Michael Koster said:
Thank you Michael; I miss that vibration testing stand I used in our laboratory 30 years ago. However, management did not know that we used it (very expensive peace of equipment) after hours when were tempted to make a PCB as fast as possible, otherwise it was needed to ask ladies in a chemical laboratory, and even bring them a chocolate to get it faster, out of a queue.
I still want to build some out of a speaker motor, but catastrophically have no time.
Heating is fine today outside, so it is done already. I'm going to solder it tonight. I was afraid that my FeCl is already exhausted, but it appeared to be fine.
Thanks gentlemen!
When I saw that Scorpio as a poster holder in some store I immediately understood how convenient it may be to solder XLR and TRS cables.
Hinges were made for easy tweaking of the prototype.
3-d construction reflects the name: "Tower". This compartment will be mounted on top of the amp, with tall narrow heatsink on it's back.
When I saw that Scorpio as a poster holder in some store I immediately understood how convenient it may be to solder XLR and TRS cables.
Hinges were made for easy tweaking of the prototype.
3-d construction reflects the name: "Tower". This compartment will be mounted on top of the amp, with tall narrow heatsink on it's back.
Ok, one tube channel is done, feedback loop closed.
I had to replace 6N2P by 6N1P to deal easier with Miller capacitance of triode strapped 6P15P, otherwise some dynamic phase shift would be introduced.
On pictures: 100 KHz triangles, 1.5V peak input, 120V swing output (95V swing will be needed actually on the peak output power).
I will need to decrease a coupling capacitor to stop 1 Hz ringing on transients.
I did not show noises now because when the cover is open some 400 KHz garbage is well visible, about 2 mV (-76 dB level). There will be a common cover, and a smaller one for an input tube. After that I'll check how noisy it is.
I had to replace 6N2P by 6N1P to deal easier with Miller capacitance of triode strapped 6P15P, otherwise some dynamic phase shift would be introduced.
On pictures: 100 KHz triangles, 1.5V peak input, 120V swing output (95V swing will be needed actually on the peak output power).
I will need to decrease a coupling capacitor to stop 1 Hz ringing on transients.
I did not show noises now because when the cover is open some 400 KHz garbage is well visible, about 2 mV (-76 dB level). There will be a common cover, and a smaller one for an input tube. After that I'll check how noisy it is.
The problem was solved by adding one 2.2 micro farad film capacitor after a diode rectifier, before a choke. Now going back to the amplifier: PS problem had been solved. This is the example of creating new problems by solving former ones: in order to reduce diode currents and ripples I used LC filter that created new problems on frequencies way below rectified 120 Hz.
Probably a better idea would be to use a shunt regulator in case of LC filter, but for this prototype I am not going to redesign the power supply completely.
Probably a better idea would be to use a shunt regulator in case of LC filter, but for this prototype I am not going to redesign the power supply completely.
Here is 500 KHz 100V P-P response with 6N2P input tube, looks highly asymmetrical (for my taste). However, it is way above officially accepted audio band, but anyway it is a symptom that indicates presence of some non-linear phase shifts. Since subconscious sensitivity to phase shifts is 1,000 times better than a conscious one let's improve it anyway. The less of distortions we add is the better.
