Hi Guys (& gals) sorry for the long wait.
Just now I finally mounted the EMC kit in my NCD - and succeeded in breaking the power button while reassembling
First tests (without speaker cables attached) show no influence of the amp on DAB of FM reception at all, but that might change.
As I posted earlier, separation of speaker cables from antenne minimized the disturbance problem a lot - for a long time I only rarely had trouble, and then only at sundown and sunset - guess the DAB signal gets weaker or disturbed at that time.
For some reason (not quite sure why) the problem has gotten worse again lately, so I am excited whether this will help.
Will go to the attic now to get another power button - and hopefully post more later...
Just now I finally mounted the EMC kit in my NCD - and succeeded in breaking the power button while reassembling
First tests (without speaker cables attached) show no influence of the amp on DAB of FM reception at all, but that might change.
As I posted earlier, separation of speaker cables from antenne minimized the disturbance problem a lot - for a long time I only rarely had trouble, and then only at sundown and sunset - guess the DAB signal gets weaker or disturbed at that time.
For some reason (not quite sure why) the problem has gotten worse again lately, so I am excited whether this will help.
Will go to the attic now to get another power button - and hopefully post more later...
OK, everything put together again and working... you can see the caps, copper tape and big ferrites (I had to get bigger ones than Lars sent me because of the very thick speaker cables ). Put a ferrite on the power cords too, just in case.
Ended up gluing the stupid power button - too much hassle to solder it out of the PCB...
The clear thingy that you can see strapped to the amp board with the red strip is a light-guide to bring the blue light up to the front panel ... I didn't feel like soldering around on the module itself (suggestion for Lars ... add pins for an external LED?).
/cdl
). Put a ferrite on the power cords too, just in case.Ended up gluing the stupid power button - too much hassle to solder it out of the PCB...
The clear thingy that you can see strapped to the amp board with the red strip is a light-guide to bring the blue light up to the front panel ... I didn't feel like soldering around on the module itself (suggestion for Lars ... add pins for an external LED?).
/cdl
Attachments
Progress report...
Despite promising first test, there is still some interference after mounting the EMC kit. I will test for a couple of days and then report, but my first impression is that the problem is less now than it was. On the workbench (ah, I mean dining table) without speaker cables connected (or with short test ones) there was little or no disturbance (evaluated by drop in the signal strength indicator of the tuner).
Once back in place and with the big speakers attached, the problem is back, but seems less.
It is still intermittent - mainly at sunrise and sunset, and especially strong when the amp has just been turned on - it gets less when the amp has been on for a while.
I posted some pics and construction details of the amp in this thread in case anyone cares ;-)
I have a feeling this problem has something to do with the length of the speaker cables. I have pretty long ones - 7 metres. And since I'm biwiring, there's 4 of them... how about the rest of you guys who have EMC trouble, do you have long cables too?
The way my setup is right now I don't even need those 7m cables, will consider buying some shorter ones (no, no, I'm not going to cut them - might need the long ones again in the future).
Will post back next week.
/cdl
Despite promising first test, there is still some interference after mounting the EMC kit. I will test for a couple of days and then report, but my first impression is that the problem is less now than it was. On the workbench (ah, I mean dining table) without speaker cables connected (or with short test ones) there was little or no disturbance (evaluated by drop in the signal strength indicator of the tuner).
Once back in place and with the big speakers attached, the problem is back, but seems less.
It is still intermittent - mainly at sunrise and sunset, and especially strong when the amp has just been turned on - it gets less when the amp has been on for a while.
I posted some pics and construction details of the amp in this thread in case anyone cares ;-)
I have a feeling this problem has something to do with the length of the speaker cables. I have pretty long ones - 7 metres. And since I'm biwiring, there's 4 of them... how about the rest of you guys who have EMC trouble, do you have long cables too?
The way my setup is right now I don't even need those 7m cables, will consider buying some shorter ones (no, no, I'm not going to cut them - might need the long ones again in the future).
Will post back next week.
/cdl
Wima MKP's Decoupling...
Making a new (temporary) housing gave me the opportunity to add some WIMA MKP’s (3,3uf) to the power supply. Result is difficult to compare because I do not have two sets to do a real A-B comparison so I have only my memory to work with and that is not very reliable () now is it…!
But to me (for what it is worth : Sound seems softer, more “analogue” but also less “vibrant” (sorry exact words evade me).
Don’t know if I like it. Previous sound may have been a bit harsh but very explicit. Might be it is nothing more then just getting used to….
Keep you posted, Regards, Eric.
PS : Set is dead-silent at 0 input, no hiss whatsoever… Just a small “piep” when powering down…
Making a new (temporary) housing gave me the opportunity to add some WIMA MKP’s (3,3uf) to the power supply. Result is difficult to compare because I do not have two sets to do a real A-B comparison so I have only my memory to work with and that is not very reliable () now is it…!
But to me (for what it is worth : Sound seems softer, more “analogue” but also less “vibrant” (sorry exact words evade me).
