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Old 29th December 2013, 05:50 PM   #7401
Julf is offline Julf  Europe
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Quote:
Originally Posted by markusA View Post
The signal is currently floating and referenced to signal ground as per the power-amp.
It can't be both "floating" and "referenced to signal ground" at the same time.

A differential input is just that - differential. So the signal is based on the difference between the inputs, and is *not* referenced to ground in any way.

If by "power-amp" you mean the nc400, it does not reference the inputs to ground.

Quote:
Viewing the differential of hot and cold I get 3.3V at full swing I.e. 3.3V peak.
No, that would be peak-to-peak, not peak.

Quote:
(Hot +1.65V and cold -1.65V)
Again, they are not referenced to some halfway point.
 
Old 29th December 2013, 06:07 PM   #7402
markusA is offline markusA  Sweden
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It might be that my terminology is totally off but regardless of that. Right now I have a transformer output. The transformer input sees a 1.65V bias to both hot and cold. When the hot peaks it'll hit 3.3V and at the same time the cold will be at 0V. On the transformer output the difference between hot and cold will be 3.3V.
(My old amps were single ended and I used a Xlr to RCA cable to take care of that. )
Is that considered 2.3Vrms or 1.15Vrms now that we're talking balanced connection?
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Old 29th December 2013, 06:23 PM   #7403
Julf is offline Julf  Europe
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Quote:
Originally Posted by markusA View Post
It might be that my terminology is totally off but regardless of that. Right now I have a transformer output. The transformer input sees a 1.65V bias to both hot and cold. When the hot peaks it'll hit 3.3V and at the same time the cold will be at 0V. On the transformer output the difference between hot and cold will be 3.3V.
(My old amps were single ended and I used a Xlr to RCA cable to take care of that. )
Is that considered 2.3Vrms or 1.15Vrms now that we're talking balanced connection?
The only thing that matters is "the difference between hot and cold will be 3.3V" part. That means that your signal is 3.3 V peak-to-peak, or 1.65 V peak, corresponding to 1.17 V rms for a sine wave.

I am not sure it is just a confusion of terminology - I am not sure you understand the fundamental principle of a differential input. The output of your transformer doesn't "know" one of the inputs is connected to ground - it just sees a voltage between the transformer output pins. Measuring just one of those pins against ground doesn't produce any meaningful result.
 
Old 29th December 2013, 06:32 PM   #7404
markusA is offline markusA  Sweden
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Ah, gotcha. It's been a while since I was messing around with this stuff and I needed a refresher.

I did confuse things but now I get it. Looks like I'll rewire for twice the output voltage later on depending on if I need it or not.
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Old 12th January 2014, 03:18 PM   #7405
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Default ncore subsonic observation

Just made an observation, while having ncores amplifying L channels woofer and another amp doing the amplification for the R woofer (no Crossovers between amps and drivers) The side with the ncore showed a much more pronounced membrane movement (membrane control?), when feeding with a 2Hz sine wave. I swapped amps and speakers to exclude gain/source imbalances. The side with ncore always stayed the one with the much more pronounced membrane movement. Does this ncore (much more dynamic) subsonic behaviour point towards a more dynamic behaviour in the audible range? Or is it rather a nonsense observation?
 
Old 12th January 2014, 03:21 PM   #7406
fpitas is offline fpitas  United States
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I'd guess it's because the NCORE low frequency response goes down to DC, and most other amps don't.
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Old 12th January 2014, 03:27 PM   #7407
Julf is offline Julf  Europe
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The side with the ncore showed a much more pronounced membrane movement (membrane control?), when feeding with a 2Hz sine wave.
Careful - that sounds like a good way to destroy your woofer.

Yes, the ncore, being DC-coupled, can reproduce the 2 Hz, while most other amps probably won't - but the speaker might not be designed to take any significant energy that low in frequency.
 
Old 12th January 2014, 03:29 PM   #7408
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Quote:
Originally Posted by fbee View Post
Just made an observation, while having ncores amplifying L channels woofer and another amp doing the amplification for the R woofer (no Crossovers between amps and drivers) The side with the ncore showed a much more pronounced membrane movement (membrane control?), when feeding with a 2Hz sine wave. I swapped amps and speakers to exclude gain/source imbalances. The side with ncore always stayed the one with the much more pronounced membrane movement. Does this ncore (much more dynamic) subsonic behaviour point towards a more dynamic behaviour in the audible range? Or is it rather a nonsense observation?

Does the other amp have capacitor coupling at its input for DC protection? If so, it may be attenuating signals as low as 2 Hz.
 
Old 17th January 2014, 08:58 AM   #7409
fbee is offline fbee  Germany
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The comparison was UCD400
AFAIK UCDs internal input stage terminates with 10uF

Nevertheless, the movements of the cone with ncore stay (optically) more intensive when the frequency is raised to 5,10,15,20Hz
 
Old 18th February 2014, 08:24 PM   #7410
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Looking to sell my Ncore 400 dual amps. 1 SMPS and 2 Ncores per box for biamping. 800 per side. Thanks!
 

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