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Class D Switching Power Amplifiers and Power D/A conversion

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Old 1st September 2004, 04:06 PM   #381
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So at risk of labouring the obvious: On your UCD module, you have pins for signal positive, negative and signal ground. So we wire an incoming balanced signal with the twisted pair signal wires to the positive and neg lines on the UCD. Then we take the balanced cable shield connection straight to the chassis (not to the star connection ground point?). What is then connected to the UCD signal ground line?
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Old 1st September 2004, 04:10 PM   #382
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Quote:
Originally posted by wytco0
classd and Jan-peter, thanks for reminding me that these modules are not digital, silly me
Well, sure they ain't digital, but I think that doesn't negate the desire to have an "integrated" power amplifier. These cheap high quality modules open up some very interesting options for having some very high quality active speakers, and optional integrated volume control does solve a few problems.

In a nutshell it's quite hard finding a 12 way volume control... Even if I needed to put all the same type of amp in the system to make this work, it would still be an interesting compromise.

Is there an opportunity to work something in by altering the way the comparator works, or is the only option the TACT way, where the voltage is varied? (Which then presumably puts a lot of design issues into the powersupply)
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Old 1st September 2004, 05:02 PM   #383
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Default UcD180 results

I just got my UcD180s wired up and put them on my audio Precision for testing. I am very pleased that they worked first try and the specs I have measured so far seem excellent. I am getting slightly better THD+N than the ICE Power modules I have been using the past couple years. 0.015% vs 0.018%. The S/N ratio with an unregulated power supply was 108db (A-weighted) and of course, the frequency response was as flat as anyone could want. I will publish graphs from the AP in the next few days. Extensive listening tests will be done this weekend.

However, at this stage of the game I can say that I am happy with the results and I recommend these modules to the DIY market. I also have a pair of the UcD400s but have only just now dug up power transformers to test them. I will post results for those as well, as soon as I have them.

In the mean time I am going ahead and designing a 1U rack amp using two UcD180s with a small 24/96 DSP included using the TAS3103.
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Old 1st September 2004, 07:59 PM   #384
jam is online now jam  United States
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I thought that the UcD400 modules wern't shipping for a few weeks yet?
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Old 1st September 2004, 08:23 PM   #385
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Ewildgoose,

Quote:
On your UCD module, you have pins for signal positive, negative and signal ground. So we wire an incoming balanced signal with the twisted pair signal wires to the positive and neg lines on the UCD. Then we take the balanced cable shield connection straight to the chassis (not to the star connection ground point?). What is then connected to the UCD signal ground line?
Connect this three wires to a XLR, whereby pin#1 of the XLR must be connected to the chassie.

Quote:
Is there an opportunity to work something in by altering the way the comparator works, or is the only option the TACT way, where the voltage is varied? (Which then presumably puts a lot of design issues into the powersupply)
No, this not possible you can only control the volume by changing the powersupply voltage by an open loop Class-D. The UcD is not an open loop, but a self oscillating Class-D amplifier.

You can consider perhaps those digital volume control IC, some are not bad at all......


Dmfraser,

Thanks for spending some time to evaluate our products. I highly appreciate this

Jam,

We have a small serie of a preproduction samples of the Ucd400. We have send several to some of our potential customers.

Regards,

Jan-Peter

www.hypex.nl
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Old 1st September 2004, 08:27 PM   #386
jam is online now jam  United States
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Jan-Peter,

Thanks.


Dan Fraser,

We are egerly awaiting your report. How about a comparison with the ice-power modules?
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Old 1st September 2004, 09:19 PM   #387
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Quote:
Originally posted by ewildgoose

Is there an opportunity to work something in by altering the way the comparator works, or is the only option the TACT way, where the voltage is varied? (Which then presumably puts a lot of design issues into the powersupply)
There is no such opportunity. The UcD amps (and most other analogue class D amplifiers) have their voltage gain set by a pair of resistors in a very similar way to a standard linear amplifier. The only way to change the gain on a UcD amplifier, like a linear amplifier, is to modify this feedback network. Only with class D amplifiers it's more complicated because you have to make the loop gain track as well (although this would be a good idea with linear amps too - which explains the popularity of current-feedback topologies that do so automatically).

So really, really, forget that UcD switches. It walks like an analogue amplifier and it quacks like one.
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Old 1st September 2004, 09:25 PM   #388
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Quote:
Originally posted by ewildgoose
So at risk of labouring the obvious: On your UCD module, you have pins for signal positive, negative and signal ground. So we wire an incoming balanced signal with the twisted pair signal wires to the positive and neg lines on the UCD. Then we take the balanced cable shield connection straight to the chassis (not to the star connection ground point?). What is then connected to the UCD signal ground line?
Shield is at least connected to the UcD ground pin, hot to noninverting in, cold to inverting. It is further recommended to tie the shield to chassis as well by making a direct connection from pin 1 of the XLR chassis part to the earth lug that's also on it. Don't use the black neutrik chassis parts, because the black paint prevents the thing from electrically contacting the chassis.
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Old 1st September 2004, 10:19 PM   #389
pburke is offline pburke  Germany
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Quote:
Originally posted by Jan-Peter

Jam,

We have a small serie of a preproduction samples of the Ucd400. We have send several to some of our potential customers.


I'm a potential customer, too


but I guess then some customers are more potential than others <g>


PS - that entire XLR balanced to unbalanced gear wiring thing should be put in a simple FAQ - I'm getting a headache just reading the discussion (probably because I didn't get one of those UCDs in the mail so I can visualize this better


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Old 1st September 2004, 10:46 PM   #390
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Default UcD vs ICE

What is in common:

Both will work from an unregulated power supply.

Both are analog amplifiers. What this means is that while they are both switching amplifiers, the amplifiers are analog in that the pulse width of the PWM output is an analog of the audio and that the PWM signal is created by comparitors and other such devices. An amplifier is digital only if at some point the internal signal is in some pulse code format. That is not the case with either of these.

Both have comparible THD+N, frequency response and other specs with maybe a slight edge with the UcD product.

Both have feedback loops and thus have the advantages and disadvantages of feedback.

Both have a balanced input.


Differences

UcD uses a dual power supply. ICE uses a single polarity main power supply plus separate 12V to 15V supplies depending on model.

UcD is a half bridge unit with no standing DC on the output. Therefore it is bridgeable.

ICE is a full bridge unit. There is standing DC on each side of 1/2 the supply. They cannot be used in stand alone amplidiers because if this DC voltage and receive agency approval. As well, they cannot be bridged further.

UcD appears to be available to the DIY market. I do not know of any source of ICE modules for the DIY market.

The UcD people have sent me samples of the 180 and 400. The ICE people sample me on all their new units and bought me a nice dinner in New York City last October.

ICE have modules now with a built in switching power supply.

UcD has current limiting. The UCE ASP series have current limiting but the A series does not.

Overall, for ease of use, the UcD are easier to deploy as there are fewer connections to be made and fewer power supply voltages needed. The UcD are easier for a builder of linear amplifiers to relate to. The only difference is heatsink size. The ICE module needs more thought given on how it is to be deployed as it does need more supply voltages and the mounting is not quite as friendly.

However, I do have a lot of experience with the ICE modules, having deployed thousands of ICE modules and once they are properly deployed, they are an excellent sounding and very reliable amplifier. Just don't short the output on a A series unit or short either speaker line to ground. This restriction is OK on a powered loudspeaker but not on a stand alone amp.

To build a stand alone amp, in the conventional manner, the UcD are easier to deploy and likely to be somewhat more reliable because of the current limiting. More suitable for the DIY market.
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