Don’t know if I like it. Previous sound may have been a bit harsh but very explicit. Might be it is nothing more then just getting used to….
Keep you posted, Regards, Eric.
PS : Set is dead-silent at 0 input, no hiss whatsoever… Just a small “piep” when powering down…
Attachments
Excellent work Eric! Very neat and professional look!
I like the whole layout. It seems you've paid a lot of attention to screening stray fields from the transformer. Is that the secret to no hum and hiss? Do you have the power cable screened in aluminium block too?
Also, how did you secure the WIMAs on the aluminium block? Way cool.
I'm building my NCD monoblocks in die-cast aluminium enclosures. Space is tight. So tight that every component: NCD, PSU, softstart and transformer are very closely packed. Upgrades seems limited. So I'm considering bigger boxes if I can't trace the little hiss and hum that's coming through. I do suspect the high gain is revealing noise from the DAC.
Cheerios, dan.
I like the whole layout. It seems you've paid a lot of attention to screening stray fields from the transformer. Is that the secret to no hum and hiss? Do you have the power cable screened in aluminium block too?
Also, how did you secure the WIMAs on the aluminium block? Way cool.
I'm building my NCD monoblocks in die-cast aluminium enclosures. Space is tight. So tight that every component: NCD, PSU, softstart and transformer are very closely packed. Upgrades seems limited. So I'm considering bigger boxes if I can't trace the little hiss and hum that's coming through. I do suspect the high gain is revealing noise from the DAC.
Cheerios, dan.
Attachments
Hello Dan,
Yee, I did pay some attention to stray fields, not only from powerlines, and transformers but shielded output wires as well.
I've glued the WIMA's to the aluminium. Have al look at ;
http://www.diyaudio.com/forums/showthread.php?s=&postid=1778630#post1778630
This all prevented any humm at al. But what realy did the trick concerning hiss was the additional left-to-right ground-wire (just as in the cookbook 1.06).
It is realy dead-silent now. If you want a can mail some extra photo's.
I am still looking for a firm who can mill a monoblock from 1 piece of full aluminium. But that will be the next project.
Having a glance at you solution, it is very tight indeed. Good luck & fun with building a new one your own...!!!!
Cheers, Eric.
Yee, I did pay some attention to stray fields, not only from powerlines, and transformers but shielded output wires as well.
I've glued the WIMA's to the aluminium. Have al look at ;
http://www.diyaudio.com/forums/showthread.php?s=&postid=1778630#post1778630
This all prevented any humm at al. But what realy did the trick concerning hiss was the additional left-to-right ground-wire (just as in the cookbook 1.06).
It is realy dead-silent now. If you want a can mail some extra photo's.
I am still looking for a firm who can mill a monoblock from 1 piece of full aluminium. But that will be the next project.
Having a glance at you solution, it is very tight indeed. Good luck & fun with building a new one your own...!!!!
Cheers, Eric.
Attachments
Re: Wima MKP's Decoupling...
VERY nice work, Eric. Thanks for sharing your experience with the extra PSU caps.
Bro, your layout looks extremely tight - I imagine it must be difficult to fit everything that close. But cool to have a compact amp!
Are you using the NCD connected directly to your Airport Express with no volume control / preamp or similar in between? And controlling volume in the Airport Express?
How is that working?
I definately think the high gain reveals any noise caused "earlier" in the system - most of "my" hiss disappears when I mute my preamp (relay short-circuits the outputs). A (very) little hum remains, I'm guessing it's either stray fields from the transformer or maybe some groundloop noise caused by my computer being connected to the preamp.
/cdl
wtfaidh said:
VERY nice work, Eric. Thanks for sharing your experience with the extra PSU caps.
bro said:
Bro, your layout looks extremely tight - I imagine it must be difficult to fit everything that close. But cool to have a compact amp!
Are you using the NCD connected directly to your Airport Express with no volume control / preamp or similar in between? And controlling volume in the Airport Express?
How is that working?
I definately think the high gain reveals any noise caused "earlier" in the system - most of "my" hiss disappears when I mute my preamp (relay short-circuits the outputs). A (very) little hum remains, I'm guessing it's either stray fields from the transformer or maybe some groundloop noise caused by my computer being connected to the preamp.
/cdl
firstly, thanks Eric and cdl for your comments. Really appreciate wonderful people like you! Many blesses...
I've been using low powered Tripath amp for a couple of years. So this NCD is giving me way too much fun with all the music! And hence I'm a little lazy to fix the hum and hiss. Anyway, I could only hear it when I stick my ears to the speakers. Of course I will eventually find the copper sheet to shield the singing 500VA transformers. and possibly add RF filtering at the power entry. hee hee.
The decision to go with small enclosures was due to a couple of reasons:
1. Lars kept mentioning short cable lengths in the cookbook.
2. The "monocoque" diecasts are available fairly cheaply from RS.
3. My first choice with pre-cut aluminum didn't work out. I had to buy whole lengths of aluminum bars. Imagine the surplus.
4. I prefer small amps so that I can chuck them around in my small apartment.
5. 3D modelling with Google sketchup helped a bit.
