Thank you for helping us to refocus.
If one googles on the internet, or goes back to the very popular, original "Hiraga Le Monstre" thread :
https://www.diyaudio.com/community/threads/hiraga-le-monstre.5462/
One can find many different interpretations of the LM circuit, ranging from different transistor combinations, different resistor and bias values, different power supplies, different open and closed loop gain, etc.
We don't intend to make a new thread to add to that.
Instead, some statements were made that only the original with exactly the same active and passive components specified in the article from decades ago is worthy of being called the "real" Le Monstre.
We want to find out for ourselves how true that is. And to do so, one needs to have at least one example as close to the original as possible to serve as the reference, and then ABx tests others against. This reference is our LM Deluxe, with TaN resistors, including Shinkoh on the feedback network, TOCOS RA12P trimmer, and all original BJTs. The only exception is the JFETs, where we used 3.5mA Idss GR grade instead of truely unobtainium Y grade.
But as already described in the article, we found a good way to use a very stable bypass current source to reduce the bias of GR grade back to the original. The only difference of that combination, compared to Y grade, is slightly higher transconductance at bias. For example, for 2SJ74, Yfs at 4mA is 30mS, compared to 22mS at 2 mA. The effective difference in source resistance is therefore 12R, and is swamped by the resistance of the RA12P. If one wants to, one can also add 12R at each end of the RA12P. Then it is 99% true to the original.
And then we went as far as sourcing two car batteries as power supply, as in the original.
Patrick
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We then built another example, with the same transistor set, but just "normal" good quality passives. This enables a differentiation as to what difference those exotic passives can make.
And then a third example with "modern", readily available transistors, chosen to have very close characteristics to the original, to see how these potential replacements can perform. We also explained how these were chosen, and why we considered some others (e.g. 2SK246/2SJ103) to be unsuitable.
The only interpretation of our own is the LM19, which we did because of our own need for 4 ohm load. We included this, not because of any claims to mimic the original, but we thought it might be interesting to some others who has the same loading issue.
And again, it is not about making a better (sounding or measuring) Le Monstre. It is only to find out how close one can come to the original, and with what means.
Hopefully second audition session this weekend.
🙂
Patrick
And then a third example with "modern", readily available transistors, chosen to have very close characteristics to the original, to see how these potential replacements can perform. We also explained how these were chosen, and why we considered some others (e.g. 2SK246/2SJ103) to be unsuitable.
The only interpretation of our own is the LM19, which we did because of our own need for 4 ohm load. We included this, not because of any claims to mimic the original, but we thought it might be interesting to some others who has the same loading issue.
And again, it is not about making a better (sounding or measuring) Le Monstre. It is only to find out how close one can come to the original, and with what means.
Hopefully second audition session this weekend.
🙂
Patrick
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Patrick, I really appreciate your approach, that's why I wouldn't want to see this post go off in all directions with the presentation of many achievements.
A significant number of interpretations of the "Le Monstre" amplifier have been made and everyone has their own comments, but no one is able to say whether the result is better, worse, or equal to the original. And since everything is relative, it is absolutely essential to have an element of comparison if we want to situate ourselves and progress, hence the obvious validity of your approach. 👍
I look forward the second audition session. 😉
A significant number of interpretations of the "Le Monstre" amplifier have been made and everyone has their own comments, but no one is able to say whether the result is better, worse, or equal to the original. And since everything is relative, it is absolutely essential to have an element of comparison if we want to situate ourselves and progress, hence the obvious validity of your approach. 👍
I look forward the second audition session. 😉
BTW, after 20 years with this forum, I finally persuaded myself to learn to use the "ignore" function.
It is a very nice feature. 🤓
Patrick
It is a very nice feature. 🤓
Patrick
We have been asked by PM for PCBs and kits.
Please let us finish all our ABx test first.
Then we can conclude, in our opinion, what configuration has what advantages and disadvantages .
After that, we can offer what is difficult to get.
But as already mentioned, you don't really need anything from us, especially for LM modern.
Gerbers are already published for the original Hiraga PCB.
And most devices are relatively easy to get.
Maybe only the matched JFETs.
Patrick
Please let us finish all our ABx test first.
Then we can conclude, in our opinion, what configuration has what advantages and disadvantages .
After that, we can offer what is difficult to get.
But as already mentioned, you don't really need anything from us, especially for LM modern.
