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Old 23rd March 2011, 04:14 PM   #1
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Default UCD vs NCC200

Hi all,

As I consider to try something new like the hypex UCD modules and/or Jensen four pole caps for my home build amp, I wanted to get your advices and experiences on the subject.

I currently have a ncc200 based amp and an ICEPOWER A500 based amp, both with linear supply and various tweaks. Both have each their unique stregths but also flaws (to my ears at least...) The ICE sounds undistored, clear and seems pretty unmasked and with a somewhat delicate instrument reproduction, though it also seems abit slow and musically detached. Like it never really gets into the music. On the other hand, the NCC200 has a heavier and more distorted presentation but with more drive. Both sounds good in their own respect, but I would really like to be able to combine the drive of the ncc200 with the delicacy and clarity of the ICE.

Would hypex UCDīs be a possible way to achieve this? Or are there other designs (any class) that I should consider?

Could the four pole jensen caps or BHC T-net caps be a way to improve the ncc200īs over their current 22000uF Kendeil caps? Or are there other caps to consider?

Any ideas, experiences or other thoughts would be very appreciated

cheers,
Juhleren
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Old 23rd March 2011, 11:40 PM   #2
Javin5 is offline Javin5  Switzerland
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In the early days of the UcD, there was a very long thread in this forum, discussing various mods and the use of non-Hypex power supplies. As far as I recall, some posters reported very favorably about the use of 4-pole caps (I think that`s what the T-nets are). So if you have any, by all means try them.
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Old 24th March 2011, 12:27 PM   #3
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Thank you for replying Javin5,
I actually got the idea from these old threads you refer to, but as I havenīt been able to find more info i hoped that someone in this knowledgeable community had some experience to share on the topic.
Unfortunately i havenīt got any of these rather expensive four pole caps, but consider to source them if good results can be expected.
- I especially fancy this cap designs promise of better filtering, separation from rectifier bridge, and the vastly improved high speed/frequency performance. But one thing is theoretical gains, another is how it translates into practical gains in reality. It would for sure be nice to make my ncc200 amp perform better and more independently of niose polution on the grid.
Are current users of UCDīs moved onto SMPS supplies, or are there just little to discuss concerning powersupplies these days? (maybe these questions are relevant for the power supply forum?..)
Basically Iīm just very curious of what i could expect from the UCD design compared to my current NCC200 amp, so any experiences or comments would be greatly appreciated.

cheers,
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Old 6th April 2011, 09:30 AM   #4
savvas is offline savvas  Greece
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I have built NCC200 and I don't described the sound of it as distorted, it's very clean actually and neutral (good parts and no input caps will improve things in this direction)
I also had ICE 1000 based amp (EAR1000 with onboard psu) and the word that comes to mind is 'refined'. Dynamics were nowhere near a good A/B amp and miles away of a Class A amp.

Due to poor noise rejection of the RCA based amps like NCC200, people who built them prefer to use an CLC psu like CAP6 from Avondale. I have T-Nets in my pre and they improved transparency and oundstage a great deal.
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Old 6th April 2011, 11:10 AM   #5
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Quote:
Originally Posted by savvas View Post
I have built NCC200 and I don't described the sound of it as distorted, it's very clean actually and neutral (good parts and no input caps will improve things in this direction)
I also had ICE 1000 based amp (EAR1000 with onboard psu) and the word that comes to mind is 'refined'. Dynamics were nowhere near a good A/B amp and miles away of a Class A amp.

Due to poor noise rejection of the RCA based amps like NCC200, people who built them prefer to use an CLC psu like CAP6 from Avondale. I have T-Nets in my pre and they improved transparency and oundstage a great deal.
Thanks for your reply Savvas,

The ncc200 doesnīt distort but compared to my ICE it certainly adds more to the signal (I use very transparent speakers and cables, so this is very evident on my system). The EAR1000 and the EAR TWO are reported to be quite different as are their powersupplies, though `refinedī as you say seem to cover my perception of my ICE well too.

What kind of mods have you made on your ncc200īs apart from bypassing the input cap?
Regarding `good partsī I though i paid good money for the boards from avondale to be delivered with top quality parts. Iīm very interested to hear which parts you would recommend to improve upon, and how?

