I have fitted one TKD stepped potentiometer (10K) per NCore monoblock. (fitted in the amplifier, as not to make the leads too long) I use a combination of the digital attenuation from Amarra and the potentiometer for volume control. (my DAC is "only" 18 bit and I don't want to loose too much resolution with digital attenuation only) The TKD potentiometer didn't harm the sound, perhaps a very minor difference, but I am still VERY happy with the sound. (and I am VERY critical)
I am not Bruno, but I do own a (non DIY, but originally build by First Watt) B1 which is modified quite a bit. (better caps and better pot, different resistors) Even before owning a NCore amp, it was clear to me that the B1 isn't the last thing for resolution (to say the least...). So I woulnd't recommend you to use it, it isn't balanced either. I like connecting my DAC (12 Ohms output impedance balanced output) directly to the NCore with TKD pot a lot better. But why not try it yourself? (assuming you own a B1 yourself)
Digital software based attenuation for the win =)
Good enough and very much the most simple solution
With today's digital, this is very true.
Unless, like me, you have a focus on the analog domain. My LP12 still beats my digital sound and so my crossovers and volume controls must remain analog.
But a correct digital attenuator only adds a tiny tiny bit of high frequency noise, far below what is hearable. With a 24 bit DAC you can easily throw away 48 db or 8 bits without getting hearable noise.
You are assuming a DAC performing at the 144dB theoretical maximum here...
In reality it is typically < 120dB, so by throwing 48dB you are left with around 70dB... (whivh might be enough already, depending on your noise floor...)
I tried it and listened =)
Easy way of trying is to take two identical tracks, invert one and then attenuate one by X amount and then amplify it afterwards. Then listen to the sum of them and see if you can hear anything, I couldn't even when chopping away 48 db. ( When looking at a spectum analysis the noise was ~ 70-90 db down if I remember correctly. )
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That is not the same thing at all: when staying in your audio software and modifying the volume you are still dealing with the full 144dB that the 24bits give you. This is not the same when you go trough your DAC at -48dB.
Do your test like that: if your DAC has say a 110dB S/N ratio then remove (144-110)+48=82 dB from it, and add them back again and do your listening test.
Level matching is important when you connect your DAC directly to the amp in order to get the most out of the DAC's dynamic range and resolution. Most DACs have much too hot output levels, and you may well end up on -30 to -40dB peak in the digital domain at your preferred listening level.
Thats why I removed R141 and reduced the NC400's gain by 12.5 dB (if I remember correctly).
Thats why I removed R141 and reduced the NC400's gain by 12.5 dB (if I remember correctly).
Very good...
Point sErik. It is nice that there is the option to adjust the gain on the nCore for this reason. my DAC is 1.9 V out at 0 dB, and works great in my system with the stock gain of 26 dB. With low average level audiophile style recordings (Reference Recordings HRx) I am at -2 to -5 dB on the (digital) volume control, and with stuff at higher average levels I rarely have to go to more than -20 dB of attenuation.
But for some DACs adjusting the nCores' gain will be a very good idea to match with the DACs output levels and avoid using too much attenuation.
Point sErik. It is nice that there is the option to adjust the gain on the nCore for this reason. my DAC is 1.9 V out at 0 dB, and works great in my system with the stock gain of 26 dB. With low average level audiophile style recordings (Reference Recordings HRx) I am at -2 to -5 dB on the (digital) volume control, and with stuff at higher average levels I rarely have to go to more than -20 dB of attenuation.
But for some DACs adjusting the nCores' gain will be a very good idea to match with the DACs output levels and avoid using too much attenuation.
warm up
Does warm up affect the sound - in other words are there benefits to leaving the smps in standby? What are owners' experiences?
Second question: there is reference way back in this thread to a case GB. I've tried searching the GB forum but can't find anything. can somebody point me to it if its still live.
Does warm up affect the sound - in other words are there benefits to leaving the smps in standby? What are owners' experiences?
