Yes Probably!!!, Thanks for the compliments! I turn all the stones.
Right now I my audio analyzer doesn't work... I use a 192kpbs thd analyser and an oscilloscope of 100 mhz with arbitrary wave form generator, which is incredible.
Right now I my audio analyzer doesn't work... I use a 192kpbs thd analyser and an oscilloscope of 100 mhz with arbitrary wave form generator, which is incredible.
These are out of production and the only way to make it work is with windows 8 or 7, I am in the process of purchasing a laptop only for that, it is less costly than buying the testers and time saving.
I want to measure it :!!!!!!, I just cant wait to hear it in stereo without that ***** ultralinear. Not that UL is bad, it is bad on many recordings versus the wall of sound of CF+pentode, UL sounds like a ball of sound which is more a mess than anything else, with shouting in the middle of the tumult.
Yes it is! I knew it was possible to obtain clear intelligible sound from tube amplifiers.
On a typical tube amplifier the words starting with Pff, Thhhu, Fwas, Ckkheee, you cannot hear the attack on the P,T, F, C, etc.
And sometimes even less the other intonations, you only hear the ffff, uuuu, aaaa, eeee, the ending.
On some solid state amplifiers it has more dynamics, but then you cannot hear anything, only the SSSSSS, ssssss, TSSSSSS, and some tube amp are a bit like this with romantic harmonics and rounded textures.
The only tube which attempts at clarity is the kt88 and kt120 better, kt77 is horrible, and other smaller tubes are just sweet and romantic. UL is not by choice it is mandatory because the triode sound is lacking the attack etc.
When I heard the symmetrical output transformer winded on a C core without a gap I knew right away it had better sound than the EI core, and I was inclined to try cathode feedback and pentode because many people said good things and others cursed the pentode a lot and said it sounded solid state, which is so false.
On a typical tube amplifier the words starting with Pff, Thhhu, Fwas, Ckkheee, you cannot hear the attack on the P,T, F, C, etc.
And sometimes even less the other intonations, you only hear the ffff, uuuu, aaaa, eeee, the ending.
On some solid state amplifiers it has more dynamics, but then you cannot hear anything, only the SSSSSS, ssssss, TSSSSSS, and some tube amp are a bit like this with romantic harmonics and rounded textures.
The only tube which attempts at clarity is the kt88 and kt120 better, kt77 is horrible, and other smaller tubes are just sweet and romantic. UL is not by choice it is mandatory because the triode sound is lacking the attack etc.
When I heard the symmetrical output transformer winded on a C core without a gap I knew right away it had better sound than the EI core, and I was inclined to try cathode feedback and pentode because many people said good things and others cursed the pentode a lot and said it sounded solid state, which is so false.
We all have opinions.
It would be good if you focus on getting your schematic published here so that the discussion can be about objective engineering, and not a subjective monologue.
I published everything, just at this point I don't think the schematic matters too much, its much about the choice of tubes and output transformer configuration than anything else... This is where I am right now, I used 3 schematics to get to the sound which I liked and it didn't make much difference, they are all published, nothing special.
the only thing which I designed is change a little bit the values, and use el822 in the ecc99 ltp current sink.
The only thing special the final design will have is a dedicated transformer for power supply of input tubes and pentode voltage, it will be and underpowered el120, due to going more into class A pp, and not willing to purchase two more power transformers, the amp will be happy with 480V B+ instead of 600, 45 watts will be sufficient, especially with my new 3 way more efficient loudspeakers in construction.
the only thing which I designed is change a little bit the values, and use el822 in the ecc99 ltp current sink.
The only thing special the final design will have is a dedicated transformer for power supply of input tubes and pentode voltage, it will be and underpowered el120, due to going more into class A pp, and not willing to purchase two more power transformers, the amp will be happy with 480V B+ instead of 600, 45 watts will be sufficient, especially with my new 3 way more efficient loudspeakers in construction.
