Avondale NCC300 amp project ..
- Thread starter laverda
- Start date
misterc6
Wasted and wounded, it ain’t what the moon did
I have some MFR5s here left over from previous builds, let me know what you need.
laverda
pfm Member
It lives.....
DC offset is less the .5mv. (Brilliant) But within a short time the heat spreader was quite warm so I hooked up the + rail through a meter and found it was drawing over 1 amp, a quick double check and yes this can pull some current. Quick twiddle of the bias pot and things were under control 250ma steady state....
The bias is set at 2.0v across the bases of the drivers as per Les's instructions. This may be to much...while we await his resistor update.
DC offset is less the .5mv. (Brilliant) But within a short time the heat spreader was quite warm so I hooked up the + rail through a meter and found it was drawing over 1 amp, a quick double check and yes this can pull some current. Quick twiddle of the bias pot and things were under control 250ma steady state....
The bias is set at 2.0v across the bases of the drivers as per Les's instructions. This may be to much...while we await his resistor update.
laverda
pfm Member
Les, all.
On my build I don't seem to have a problem driving the bias up. I have only changed the 2k7 for a 3k3. With this config I am able to get +2.3v across the base's of the MJE15030 & 31. Which translates into +500ma of current flow at +rail. The spreader gets quite hot at this bias setting. I know I have to strap it to the heat sinks of the case but this may well be enough for me...
That said, if it turns out I will/do need more bias I can easily drop another resistor in the 2k2 slot..I was thinking 1k5 as in the 220's. It's clear that this is a different animal to any of the previous Avondale amps.
On my build I don't seem to have a problem driving the bias up. I have only changed the 2k7 for a 3k3. With this config I am able to get +2.3v across the base's of the MJE15030 & 31. Which translates into +500ma of current flow at +rail. The spreader gets quite hot at this bias setting. I know I have to strap it to the heat sinks of the case but this may well be enough for me...
That said, if it turns out I will/do need more bias I can easily drop another resistor in the 2k2 slot..I was thinking 1k5 as in the 220's. It's clear that this is a different animal to any of the previous Avondale amps.
flashgo
DIY Practitioner
I just swapped out the 2k2 and replaced with a 1K. Bias set to 2v2.
Output offset -8mV. Things running nice and cool, except for Q4 which has run hot since the beginning. In particular, the output trannies are running 24-25° as measured by an IR thermometer. And that's when playing music through an Ergo IX.
I can't say I've heard any difference across a huge range of bias settings, but I've really got to get the stereo configuration going.
Output offset -8mV. Things running nice and cool, except for Q4 which has run hot since the beginning. In particular, the output trannies are running 24-25° as measured by an IR thermometer. And that's when playing music through an Ergo IX.
I can't say I've heard any difference across a huge range of bias settings, but I've really got to get the stereo configuration going.
laverda
pfm Member
Please don't read this the wrong way:
There won't be any boards on general release - at least for the time being.
I've supplied sets to folks whom I know personally and can trust to build
and test them without imposing too much on others so once proven, they
MAY become available as DIY projects.
The NCCs were designed for conversion of the NAP135s and this is where
my future business will be focussed at least for the time being.
Many thanks to those friends who've taken the trouble to build and give
feedback.
There won't be any boards on general release - at least for the time being.
I've supplied sets to folks whom I know personally and can trust to build
and test them without imposing too much on others so once proven, they
MAY become available as DIY projects.
The NCCs were designed for conversion of the NAP135s and this is where
my future business will be focussed at least for the time being.
Many thanks to those friends who've taken the trouble to build and give
feedback.
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laverda
pfm Member
I feel very privileged to be part of this NCC300 self build team...Thanks Les. This will be my last post regarding this build project from me. I may comment on the final/finished amps as I feel this needs to be part of the NCC300 'round up'. But I don't want to raise individuals expectations on the availability as a DIY build.
