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Old 21st March 2009, 09:16 AM   #11
cdl is offline cdl  Denmark
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Originally posted by Thzar

You said "short input- to inputGND?"
Thzar, I'm sorry to hear that you can't get it working, even with the Creative Zen player Either something is very wrong with the wiring, or with the modules themselves - however, I doubt that both modules should be defective. Maybe they are disturbing oneanother - can you try out each module on its own (with the other one unpowered and disconnected)?

You are right, the instruction to short the unused -input to GND has been removed from the cookbook 1.06 - it was there in the earlier ones. You can still se a "trace" of it on page 14 where Lars didn't put in a new figure But anyway - the important thing is to either leave the unused -input unconnected, or connect it only to the GND terminal of the NCD module, as bro pointed out too (page 10) - don't do as on page 2.

So you say that grounding the chassis didn't help at all... so something more serious seems to be the problem. Is the grounding between the modules connected as on P10 / P19 in the cookbook?

Good luck and keep us posted - cdl
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Old 3rd April 2009, 11:30 AM   #12
Thzar is offline Thzar  Sweden
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Breaking News!!!!!!

I got my wall outlet changed to earthed.

Everything changed!

Now, my Newclassd amps is dead quiet even with a realtek AC97 70 db s/n soundcard.

With no change in wiring.

I guess that the computer MUST be earthed or all hell is breaking lose. But I cant explan the prob with the mp3player.

But I repeat - its dead silent. almost there is a slighty bit of noise but its so quiet.

But things must work without earthed wall outlets.?

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Old 3rd April 2009, 11:33 AM   #13
cdl is offline cdl  Denmark
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I'm happy to hear that!!!!

I'm sure you will enjoy the modules a lot - I wouldn't part with them for any price. Good to hear you don't have noise from the PC coming in ;-)

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Old 3rd April 2009, 12:49 PM   #14
bro is offline bro  Singapore
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Congratulations Thzar!

I thought I had problems too with hum and hiss. That is until I swapped to another source and realized that the NCDs are dead silent. No need for the EMC kit and screening for the transformer at all.

Now I have to deal with my naughty DAC and, maybe, the hot ferrite.
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Old 17th November 2009, 10:23 AM   #15
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Congratulations to You all guys!

On the contrary I do have two burned NCD1 modules and three burned base/mid speaker elements as the result of a problem that I have had since I got my NCD to work.

The setup is very simple: A Thermaltake HTPC, E-MU1616M soundcard, NCD1 dual mono and a pair of Thiel speakers (before they were burned out by the amp).

The dual mono setup is done completely 100% from the cookbook, and are checked and double, and triple checked again, and more than that.

From the beginning the NCD shuts down as soon as i play on high-mid volumes. A tiny little bit faster in one of the channels, but both in higher but still not High listening volumes.

A few weeks ago they shut down AND burned to death, and before doing so the voic coils of my Thiel C220-T6 element went to charcoal.

I have measure everything I think I can. No problems with ground as far as I can se. Everything is connected as it should and as far as I can measure I use an electronic normal measure intrument) there is no DC from the soundcard when playing music with any musicplayer (Foobar, Mediaplayer etc).

Does anyone have any idea of what this could be???

So far I got burned speaker element for € 1200 worth and I dont like "trying" any more

So You guys with a lot more electronical experience - any ideas?
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Old 17th November 2009, 11:00 AM   #16
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I´m been using an old 70s Sentec poweramp instead of the dead NCD1 amp and it does the job absolutely fine on all listening levels. . .
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Old 17th November 2009, 01:20 PM   #17
cdl is offline cdl  Denmark
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Really sorry to hear of your (very expensive!) troubles :-(

Sounds like you have to do some serious troubleshooting using only old "disposable" speakers until you are 100% sure everything is OK. I would also advise strongly against connecting a high-gain power amp like the NCD directly to a soundcard in a computer without "something" in-between (sorry guys, just bad experience with that sort of setup). Until you have this sorted out 100%, do at least use a simple volume control pot (connection of it is described in the cookbook).

