Avondale NCC300 amp project ..

[flashgo]

Nice Job Flash
I see you have the speaker protection boards in there as well, did the heat sink come in one piece for that & the NCC300 ?

Hi Alan,

It's the original NAP135 heat sink, and it accommodates both boards on one heat sink.

Les warned me that you can't use the normal Avondale mounting scheme because the shelf on the heat sink is so thick (0.335") that any extra spacing will prevent the power transistor legs from showing through to the PCB. Instead, Les advised gluing some thin mica insulators onto the bottom:

I don't know if that's visible enough, but there's fresh glue between the holes on the metal lip. This was just before laying the micas into place. This worked so well, that there was still space for ceramic insulators between the transistors and the top surface. I kept the original tubes inside the passages through the heat sink lip.

The SPM1 is labelled "Loudspeaker Protection & Fan Control Module", so there's a lot packed onto the board. I still have to tune the fan module, but eliminating the turn on and off thumps is great! It adds to the sense of "blackness" with this amp. Meanwhile, the transistors and the heat sink are barely above ambient temperature!

Flash

 

[chiily]

Here are a couple of shots of the current progress of mine
20180224_172012 by Alan Towell, on Flickr
20180224_171932 by Alan Towell, on Flickr

Alan

Really great work there. Those boards look up to the usual Avondale standard.

I would expect the heatsink would be pricey, I don't have any NAP135s handy.

 

[337alant]

chilly
Thats a nice lump of a heat sink , think Les said he was going to get some made similar ?
Good idea with the glue to keep the mica washers in place
I have a few NCC200 heat sinks and a pair of them fits the NCC300 boards exactly so I could use them

Alan

 

[RJHarker]

I've 4 135's as projects at the moment. Everything's always for sale... Unless LesW wants to let go of some boards, and I'll build myself.

 

[LesW]

My thanks to the guys for all the superb effort, I'm well pleased this project is
taking off.

I'm well advanced with a scheme for comverting the NAP135s and that was the
main object of designing this board.

If there's sufficient interest, I might be persuaded to put together some kits
for the 135s consisting of 2 X NCC300 PCB, 2 X SPM1 PCB, a set of small
(sometimes hard-to-get) heatsinks for both boards and a few rare parts
to enable home constructors to convert these popular amps .

The income from this would offset some of the investment there's been so
far so I'd be grateful for the business.

Let me know what the team thinks.

 

[chiily]

Les,

I would be interested in a 'kit. Your previous PCBs have been superb in build and performance.

 

[RJHarker]

Absolutely interested.

 

[Chops54]

Same here. I'd like a pair of NCC220 boards too.
Would you be in to take a phone call this evening Les?

 

[chiily]

Same here. I'd like a pair of NCC220 boards too.
Would you be in to take a phone call this evening Les?

Queue jumper...

 

[TOR]

Les, I’d be very interested in boards and sinks!! Anything that can be done to support development is great!!!

 

[flashgo]

Les, I've got another pair of 135s to convert, and the way this first one sounds, I'll be looking for another pair of 135s to complete a 6 pack for my 'briks. So sign me up for 4 more kits!

Right now, I've got the one completed 135 NCC300 conversion on the left Ergo IX and an NCC220/HCR200 converted 250 bi-amping the right. The sound quality is insane! With just one channel of NCC220/HCR200 on the right Ergo, there was no comparison. Bi-amping brought the power into better balance, but the NCC300 still dusts the 220 with its magic clarity and dynamic grip. At some point, I'll upgrade the 220s to separate front end and output rails and do another comparison.

I'll be spending Saturday freeing up another 135.

 

[chiily]

I have a few NCC200 heat sinks and a pair of them fits the NCC300 boards exactly so I could use them

Alan

Thanks Alan. That's good to know.

 

[LesW]

I'm having a shedload of problems with the new VOIP system from Virgin installed
last week so if anyone would like a chat about this project, call me on mobile:

07484 782048

Thanks, Les

 

[Chops54]

Queue jumper...

Not me matey

It must be three or four years ago since I had a discussion with Les about paralleling NCC200 output devices. He told me to patient and wait. I think the waiting's over but unfortunately I don't have the time atm to take on another project. No harm in having another chat about it though is there? I might just stock up on a couple of boards whilst I'm at it

 

[flashgo]

I have a few NCC200 heat sinks and a pair of them fits the NCC300 boards exactly so I could use them

I suspect this will work just fine. Running with the case open, the power transistors aren't even warm. Perhaps that's testament to the passive heat radiation of the 135 heat sink, but it's so cool, it'll probably be fine with the standard Naim/Avondale heat spreaders. The Modushop Dissipsantes will also work.

 

[laverda]

Good progress on the NCC300 build but awaiting some bits from RS and Farnell to complete..Farnell have 0 stock of 6.2k and 220r MFR5's, along with BZX 7.5v err. Had to source off eBay .

The front end is not soldered yet and critical components will be removed prior to setting up regs so that it doesn't see anything.

Questions for those who have already succeeded in this build.

Preferance for 10uF 100v & 63v (Id use 100v in both) caps for PSU as screened on the board are Pans. I have 100uF sorted with some nice Rubycons.

BC546 input matching? get them as close as...?

TIA

Graham

 

[flashgo]

Hi Graham,

I had some old Blackgate 10uF 100v caps I used.

My BC556s are only Q10 10% > Q9 as that's the best I could find, but I can't remember what I did for the BC546s. At any rate, they weren't > 10% different, and the output offset is < 2mV.

I love those heat spreaders. Did you make them? Will they be mounted to some serious fins?

Flash

 

[laverda]

Hi Graham,

I had some old Blackgate 10uF 100v caps I used.

My BC556s are only Q10 10% > Q9 as that's the best I could find, but I can't remember what I did for the BC546s. At any rate, they weren't > 10% different, and the output offset is < 2mV.

I love those heat spreaders. Did you make them? Will they be mounted to some serious fins?

Flash

Thanks Flash

Just checking...My BC556s are from why back and their going to be used. The BC546s I have measured 10% different for a couple of pairs so all good there.

The spreaders Les supplied but there an easy 2"x2"x1/4" ali T

The case I'm suing is a HiFi 2000 5U deluxe with large finned heat sinks and will be a dual mono amp.

Graham

 

[flashgo]

Graham,

I'll be following your build closely as I have a similarly massive case plus a Canterbury traffo left over from an abandoned duo-mono HackerNAP build. The NCC300 is a good fit to those fins. How are you planning to manage the weight? The bottom plate isn't that strong, and it's a beast to move that thing on and off a rack. I was thinking of mounting it on inline skate casters and just wheeling it around.

Flash

 

[337alant]

I suspect this will work just fine. Running with the case open, the power transistors aren't even warm. Perhaps that's testament to the passive heat radiation of the 135 heat sink, but it's so cool, it'll probably be fine with the standard Naim/Avondale heat spreaders. The Modushop Dissipsantes will also work.

The modushop Dissipsantes are excellent cases, not cheep now but excellent all the same, the voyagers don't even break sweat even after a dam good thrashing

Alan