Previous page, post 95, this is the basic idea, it is not perfect, there is an increase in hum when the volume control is turned way up. It is more my fault with the input wire placement and everything 2 mm from the power line in. It is very cramped inside this case...
I am taking great steps to doc everything in the project here, including my problems, and instead of leaving the forum, I wait for a new laptop so that I can post some measurements, this is very annoying because I would not wait and just be happy building the final amplifier, no other details needed, as long as anyone is equipped with a scope, and knows how to adjust feedback and insert low pass filter and fix any problem the schematic will work very well.
Just an example, tonight I am listening the Messiah of Handel which I used to see at least once a year at the National Art Center... it is a recording Archiv, Trevor Pinnoch, and I was listening to the He is the King of Glory, the Lord of Hosts.
And this is the first time it is very distinguishable, the His , you can hear the singers say the 'H' in the words His, and Hosts, on other amplifiers it is not very clear when a chorale sings, I can't wait to listen how it sounds in stereo and compared to a solid state amplifier mono block which I just purchased, it cost way more than my tube amp... let see!
And this is the first time it is very distinguishable, the His , you can hear the singers say the 'H' in the words His, and Hosts, on other amplifiers it is not very clear when a chorale sings, I can't wait to listen how it sounds in stereo and compared to a solid state amplifier mono block which I just purchased, it cost way more than my tube amp... let see!
powerful!
with reserve!
How do 6f12p behave in terms of excitation due to high gain?
but the most interesting thing is the microphone effect - have you observed it?
if so, how did you fight it?
I don't find them microphonic at all... Unless you hit them with a spoon or something but I've heard more microphony from 12AU7 to be honest.
It depends on the tubes I'm using for output, but something like 6P45S as a triode pair in push pull I aim for 300Vpp hence the 600V B+ for the front end 🙂
I am finding much interesting data on the THD tests of the kt88 with Pentode and CF.
It performs way better than Ultralinear + Cathode Feedback !!!
What is strange is that my THD is way less than with the other transformer which was on UL, it doesn't have the Kt120 figures at all but it is an improvement.
What is striking is that on my PP amps the third harmonics are the dominant generator of THD, now on the CF Pentode, it has the opposite spectrum, exactly like a Single ended, the dominant is the second, then third, then all the others very low.
So with a 25 watt transformer at 10 Watts 1khz it makes 0.52% Thd which is dominated by 3rd harmonics.
The new configuration makes 0.24% Thd , the without the 2nd harmonics it is only 0.05% of 3rd harmonics. This is a little bit more than what a kt120 tube would produce at 10 Watts on a 100 Watts output transformer, in 3rd harmonics.
It performs way better than Ultralinear + Cathode Feedback !!!
What is strange is that my THD is way less than with the other transformer which was on UL, it doesn't have the Kt120 figures at all but it is an improvement.
What is striking is that on my PP amps the third harmonics are the dominant generator of THD, now on the CF Pentode, it has the opposite spectrum, exactly like a Single ended, the dominant is the second, then third, then all the others very low.
So with a 25 watt transformer at 10 Watts 1khz it makes 0.52% Thd which is dominated by 3rd harmonics.
The new configuration makes 0.24% Thd , the without the 2nd harmonics it is only 0.05% of 3rd harmonics. This is a little bit more than what a kt120 tube would produce at 10 Watts on a 100 Watts output transformer, in 3rd harmonics.
at what depth of negative feedback?
because it is easy to achieve low TND simply by increasing the depth of negative feedback (although it will be a “dry” “tasteless” “transistor” sound)
for example - what is your TND with a total feedback depth of 4 dB?
here it is important that after the bass reflex everything is as symmetrical as possible
- selection of lamps in pairs
- selection of capacitors based on capacitance identity
etc etc
the spectrum analyzer really helps to fine-tune the amplifier
but the depth of negative feedback should not exceed 4-6 dB - otherwise the sound will be “dry” “transistor”, etc., etc.