Avondale NCC300 amp project ..
- Thread starter laverda
- Start date
martin clark
pinko bodger
Lovely, creative re-use, with a very clean & logical internal layout to really exploit the case section: DIY invention at its best!
torstoi
pfm Member
It's a rare case my view transforms from not liking something (no particular friend of Apple design as such)
to absolutely loving it in the process of watching the pictures of your build.
What's even more impressive to me, though mostly invisible..is the smart way of using the space inside.
Short ways in the 3D, well packed..but not appearing crammed in any way.
Absolutely stunning execution !
to absolutely loving it in the process of watching the pictures of your build.
What's even more impressive to me, though mostly invisible..is the smart way of using the space inside.
Short ways in the 3D, well packed..but not appearing crammed in any way.
Absolutely stunning execution !
chiily
PFM Special Builder
Thanks chiily. If you're serious about a case for your KSA PM me and we might be able to sort something out.
I've been thinking for a while about making enclosures. I've been talking to someone who may be able to laser cut the panels and then it's just a bit of drilling and tapping and some painting or anodising maybe. The market is awash with Chinese stuff but it seems to be getting more and more expensive. Maybe I'm just daydreaming or talking bollocks
I was browsing G5 cases in eBay, looking for dimensions.
The KSA50 would need a case at least 4U in height and a panel in the base, as you've done cos it is so darn heavy....
Looks brilliant painted btw
Chops54
pfm Member
Thanks fellas. I have to admit that I made a mistake when I cut the case down. The goal was to make it as compact as possible whilst keeping the transformers and LS protection boards seperate from the active bits but unfortunately I cut the case 50mm short. That meant I had to turn the Cap6 boards sideways and put the MiniCaps underneath and hence the reason why the LS protection boards are back to back on top.
Today's job is to get the feet made. I'm going turn them out of plywood, paint them and simply stick them on the bottom of the enclosure to cover the bolt heads which protrude underneath.
Today's job is to get the feet made. I'm going turn them out of plywood, paint them and simply stick them on the bottom of the enclosure to cover the bolt heads which protrude underneath.
Chops54
pfm Member
The mistake I made was not realising that the inside dimensions would be somewhat smaller than the outside dimensions. When the case is laid flat it is quite deep though. I'll measure the depth if you like.
Hi I would like to build an NC220 or preferrably a NCC300 pair. Where can I get a set of circuit boards? What is the recommended transformer VA to run a stereo pair. Also do you recommend softstart and speaker protection circuits for this amp?
I was thinking a 4U case from DIY audio or the like.
Thanks
I was thinking a 4U case from DIY audio or the like.
Thanks
laverda
pfm Member
Brilliantly executed piece of light engineering and up cycling at its best.
Budding DIYers can take many ideas off this single thread... like it a lot.
Dougie2404
cranky old git
Just where are you going to hide this one chops?
Speak at the weekend, hope you're keeping well, same with al on the forum of course.
Speak at the weekend, hope you're keeping well, same with al on the forum of course.
Chops54
pfm Member
Hi Dougie,
I’m doing ok thanks. Just picked up a couple of days work too so things are looking up.
The NCC300 is going under the tv in place of the Voyagers. The Voyagers will go in the upstairs system and then I’ll probably sell the Alpha 8s. I believe these are the rarest of Les’s creations and I’ll be sorry to see them go.
The parts have turned up for the phono stage and I’ve already started laying it out. I have to finish the amp first but I’m hoping to have Emerald number 4 done sometime next week.
Talk soon.
I’m doing ok thanks. Just picked up a couple of days work too so things are looking up.
The NCC300 is going under the tv in place of the Voyagers. The Voyagers will go in the upstairs system and then I’ll probably sell the Alpha 8s. I believe these are the rarest of Les’s creations and I’ll be sorry to see them go.
The parts have turned up for the phono stage and I’ve already started laying it out. I have to finish the amp first but I’m hoping to have Emerald number 4 done sometime next week.
Talk soon.
Chops54
pfm Member
Didn't have much time to play last week but I managed to spin some feet from a piece of plywood, paint them and stick them on.
I also managed to make a small fuse board from a piece of tufnol and some pcb mount fuse holders. The three fuses are one each for the minicaps and one for a small dual secondary tranny for the LS protection boards.
Here's a shot of the lower part of the enclosure housing the transformers and the Minicaps. I wanted the LS protection boards here but because I made a mistake with the dimensions it ended uplike this
I started wiring the amp today but unfortunately the Cap6 boards have to come out. Funds are tight so I robbed them from another project and they need a few more 0v terminals. The boards are at home in my office workshop being sorted atm. Tomorrow I have to pull out that upper panel and finish the mains wiring before i can refit the Cap6 boards.
This will give you all an idea what it will look like with the heatsinks and NCC300 boards installed.
I also managed to make a small fuse board from a piece of tufnol and some pcb mount fuse holders. The three fuses are one each for the minicaps and one for a small dual secondary tranny for the LS protection boards.
