http://www.homecinema-fr.com/forum/post174496579.html#p174496579
http://ddata.over-blog.com/1/74/30/05/Divers/Hiraga/Hiraga_Bop.pdf
http://ddata.over-blog.com/1/74/30/05/Divers/Hiraga/Hiraga_Bop_Bode.pdf
http://ddata.over-blog.com/1/74/30/05/Divers/Hiraga/Hiraga_Bop_Dist.pdf
http://ddata.over-blog.com/1/74/30/05/Divers/Hiraga/Hiraga_Bop_Sat.pdf
http://ddata.over-blog.com/1/74/30/05/Divers/Hiraga/Hiraga_Bop.pdf
http://ddata.over-blog.com/1/74/30/05/Divers/Hiraga/Hiraga_Bop_Bode.pdf
http://ddata.over-blog.com/1/74/30/05/Divers/Hiraga/Hiraga_Bop_Dist.pdf
http://ddata.over-blog.com/1/74/30/05/Divers/Hiraga/Hiraga_Bop_Sat.pdf
On top of everything, what make people think super low output impedance translate to lower distortion? It is better IF the load is a resistor that has a fix value. BUT speaker impedance varies big time with frequency and the power deliver to speaker is totally frequency dependent. So the output power is frequency dependent.
Do people listen with the spectrum analyzer or with their ears?
Do people listen with the spectrum analyzer or with their ears?
Alibear, yes, I well know the Sugden products from your own good country. Sure, class A amps have a valuable place in amplifier history, but the tradeoff is heat, bulk and excessive power consumption. And Hiraga himself called it "Le Monstre".
Do you drive a roller, alibear ? Mine's a Corolla wagon and I wouldn't have anything else. My point was that class AB at 150 mA Iq is fine for moderate listening levels AND good fidelity. The AKSA range seem to have got it right IMO. Hugh Dean is a close and respected friend.
Do you drive a roller, alibear ? Mine's a Corolla wagon and I wouldn't have anything else. My point was that class AB at 150 mA Iq is fine for moderate listening levels AND good fidelity. The AKSA range seem to have got it right IMO. Hugh Dean is a close and respected friend.
Hi Ultimatex86
It seems quite a challenging circuit with good simulated results. I say challenging because this circuit appears to have a huge open loop gain which translates also into this very low theoretical output impedance. However, have you built this circuit and with good practical stability that correlates with the simulation? PCB layout surely must be done carefully....
However, I do not want to hijack this thread too...
Fab
I think the Hiraga, described as Le Monstre because it makes a big sound from a small power, is a very good amp from a sonic POV. To me, efficiency is important, but we cannot ignore the engineering in this little amp because it makes such beautiful music - even if the THD is high, but H2 dominant.
Hugh
Hugh
Yes Hugh in this world of cheap ghetto blaster audio the consensus sure is that high thd makes "such beautiful music".......big sigh. Ever the diplomat ??
Hint : To get the "musical" high thd "Hiraga" mushy H2 sound for much less expense (and power consumption) configure a 12AU7 as a diff amp with 12 volts on the plates, and drive one of the new (cheap) class D 50 watt low distortion amp modules. Bingo. Sold ?
The 12AU7 idea is used by guitarists as an EFFECTS BOX.........go figure.
Hint : To get the "musical" high thd "Hiraga" mushy H2 sound for much less expense (and power consumption) configure a 12AU7 as a diff amp with 12 volts on the plates, and drive one of the new (cheap) class D 50 watt low distortion amp modules. Bingo. Sold ?
The 12AU7 idea is used by guitarists as an EFFECTS BOX.........go figure.
That might be the reason there are people that prefer tube amp in audiophile. The one that considered the best are the SE amp that has more even harmonics. But they are not cheap.
The two amps that impressed me most were a Cary SE driving a Sonus Fabus and a YBA driving my JMLab 913 speakers. They both are not known for low distortion. Not only me that are impressed with those two, the two high end stores used them as reference amp in their special room that had only their highest end speakers.
I designed tube guitar amps and effect pedals. I am planning to design a tube power amp after all these. I decided to go with SS first because I designed tube guitar amps and I want to change the paste first before going back to tubes.
I think people listen by spectrum analyzer miss the whole point all together. But of cause, it's their money.
The two amps that impressed me most were a Cary SE driving a Sonus Fabus and a YBA driving my JMLab 913 speakers. They both are not known for low distortion. Not only me that are impressed with those two, the two high end stores used them as reference amp in their special room that had only their highest end speakers.
I designed tube guitar amps and effect pedals. I am planning to design a tube power amp after all these. I decided to go with SS first because I designed tube guitar amps and I want to change the paste first before going back to tubes.
