What they all were 🙂
And firstly a big thanks to those who listened.
I listened a few times and have to say that to me, the Europa loses out sonically. Its seems constricted and lacking openness and 'air' to me. The original (and sim) have the recommended 1nF cap across the VAS transistor and I can tell you that really slugs the rise times and consequently gives a poor square wave response.
OK, so we are talking degrees of differences here but I think overall one amp drew more negative comments than the other two. For me that genuinely was the Europa.
The JLH acquits itself very well I think, and were it not for the fact its Class A (I love low power designs) then this would for me be a serious contender.
I'm obviously pleased the FET amp did so well here, but its one heck of a complex design to carry through to a real build.
Question for you folks
Do you think this kind of test has any real validity ? It could be fun at a later date to try other designs, perhaps with more complex reactive loads (assuming the simulations ran in a reasonable time frame).
And firstly a big thanks to those who listened.
Code:
[B]Amp1 = JLH69
Amp2 = Europa
Amp3 = Vertical FET [/B]I listened a few times and have to say that to me, the Europa loses out sonically. Its seems constricted and lacking openness and 'air' to me. The original (and sim) have the recommended 1nF cap across the VAS transistor and I can tell you that really slugs the rise times and consequently gives a poor square wave response.
OK, so we are talking degrees of differences here but I think overall one amp drew more negative comments than the other two. For me that genuinely was the Europa.
The JLH acquits itself very well I think, and were it not for the fact its Class A (I love low power designs) then this would for me be a serious contender.
I'm obviously pleased the FET amp did so well here, but its one heck of a complex design to carry through to a real build.
Question for you folks
Do you think this kind of test has any real validity ? It could be fun at a later date to try other designs, perhaps with more complex reactive loads (assuming the simulations ran in a reasonable time frame).
Yes. Don't think I've heard it before. Makes me want to investigate further.
Do you think this kind of test has any real validity ?
Not qualified to answer this. No knowledge of accuracy of sims. Bit sceptical
The only way to find out would be to compare some models to the real amps. How close are we actually coming with simulations?
Another thing would be to compare models tested at 44.1 kHz, to upsampled model tests. For Example, maybe the Europa would sound different. Some of what we heard with that model might have been due to frequency aliasing. At this point we don't know.
And you raise a good point, that the effects of complex loads probably ought to be taken into consideration.
The JLH is certainly a (very) decent performer, although I would say that if you are interested in building one, then go for the original as here and not the later DC coupled concoctions.
I had no idea how these tests would pan out although I'm pleased in a way that the Europa seemed to be the odd one out as that tallies with the simulated data as regards distortion and so on. So something is going right so far.
I had no idea how these tests would pan out although I'm pleased in a way that the Europa seemed to be the odd one out as that tallies with the simulated data as regards distortion and so on. So something is going right so far.
Thanks Mark. Yes, complex loads are something I want to investigate. I've only Bob C's example from his book as a guide... speaker theory and design isn't my strong point at all... and what I would really like is a tougher load than Bobs example.
I just think its a very elegant design and the one I'm most familiar with. The later DC coupled versions with their current sources and poor control of offset voltage don't (imo) stay true to the original concept.
Thanks. I've got very complex amps and do like the simplicity. Into fullrange drivers too, so..........bit more minimalism
Hello again Mooly. Can you point me in the direction of a good thread to read about JLH amp? Thanks
The Europa was not the odd one out for me. That was #1. It sounded congested compared to the others and to the original. But I can't really chalk that up to anything other than imagination. I wasn't able to do a true blind test.
If you search the forum you will find lots of references to various incarnations of it.
This seems to be the enduring thread:
http://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier.html
These seem to be a collection of the original correspondence on the JLH from Wireless World days:
The Class-A Amplifier Site
The Class-A Amplifier Site
Now that is a bit strange if I'm honest 🙂 Can't explain that at all, other than to acknowledge that we do all perceive sound differently. I found I could switch files very quickly in Windows media player although I did use Foobar as well.
Bit of puzzlement over that one then.
Look at your poll results. I'd say it's a wash. With 13 votes split 3 ways, one amp has to get more votes than the others.
I think the JLH has gained another vote since earlier. Yes, that is a pretty even split although you could spin it that either 1 or 3 were preferred over 2. Can you do that with stats 😉
Seriously though, everyone has to take as they find with the listening. What appeals to one doesn't always appeal to another.
Seriously though, everyone has to take as they find with the listening. What appeals to one doesn't always appeal to another.
It's not clear if the results would have been different if people all used the same reproduction system, or different reproduction systems than they did. That is, it's not clear we can separate out the listening environment from amplifier model preferences, and talk about preferences in isolation.
Hats off. This is really a useful and innovative idea to test an amp. Im sure it has validity as long as we understand and take into account the assumptions used in the modelling (and having good ears of course). This is also equally true with analyzing amp performance using simulation only.
Two issues are the effect of environmental interference or power supply and the effect of parts mismatch in the real build (some circuit can be very sensitive).
BTW, my listening preference was for amp1. I thought this is the fet amp and amp3 was jlh. This guess is mainly based on the superior fft of the fet amp which seems to me to be too good to be true.
Simulation doesnt have to be exact representation of reality, but it must show good correlations and differences. The FFT for example, from your sim it is obvious that amp3 has no drawbacks at all when compared to amp1. I dont think this is true in real life. So the simulator should model this differences. In my experience, theres no class b amp that can match class a amp in certain area of quality. I can see this differences in simulation where class a amps always have clean vhf distortion. The jlh for example, with my simulation setup, at 20khz the response is -210dB! This is unachievable with any class b amps i have simulated, not even from current feedback amps.
Your class b amp, once the right setup is used, i believe will show what i have usually seen in class b amps FFTs, which represents my dislike over the jlh. The fet amp to my ears was very slightly less fatiguing than jlh. This is strange. I believe this is because the system relies on the theoretical perfect matching of the model and negates the effects of HF combined with power supply.
There is an amplifier here that appears to be Class AB, and they describe a novel feed-forward method for controlling crossover distortion, yet if you take a look at the specs, I don't think I have seen anything better: https://benchmarkmedia.com/collections/products/products/benchmark-ahb2-power-amplifier
Have you heard the amp? Do you believe in the spscs?
Its an irony. Lets say a perfect amp is scored 10. If people cannot differentiate two amps with scores of 4 and 5, how will they recognize the sound of amps with score 6, 7, 8, 9 or 10??
Many amps have high scores but left unnoticed because most people have no idea how a good amp should sound like. The only metrics Benchmark can use is the measurement. But thd and noise is not sufficient! Do you have detail of the schematics? Is it bipolar output stage? IIRC it uses Sanken MT-200.
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