i am unsure what you mean by less clean ?
as in noise or aesthetics or topology ?
the amount of caps is probably overkill but both amps have relatively low PSRR so they dont hurt.
-Dan
as in noise or aesthetics or topology ?
the amount of caps is probably overkill but both amps have relatively low PSRR so they dont hurt.
-Dan
Speaking of caps wouldn't those 1F or larger caps intended to
be used for large car audio amps be good for this aplication.
By the way anyone have a cheap set of boards for this amp?
be used for large car audio amps be good for this aplication.
By the way anyone have a cheap set of boards for this amp?
danieljw, thanks for the post, very informative.
That is what I was thought, to try the amplifier with batteries only first, as two 80AH batteries will last more. It is also a bit cheaper than aqcuiring these big caps.
I think the biggest problem with batteries is the voltage variations as the battery discharges, which will affect the bias setting, so one should continuously set the bias or should use the battery for less time before it descharges completely and have a voltage drop. Of course in such configurations only deep cycle batteries should be used.
Also voltage and amp meters must be used to contonuously monitor the voltage and the amp drawn. Since the PSU will be in another box changing the configurations won't be a problem.
I will let you know about the results, but I feel that appart from the time restriction factor of the batteries it won't dissapoint, as it is clean and straight forward. Anyway five hours a day continuously is very fine to me 🙂
That is what I was thought, to try the amplifier with batteries only first, as two 80AH batteries will last more. It is also a bit cheaper than aqcuiring these big caps.
I think the biggest problem with batteries is the voltage variations as the battery discharges, which will affect the bias setting, so one should continuously set the bias or should use the battery for less time before it descharges completely and have a voltage drop. Of course in such configurations only deep cycle batteries should be used.
Also voltage and amp meters must be used to contonuously monitor the voltage and the amp drawn. Since the PSU will be in another box changing the configurations won't be a problem.
I will let you know about the results, but I feel that appart from the time restriction factor of the batteries it won't dissapoint, as it is clean and straight forward. Anyway five hours a day continuously is very fine to me 🙂
woody said:
That sounds like a really good idea.
Lumba Ogir said:
do you mean they are deteriorating in terms of the sound or the high freq roll off... ??
neazoi said:
Yeah that is a good point Neazoi, 5 hours is pretty good. oh by the way are you planning to make a run of boards?
-Dan
Yes I do, in the next days/weeks I will make my set. I can make an extra set if you like but do not expect epoxy covered proffessional PCBs. These are all home made, although they are good printed quality.
I'm very interested in the result and a set of boards too ofcoarse.neazoi said:
I saw you mod on the trimmer..nice!
Kees
(i feel quite flattered that this design is really coming to life 🙂 )
I can make another pair too, no problem.
I do not see anything unusual with your PCBs, the same star GND as the original Hiragas PCBs but with a more modern tone. So I am going to go for them.
In such small PCBs you do not have long paths of GND so I believe a star topology wouldn't be necessary either way
One last thing, I am thinking of replacing the bias resistor on the base of the drivers with another trimmer, to easily adjust the bias for voltage differences in the battery, when discharged. I am not sure about the sound effect so this is a thought yet. but if I decide this I have to adapt the pcb accordingly.
I do not see anything unusual with your PCBs, the same star GND as the original Hiragas PCBs but with a more modern tone. So I am going to go for them.
In such small PCBs you do not have long paths of GND so I believe a star topology wouldn't be necessary either way
One last thing, I am thinking of replacing the bias resistor on the base of the drivers with another trimmer, to easily adjust the bias for voltage differences in the battery, when discharged. I am not sure about the sound effect so this is a thought yet. but if I decide this I have to adapt the pcb accordingly.
neazoi said:
Yes i am interested in the boards as long as they are not expensive...
neazoi said:
good idea...
looks like some more monsters are on the way 🙂
I am not sure i understand why Lumba,
can you add some info for me ??
by my calculations the 68pF only come into play in the HF region
and the 2200pF is there for a similar reason HF stability,
I understand the stance on audio being affected my how the amp performs many octaves higher, but it measures out to the hundreds of kHz,
Perhaps you can shed some light - i am open to hear your thoughts on this ?
-Dan
can you add some info for me ??
by my calculations the 68pF only come into play in the HF region
and the 2200pF is there for a similar reason HF stability,
I understand the stance on audio being affected my how the amp performs many octaves higher, but it measures out to the hundreds of kHz,
Perhaps you can shed some light - i am open to hear your thoughts on this ?