I know many regard the CLC PS approach to be the right one for the RCA design, but I feel there is something fundamentally wrong with it, and in relation to preamps PS it has been reported to `sit on the soundī somewhat though it should clean things up. Did you feel that there were any audible downfalls regarding the implementation of the T-nets in your pre?

cheers,
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Old 10th April 2011, 08:36 PM   #6
savvas is offline savvas  Greece
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Aside from input cap, feedback cap has great impact on SQ of NCC200

Elna Silmics II are on the soft side with luck on bass.
Wet tantalums are very dynamic, with great bass and revealing HF. Some luck of midrange maybe due to HF extension
Evox MMKs sound almost the opposite of wet tants. Great midrange, not as dynamic as wet tants, softer HF response and not great bass, still better than Silmics
Obbligatos (very big) didn't emphasize on any frequencies but were not as clean as MMKs and wet tants (a hint of grain). They had good soundstage but not as good as the above two.

My system is quite revealing so I'm positive of the character of the above caps

I haven't heard any downfall using T-Nets. I'm gonna try the Sikorels that I have in hand in the near future.

Edit: I'm quite biased on Hypex modules at the present (hey we are at Class D forum after all) heven't heard them though

Last edited by savvas; 10th April 2011 at 08:46 PM.
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Old 21st July 2011, 01:10 PM   #7
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Got some UCD100OEM modules to play with, and iīm not disappointed at all.

Initially I was, but playing around with the PS really changed the game for the little bastard. As it seems these little hypex modules are very sensitive to the PS especially its HF abilities. The good thing is that it seems that one can tune the sound by tuning the PS to get what one prefers.

Compared to the ICE its much more coherent and direct with uncomparable timing and its faster and more controlled than the NCC200 and gets more `colorī through on the instruments -which does not seem to be coloration but related to its immediacy in the presence band from 1-4 kHz.

Very interesting on a 500VA 24,5VAC toroid and a single pair of 10ī000 uF Rifas.
The pin arrangement on this OEM style amp is a pain in the A... though

The only thing I canīt figure out yet is that it has a rather loud background noise (mostly on one channel) which it picks up from both my ARC LS2 and Naim 82 pres. Nothing connected or from the variable head phone output on my cheap DVD player doesnīt say a thing so the noise seems to be something with the preīs and the module and/or my wiring... The modules have no input buffer so Iīm driving the modulators directly from the source and employing AC coupling doesnīt help. Also Iīm using RCA cables so the ground is attached to the inv. input
-Any thoughts from you clever guys and gals would be greatly appreciated

Also I made the link between the caps the common ground with the ground secondaries of the toroid attached, as well as the modules grounds and the speakers ground. Is this the "right" way to do it or should I make the modules the common ground instead/could this be the reason of the elevated background noise?

cheers,
Joakim
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Old 24th July 2011, 09:39 AM   #8
avr300 is offline avr300  Denmark
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Have you created a ground loop ? Is your case connected to signal ground ?

Shoot a picture of the rig an post it here.
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Old 24th July 2011, 12:50 PM   #9
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Hi avr300,

My case is not connected to ground. The RCA input is connected to non-inverting audio input (signal) and inverting audio input (RCA ground wire). The modules are grounded through their ground connection to the common ground between the two Rifa supply caps.

I can post a photo later, but due to the proximity of the 14 pins connectors it will be impossible to see how things are wired. The strange thing is that with nothing, or a transistor radio or my cheap dvd player connected there is no noise at all. Its only there with either of my naim or audio research preamps connected. The noise also disappear when i mute my audio research pre... -maybe its a impedance mismatch between the 1.8 kOhm UCD modulator and the preamps...

Also the only thing about the presentation of the UCD100 that I dislike is that I find the sound very tight and somewhat unnaturally `closed inī. Though it helps the high frequency reproduction a lot, this is further enhanced when I bypass the supply caps with very small film caps. Is this a sonic feature of the Hypex UCDīs that others can relate to? -Could it be an effect of driving the modulator directly from preamp without using a buffer stage?

cheers
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Old 24th July 2011, 02:25 PM   #10
avr300 is offline avr300  Denmark
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And your RCA sockets are isolated from the case ?

Also, try with only one channel connected to the pre.

Last edited by avr300; 24th July 2011 at 02:29 PM.
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