My new LM3886 chip amp with BB OPA2604 op amp front ends came today. I will try this out to see if it sounds better than class D I have been using all along.
If it does sound better, it might be the basis for the test amp for the final Round 4.
If it does sound better, it might be the basis for the test amp for the final Round 4.
You are not supposed to say which driver you picked publicly until the reveal. You can post it hidden inside a text file if you want. Let's keep the discussion to the process and how you listened, etc.
Although people like to shun class D in absolute terms I wouldn't doubt the capabilities of the TPA311x series. Sure, they don't have the best objective performance in terms of what is possible nowadays, but they do sound subjectively very nice.
I've used a number of TI's recent class D single chip devices and have nothing but praise for them.
I've used a number of TI's recent class D single chip devices and have nothing but praise for them.
Yes, you have said you use 3116's before. I think you also run a class A amp on your mid and tweeters, a class AB on your mid woofer and class D on the woofer or something like that. I have never used a class A so wonder what that can sound like.
Never seen/used LM3886 in plastic casing before. But with LM3875, I have never been satisfied with the plastic version.
Curious what is considered the best objective performance nowadays?
I thought that classD was all the rage in the audiophile world right now. But I also know that old school big iron classA is hard to beat.
I have owned or done home trial on all types of amps over the years. kind of settled on single-ended classA tubes for my living room (goldentubes se40) but i also like classA solid state. classD in a low power application (5-10watts) is very nice though. Would love to pick up some accuphase classA amps someday though.
My new LM3886 chip amp with BB OPA2604 op amp front ends came today. I will try this out to see if it sounds better than class D I have been using all along.
If it does sound better, it might be the basis for the test amp for the final Round 4.
Hmm... It Certainly Ain't a Modulus 86 😉
LM3886 Amp requires genuine skills to design /build a stellar example.
None of which come from Ebay.
As a guess your results could/should be Decent .
But up to the potential of the chip? Seriously unlikely imo
Good luck though.
Sounds great with dual 19v SMPS!
This amp sounds pretty nice - need more time to listen critically but so far so good. I love the fact that I can power it with a pair of $6ea 19v 4.6amp SMPS bricks. The bass is clean and the highs are clear. I think better than a stock $15 TPA3116D2. Quite a bit of power reserves. Sure it ain't no Modulus386, but it also came pre-built and only cost $40 (shipping included). This is Aliexpress, the home of cheap but good amps. That's a Pentium 460-pin QFBG solid copper heatsink (nickel plated).
I am listening to Miles Davis right now. 😀
This amp sounds pretty nice - need more time to listen critically but so far so good. I love the fact that I can power it with a pair of $6ea 19v 4.6amp SMPS bricks. The bass is clean and the highs are clear. I think better than a stock $15 TPA3116D2. Quite a bit of power reserves. Sure it ain't no Modulus386, but it also came pre-built and only cost $40 (shipping included). This is Aliexpress, the home of cheap but good amps. That's a Pentium 460-pin QFBG solid copper heatsink (nickel plated).
I am listening to Miles Davis right now. 😀
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Tom Christensen's Modulus 86 is objectively (and subjectively, based on the listening experiences of a friend) the best sounding amp ever - I mean beats any amp at any price:
http://www.diyaudio.com/forums/vend...mposite-amplifier-achieving-0-0004-thd-n.html
Something to do with ultralow 0.0002% HD at 35w (8ohm) at 1kHz, -125dB noise floor, and 90dB CMRR.
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Subjective blind testing of a transient perfect vs LR2 XO
Check out this test here:
http://www.diyaudio.com/forums/multi-way/277691-s-harsch-xo-4.html#post4407112
See if you can hear the difference with a transient perfect XO. Everything else being equal.
Check out this test here:
http://www.diyaudio.com/forums/multi-way/277691-s-harsch-xo-4.html#post4407112
See if you can hear the difference with a transient perfect XO. Everything else being equal.