-Dan
Dan,
missing bandwidth means distortion. Extending Cob to 70pF in a voltage amplification stage is devastating. These caps, even much smaller values, do a lot of damage sonically, please believe me.
missing bandwidth means distortion. Extending Cob to 70pF in a voltage amplification stage is devastating. These caps, even much smaller values, do a lot of damage sonically, please believe me.
i get what you are saying.... it is a valid point,
the Cob is 55-65 for 2SC1096/2SA634... perhaps i can remove them due to the input filter (and the amp seems stable....
i guess if you look at it as 68pF + 65pF that is 133pF
using 1/(2PiFC) at 20kHz that is 59832.7Ohms..... Hmmm
at 20Hz 59.8327 MOhm.... so HF could be affected....??
Perhaps it is time for these caps to go.....
What is the resoning behind the 2200pF being a problem ?
(if i do remove them i will do before and after listening and measurement tests.)
-Dan
the Cob is 55-65 for 2SC1096/2SA634... perhaps i can remove them due to the input filter (and the amp seems stable....
i guess if you look at it as 68pF + 65pF that is 133pF
using 1/(2PiFC) at 20kHz that is 59832.7Ohms..... Hmmm
at 20Hz 59.8327 MOhm.... so HF could be affected....??
Perhaps it is time for these caps to go.....
What is the resoning behind the 2200pF being a problem ?
(if i do remove them i will do before and after listening and measurement tests.)
-Dan
Dan,
Please be cautious when removing these caps, maybe you should wait. Firstly, the 2SC1096/2SA634 is obsolete having poor specifications. Would it be possible to use some type in TO-126 package?
Exactly, compare it to 1.6/1.8pF for 2SD756/2SB716.
Please be cautious when removing these caps, maybe you should wait. Firstly, the 2SC1096/2SA634 is obsolete having poor specifications. Would it be possible to use some type in TO-126 package?
probably what i will do is keep the "Le class A" the same as it is currently because it was designed to "sound" a certain way and it does in fact sound very good in my opinion. I think the caps were added for stability and measured performance and listening is very good.
I think I will build another "Le monstre" with batteries this time.
Le class A is almost as good as Le monstre but there is somthing about this tiny power monstre amp that is special......
What (everyone) do you think about using newer devices - perhaps with better spec than the originals used in "Le monstre"
for example better JFETs with lower noise (if possible)
I would say the input devices in the Le monstre may be hard to better in terms of noise/Cob etc though
thoughts anyone?
-Dan
I think I will build another "Le monstre" with batteries this time.
Le class A is almost as good as Le monstre but there is somthing about this tiny power monstre amp that is special......
What (everyone) do you think about using newer devices - perhaps with better spec than the originals used in "Le monstre"
for example better JFETs with lower noise (if possible)
I would say the input devices in the Le monstre may be hard to better in terms of noise/Cob etc though
thoughts anyone?
-Dan
It certainly does, but improvements are still possible.
For stability only.
A very good idea.
That`s due to the superior, exceptionally clean topology and carefully chosen parts.
Newer, yes, but hardly better.
True.
Thanks for the detailed reply Lumba.
I agree with you on all comments with this one.
I did a search earlier today for readily available parts which have similar or better spec than the le monstre transistors.
not so easy to find...
-Dan
I agree with you on all comments with this one.
I did a search earlier today for readily available parts which have similar or better spec than the le monstre transistors.
not so easy to find...
-Dan
Also, Le Monstre has an outstanding driving ability and stability under almost any type of load, without a single additional part. The current feedback mode is an important reason for that.
I am glad you wish to make the battery version, that makes two of us 🙂
Before I print the PCBs I am trying to add the option to accept a precision trimmer for 1K too, in order to set the bias correctly. Audiomanics, if you could provide the pcb file it would be much easier than trying to edit the image.
A good and cheap option for the batteries if someone lives in Greece: http://www.eshops.gr/index.php?act=viewCat&catId=589
Before I print the PCBs I am trying to add the option to accept a precision trimmer for 1K too, in order to set the bias correctly. Audiomanics, if you could provide the pcb file it would be much easier than trying to edit the image.
A good and cheap option for the batteries if someone lives in Greece: http://www.eshops.gr/index.php?act=viewCat&catId=589