It was one dispute, what solid amplifier can’t be made without feedback in signal path. After several tests I devised balanced topology that works well. I made more then ten copies of such amplifiers with different power supplies, servo and variations. My last variant has no any servo. But it demand of accurate selection of transistor in pairs.
I add several information
Max output power of this amplifier is 20-25 W
Damping factor = 4
Frequency response 5 Hz - 67 kHz by -3 dB
1% harmonic distortion is reached on 7 W
Harmonic level and spectrum is not depend on frequency.
THD level as function of frequency on different levels represents on figure
Max output power of this amplifier is 20-25 W
Damping factor = 4
Frequency response 5 Hz - 67 kHz by -3 dB
1% harmonic distortion is reached on 7 W
Harmonic level and spectrum is not depend on frequency.
THD level as function of frequency on different levels represents on figure
Attachments
Nice tube-style amplifier!
Can you give some details on VT5 & VT6? Are those really high-voltage high-power JFETs? And the FETs in the driver stage, what are their specs?
- Klaus
Can you give some details on VT5 & VT6? Are those really high-voltage high-power JFETs? And the FETs in the driver stage, what are their specs?
- Klaus
bigwill, yes it has sound likes very good triode PP amplifier in class A, but without tube's colour.
Parameters of transistors:
2Ï903
power disipation - 6W
max ds voltage - 20V
S=50-60mS (Id = 50mA)
Cgd=13pF
Cgs=15pF
2Ï926A (SIT, triode characteristics)
power disipation - 50W
case - TO-3
max Uds - 450V
Ri = 270 Ohm
Parameters of transistors:
2Ï903
power disipation - 6W
max ds voltage - 20V
S=50-60mS (Id = 50mA)
Cgd=13pF
Cgs=15pF
2Ï926A (SIT, triode characteristics)
power disipation - 50W
case - TO-3
max Uds - 450V
Ri = 270 Ohm
Output transformers and interstage inductors we made in our laboratory (www.lampovik.ru). Power transformers and power inductors made in Russia by order. Input transformer-attenuator made in Moldova by Vorobiev, it's analog of Sowter 9335. Transformer after attenuator for variable output is Sowter 3575.
Attachments
... and take a look at the other great projects of these guys! Big bottled tube stuff, tesla coils, all beautifully handmade and packaged... impressing....
- Klaus
- Klaus
Thanks! We endeavour 😎
We decided to make devices in wood cases. Wood creates warm atmosphere around.
We decided to make devices in wood cases. Wood creates warm atmosphere around.
Sometimes minor compromise is necessary due to conflicting parameters🙂
Extremely cool amplification devices however...
Extremely cool amplification devices however...
Very nice amp. Only extremely difficult to build or at least a lot more difficult than a tube amp following a similar topology.
So, why use solid state then?
So, why use solid state then?
There are several reasons.
1. Variety. This is one more amplifier type.
2. Sound. It has specific sound. It resembles on triode PP amplifier in softness and purity. It has the same soft clipping. But it has no tube coloring. Comparing with tube amplifier it has much more resources.
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