le class a- 4 ohms driving capability?
hi all,
reference: the class a amplifier site; jean hiraga's super class a;
i was running the 30 watts amp. with microcap7 simulation, this configuration can't drive more then 6 ohms, did some one succeed to increase the driving to lower loads like 4 ohms?
any help is very much appreciated
best regards
Williams
hi all,
reference: the class a amplifier site; jean hiraga's super class a;
i was running the 30 watts amp. with microcap7 simulation, this configuration can't drive more then 6 ohms, did some one succeed to increase the driving to lower loads like 4 ohms?
any help is very much appreciated
best regards
Williams
hi all,
1- i did increase the bias and it didn't help
2- i don't have the original transistors in my library so i had to use western replacements; the problem is that is very sensitive when driving high current because of high Vin (in order to get 30 watts output at 8 ohms), then the distortion of the VAS the 2SA634 and 2SC1096 is very high, the result is a summing a sine wave at the output that is very none linear.
3- the circuit is so simple that every thing is influencing every thing, but if you will follow the shapes of the wave forms at each base/collector, can see the problem
4- even that the output looks clean of distortions it is feed with distorted input (at high levels)
When the Vin is 1.4Vp the amp should deliver 30 watts at this point; all ready the VAS is totally distorted, I will like this amp to be able to drive 4 ohms as well, do you think it is possible, but 8 ohms looks as a big task.
5- it should be an amp that can drive 4 ohms and is very disappointed that is not
Best regards,
Williams
PS: if you like to take a look I can mail you the schematics
Williams
1- i did increase the bias and it didn't help
2- i don't have the original transistors in my library so i had to use western replacements; the problem is that is very sensitive when driving high current because of high Vin (in order to get 30 watts output at 8 ohms), then the distortion of the VAS the 2SA634 and 2SC1096 is very high, the result is a summing a sine wave at the output that is very none linear.
3- the circuit is so simple that every thing is influencing every thing, but if you will follow the shapes of the wave forms at each base/collector, can see the problem
4- even that the output looks clean of distortions it is feed with distorted input (at high levels)
When the Vin is 1.4Vp the amp should deliver 30 watts at this point; all ready the VAS is totally distorted, I will like this amp to be able to drive 4 ohms as well, do you think it is possible, but 8 ohms looks as a big task.
5- it should be an amp that can drive 4 ohms and is very disappointed that is not
Best regards,
Williams
PS: if you like to take a look I can mail you the schematics
Williams
Hi Williams,
it is very important to use output devices with high DC current transfer ratio in order to keep the VAS distortion low, (will inevitably be pretty high, I`m afraid).
it is very important to use output devices with high DC current transfer ratio in order to keep the VAS distortion low, (will inevitably be pretty high, I`m afraid).
hi lumba,
thanks for the answers, what do you think about this amp particularly?
is it worth to build it. Did someone you know built it? It is very simple and challenging
see the schematic from the site, I will like to get your opinion
best regards,
Williams
thanks for the answers, what do you think about this amp particularly?
is it worth to build it. Did someone you know built it? It is very simple and challenging
see the schematic from the site, I will like to get your opinion
best regards,
Williams
Yes it is worth it. But given the choice I would build an F5. It is basically a Jean Hiraga amp with two gain stages.
Williams,
your concerns over the driving capability is unfounded. On the contrary, people say it is able to drive anything. The current feedback topology gives stability and speed.
your concerns over the driving capability is unfounded. On the contrary, people say it is able to drive anything. The current feedback topology gives stability and speed.
hi tinitus,
thanks a lot for your answer
i will appreciate it very much if you can send/mail some more info to the forum
or to my private email
it is very encouraging that can drive low loads
it is difficult to read the schematic mailed by you, can you enlarge it and send some more info
thanks a lot
Williams
thanks a lot for your answer
i will appreciate it very much if you can send/mail some more info to the forum
or to my private email
it is very encouraging that can drive low loads
it is difficult to read the schematic mailed by you, can you enlarge it and send some more info
thanks a lot
Williams
hi all,
what i have to do now is to order the parts and start working
while i will sweat maybe will need some assistance from you
best regards and thanks a lot,
Williams
what i have to do now is to order the parts and start working
while i will sweat maybe will need some assistance from you
best regards and thanks a lot,
Williams
Hi, I will do what I can, but Im not very good at such things
Driving low impedance
Back then I had no idea
Now, reading Nelson Pass "leaving classA", and from good members teaching how F5 classA biasing works, its surely not just a matter of amps surviving
Back then Hiraga was special, and may still be better than most
But having Nelson Pass among us, and the way he supports us, gives it a different perspective
Besides, from what I hear, the LeAudiophile/Hiraga "8watt Monster" was an improvement
I know some people made a bigger version of "8watt Monster", and they think its the worlds best amp
Well, today my money is on F5
Not alone because of its quality, but also because theres a lot of support and knowledge around in here
Though, if my goal was very low impedance drive, Im not even sure I would choose classA
I have a 50watt AB that drives 2ohm with ease, and survives 1ohm, and its with just a single pair of output transistors
And it sounds so good that I really dont need any better
Remember that say a good 20watt/8ohm AB amp will deliver 80watt into 2ohm load
A 20watt classA would not be classA any longer
4ohm is not low impedance, is it😛
edit, why do you call yourself "WilliamsAudio" ?
Do you have commercial relations ?
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Hi,
well i was too lazy to built it from scratch so i got a kit from HK, the version with jfets at input and 2n3055 at output
getting very hot; about 70°C absolute
surprising!! is driving my ACOUSTAT 3 nor bad at all. it is very clear and detail with a fantastic stage
now i am working finding pcb and components for the 50 watts version, so far this stuff is too expensive
Cheers,
Williams
well i was too lazy to built it from scratch so i got a kit from HK, the version with jfets at input and 2n3055 at output
getting very hot; about 70°C absolute
surprising!! is driving my ACOUSTAT 3 nor bad at all. it is very clear and detail with a fantastic stage
now i am working finding pcb and components for the 50 watts version, so far this stuff is too expensive
Cheers,
Williams
about
www.tmr-audio.de/tests/audio_11_84.pdf
you will find a German test report from the magazine "AUDIO" of this amp together with follow amps:
Accuphase P600, Luxmann M-05, Krell KMA-100, Restek E3 and TMR-1000ES.
www.tmr-audio.de/tests/audio_11_84.pdf
you will find a German test report from the magazine "AUDIO" of this amp together with follow amps:
Accuphase P600, Luxmann M-05, Krell KMA-100, Restek E3 and TMR-1000ES.
I have built dozens of these 30W class A amplifiers in the 1980ies, all with regulated power supplies. They sound much better than the original Le Classe A by La Maison de L'Audiophile.
From my eperience, they can easily drive all kinds of speakers and impedances.
I still like them and am currently driving high efficiency 16" woofers up to around 630Hz by my last one built in 2010.
From my eperience, they can easily drive all kinds of speakers and impedances.
I still like them and am currently driving high efficiency 16" woofers up to around 630Hz by my last one built in 2010.
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Hello Permaneder,
Please describe the Regulated PSU for Hiraga. Do you using Kaneda style regulated PSU?
Regards,
JOsh
Please describe the Regulated PSU for Hiraga. Do you using Kaneda style regulated PSU?
Regards,
JOsh
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