My suggestions for your problem would be (I know you checked some of this, but check again!!):

1) DC somehow arising between your PC and the NCD, possibly your soundcard not liking the low impedance of the NCD
2) are you ABSOLUTELY sure you corrected the input correctly? ground from the source goes to ground on the amp NOT to the (-) input, when you are running single-ended.
3) I would use a different, (non-powered, unbalanced) source THAT YOU KNOW IS GOOD for initial troubleshooting to eliminate any ground etc. problems. I used my MP3 player (before you turn the amp on, turn the volume ALL the way down and don't fiddle with connections of course!)
4) High frequence (possible inaudible) signal from the soundcard loading amp and speaker very heavily? You might need some sort of oscilloscope to make sure. The burning of your bass speakers would rather indicate DC though.
5) Grounding. Make sure that you have both the PC and everything connected to it in earthed wall outlets (and use 3 prong plugs of course!). The NCD of course also needs an earthed outlet / 3-prong plug etc. If you don't have earthed outlets, buy a power strip WITH an earth rail and plug both amp and PC into that. Measure that amp GND and PC chassis are well connected.
6) Check your power supply - are the rail voltages fully symmetric? Reaching the NCD modules correctly (measure it on the module?).
7) Make some measurements on the speaker terminals, with test resistors and/or disposable speakers connected. Measure DC; there should be none, but if any is present on input (or if something else is wrong) you will see it on the output (measure with and without anything playing). Measure AC on the output with nothing playing as well - there should be practically nothing. Signal should increase as you turn up the volume.
8) check again! for DC - any imbalance in the rails or DC on the input might cause such problems.

Just because your old amp works fine does not exclude the above - your old amp certainly has some DC blocking circuitry (probably capacitors), almost certainly has a high frequency filter or bandwith limitation of a sort, and most likely has lower gain. I am almost certain you must have a mistake somewhere in the wiring / power supply and/or some of the above (otherwise perhaps something is wrong with your EMU) - the modules shutting down when increasing volume is a sure sign that something is WRONG. I never experienced mine shutting down even when putting out a lot of watts.

That was my input. Hope we can help you find the mistake - I have been very happy with my NCD-1 for ages now, and there is no doubt you deserve that too!
By the ways, I also listen to soundcard output (Creative Audigy2 ZS) - and my DIY DAC which has a little DC on the output - but I run them through my preamp which has a DC servo... But even with quite some DC on the input my NCD's kept on playing without doing anything nasty (except a loud bang on power-up because of the DC).

When you get around to it, try post back your rail voltages, voltages on the speaker posts (AC+DC), resistance in ohm between chassis etc. You might want to try using a disposable cheap USB soundcard (~100 kr.) as an oscilloscope with some suitable software (winscope or similar).

Good luck - cdl
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Old 17th November 2009, 01:41 PM   #18
Thzar is offline Thzar  Sweden
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That sucks.

Only explanation I got is if you had the NCD running and turned on or off your computer still connected to the NCD modules. Nasty things can happen.

Always use DC blocking cap on input.

But your NCD modules burn to death so there´s someting else.
Defect modules, NCD had some trouble with early modules.
Contact Lars at NewclassD.

Last edited by Thzar; 17th November 2009 at 01:45 PM.
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Old 17th November 2009, 05:40 PM   #19
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Thank You guys,

I try to answer the suggestions as work them through. I also contacted Lars that (as always) answered quickly - and he wants me to send the amp down. I try to measure some more before I do that.

Comments to Your numbered suggestions CDL:
1) I did measure DC between hot and ground on the outgoing cables (no amp connected - as it already had burned) from the Soundcard - No DC there at all. Should I measure in some other way?
2) Absolutely shure. Checked and checked again - I read the cookbook very thoroughly . Started with unbalanced and moved over to blanced after reading on Josef Svalanders homepage about fourtwinned cables etc. At that point I had never used balanced XLR contacts before and was suprised by the placement of the G H C pins in the contact (Intuitive the G would be be pin 3 (C) and not no 1) - but did it all right from the beginning. Checked, checked again and again.
3) I agree it seems like DC (and in that case from the SC) - Should the safety circuit in the NCD take care of that? It now could be a good idea to try with a MP3 player (I didnīt think that was necessary before - but I guess I have to changemy mind :-/ )
4) Could be, but seems like a farfetched cause - I think I stay with DC for a while.
5) Both the equipments has a grund cable and I have a new electrical system in the house with grund in every socket outlet - and no grund problems in the house. The PC and the amp are not connected wtih any Separate ground cable - as they both are grounded through their power cables.
6) I have 56-57V DC from V- and V+ to GND and 117V between them. Cant find any measurable DC on V-gate. . . Hmmm ???? Have 42V AC into the 4 pole power supply.
7) Iīll do that more thoroughly than before
8) Donīt know were more to measure . . . There is just a little little tick when switching the PC on and off with the NCD on - so there is not any DC there when there is no musik on I think.

I will also draw a drawing of ALL cables drawn in the case with measurement everywhere I could measure something - without looking in the cookbook. Just to be sure that I donīt just oversee something that my brain correct on the way from my eyes reading of the cookbook to the reading of the cabling in the amp.

Anything else fellows?
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Old 17th November 2009, 05:41 PM   #20
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BTW: I have had enjoyed the amp - but just not on higher volumes :-)

It really playes great ! ! !
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