Gerbers are already published for the original Hiraga PCB.
And most devices are relatively easy to get.
Maybe only the matched JFETs.
Patrick
So, not trusting my own ears only, I had a few friends over this week to listen to two versions as outlined by Patrick above.
Version 1 - Le Monstre as close as possible to the original, with battery supply, tantalum resistors etc etc.
Version 2 - Le Monstre modern, with all modern components except for the jfets, powered via Didden super regulators adjusted for the extra current draw. The Didden regs were fed via a lab supply.
The room setup was as outlined before in this thread, and with the ABx switching box that Patrick mentions above, we could easily switch from one to the other on the fly via a handheld switch at the listening chair. I did tell the guys how each amp was configured (not in detail, but just saying one was as close as possible to the original, and another with modern components) but I did not tell them which was which. I asked them the purpose here was to tell if there was any difference between both versions, and if so what was that difference, and also which they preferred. Both amps were allowed to idle for about 30mins before we did any listening. We threw a wide variety of tracks on - everything from good sounding material, to not so good, simple and more complex arrangements etc.
They found it very hard to tell any difference between both versions - once or twice, one of them would mention they thought they could hear a slight difference, but it was not consistent. The only consistent comment that popped up repeatedly was that they thought the bass was ever so slightly tighter on the Le Monstre modern version. But on many tracks they shook their heads and said they could not hear any difference at all. After listening hard for a while, we just let music play..... and I did notice that although they switched back and forth now and again, primarily they stuck with the Le Monstre modern. Maybe that is as good an indicator as anything.
I think if the goal was to see if a modern version could equal the original, well, the answer is there now.
Version 1 - Le Monstre as close as possible to the original, with battery supply, tantalum resistors etc etc.
Version 2 - Le Monstre modern, with all modern components except for the jfets, powered via Didden super regulators adjusted for the extra current draw. The Didden regs were fed via a lab supply.
The room setup was as outlined before in this thread, and with the ABx switching box that Patrick mentions above, we could easily switch from one to the other on the fly via a handheld switch at the listening chair. I did tell the guys how each amp was configured (not in detail, but just saying one was as close as possible to the original, and another with modern components) but I did not tell them which was which. I asked them the purpose here was to tell if there was any difference between both versions, and if so what was that difference, and also which they preferred. Both amps were allowed to idle for about 30mins before we did any listening. We threw a wide variety of tracks on - everything from good sounding material, to not so good, simple and more complex arrangements etc.
They found it very hard to tell any difference between both versions - once or twice, one of them would mention they thought they could hear a slight difference, but it was not consistent. The only consistent comment that popped up repeatedly was that they thought the bass was ever so slightly tighter on the Le Monstre modern version. But on many tracks they shook their heads and said they could not hear any difference at all. After listening hard for a while, we just let music play..... and I did notice that although they switched back and forth now and again, primarily they stuck with the Le Monstre modern. Maybe that is as good an indicator as anything.
I think if the goal was to see if a modern version could equal the original, well, the answer is there now.
Please do not switch while playing music. Stop the music, wait at least 10 seconds so that the hearing can process, remember, adjust and categorize. Then, after at least 10 seconds, listen with the other device (or with the same device for my part - but this should be within the expected range: you should announce that the same device can also continue to run as a comparison for the purpose of a control test).
The ear is a difference perceiver. It must also be able to relate these differences.
The ear is a difference perceiver. It must also be able to relate these differences.
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Good AB comparisons rely on rapid switching between sources - the human auditory memory is only a few seconds long, so waiting will defeat the comparison, leaving it to be based on anything other than auditory memory (ie bias). The short length of auditory memory is probably why people struggle to learn to pronounce long unfamiliar words such as "Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch" in one go, yet can usually handle "floccinaucinihilipilification" - it fits in the buffer whereas the town in Anglesea doesn't. Waiting 10 seconds is a sure way to clear the memory buffer that handles sound itself.
For instance would you be able to distinguish similar but slightly different colours if you had to wait ten seconds in darkness between each sample - clearly not as well if switching back and forth rapidly... Visual memory has similar issues (and the eye adjusts for background colour automatically too of course) - probably true of auditory system as well.
For instance would you be able to distinguish similar but slightly different colours if you had to wait ten seconds in darkness between each sample - clearly not as well if switching back and forth rapidly... Visual memory has similar issues (and the eye adjusts for background colour automatically too of course) - probably true of auditory system as well.