The trouble with class A amplifiers, or any amplifiers for that matter, is that the implementation is absolutely critical if you're going to reap all the benefits of what it can provide. Class A, in absolute terms, is the lowest distortion class of amplifier that is actually possible, but to realise everything that it can provide requires that the rest of the amplifier design is top notch.
Of course the biggest reason that people like going to class A, even if those other issues are not ironed out, is because it completely eliminates crossover distortion. This is one of the most horrible sounding of all the distortion increasing mechanisms in push-pull solid state amplifiers as it throws out lots of high order harmonics. For a given design, the degree to which crossover distortion mucks up the performance gets worse at low output power levels and statistically it at its best when the amplifier is putting out full power. Therefore the more sensitive your loudspeakers the less power you need and the more susceptible you will be to hearing crossover distortion.
Class A is simply a method of biasing the output stage and some amplifier topologies are far more tolerant of an improperly biased output stage than others, so crossover distortion audibility is also very dependent on the amplifier design too. Underbias an output stage and crossover distortion becomes worse, in some cases significantly worse, but find the sweet spot and it reduces down to a very low level, such as in the Modulus.
Of an amplifier that I built, it follows a current feedback architecture and is very low distortion indeed and is also very low noise.
Here is the 1 watt into my 9.4 ohm dummy load real world measurement.
This is with the amplifier optimally biased, such as in the Modulus. The distortion here is already ridiculously low and to get performance like this requires excellent circuit design (many thanks to those in the slewmaster thread) and excellent circuit layout. Without the excellent layout all the good of what the circuit can provide goes to pot.
Bias it into class A however this happens.
What was once ridiculously low is now even a little lower. Certainly many would argue that no one is going to hear this, but from an objective point of view the engineer in me says class A = better measured performance therefore, if possible (if the loudspeakers are high enough sensitivity) I want it!
So far class D cannot quite reach the level of performance that an optimally designed and built class A can provide, but it's not that far behind. I have absolutely no idea what limits class D performance and what improvements to technology would be required to make that possible. Maybe better MOSFETs for the switching output stages? I know MOSFET design is always improving and this results in better SMPS design of all types, so I can't see why this wouldn't be the case in a class D amplifier too.
Currently the ncore offers pretty much the best objective performance of all class D amplifiers with something very NDA agreement stuff from zetex also doing quite nicely. Although it seems like the DDFA stuff from zetex has been bought by CSR. Nevertheless both of these class D designs types include the output filter within the feedback loop, taking mutiple feedback points, I believe one before the filter and one after it? Thus helping to further linearise the system performance.
Stability is one key issue for most systems. The modulus is an example of this. The LM3886 is a pretty easy to use and forgiving device, the modulus uses it to great effect, but pushes its performance significantly beyond what it is capable of alone by using a very wide bandwidth and high quality opamp as an error amplifier. This vastly changes the way feedback is utilised and as a result it turns the generic performance of the LM3886 into something downright unbelievable. It also makes the nested opamp + chipamp far more susceptible to oscillation and this is one of the reasons why it's worth buying the pre designed PCBs, this isn't an amplifier especially suited to the point to point wire it up in a biscuit tin, easy weekend, type project.
I think the same is true for class D amplifiers. TI, for example, provide a number of products at different performance levels and some have rather nice objective performance, but in other areas those amplifiers fall down. I'm sure TI could design a ready to order finished design (such as an ncore module) that would significantly outdo the performance of their 'easy to use' and affordable chip amps, but that wouldn't be giving the market what it demands.
Build your own!
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5th Element,
Thanks for the explanation of what it takes to get a class A or AB to work well. What gear do you use to measure the HD of the 9ohm resistor? That is a pretty sound card you have to resolve that low of HD and to have low self-noise as well.
Btw, I noticed a slight improvement in reduction of HD, at the speaker measured with mic when using the LM3886 amp vs my TPA3116D2. So far though the sound quality of the modified TPA3116 is quite comparable as far as I can tell. I just have a lot more power reserves with the LM3886 (double the ps rail with two 19v bricks).
