Hi all
based on the info from TubeCAD, I built a super triode connected chip amp. The "turbocharger" is a OPA541 power amp. Originally I wanted to connect a 6922 as a super triode, but later changed to a 6SN7. The major reason for the change is the low gain-bandwidth product of OPA541. With a high mu (33) of 6922, the bandwidth will be very limited. 6SN7 having a mu of 20 will give a more reasonable bandwidth. Of course the main attraction of this concept is to have the sound signature of 6SN7 while having a decent output power to drive the loudspeaker.
I basically follow the concept in TubeCAD with some adaptation. The 6SN7 is biased at 8mA, using a TL431-npn transistor CCS. The OPA541 works from a +/-20V, giving at least 30W output power.
Just completed building today, the circuit works! Definitely it sounds like a tube amp with quite a amazing bass (compared to my current Nelson Pass- JLH MOSFET amp). Still need to spend more time in listening but would like to say that the concept is a practical one using chip amp.
based on the info from TubeCAD, I built a super triode connected chip amp. The "turbocharger" is a OPA541 power amp. Originally I wanted to connect a 6922 as a super triode, but later changed to a 6SN7. The major reason for the change is the low gain-bandwidth product of OPA541. With a high mu (33) of 6922, the bandwidth will be very limited. 6SN7 having a mu of 20 will give a more reasonable bandwidth. Of course the main attraction of this concept is to have the sound signature of 6SN7 while having a decent output power to drive the loudspeaker.
I basically follow the concept in TubeCAD with some adaptation. The 6SN7 is biased at 8mA, using a TL431-npn transistor CCS. The OPA541 works from a +/-20V, giving at least 30W output power.
Just completed building today, the circuit works! Definitely it sounds like a tube amp with quite a amazing bass (compared to my current Nelson Pass- JLH MOSFET amp). Still need to spend more time in listening but would like to say that the concept is a practical one using chip amp.
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A cathode follower with the anode as an input, will be a difficult one for "DualTriode" :lol:
Why 200V ? Probably 120V and a current of 4mA will give the same result.
Mona
Why 200V ? Probably 120V and a current of 4mA will give the same result.
Mona
Hi. I'm not quite skilled to appreciate your project but that hybrid version looks interesting. Do you use one 6SN7 for both channels?
Well at 4mA we are stil above the rounding of the lines.And if you are after linearity, why use tubes ?
Mona
Mona
@FYC: where do you source your OPA541? I tried this but i stubbornly used LM1875. Unsurprisingly, i end up with an oscillator.
I found OPA541 in Ebay but i don't fully trust them when it comes to semiconductors. Actually i wouldn't mind running fake chips with lowered voltage rails to be gentle to them but i'm not sure if they're unity-gain stable.
I found OPA541 in Ebay but i don't fully trust them when it comes to semiconductors. Actually i wouldn't mind running fake chips with lowered voltage rails to be gentle to them but i'm not sure if they're unity-gain stable.
A good question. I can think of some good reasons to make a tube amplifier; I can't think of any good reason to use a triode as the feedback element for a chip amp when resistors are hugely more linear than any triode.Ketje said:
As you say, using the anode as an input may create issues for some people!
My thoughts are:
When selecting an operating point, I would try to select the one with better linearity within the operating limits like power dissipation etc.
Using the triode in the feedback loop is to impose the triode sound over the chip amp, this is the main theme behind this concept. The chip amp in theory only provide the horsepower but the driving "characteristic" comes from the triode.
I cannot explain more as I am no expert. TubeCAD provides a detailed description in several occasions.
When selecting an operating point, I would try to select the one with better linearity within the operating limits like power dissipation etc.
Using the triode in the feedback loop is to impose the triode sound over the chip amp, this is the main theme behind this concept. The chip amp in theory only provide the horsepower but the driving "characteristic" comes from the triode.
I cannot explain more as I am no expert. TubeCAD provides a detailed description in several occasions.
Yes, the idea is to add triode distortion to music. Deliberately adding distortion seems daft to me, but then I am not an 'audiophile'.
Well this is kind of a fairy tale for audiophiles:
You get the sound of a SET, but you get much more output power (say 25W iso 2.5W), and you pay only $150 for all the components.
Too good to be true? That drives me to experiment with it.
You get the sound of a SET, but you get much more output power (say 25W iso 2.5W), and you pay only $150 for all the components.
Too good to be true? That drives me to experiment with it.
DF96... i´m blown away by the enthusiasm, how you enjoy being negative on (m)any tube discussion
