D-100 or D-200 speaker-out DC offset with respect to ground

Wombat_VC · « **on:** 4 Aug 2005, 01:27 am »

My speaker configuration is very sensitive to any DC offset voltage at the speaker terminal with respect to gound. What is the DC offset voltage present at the speaker-out of D-100 or D-200?

CIAudio · « **Reply #1 on:** 4 Aug 2005, 05:42 am »

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My speaker configuration is very sensitive to any DC offset voltage at the speaker terminal with respect to gound. What is the DC offset voltage present at the speaker-out of D-100 or D-200?

Typically a few mV, and the amps have a protection circuit that will shut them down in the case it exceeds 50mV. It would only reach this level if there was an internal failure. Unlike other Class D designs, there is no floating DC (half rail voltage) on the output terminals.

Wombat_VC · « **Reply #2 on:** 4 Aug 2005, 10:05 am »

Quote from: CIAudio

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Typically a few mV, ...

Let me try to understand it correctly. The few mV refers to the voltage between Speaker (+) to ground, or Speaker (-) to ground, and NOT Speaker (+) to Speaker (-). Am I right?

How about the offset between Speaker (+) and Speaker (-)?

My speakers are Definitive Technology BP7004 which, in addition to the usual speaker-in terminals, have line-level input connectors for the LFE channel. The built-in sub of the speakers will sum signals from both the speaker-in and the LFE. Since I use both types of input, there will be a serious ground-loop problem that can fry the speaker electronics if the amp I use has a floating DC. Many switching amps are no-go for me because of this limitation.

CIAudio · « **Reply #3 on:** 4 Aug 2005, 01:52 pm »

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Let me try to understand it correctly. The few mV refers to the voltage between Speaker (+) to ground, or Speaker (-) to ground, and NOT Speaker (+) to Speaker (-). Am I right?

It's a few mV in either case, speaker (-) and signal ground are common.

Other designs (ICE, Tripath, Nuforce, etc) use a single rail supply, which means you'll have half the supply voltage from either speaker terminal to ground. An amplifier with a 60v supply will have 30vDC from each spkr terminal to ground. Our amplifiers use a split rail linear supply and do not have this problem. They will work fine with powered woofers that use high level input from the main amplifier.

Wombat_VC · « **Reply #4 on:** 5 Aug 2005, 02:04 am »

This is good news to me. Looks like D-200 is the only switching amplifier I can use.

I'm from Singapore. Is there any way I can listen to the D-200 in Singapore?

CIAudio · « **Reply #5 on:** 5 Aug 2005, 04:34 am »

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I'm from Singapore. Is there any way I can listen to the D-200 in Singapore?

We are setting up a distributor in Singapore/Malaysia. We just sent them a sample pair of D-100's today and they'll have them next week.

Contact Steve Ng at
MUSICLINK AV DISTRIBUTION
100 BEACH ROAD #02-46-49
SHAW TOWER
SINGAPORE 189702
Phone 65-62911106

Wombat_VC · « **Reply #6 on:** 5 Aug 2005, 07:39 am »

Musiclink. Interesting! I can listen to both CIA and NuForce in the same showroom.

pturn · « **Reply #7 on:** 5 Aug 2005, 02:57 pm »

One of the reasons for purchase was the standard speaker output, my REL sub acts funny with some other class D amps, for example, the PS audio HCA-2 had to be left on all the time (not that that was a problem) switching it off would induce humm in the sub.

They are beautifull and compact, cant wait to fire em up later today...

Paul