The second lives and measures better than the first with offset at 0mv with 2.2v across the drivers. Note that there is a DB237 bolted to the spreader (not in circuit yet) but will be in the final config.
Graham
The second lives and measures better than the first with offset at 0mv with 2.2v across the drivers. Note that there is a DB237 bolted to the spreader (not in circuit yet) but will be in the final config.
Graham
337alant
Negatively Biased
Its a brilliant design Les and it looks absolutely stunning in Flashes 135 case
Im also very greatful for the opportunity to build a pair of these amplifiers and I'm really looking forward to firing mine up when I get some time off work, I'm sure it will sound as good as it looks
Alan
Im also very greatful for the opportunity to build a pair of these amplifiers and I'm really looking forward to firing mine up when I get some time off work, I'm sure it will sound as good as it looks
Alan
After sleeping on it, I've decided to soften my approach to the supply of PCBs but for
now, I'd rather allow the project to mature before jumping in with both feet.
This project has taken me by surprise as I had no idea it would perform as it does.
My post has been edited to reflect my change of stance and I offer apologies to
anyone if I caused offence.
now, I'd rather allow the project to mature before jumping in with both feet.
This project has taken me by surprise as I had no idea it would perform as it does.
My post has been edited to reflect my change of stance and I offer apologies to
anyone if I caused offence.
laverda
pfm Member
OK ..Here's my progress this morning
Yes its powered up on the bench, no flash, no bang, no smoke...result.
I'll do some final setting up, I note the regs were set up at 55v on the bench without the outputs in circuit but now in anger they are at 50v +- 2v. Nothings getting warm 'as yet' So Ive set all the regs to 50v and rock steady.
I like many have been watching this thread with interest. As the owner of is Voyager clone I am indebted to Les for sharing his PCB’s and some of his hard gained knowledge giving me the opportunity to build a truly wonderful amplifier. Should the NCC300 boards become available to the wider community in the future I for one will be more than interested in another project, just don’t tell the wife
flashgo
DIY Practitioner
SQ report
I'm running the following side-by-side A-B configuration. Some may argue with how much I can hear when the sound is mixed together, but even with its limitations, this approach has worked for me over the years.
When I switched the right side from a single channel to a 2-channel bi-amp, the amps came into better register. It's all full complementary, and I think that makes a huge difference over historical Naim & Avondale amps. In terms of a shoot out between the NCC300 ad the NCC220, they're both terrific, but the former has the edge in power, and it's front end regulated. The NCC300 has some extra magic that I'm still having trouble pinning down. There's just no resistance to listen to anything at any sound level. It's clean and dynamic with no pretense. Everyone who listens taps their feet in no time.
I used to think my USB-DAC was pretty good and almost as good as my vinyl input. That was through various tweaked Naim amps. With the above system, vinyl totally trounces the DAC. The level of discrimination through the amps is just that much higher.
The next 135 is on the bench, but I expect it'll be 2 or 3 weekends before I can report the full stereo NCC300 experience. Graham, it's in your hands!
I'm running the following side-by-side A-B configuration. Some may argue with how much I can hear when the sound is mixed together, but even with its limitations, this approach has worked for me over the years.
When I switched the right side from a single channel to a 2-channel bi-amp, the amps came into better register. It's all full complementary, and I think that makes a huge difference over historical Naim & Avondale amps. In terms of a shoot out between the NCC300 ad the NCC220, they're both terrific, but the former has the edge in power, and it's front end regulated. The NCC300 has some extra magic that I'm still having trouble pinning down. There's just no resistance to listen to anything at any sound level. It's clean and dynamic with no pretense. Everyone who listens taps their feet in no time.
I used to think my USB-DAC was pretty good and almost as good as my vinyl input. That was through various tweaked Naim amps. With the above system, vinyl totally trounces the DAC. The level of discrimination through the amps is just that much higher.
The next 135 is on the bench, but I expect it'll be 2 or 3 weekends before I can report the full stereo NCC300 experience. Graham, it's in your hands!
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