great sound stage.
Will be my best amp I think.

https://www.dropbox.com/s/h6vjfxpytmf946k/QudosDM 1.JPG?dl=0
https://www.dropbox.com/s/ytt443wozubr8kp/QudosDM 2.JPG?dl=0

Chris
Click to expand...
I turn my Qudos monoblock ex Naim 110's an hour before I need them, likewise I reckon they will see me out!
 
chrisn said:
This finally is my dual mono Qudos which has taken a long time.
Runs off 44v and set up as per instructions 120mA.
The wiring isn't pretty and is fairly basic stuff apart from silver plated PTFE for signal output and Mogami Neglex microphone for signal input.
The big heatsink is internal but well vented top and bottom, still needs more height on the rack to keep it cool than the NCC200 Nap180 it replaces.
It is in a Mogami 8cm high case on Quadraspire with on 10cm uprights.
Sounds great though, all you could possible want. A bit lean on start up but after 20 mins is full sounding, detailed with great sound stage.
Will be my best amp I think.

https://www.dropbox.com/s/h6vjfxpytmf946k/QudosDM 1.JPG?dl=0
https://www.dropbox.com/s/ytt443wozubr8kp/QudosDM 2.JPG?dl=0

Chris
Click to expand...
Nice job Chris :cool:

Alan
 
chiily said:
Ta. That's brilliant. I'll start decoding the resistor bands when I have a little time later this weekend.
Click to expand...

So, from I can make out Les does appear to be building new boards with, R4 & R27 @ 27R and R5 & R26 @ 15R. C9 & C10 are 4.7nF.

Question is now, is it worth getting the old soldering iron out??
 
Hmm, I had the resistors per the latest 1.3 spec on Les' circuit diagram, but C9 & C10 were 100nF, so that's a big change. Does it matter?
 
None of those values on my build. C9 and C10 are 470pf. There are no id numbers on my diagram or my boards for any of the resistors but I have 100R and 220R for the two resistors in the network with C9/10.
 
chiily said:
So, from I can make out Les does appear to be building new boards with, R4 & R27 @ 27R and R5 & R26 @ 15R. C9 & C10 are 4.7nF.

Question is now, is it worth getting the old soldering iron out??
Click to expand...

From my discussions with Les, it's more an evolution than a revolution, so I suspect the change would be modest. I believe that C9 and C10 are in fact optional, so the exact value is likely to be non critical.
 
RichardH said:
From my discussions with Les, it's more an evolution than a revolution, so I suspect the change would be modest. I believe that C9 and C10 are in fact optional, so the exact value is likely to be non critical.
Click to expand...

There are compensation networks on the bases of the driver transistors which help to maintain the stability of the amplifier, C9 and C10 are parts of these networks and I don’t think they can be regarded as optional.

The upper network feeding the base of TR7 is made up of R4 in series with C9 with R5 in parallel with that combination. If you think C9 is optional then R4 is also optional which just leaves R5 as a single resistor in the base of TR7. A similar argument applies to the lower network.

Mine was one of the first builds and I’m immensely happy with it. I’m going to wait a few more months for the evolution to settle before getting the soldering iron out again.
 
I've just completed this pair of NCC220 Cap6 50v mono blocks in Modushop cases
I've used RS Nuvotem transformers 0-35v x2 I think 300vA each which Graham kindly supplied at a low cost (thank you)
They are a bit grainy so far and ? harsh. Still good and may settle down
One also hums which is a nuisance
I am not convinced about the sound
I prefer the sound to the Avondale transformers previously described in this thread which supply 44v and just sound right
Eventually I need 4 channels for active IBLs but not sure I am there yet

https://www.dropbox.com/s/yzb8n4h1n38782r/Modumono1.JPG?dl=0
https://www.dropbox.com/s/mab7vwjw06rbmyb/Modumono2.JPG?dl=0
https://www.dropbox.com/s/55c9o9h2y84e4nf/Modumono3.JPG?dl=0,

Advice please?
 
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