Second question: there is reference way back in this thread to a case GB. I've tried searching the GB forum but can't find anything. can somebody point me to it if its still live.
I don't find any difference with warmup but I usually put the system on before I"m going to listen anyway. I'm still a believer that it's your ears that need to warmup.
Try listening and then walking out of the room for 5 min or so and come back. You will most likely find that it's too loud.
This case? CNC mono chassis $71.50ea + shipping Utah
http://www.audiocircle.com/index.php?topic=106336.0
I agree - "warmup" is usually a perceptual effect. With the nCores, I would assume most of the possible temperature-related changes in component values (if any) would be compensated for by the feedback loop.
B1
No, I don't own a B1. I just thought when I'll have finished building the ncore amp I might opt for something more difficult to build. The ncore will me my first DIY project in the electronic domain...but thanks for your comments on the B1 . I would definitely want something with high resolution powers.
No, I don't own a B1. I just thought when I'll have finished building the ncore amp I might opt for something more difficult to build. The ncore will me my first DIY project in the electronic domain...but thanks for your comments on the B1 . I would definitely want something with high resolution powers.
The only advantage of leaving the SMPS (and NC400) on is that it might have a longer life. There is no sonic advantage at all.
I always turn my system off when its not being used, it saves me a little on the electricity bill ....
Up and running
After some difficulties to understand which cable needs to connect to which pin of the XRL input the first mono amp is up and running. Connected it to an old loudspeaker just to make sure that I didn't make any mistake in order not to blow up my main rig. But sounds just fine. After the holidays when the amp cases hopefully will have arrived I will report on my sound impressions.
After some difficulties to understand which cable needs to connect to which pin of the XRL input the first mono amp is up and running. Connected it to an old loudspeaker just to make sure that I didn't make any mistake in order not to blow up my main rig. But sounds just fine. After the holidays when the amp cases hopefully will have arrived I will report on my sound impressions.
Hi Julf - you've clearly never owned a Class A amp then! Certainly with Pass and First Watt amps there is a very big difference between initial turn on and 1 hour later - but that is fully to be expected because its about reaching optimal operating temperatures for the FETS. Its pleasing to hear that the ncores don't require the same.
I did this test on my Class A amps before I purchased NCores.
How long does it take for your amp to heat up?
My...
Experience with the nCores has been different... I found that they, at the very least, needed a few days of break in to come on song. I found them to sound good at first, but that the low level detail retrieval and high frequency extension was just not there initially. In fact I was quite dissappointed in the sound at first (the reports from others had my expectations quite high). Considering the number of electrolytic caps in the SMPS 600 and nCore itself, I do not find this surprising.
I have not had enough experience with them yet to know if the same factors will aplly to warm up, but I suspect that they will. Good news is that keeping the nCores "on" is really not a big deal, especially compared to my Pass which uses 250 watts at idle...
I have read a couple of "shootout" type comparisons with other amps vs nCore where some have said the nCore sounded a little veiled in the high frequencies... I suspect that this observation may be related to the nCore being compared in a cold state to amps that were powered up continuously (or, maybe, the traditional amps had quite a bit of rising distortion with frequency...)
Experience with the nCores has been different... I found that they, at the very least, needed a few days of break in to come on song. I found them to sound good at first, but that the low level detail retrieval and high frequency extension was just not there initially. In fact I was quite dissappointed in the sound at first (the reports from others had my expectations quite high). Considering the number of electrolytic caps in the SMPS 600 and nCore itself, I do not find this surprising.
I have not had enough experience with them yet to know if the same factors will aplly to warm up, but I suspect that they will. Good news is that keeping the nCores "on" is really not a big deal, especially compared to my Pass which uses 250 watts at idle...
I have read a couple of "shootout" type comparisons with other amps vs nCore where some have said the nCore sounded a little veiled in the high frequencies... I suspect that this observation may be related to the nCore being compared in a cold state to amps that were powered up continuously (or, maybe, the traditional amps had quite a bit of rising distortion with frequency
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