ducati_EL34
Addicted Member
Ahem, you don’t think a nice Class A 25w/ch. mosfet amp would also drive them with aplomb?
There's No Question -- KHorns Need Tube Gear
- Thread starter Parallax982
- Start date
Parallax982
Super Member
I don't know what that is.
ducati_EL34
Addicted Member
What is it that you do not know?
Parallax982
Super Member
a nice Class A 25w/ch. mosfet amp
ducati_EL34
Addicted Member
Are you being obtuse, or just trying to be funny? Okay, I will play along. It is a power amp (and preamp) with mosfet semi conductors, run in class A mode. MOSFETs are close in characteristics of a VT amp.
Parallax982
Super Member
You're talking way over my head. I don't have the background to understand. I don't know what "VT" means. Too much jargon. Talk to me the way you would to someone who isn't an engineer and has no background other than enjoying music. I have a Fisher 400. That's my only tube gear. I have several vintage transistor receivers. Have done a bit of work on them but my knowledge is limited.
Suggest googling class A, class AB, Class B, Class D amplifiers…etc…
Class A amplifiers run hot as the transistors are fully powered all of the time (inefficient). Many people believe the sound is closer to tubes…smooth, good tone, etc…versus typical class AB amplifiers. No crossover distortion as would have with class AB amplifiers. Some people believe they sound boring compared with class AB or other.
Many class AB amplifiers operate at low or very low watts output in class A. I find this relevant to owners of high sensitivity loudspeakers eg Klipschorn. However, some class AB amplifiers sound better when having to push a decent amount of watts.
Although I resorted to generalizations, I don’t believe in the constant generalizing about amplifier topologies and was the initial reason for my post when you proclaimed Klipschorns “need tubes, no question”. Although it may be your preference, this is simply not true.
To give a real world example, my ~5W/channel Realistic SA-175 is class AB output stage but sounds like tubes. It is also not class A though the input and driver stages apparently are. This is an example of why I do not believe the generalizations.
Parallax982
Super Member
Yes, you're right. I should not have generalized like that. I have just enough knowledge to step in it. :0)
ducati_EL34
Addicted Member
I resize you are talking in general terms. However, class A mode does not make a SS amp sound more like a tube (VT) amp. Tube amps can me built to run in either class A or AB.
What make a mosfet transistor sound like a tube amp is that the mosfet transistor has the same characteristics as a vacuum tube. They are both voltage devices, whereas an NPN or PNP transistor is a current device.
Yea class A whether tube or transistor is inefficient. However, I am not bother by it. I have other appliances and an HVAC system that is way more power hungry than a class an amp, especially for the limited amount of time the amp is used.
Thanks for the info.
A lot of these npn amps that I have heard sound closer to tubes and I suspect this has to do with the distortion. The ones I like always have higher distortion. I’ve also heard mosfet amps with low distortion that don’t sound like tube amps and…don’t sound very good.
ducati_EL34
Addicted Member
Well sure, you can make anything sound like crap. What bipolar transistor amps have you heard that sounded like a tube amp? The reason I ask is, most bipolar transistor amps, have very low distortion. This was a big selling point in the 70s and 80s.
ducati_EL34
Addicted Member
But different types of distortion. Tubes produce more ever order harmonics than odd order. Bipolar transistors are just the opposite, and even order is more pleasant to the ear/brain than odd order.
Not necessarily. Depends on the circuit.
Ralph Karsten spoke in this forum about the Realistic SA-175C (bipolar) and its abundant 2nd harmonic distortion making it sound like a tube amp. I love this amp but it only puts out about 5 watts. The Kenwood KA-2002 is similar. There are others similar to this and from the same era.
ducati_EL34
Addicted Member
And how does he get around the bipolar transistor’s inherent nature to produce odd order harmonics?
Imho khorns do pair well with tubes.
I have a friend who has a vintage Macintosh tube amp, with som Mac speakers.
it sounds great.
he is in to tube rolling, and has the money to engage in this particular tube rolling pursuit.