Here's a shot of the lower part of the enclosure housing the transformers and the Minicaps. I wanted the LS protection boards here but because I made a mistake with the dimensions it ended uplike this
I started wiring the amp today but unfortunately the Cap6 boards have to come out. Funds are tight so I robbed them from another project and they need a few more 0v terminals. The boards are at home in my office workshop being sorted atm. Tomorrow I have to pull out that upper panel and finish the mains wiring before i can refit the Cap6 boards.
This will give you all an idea what it will look like with the heatsinks and NCC300 boards installed.
Chops54
pfm Member
A question for the team. There's a lot of Ov returns to the Cap6 boards. Four on the DC end and two on the AC end ( not counting the transformer secondary connections) The two on the AC end are the 0v for the loudspeaker output and the other is for the LS protection board. The Ov point for the LS protection board isn't actually part of the grounding scheme. It's purely the return for the DC detection circuit so does it have to go back to the input end of the Cap6 board? It's easier for me to pick it up from the loudspeaker output terminal for instance. Any views?
Chops54
pfm Member
I've been fairly busy over the last two weeks so I haven't been able to spend much time on this but at long last I managed to get her fired up. Unfortunately I had an incident and took out a fair part of the right hand board. They included the three transistors in the bias chain, the two driver transistors, three output emitter resistors and several bias chain resistors. I actually had flames coming up from the board Anyway I've replaced all the duff parts including the output transistors and protection diodes and all four emitter resistors. I've just powered up with the output section disconnected and I can swing the bias right through to 2.4 volts. Whilst I was doing this a thought crossed my mind regarding the regulators. If I read prior posts correctly the regs should be set at 55 volts which will drop to 50 volts under load. How do I check the unloaded voltage? I'd need to do that before I fitted the front end components wouldn't I as there's no way of separating the regs from the front end once the board is built up? I'm just wondering how else would I know the regs are actually working as opposed to just dropping the voltage?
Anyway I've replaced all the duff parts including the output transistors and protection diodes and all four emitter resistors. I've just powered up with the output section disconnected and I can swing the bias right through to 2.4 volts. Whilst I was doing this a thought crossed my mind regarding the regulators. If I read prior posts correctly the regs should be set at 55 volts which will drop to 50 volts under load. How do I check the unloaded voltage? I'd need to do that before I fitted the front end components wouldn't I as there's no way of separating the regs from the front end once the board is built up? I'm just wondering how else would I know the regs are actually working as opposed to just dropping the voltage?
337alant
Negatively Biased
Si sorry to hear about your incident its a real bummer when it happens, I've been there done that got the scorched T-shirt
Testing the front end regs is the first step of the build and you only populate the regs before anything else, this way you can add a load and test the drop out .
[url=https://flic.kr/p/24snW5H]
20170904_185549 by Alan Towell, on Flickr[/URL]
That said if the reg will adjust up and down then it should be OK, try adjusting it down to 40V, if it does that its working
The front end only takes about 20ma so its hardly any load, if the amp is working then its under load.
I adjust mine so its just a few volts higher than the output
Alan
Testing the front end regs is the first step of the build and you only populate the regs before anything else, this way you can add a load and test the drop out .
[url=https://flic.kr/p/24snW5H]20170904_185549 by Alan Towell, on Flickr[/URL]That said if the reg will adjust up and down then it should be OK, try adjusting it down to 40V, if it does that its working
The front end only takes about 20ma so its hardly any load, if the amp is working then its under load.
I adjust mine so its just a few volts higher than the output
Alan
Chops54
pfm Member
I never gave it a thought when I populated the boards Alan. I don't remember reading anything about building the regs first and load testing them but maybe I missed it As it stands the regs do adjust and drop voltage ok but I've not taken them down as low as 40 volts. If I feel the need to load test them I might cut the tracks.
As it stands the regs do adjust and drop voltage ok but I've not taken them down as low as 40 volts. If I feel the need to load test them I might cut the tracks.
S-Man
StrivingON
No need to cut any tracks!!
Just connect a 3K9 1W resistor across the output of each regulator. This should pull 10mA (at 39V) extra from the reg.
You should get <2mV of drop on the regulated voltage.
This indicates that the output resistance of the reg is <200 mOhms.
Or if you are feeling clever, you can switch a square wave load across the rails (one rail at a time) and observe the transient response and the output voltage variation with a 'scope.
(At least you are building something. My own NCC300s have been parked for months while I sort out other people's houses)
Just connect a 3K9 1W resistor across the output of each regulator. This should pull 10mA (at 39V) extra from the reg.
You should get <2mV of drop on the regulated voltage.
This indicates that the output resistance of the reg is <200 mOhms.
Or if you are feeling clever, you can switch a square wave load across the rails (one rail at a time) and observe the transient response and the output voltage variation with a 'scope.
(At least you are building something. My own NCC300s have been parked for months while I sort out other people's houses
)