Eric: Forgot to mention a Dac after Airport Express. I'm using itunes to control volume at the moment. I hope to add the lightspeed attenuator to the dac soon. No preamp in the path. btw, I use "itunes remote" on ipod to control itunes. works great!
Here's my first choice (similar to http://www.hexateq.com/premium_series.html):
Many blesses...I've been using low powered Tripath amp for a couple of years. So this NCD is giving me way too much fun with all the music! And hence I'm a little lazy to fix the hum and hiss. Anyway, I could only hear it when I stick my ears to the speakers. Of course I will eventually find the copper sheet to shield the singing 500VA transformers. and possibly add RF filtering at the power entry. hee hee.
The decision to go with small enclosures was due to a couple of reasons:
1. Lars kept mentioning short cable lengths in the cookbook.
2. The "monocoque" diecasts are available fairly cheaply from RS.
3. My first choice with pre-cut aluminum didn't work out. I had to buy whole lengths of aluminum bars. Imagine the surplus.
4. I prefer small amps so that I can chuck them around in my small apartment.
5. 3D modelling with Google sketchup helped a bit.
Eric: Forgot to mention a Dac after Airport Express. I'm using itunes to control volume at the moment. I hope to add the lightspeed attenuator to the dac soon. No preamp in the path. btw, I use "itunes remote" on ipod to control itunes. works great!
Here's my first choice (similar to http://www.hexateq.com/premium_series.html):
Attachments
bro said:I prefer small amps so that I can chuck them around in my small apartment.
I am afraid that my primary transformers (42V-0/0-42V, 1000 Watt) will not fit in a tihgt case... ;-)
Using a "Airport Express" for conveniance is a fine choise (I am using a SqueezeBox Myself),
But if you want to hear the NCD's sing : use a conventional CD player...!!!
Cheers, Eric.
Status on EMC
I posted previously about my EMC problems in relation to DAB reception (and probably FM as well, but I don't use that currently). The problem with DAB is intermittent (mostly at sunrise and -set, and especially strong just after turning on the amp, tends to decrease when the amp has been on for a while). I also noticed that having a D-Link USB WAN adapter close to a speaker cable caused significant bandwidth deterioration (even with EMC kit), but moving it 1m away from the speaker cable solved the problem.
First test with the EMC kit was promising, but with long speaker cables attached, the problem was back, although less severe.
The other day I finally attached my new speaker cables (3m x4 for biwiring), which seems to further reduce the problem a bit, but it's still noticeable :-/
On the brigth side, reception is tolerable now. The following 4 things have reduced the EMC:
1) Moved DAB antenna away from the amp connecting it through some 4m of shielded cable. Carefully separated "noisy" speaker cables from the antenna cable in the "snake garden" behind the hifi (speaker cables go right, antenna goes to the left). Attached clamp-on ferrites to the shielded cable at the antenna connector on the tuner (doesn't seem to limit signal strength)
2) Mounted EMC kit and clamp-on ferrites chokes on all power cables.
3) Replaced long speaker cables (4x7m) with shorter ones (4x3m)
The only further thing I can think of would be to attach some 0.1µF caps in series with the speakers at the terminals on the amp (yes I know this might affect the treble). Will try this once I come across the ones I have lying around somewhere, I guess i'll just connect them to some banana connectors and try plugging them in to see if it helps.
Otherwise I am out of ideas. So Lars, you are most welcome with your spectrum analyzer any time
/cdl
I posted previously about my EMC problems in relation to DAB reception (and probably FM as well, but I don't use that currently). The problem with DAB is intermittent (mostly at sunrise and -set, and especially strong just after turning on the amp, tends to decrease when the amp has been on for a while). I also noticed that having a D-Link USB WAN adapter close to a speaker cable caused significant bandwidth deterioration (even with EMC kit), but moving it 1m away from the speaker cable solved the problem.
First test with the EMC kit was promising, but with long speaker cables attached, the problem was back, although less severe.
The other day I finally attached my new speaker cables (3m x4 for biwiring), which seems to further reduce the problem a bit, but it's still noticeable :-/
On the brigth side, reception is tolerable now. The following 4 things have reduced the EMC:
1) Moved DAB antenna away from the amp connecting it through some 4m of shielded cable. Carefully separated "noisy" speaker cables from the antenna cable in the "snake garden" behind the hifi (speaker cables go right, antenna goes to the left). Attached clamp-on ferrites to the shielded cable at the antenna connector on the tuner (doesn't seem to limit signal strength)
2) Mounted EMC kit and clamp-on ferrites chokes on all power cables.
3) Replaced long speaker cables (4x7m) with shorter ones (4x3m)
The only further thing I can think of would be to attach some 0.1µF caps in series with the speakers at the terminals on the amp (yes I know this might affect the treble). Will try this once I come across the ones I have lying around somewhere, I guess i'll just connect them to some banana connectors and try plugging them in to see if it helps.
Otherwise I am out of ideas. So Lars, you are most welcome with your spectrum analyzer any time
/cdl
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