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QUDOS - the brilliant new amplifier boards from Avondale

The grand(ish) plan, that I can't quite shift from my head, is to build another stereo 220 amp, get hold of a minidsp 4x10HD, a sub (maybe two in the long run...) and run everything active and let the mini monitors only handle stuff over 100Hz or thereabouts. The ports chuff like a train on bass heavy music, but sound good otherwise. All possibly complete overkill for a 8x10 single bedroom being used as a home office :)
 
That’s uncanny James! I was thinking of something similar using a pair of NCC300s and a pair of NCC220s ( both of which I have) in conjunction with minidsp to actively run either my IMFs or my TDLs. I believe minidsp are giving up with the kits?
 
Looking at the boards linked to on eBay between tp1 and c1 there is a 1k and a 22k resistor. Make them both 1k. Can’t remember if I had to redo the bias but you ought to check it
 
timH said:
Looking at the boards linked to on eBay between tp1 and c1 there is a 1k and a 22k resistor. Make them both 1k. Can’t remember if I had to redo the bias but you ought to check it
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Thanks, I'll give that a try and hope it doesn't any magic smoke to escape :)
 
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divedeepdog said:
Is that regulated amp then, like a Nap250/135? I've got older Voyagers with NCC200 / HCR front end. Must get them to Avondale towers for updates, 220's (with HCR ) or 300's ??
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Yes, I decided to get the Reg & Qudos boards this time round for the new amp build. I should have actually tested with and without the reg boards to see what differences there are, but didnt really have the time to do it.
 
I hope you all don't mind me intruding on a thread that I am so clearly not qualified to be a part of - I know how to open a black box, can change a fuse but otherwise know nothing whatsoever about building an amp..

I currently have an Avondale Zap 250 with these bits inside (its a Naim 250 case) -
2 x NAIM NAPA4 power amp boards serviced by Avondale and SOA components removed.
2 x 350VA toroidal transformers
2 x MiniCap6 rectifier/smoothing boards

I have just asked Les about upgrading it, and he suggests that I can drop in some Qudos modules, and that it really is plug and play.
I've tried to understand a little of the last 40 pages of this thread and while most of it is way beyond me it seems that there really is only half a dozen push connectors to swap over, though Les does say that there is a test using a multimeter to do, which fills me with dread, as I've never used one, but I guess it isn't too hard, and am sure I can ask if I struggle.
One question is that some of you say the amp should be turned off when not in use - my Zap 250 is used maybe 10 hours a day so I leave it on at all times - do I need to turn it off (the switch is at the back, so it would be a bit of a pain if I did need to)
The other part of my question is this - are there any other bits that it might be beneficial to replace, and if so, are there people here who might consider doing the work for me - obviously I'd be happy to pay. I'm in Cornwall, but often up in London.
 
That’s uncanny James! I was thinking of something similar using a pair of NCC300s and a pair of NCC220s ( both of which I have) in conjunction with minidsp to actively run either my IMFs or my TDLs. I believe minidsp are giving up with the kits?
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If my next ebay purchase works out, I'll have an unused minidsp and room correction mike to sell on. If you're interested, let me know.
 
steveinspain said:
I hope you all don't mind me intruding on a thread that I am so clearly not qualified to be a part of - I know how to open a black box, can change a fuse but otherwise know nothing whatsoever about building an amp..

I currently have an Avondale Zap 250 with these bits inside (its a Naim 250 case) -
2 x NAIM NAPA4 power amp boards serviced by Avondale and SOA components removed.
2 x 350VA toroidal transformers
2 x MiniCap6 rectifier/smoothing boards

I have just asked Les about upgrading it, and he suggests that I can drop in some Qudos modules, and that it really is plug and play.
I've tried to understand a little of the last 40 pages of this thread and while most of it is way beyond me it seems that there really is only half a dozen push connectors to swap over, though Les does say that there is a test using a multimeter to do, which fills me with dread, as I've never used one, but I guess it isn't too hard, and am sure I can ask if I struggle.
One question is that some of you say the amp should be turned off when not in use - my Zap 250 is used maybe 10 hours a day so I leave it on at all times - do I need to turn it off (the switch is at the back, so it would be a bit of a pain if I did need to)
The other part of my question is this - are there any other bits that it might be beneficial to replace, and if so, are there people here who might consider doing the work for me - obviously I'd be happy to pay. I'm in Cornwall, but often up in London.
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My skill level isn't much past yours, and I've done that NAP board swap a few times. It's quite easy, with three things to keep in mind:
  1. You'll need new heat sync compound when you swap the amp modules. This is basically the same stuff you use for a computer CPU heat sync, and can be purchased in numerous places.
  2. The spades will probably be larger on the QUDOS board than on your Naim NAP boards. In that case, you'll need to change the female spade plugs in the internal wiring. That's a bit tricky, and pretty much requires a crimping tool to do the job. Here's a good collection of spade connectors, but you can find them elsewhere. The Naim boards are probably the smallest size, while the QUDOS are likely the largest. https://www.amazon.co.uk/dp/B07X4CKCJ2/?tag=pinkfishmedia-21
  3. Yes, you'll need to set the bias, which requires a multimeter. It seems really scary the first time you do it, but remember to make very small adjustments with your little screwdriver, and be patient to see the result before adjusting it further. You're supposed to wait until it's stable for a while, so you'll have lots of time to calm your nerves as you watch it. ;)
Mike Hanson
 
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When did you last speak to Les?
I understood that he was setting up his completed Qudos boards these days such that they didn't need the bias to be adjusted by the user. The Qudos boards can take a high level of bias because they're "self regulating" with regard to bias, if it's a bit high and the output transistors start to get too hot the board automatically reduces the bias level to restore a safe temperature. When I spoke to Les 2 years ago to order a pair of his new boards he said "if you listen at moderate levels you might be listening completely in Class A", one of the benefits of this updated design!
If you do have to set up the bias then it's straight forward and Les provides illustrated instructions - just remember to allow the power supply to fully discharge before connecting or disconnecting the +ve supply to the boards (check it with your multimeter).

The spade connectors are either 6.3mm or 2.8mm depending on whether your NAPA boards are from a 250 (6.3mm) or 140/180 (2.8mm). Tell Les which yours are (probably 6.3 if your amp is already "Avondaled") and he'll fit suitable spades.

Les advised me to switch the amp off when not in use, and ideally back on 30 minutes before "serious listening". The higher bias setting does make them run a bit warmer than Naim boards and Les's previous design.

And I think you'll find it worthwhile!
 
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Thank you both very much - I guess I should send Les pictures and mention leaving the amp on.
He's currently waiting for more stock so it'll be a few weeks but I expect I'll be back asking more and thanking you again..!
 
I put QUDOS boards into my Voyagers about a year ago, and I definitely set the bias myself. This is the first I've heard that they're self-regulating.
 
This what Les said on his facebook page on 26th October last year:-
"I'm currently configuring the Qudos modules as a genuine 'plug-and-play', drop in conversion for many of the early Naim amps. It's as easy as fitting a 13A plug with no alteration to the wiring or terminals and no setting up whatsoever".

This would apply to modules built by Les from that date, not self builds or earlier examples like mine I assume.

I take the "no setting up whatsoever" comment to mean, well, you don't need to set up the bias.
 
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