Thanks for the explanation of what it takes to get a class A or AB to work well. What gear do you use to measure the HD of the 9ohm resistor? That is a pretty sound card you have to resolve that low of HD and to have low self-noise as well.
Btw, I noticed a slight improvement in reduction of HD, at the speaker measured with mic when using the LM3886 amp vs my TPA3116D2. So far though the sound quality of the modified TPA3116 is quite comparable as far as I can tell. I just have a lot more power reserves with the LM3886 (double the ps rail with two 19v bricks).
DDR & your RESA (i have called it false detail for at least 15 years) are 2 very different things.
An amplifier cannot be excellent unless it has VERY good DDR.
dave
With that beautifully distortion plots 5th element show us then guess it is natural amp too has better specs all over compared many other amps as a cleaner power supply, lover noice floor, higher dynamic range, and being a current feedback verse voltage feedback amp then excellent slew rate.
Godzilla says "That amp must have great DDR" in my eyes maybe be amended to "That amp must have TRUE low level detail" : )
xrk971 pretty sure response is super flat probably to lot more than 500kHz, think 5th calibrated compensation and tuned unique the particular build by hand.
planet10 try words low level detail instead of DDR, is better to understand for everybody or choose word expanding which is opposite compressor and works down there expanding downward peaks : )
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What level of performance are the ncore's at compared to good class A/B amps? I've read good things about them and like that they are 200 watt.
Technically speaking you are not measuring the HD of the 9 ohm resistor, you are measuring the HD of the amplifier driving the 9 ohm resistor. Much the same you could measure the HD of the amplifier driving a loudspeaker and it would still be very low, but the distortion that the loudspeaker produces would be much higher.
I am using the analogue inputs of the ASUS Xonar Essence STX. Measurements of which can be found here. It uses the CS5381 flagship A/D converter from cirrus logic.
The signal source, which is just as important, is a DAC based on the ES9018.
Well the TPA3116 is a BTL amplifier, so when run from one 19v brick will have the same voltage swing potential as the LM3886 run from two. Minus internal voltage losses.
Those amps have independently regulated power supplies for the front end. I figured why not go the whole hog, for lower power designs finding suitable regulators isn't that difficult.
It does indeed.
The amplifier itself was originally designed and balanced by OStripper, it was then modified by member BV. I then modded it myself to suit my intended application and tuned each channel once they were built. If set up incorrectly the performance of this amp goes completely down the drain. The amp itself has an input filter to prevent it from being exposed to high frequencies as a method of protection rather than anything else.
DDR is P10s only invention to try and coin a phrase that describes something that is apparently unmeasurable but is responsible for causing some drivers to have inherently high levels of low level detail and others to not.
It depends on what measurements you see of the ncore.
Here are some measurements of an independent amplifier using NC1200 modules.
Theta Digital Prometheus monoblock power amplifier Measurements | Stereophile.com
They clearly do not measure as well as Hypex's datasheet would have you believe, but that could simply be down to implementation of the amplifier under review. Still for the price you're paying I would expect the implementation to be flawless.
It is worth pointing out I believe that the vast majority of class A or class AB amplifiers on the audiophile market are built to standards that one would not consider state of the art. I find this a shame, but lots of designers appear to want to try their 'own thing' with amp design even if it means compromising the objective performance of said amplifier.
Sometimes this can be down to personal choices that the designer is well aware of. Nelson Pass designs like this, he's not so concerned with absolute technical performance, but more with his own ideals. Nelson still runs most of his amplifiers in class A, or with a heavy class A bias to do away with crossover distortion mind you 😉 Other times this can be down to complete negligence where the layout is the obvious issue, in other words the circuit used is excellent, but the poor design and implementation degrades the performance. This can be as simple as placing a single wire or PCB trace in the wrong place.
You would figure that most audiophile companies would weed out all of these problems, after all that's what you're paying them thousands of dollars for...nope...it's far better to build your own, at least then you know what you're getting! Like the wire, the modulus or some of the slew master combinations.
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