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  #151  
Old 19-12-12, 10:48 AM
NRWler04 NRWler04 is offline
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Gentlemen, here's a short update:

HiCap- Clone "NERO SP 1" and electronic Crossover "NERO EXO 1" are finished. Not only the sound is quite good ...

It look's also realy nice





I'll try to get better pics done with my D200.

Regards from Germany

Ingo
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  #152  
Old 26-12-12, 10:38 AM
NRWler04 NRWler04 is offline
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Over Christmas there was again some progress. Three set's of Power Amp PCB's are nearly finished. Tomorrow I will start to assemble the Amps into the housings.



So far the HiCap-Clone, the electronic XOver and the Pre Amplifier are working. The Sound is, at least for my ears, excellent .....
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  #153  
Old 01-01-13, 02:20 PM
NRWler04 NRWler04 is offline
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Update

Yesterday the first NERO Power Amplifier went into daily use.

Here's a picture from the scope. Above curve is the source signal and the bottom one the amplified signal.



The new NERO is in use for powering the low frequencies ....

Still one CPA 602 in use for high frequencies.



So far, it sounds great .....

Until end of the week next NERO SA 1 will be assembeld to went into daily use.
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  #154  
Old 01-01-13, 02:42 PM
lohk lohk is offline
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Is it noise on the scope or is the amp a bit oscillating?
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  #155  
Old 01-01-13, 02:48 PM
NRWler04 NRWler04 is offline
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Quote:
Originally Posted by lohk View Post
Is it noise on the scope or is the amp a bit oscillating?
Will test it tomorrow. You can't hear it .... Seems to be something with the connectors....

Seems that the first amp need some time for "burning in" ...

Sounds better from hour to hour ....
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  #156  
Old 01-01-13, 03:34 PM
lohk lohk is offline
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This quite long burning in process, which I have witnessed many times, is still astonishing me. There is IMO no real good explanation for it. For the Nytech style capacitor coupled circuits I may be the forming of the capacitors. But usually most technical specs settle within the first hour (for adjustments under load).
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  #157  
Old 02-01-13, 12:42 PM
NRWler04 NRWler04 is offline
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Hello Klaus,

This "Burning In" process takes now two days and my impression is, that it is still in process ...

The NERO SA 1 which is currently in use is capped with NICHICON FG, MUSE & FW. Power Supply Caps are from PANASONIC.

Sounds great ..... and getting better and better.
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  #158  
Old 03-01-13, 03:53 PM
NRWler04 NRWler04 is offline
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Quote:
Originally Posted by lohk View Post
Is it noise on the scope or is the amp a bit oscillating?

To be honest, not sure so far ....

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  #159  
Old 04-01-13, 02:49 AM
lohk lohk is offline
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The noise seen on the scope may be just noise induced by the cables and/or the setup, it may show nothing significant. There is often a bit of noise seen on the screen.
Did you try to extend the magnification to exam this "noise"? Oscillation will show up as one mayor sine frequency often (sometimes more).
How does the amp clip?
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  #160  
Old 05-01-13, 10:31 AM
NRWler04 NRWler04 is offline
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Now I have two NERO's running. One is capped with Nichicon the other with ELNA Silmic 2. the one I use to drive the High Frequencies is getting really hot. ....

The other one for the low/Mid Frequencies will stay cool.

How can I change this ?
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  #161  
Old 05-01-13, 11:28 AM
mudlark mudlark is offline
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I am no expert, but amplifiers getting hot with little load have indicated oscillation.
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  #162  
Old 05-01-13, 11:39 AM
S-Man S-Man is offline
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Quote:
Originally Posted by NRWler04 View Post

How can I change this ?
Turn it off

Seriously:
Check for oscillation
Check the bias level
Check the thermal feedback loop (i.e as the temp goes up the Vbe circuit voltage should reduce).
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  #163  
Old 05-01-13, 12:05 PM
NRWler04 NRWler04 is offline
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Originally the Amp was designed with MJ15003/MJ15004 Power Transistors. I used MJ15024/MJ15025.

Can this be the root cause?
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  #164  
Old 05-01-13, 12:14 PM
NRWler04 NRWler04 is offline
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See the boxes



Bottom: NERO EXO
Middle: NERO SA 1 - LF
Top: NERO SA 1 - HF
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  #165  
Old 05-01-13, 12:23 PM
NRWler04 NRWler04 is offline
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Quote:
Originally Posted by mudlark View Post
I am no expert, but amplifiers getting hot with little load have indicated oscillation.
Could be the oscillation you can see on the scope!?

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