High sensitivity driver amplification

Jump to Latest
camplo

camplo

Member
Joined 2019
Paid Member
#1
I hope this question doesn't get asked every other day....I am interested in a class A tube amp that is transparent and likely 10w rms if even that...

The driver is an Axi2050 on a 350hz tractrix, sensitivity is somewhere near or above 108db. 10watts seems like a good number to power this but maybe less will do? Probably 5watts bare minimum? I seen some options on ebay but I am not educated on this topic at all...I do know that I do not want coloration (harmonic distortion) associated with certain tube amps...
 
#3
Transparent is difficult to pin down in terms of class A valve amps, and arguably all amps. We know it when we hear it but, for example, whilst near enough all audio op-amps are on paper transparent, the sound coming from some of the circuits they live in don't sound so. Likewise valve circuit implementation. Easier to define the sound you like (my 'thin' may be your 'fast uncoloured' etc) and let the knowledgeable hereabouts suggest circuits and maybe off the peg models to investigate.
 
#5
You’ll want low hum and noise with high sensitivity speakers. If transparency is the goal, the Neurochrome Modulus-86 would be my first recommendation. Crossover distortion in class AB amplifiers is non existent in amps of that grade, making class-A an inefficient and pointless endeavour.
 
#7
kouiky said:
You’ll want low hum and noise with high sensitivity speakers. If transparency is the goal, the Neurochrome Modulus-86 would be my first recommendation. Crossover distortion in class AB amplifiers is non existent in amps of that grade, making class-A an inefficient and pointless endeavour.
Click to expand...

Have you heard Vfet from Mr. Nelson? 10 watts classA no feedback. I would challenge it against any chipmonk. No matter how much feedback you apply in classAB to remove crossover distortion, even nested, that kills all the dynamics in music.
 
#9
I like the sound of the class a mosfet amplifier, any recommendations on a reliable product? I also thought that tube amps where class a amps, guess I was wrong about that too...
 
Last edited:
#10
I would suggest the MoFo. It is easy to build and requires very few parts. Look it up.

Many SIT designs are coming up in the Pass Labs forum. I would jump on that train and buy up some parts while they are still available. SITs are solid state triodes, like 300Bs and 845s. There are designs right now that can produce single-ended 25 W Class A from a single device. No heaters or transformers. ZenMod has some offerings in the Swap Meet forum. If you want a ready-made product, look at FirstWatt.

Sorry, this is not really a tube recommendation, but like others have said, you will have trouble with noise and hum with 108 db/W speakers. It is not impossible to build a quiet tube amp, just more difficult.
 
#11
plenty to choose from
I like M2 best, closely followed by F1J and Aleph J
Vfet is all around great, you have chance in second lottery!
F4 is buffer, but very clean, needs preamp
F5 is a little sharp sounding to me
have not build F3 or F6 yet, not reliable source of power SITs or JFETs

Aleph J was easy build, highly recommended

what are you talking about? most tube amps are classA
 
#14
FWIW, it's easily possible to build single-ended valve amplifiers that are completely silent on 108dB/1W/1M speakers. And, no amplifier that switches from class A to AB can be monotonic, and thus will have crossover distortion artifacts. Don't believe everything you read.


All good fortune,
Chris
 
You must log in or register to reply here.
Top Bottom