I think people listen by spectrum analyzer miss the whole point all together. But of cause, it's their money.
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I built 4, 50 watt class A amps to drive my magneplanars (bi amped). Total cost of parts less than $1000. Power consumption about 800 Watts.
My iron idles at 1600 watts! It puts nice creases in my sleeve, but at the expense of twice the power consumption of my amps. To suggest that you can afford Class A only if you drive Rolls Royce is hyperbole to a silly level. If I can afford to iron my shirts, I can afford Class A. Can you afford an iron? (for the record, I drive a 1991 Nissan Pulsar Hatch. I can only dream about owning a Corolla wagon).
AKSA amps are extremely good, and no-one on this forum will tell you that you are wrong to use them. But to suggest that they are right, and Class A is wrong is just, well, wrong. To suggest that Class A is part of audio history (suggesting that they are no use today) is also wrong.
My bet would be Sigges design, casoded and run at +-60V.
One set laterals at 120mA with 5,6 ohm Rsource used as bias spreaders to 8pairs bjt's Oliver biased with 0'47Re.
Change Vas transistors to low cob TO220 types and make a good VBE (like the slew master) and you have yourself one hell of an amplifier with an OPS that is virtually non switching. While running fairly cool.
One set laterals at 120mA with 5,6 ohm Rsource used as bias spreaders to 8pairs bjt's Oliver biased with 0'47Re.
Change Vas transistors to low cob TO220 types and make a good VBE (like the slew master) and you have yourself one hell of an amplifier with an OPS that is virtually non switching. While running fairly cool.
Yes Hazard500 the roller comment was hyperbole. My wish is to say Deans amp is a good compromise as class AB is concerned and I like it. I was not intimating class A is consigned to history either. It is a design/performance choice available to all......but remember Linsley-Hood's satirical piece where he had the output devices fastened to a waterfilled radiator ? Some obviously disregard the massive inefficiency of class A.
Class A sliding bias works well and multiple designs are posted and published.
Class A sliding bias works well and multiple designs are posted and published.
no I do not drive a "roller". Cars are like most things in life, a personal choice, and if you are happy with a Corolla wagon ( whatever that is ) then that's just fine by me. Conversly just because at the moment I enjoy listening to a class A amplifier, I do not criticise well respected class AB amplifiers and their designers.
This forum is about giving and receiving help and assistance.
Alan (BMW)
This forum is about giving and receiving help and assistance.
Alan (BMW)
Member
Joined 2009
Paid Member
I think it's off-topic for the most part but this 'inefficiency' worry about Class A is often taken out of context. Many low power Class A amplifiers do not burn a lot of energy in absolute terms whereas some Class AB designs because they are designed for high-power actually dissipate a fair bit of energy. Hugh Dean has a very nice hi-end Class AB amp where the output stage is run open loop, but if I remember correctly it dissipates between 30W and 40W when idle.
Cars are a strange thing - for (too) many people they are a reflection on the owner. One perspective will have that it results in a large number of people buying more car than they need because it is important to their self-image. But there are always other perspectives.
Cars are a strange thing - for (too) many people they are a reflection on the owner. One perspective will have that it results in a large number of people buying more car than they need because it is important to their self-image. But there are always other perspectives.
If someone kept talking about how low distortion is important, Class AB and distortion really does not go together. Problem is the crossover distortion of the Class AB, what make it worst is it affect the most at low level listening.
That's what Class A excels, no crossover distortion. I am designing a Class AB with Class A for the first few watts. It burns a lot of power!!! I am limiting it to 60W of idle power per channel, it's hot too.
That's what Class A excels, no crossover distortion. I am designing a Class AB with Class A for the first few watts. It burns a lot of power!!! I am limiting it to 60W of idle power per channel, it's hot too.
Member
Joined 2009
Paid Member
Some apology needed to all Hiraga enthusiasts, I had gone a bit overthetop.
Hugh is right re the musical sound of the amp.
I will build in the next few weeks a "Death of Zen" 20W class A (DOZ)
It has a basic Linsley Hood topology and can be found on the Elliott Sound Products site.
He sell 2 neat little PCBs too.
Will let you other DIY class A enthusiasts my progress on the build.
All the best to all the Monstres class A backers
Hugh is right re the musical sound of the amp.
I will build in the next few weeks a "Death of Zen" 20W class A (DOZ)
It has a basic Linsley Hood topology and can be found on the Elliott Sound Products site.
He sell 2 neat little PCBs too.
Will let you other DIY class A enthusiasts my progress on the build.
All the best to all the Monstres class A backers
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