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Old 24th June 2012, 04:14 PM   #4561
OllBoll is online now OllBoll  Sweden
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Hello all again... I now have a more technical review of the NCore vs the Firstwatt F2J on one of my speaker drivers. The driver is currently mounted in a ported box and is specced at 90 db efficiency. The db level I have no exact number on, but was not super-quiet and not ear shatteringly loud, so don't take the exact numbers as absolute truths

First up the NCore:

Click the image to open in full size.

Next up the F2J EDIT: In my F2J I skipped the parallell resistors so output impedance should be about 700.

Click the image to open in full size.

Keep in mind that the F2J is a current source, and the response difference might mostly be due to that. But whatever the reason the measurements for me speak for themselves, I will in my future speaker probably use my NCores for the bass and midbass and then use F2Js for mids and upwards.

So Bruno... I know you said Hypex wouldn't produce a current source NCore but what about after you have delivered the DLCP... pretty please?
Attached Images
File Type: png NCore.png (120.4 KB, 1640 views)
File Type: png F2J.png (124.2 KB, 1609 views)

Last edited by OllBoll; 24th June 2012 at 04:21 PM.
 
Old 24th June 2012, 04:38 PM   #4562
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Main difference seems to be in odd (3rd and 5th) order distortion, which is normally most audible.
I guess that the F2J sounds a bit nicer in mid and treble, maybe introducing less listening fatigue.
 
Old 24th June 2012, 07:54 PM   #4563
jtwrace is offline jtwrace  United States
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Here are some NCores that I built.
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File Type: jpg DSC_0805.jpg (54.1 KB, 316 views)
File Type: jpg DSC_0806.jpg (41.9 KB, 250 views)
File Type: jpg DSC_0812.jpg (48.9 KB, 230 views)
File Type: jpg DSC_0810.jpg (47.3 KB, 220 views)
File Type: jpg DSC_0811.jpg (52.9 KB, 216 views)
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Old 24th June 2012, 08:01 PM   #4564
Julf is offline Julf  Europe
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Quote:
Originally Posted by jtwrace View Post
Here are some NCores that I built.
Oooh! Sexy!
 
Old 24th June 2012, 08:20 PM   #4565
DavidT is offline DavidT  United States
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Follow-up to Post #4554 (Past post of temp data w/ cover off, also see this for measurement parameters)


Method:

Amp at idle for 6 hrs with vented cover installed. Cut power. Remove cord. Remove chassis cover. Check power supply rails @< 24 VDC. Press TC bead against surface with finger using a 0.5 mm thick coated fiberglass cloth until temp reading stabilizes. Record non-corrected data. All data taken within 3 minutes of cover removal.

Note:

The coated fine weave fiberglass cloth reduces errors due to the heat sink effect of the finger, as well as protects it from electrical shock and heat burns!

These data are less accurate than the previous data, because I did not wait as long as previously for temp stabilization. This is a trade-off between errors due to surface cooling and errors due to thermocouple time constant.

All temp measurements were done with the power turned off and the power cord removed. Power supply rails below 24VDC.

Room air: 21.6 C


UCD 400 ( most surfaces too hot to touch > 1 sec)

Output inductor: 54 C

Main electro-cap: 51 C

Blue T-Bar: NM

User heatsink: 53 C

Non HS TO-220 devices: 85 C


NC 400 ( most surfaces too hot to touch > 1 sec)

Output inductor: 55 C

Highest temp of 10 electro caps: 61 C

User heat sink: 42 C


SMPS 600 ( most surfaces too hot to touch > 1 sec)

Main xfmer: NM

Small HS: 49 C

Large HS original: NM

Large HS w/ user CPU style HS added: 50 C


My Conclusions:

This is a stunning amount of power capability in a very small and light weight package! Well done!

Surface temperatures appear normal for reliable modern gear to me, although I prefer about 10 C more thermal margin for even more extended reliability.

The user added CPU HS (e.g. designed for horizontal use) on the SMPS600 large HS brings it's temp down to about the temp of the SMPS600 small HS.

If the SMPS600 large HS raises in temp approximately the same as the small HS with the cover installed, then the original large HS would theoretically measure about,

46.5*(49/36) ~= 63 C

The 85 C measurement on the UCD TO220's bothers me, but hey, my various UCD amplifiers have survived 6 summers just fine...


Regards, DavidT
 
Old 24th June 2012, 09:57 PM   #4566
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Quote:
Originally Posted by jtwrace View Post
Here are some NCores that I built.
is that my vectorial logo?
I would've gone for a smaller one but it's not for me to enjoy it
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Old 24th June 2012, 10:03 PM   #4567
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Quote:
Originally Posted by jtwrace View Post
Here are some NCores that I built.
Beautiful casework, JT.
 
Old 24th June 2012, 10:15 PM   #4568
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Originally Posted by Abraxas336 View Post
Will correct and report back.
Best Regards
Sven
Report?? Still have noises?

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Old 24th June 2012, 10:35 PM   #4569
pos is online now pos  Europe
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Quote:
Originally Posted by OllBoll View Post
Hello all again... I now have a more technical review of the NCore vs the Firstwatt F2J on one of my speaker drivers. The driver is currently mounted in a ported box and is specced at 90 db efficiency. The db level I have no exact number on, but was not super-quiet and not ear shatteringly loud, so don't take the exact numbers as absolute truths

First up the NCore:

Click the image to open in full size.

Next up the F2J EDIT: In my F2J I skipped the parallell resistors so output impedance should be about 700.

Click the image to open in full size.

Keep in mind that the F2J is a current source, and the response difference might mostly be due to that. But whatever the reason the measurements for me speak for themselves, I will in my future speaker probably use my NCores for the bass and midbass and then use F2Js for mids and upwards.

So Bruno... I know you said Hypex wouldn't produce a current source NCore but what about after you have delivered the DLCP... pretty please?
Interesting measurements, thanks!
And with the current source you seem to also get a slight boost in the high, probably following a rise of impedance of your driver. The same things goes around 60Hz (probably the resonant frequency of your driver in your box).
And 15dB of 3rd order distortion reduction!
This back ups my own measurements pretty well.

Have you tried the same test with a resistor on the output of the ncore (something like 2x your driver impedance should be enough to get most of the effect distortion/response-wise).
Even with such (or higher) a resistor you would get more power from the ncore than from the 5W of the F2J.

Last edited by pos; 24th June 2012 at 10:39 PM.
 
Old 24th June 2012, 10:51 PM   #4570
OllBoll is online now OllBoll  Sweden
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Quote:
Originally Posted by pos View Post
Interesting measurements, thanks!
And with the current source you seem to also get a slight boost in the high, probably following a rise of impedance of your driver. The same things goes around 60Hz (probably the resonant frequency of your driver in your box).
And 15dB of 3rd order distortion reduction!
This back ups my own measurements pretty well.

Have you tried the same test with a resistor on the output of the ncore (something like 2x your driver impedance should be enough to get most of the effect distortion/response-wise).
Even with such (or higher) a resistor you would get more power from the ncore than from the 5W of the F2J.
Yeah, before I tried to convert the NCore into a current sorce long back in this thread I also tried to put a resistor, I used 30 ohms then in front of a 8 ohm speaker. I got the frequency response slightly changed as expected and a reduction in distortion but very slight, not even close to what you got earlier in the thread where you reported 10-15+ db reduction or what I got now.

I could re-make the test with resistor included also and post graphs, and then I might even be ambitious enough to make an SPL reading so the numbers are more real =)

Last edited by OllBoll; 24th June 2012 at 10:54 PM.
 

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