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Class D Switching Power Amplifiers and Power D/A conversion

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Old 4th March 2013, 02:41 PM   #31
Toaster is offline Toaster  United Kingdom
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Entirely anecdotal of course, but I finally got to hear a pair of Hypex nCore monos yesterday at the Hi-fi Wigwam show and driving Vivid Audio 1.5s they sounded very good by any reasonable standard. Unfamiliar room, unfamiliar system, but with several other good-sounding set-ups at the show to compare that system to, they certainly weren't a limiting factor, as far as I could tell. Certainly no obvious 'class D' sound. Less expensive class D amps have sounded clear but a bit monochromatic, tonally. YMMV naturally. The nCores, in the context of the system I heard them in, showed none of this. Actually, my initial impression was that they had exactly this weakness, but this turned out to be a quality of the first track I heard. The rest of the music showed significant variations in recorded quality and style, as you would hope and expect. I've no idea exactly how good the nCores are, but they seem very good irrespective of 'class' considerations.
Entirely OT, I also had a brief listen to the KEF LS50s in a system that also included a small Ming Da single-ended triode integrated amp (18W.) and the DSPeaker equaliser DAC. Also excellent sound and the (controversial?) impression that the SIT and the nCore probably sounded more similar than different, allowing for the different associated equipment. That said, both systems were playing computer-based music through high-quality DACs into relatively compact metal-diaphragm driver equipped stand-mount speakers, so the equipment was not that different...

Last edited by Toaster; 4th March 2013 at 02:43 PM.
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Old 4th March 2013, 02:59 PM   #32
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Originally Posted by bnorrish View Post
Have you built a TPA3116D2 amp? Where can one get a PCB? Is that what you use for your primary amp? If no, what do you use?
You can purchase Texas Instruments evaluation modules for the TPA3116 and TPA3118 chips. You will only need to hook up a 24 volt/8 amp converter or power supply.
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Old 4th March 2013, 03:14 PM   #33
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I just noticed that Parts Express offers a 24 VDC 8.8 amp power supply Model PS-SP11184 @ $49.50 that should work perfect for the new Texas Instrument evaluation modules, (TPA3116 and TPA3118).
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Old 4th March 2013, 03:31 PM   #34
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What is the best place to buy the TI evaluation modules and chips?
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Old 4th March 2013, 04:21 PM   #35
RAndyB is offline RAndyB  United Kingdom
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I changed to Hypex UcD 180HG modules to drive Jordan Eikonas from Rod Elloitt's P101s.

The Hypex have better resolution (less distortion) than the P101s - listen to 10 minutes of orchestral tutti from pp to ff on both amps and you hear an easily discenible, but not a huge, improvement; that's why I bought the Hypex after listening to a friend's.

The bass did seem to be lighter after changing from P101 to Hypex. What is difficult to recognise is that there isn't very much really deep bass in most music. Very little goes below 50Hz, and very few speakers reproduce this at the right level. Much of the sound of a bass note is harmonics - in the same region as the fundamental of other instruments. A lack of resolution (greater distortion) will make bass sound heavier by adding to the harmonics - the bit we get from our system, and then interpret as bass because we know the fundamental should be there.

I've added a pair of Monacor SPH275Cs as a sub, driven by the P101s. Now it is very obvious how infrequently the frequency goes very low.

A good example is an organist seeing an fff dynamic (otherwise known as "shake the building".) S/he knows that a 32' Sub-bourdon pedal stop (down to 16Hz, few overtones) won't do much against the full Great, so s/he pulls out all the pedal stops - 16', 8' and 4' stops, then couples to whatever manual s/he isn't playing, giving everything up to 2' stops. This is any number of harmonics; but we know that it is the pedal line (usually moving at half or quarter the speed of the rest of the music) and so we recognise it as bass.

There is a track that demonstrates this rather well (Naxos 8.550582 track 2) in which the organist plays the pedals with couplers (probably to another manual) to achieve fff, then switches out the couplers as the music diminuendos - The 32' fundamental suddenly appears.

Also try http://www.organstops.org/_sounds/Cu...emy/index.html under headphones for some really low, real world, musical notes then play on your speakers.

At the top end, fiddling about with the miniDSP can make (almost) any amount of top end you wish - bear in mind that I now only hear up to 10kHz relative to a reasonably loud 200Hz. I hope that everyone has got hold of a tone generator (e.g. Tolvan Data) and listened under headphones via a good soundcard to check their hearing before spending money on stuff they can't ever fully appreciate.


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Old 4th March 2013, 04:26 PM   #36
RAndyB is offline RAndyB  United Kingdom
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PS: as all my sources now output SPDIF, there really is no reason for not going all the way to full digital amps - when I can slip it past 'er indoors!
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Old 4th March 2013, 04:32 PM   #37
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Originally Posted by bnorrish View Post
What is the best place to buy the TI evaluation modules and chips?
It looks like Mouser Electronics has the TPA3116D2EVM in stock @ $159.08. If you search, you might find one a little cheaper but the price looks reasonable.
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Old 4th March 2013, 05:55 PM   #38
AP2 is offline AP2  Italy
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I want to say a few words purely as an amateur, I think I have a good ear after so many years of listening in the range of high class AB (without interest with the company for which I have developed or other competitors who have, with sound measures, the class D perfect ).
In class AB, traditional audio measurements, have a perfect relationship with the result of listening. this is due to the total absence of phenomena that, in class D are perfectly audible (example; poor definition in the high range, not comparable with the class AB. or alteration of the harmonic content in relation to the percentage of modulation. or intermodulation when in the presence of instrumentals and vocals, raise the power, just with reactive load.) these defects are still present on many class D and are not visible to the audio measurements.
these phenomena are the result of the intrinsic concept of class D.

I listened my MC phono set to mono output: 1 channel on AB true high end, the other channel on class D on the market. connected to the two speakers B & W 802 II.
Rotating the balance quickly and repeating some passages of music (to use the short memory of the brain), the difference (to my ears) is huge and is not comparable, especially at 70% power.
then, as always there is the real world, and... marketing!
it is better (in my experience) start from a good design of class D, if possible do not use dedicated chips, and then put up good final result continually working on comparison with the class AB.


Last edited by AP2; 4th March 2013 at 05:57 PM.
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Old 4th March 2013, 06:05 PM   #39
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Originally Posted by kad View Post
Personally, I'm sold on Class D amplifiers. For their musicality, definition, and efficiency.

The press appears to agree.

The Inner Ear Magazine - Discover High End

Pioneer's Reasonably Priced SC-61 Class D Receiver

My SC-65 has 9.2 outputs low-level and high-level. Each channel can deliver up to 220 Watts @ 4 ohm.

Total AC outlet power consumption: 330 Watts. Now that's efficient!

The Sunfire TS-EQ12 delivers 2700 Watts RMS @3.3 ohms impedance, yet only consumes 600W from the outlet...

Yes, efficiency (and quality/precision) is the way of the future.

Just my two cents.

Only buy something that you'd be perfectly happy to hold if the market shut down for 10 years.
~ Warren Buffett

Our favorite holding period is forever.
~ Warren Buffett

To love is to be happy with.
~ Joe Vitale
Would anyone like to explain how a device can pump out more power than it inputs. Have we finally generated perpetual motion in electronics ???
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Old 4th March 2013, 06:07 PM   #40
qusp is offline qusp  Australia
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my guess is the sunfire is rated PMPO, not RMS
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