I wanted to get the tube sound for my klipschorns, but wanted to avoid some of the cost and complexity of chasing vintage power tubes.
I read some opinions about getting the tube sound.
the ones that sounded , to me ,the most basic to achieve were tubes in the preamp stage, and solid state power amplification.
I got a tube preamp, a new frenzel spx72, several years ago.
I paired with a vintage ss amp, a Luxman m120a.
the Luxman was the original power amp the previous owner had with the klipschorns.
it sounds great to me.
the preamp 12ax7 tubes do not get to hot, and last longer than power amp tubes.
keeping it simple is one of my goals.
YMMV. Enjoy the music
I have a friend who has a vintage Macintosh tube amp, with som Mac speakers.
it sounds great.
he is in to tube rolling, and has the money to engage in this particular tube rolling pursuit.
I wanted to get the tube sound for my klipschorns, but wanted to avoid some of the cost and complexity of chasing vintage power tubes.
I read some opinions about getting the tube sound.
the ones that sounded , to me ,the most basic to achieve were tubes in the preamp stage, and solid state power amplification.
I got a tube preamp, a new frenzel spx72, several years ago.
I paired with a vintage ss amp, a Luxman m120a.
the Luxman was the original power amp the previous owner had with the klipschorns.
it sounds great to me.
the preamp 12ax7 tubes do not get to hot, and last longer than power amp tubes.
keeping it simple is one of my goals.
YMMV. Enjoy the music
No idea. From the way the early solid state amps sound, many of them obviously have distortion profiles different from later solid state amps and they’re all bipolar. I suspect it has to do with the early solid state circuits mimicking tube circuits and the speaker coupling capacitors. The very simple Realistic amp has class A input and driver stages. That probably helps.
ducati_EL34
Addicted Member
It is not the circuit, although that plays a part. The actual device has a certain characteristics within themselves. A VT (especially a triode) produces more even than odd order harmonics. A BJT device is just the opposite. A MOSFET transistor is more like a a VT triode.
I already know all that stuff and it doesn’t interest me. I’ve owned SET, Pentode push pull, tetrode push pull, and solid state. Even the Marantz class D for a short time. Also owned a Berning amp for a long time. A long list.
What does interest me: a well known amplifier designer measures and states a bipolar npn amp of early solid state design characteristics has a lot of second harmonic (similar to tube amps). He even goes on to say that the circuit (class A input and driver stages) is playing a part in this, as I already said. I buy said examples and hear the same second harmonic.
Very interesting to find solid state amplifiers of this design to contain such even ordered harmonic and overall, higher distortion, similar to tube amps. Not the same but in some ways similar.
What does interest me: a well known amplifier designer measures and states a bipolar npn amp of early solid state design characteristics has a lot of second harmonic (similar to tube amps). He even goes on to say that the circuit (class A input and driver stages) is playing a part in this, as I already said. I buy said examples and hear the same second harmonic.
Very interesting to find solid state amplifiers of this design to contain such even ordered harmonic and overall, higher distortion, similar to tube amps. Not the same but in some ways similar.
ducati_EL34
Addicted Member
All amps/preamps have class A input, if They are single ended inputs. Just because mosfet closely resembles a VT triode in characteristics, does not mean it has higher distortion, just more even order than odd order harmonics.I already know all that stuff and it doesn’t interest me. I’ve owned SET, Pentode push pull, tetrode push pull, and solid state. Even the Marantz class D for a short time. Also owned a Berning amp for a long time. A long list.
What does interest me: a well known amplifier designer measures and states a bipolar npn amp of early solid state design characteristics has a lot of second harmonic (similar to tube amps). He even goes on to say that the circuit (class A input and driver stages) is playing a part in this, as I already said. I buy said examples and hear the same second harmonic.
Very interesting to find solid state amplifiers of this design to contain such even ordered harmonic and overall, higher distortion, similar to tube amps. Not the same but in some ways similar.
Testing one (old) amp does not speak for the characteristics of every amp topology, especially one from RS.