Test first.
A method must work.
The idea that an ear only remembers a few seconds is traditional nonsense.
Using looking as a comparison to hearing can fail.
Test first.
A method must work.
The idea that an ear only remembers a few seconds is traditional nonsense.
Using looking as a comparison to hearing can fail.
Test first.
i personally like both methods...
switching AB and that is also possible with our brain long term listening and recognition.
learning and memories is an active process.
our short brain is not able for store more then 10 seconds ..right!
but if our brain is decide that that information is "important" then we are able to store for long term.
my best example are the older conductor.t hey remember a lot of titles and they "know" how the orchestra should play it....yes every conductor has its "own" interpretation.
switching AB and that is also possible with our brain long term listening and recognition.
learning and memories is an active process.
our short brain is not able for store more then 10 seconds ..right!
but if our brain is decide that that information is "important" then we are able to store for long term.
my best example are the older conductor.t hey remember a lot of titles and they "know" how the orchestra should play it....yes every conductor has its "own" interpretation.
The tests were done for ourselves, to verify certain statements floating around.
We think they are the correct approach for us.
And we can now draw our own conclusions.
Of course everyone is entitled to his own opinion and approach.
That's why it's called DoItYourself.
🙂
Patrick
We think they are the correct approach for us.
And we can now draw our own conclusions.
Of course everyone is entitled to his own opinion and approach.
That's why it's called DoItYourself.
🙂
Patrick
unlike conductors having their own opinion of how to conduct an orchestra, designing electronic, especially analogue circuits is an exact science and not opinion based, else I need not have spent over seven years at university or 50+ years in an R&D to be influenced by opinions. It is either right or it is half wrong and you trash it and start from grassroots.
Depends on your definition of right or wrong.
What sounds good or bad is subjective.
Unlike a certain pre-defined sets of measurable design objectives.
And like everything else, engineering design is always a compromise.
Cheers,
Patrick
What sounds good or bad is subjective.
Unlike a certain pre-defined sets of measurable design objectives.
And like everything else, engineering design is always a compromise.
Cheers,
Patrick
There is nothing subjective in established scientific analysis, else it will be called hocus pocus. Is there subjectively good or bad sounding farts, silent ones I guess are worse. I also take it you won't mind being connected to a compromised heart lung machine or compromised nuclear launch control. Where the thing falls down is always a compromise. Sucks, I am sorry killing a million of my friends, merely a compromise. Heck we did not have the right concrete mix for the dam wall so we used mud. Not serious, just a compromise. Replacing the controls in a 737 with two hand strings connected to the radar is not serious, it was a well engineered compromise. A surgeons compromise gets buried, an engineers compromise is there for everyone to see.
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This is exactly why I did it this way - which you will note gave a mix of short term switching, and then longer term listening between switching as I outlined above. In addition, the idea was to play a mix of different music, to a mix of different ears (but all with much experience with a wide variety of systems).
After that, it is up to each person to read, interpret, build and listen how they choose themselves, to suit their own system and ears, and whatever preferences they might have. That is the joy of the hobby.
Congratulations on your efforts and testing. I wish you had included the LM tests without and with the regulator. The vast majority of LM users have the version without any regulator so it would be interesting to see the difference. I deliberately wrote 'to see' because the difference must be heard, at least in my case, but unfortunately I neither have the time nor the resources to make quality measurements. I think it would help new LM DIYers to decide what to do with the power supply. I have such a case with my last amplifier that I made,'ceci est un Cube', which sounds much better with regulators.
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Luckily those other listeners were unbiased and performing musicians with absolute hearing to judge this, I guess?
All is relative...
I never said nor implied they were performing musicians with absolute hearing. I simply worked on the principle that 3 sets of experienced ears are better than one set within the confines of my friend group and room size.
This thread is really not about the perfect listening test according to multiple opinions, but about an examination of a (deservedly) classic amplifier.
Anyone can do as they might please as regards listening and of course are free to post their own experiences. I can only report on what happened in my home for those who are interested and I really don't want to derail this thread from its original purpose.
This thread is really not about the perfect listening test according to multiple opinions, but about an examination of a (deservedly) classic amplifier.
Anyone can do as they might please as regards listening and of course are free to post their own experiences. I can only report on what happened in my home for those who are interested and I really don't want to derail this thread from its original purpose.