A chinese stereo 6SL7, 6SN7, 300B, 805 amp from line magnetic in "stereoplay 3/2021"
Output power 9 watt continous 1kHz 1% thd, 46 watt burst. Signal/noise ratio 74 dB.
Weight: 42 kg. Price: 5000 euro.
Schematic wanted
Output power 9 watt continous 1kHz 1% thd, 46 watt burst. Signal/noise ratio 74 dB.
Weight: 42 kg. Price: 5000 euro.
Schematic wanted
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https://www.dropbox.com/s/9e3sra1gr...PoquiXgT_2FHr25wBCAZR907o-oN9qP_vy4adVb4rAtII
https://www.dropbox.com/s/9e3sra1gr...PoquiXgT_2FHr25wBCAZR907o-oN9qP_vy4adVb4rAtII
A vacuum tube amplifier that can put out 8.5 Vrms sine wave (9 Watts into 8 Ohms), has a peak voltage of 12 Volts into 8 Ohms.
Most of those amplifiers are able to put out their peak voltage for a brief time period, in the form of a square wave (yes, at perhaps 10% or more harmonic distortion).
Surprise, the temporary/burst power out of that square wave is 18 Watts.
. . . Try it on the vacuum tube amplifier that you have.
That is one of the tests I always do when I design and build a new vacuum tube amplifier.
2:1 power burst is not bad.
I admit, that is a far cry from the 9 Watt rms to 46 watt burst of the Chinese 805 amplifier you are interested in.
Badly clipped?
But how good, or how bad does that distorted 46 Watt burst sound?
Most of those amplifiers are able to put out their peak voltage for a brief time period, in the form of a square wave (yes, at perhaps 10% or more harmonic distortion).
Surprise, the temporary/burst power out of that square wave is 18 Watts.
. . . Try it on the vacuum tube amplifier that you have.
That is one of the tests I always do when I design and build a new vacuum tube amplifier.
2:1 power burst is not bad.
I admit, that is a far cry from the 9 Watt rms to 46 watt burst of the Chinese 805 amplifier you are interested in.
Badly clipped?
But how good, or how bad does that distorted 46 Watt burst sound?
The schematic in Post # 2, lists 10% THD at 19.5V out.
19.5Vrms out into 8 Ohms = 47.5 Watts (at 10% THD).
It also says 17V @ 2% THD. 17Vrms into 8 Ohms is 36 Watts.
Those are quite different than Post number 1:
9 Watts @ 1% THD, and 46 Watt burst.
From 36 Watts to 46 watts or 47.5 watts, it seems those are probably into very hard clipping.
The schematic seems to indicate that global negative feedback is used.
The best that a single ended 805 amplifier can do may be different than that, I am just quoting what is written on the schematic.
19.5Vrms out into 8 Ohms = 47.5 Watts (at 10% THD).
It also says 17V @ 2% THD. 17Vrms into 8 Ohms is 36 Watts.
Those are quite different than Post number 1:
9 Watts @ 1% THD, and 46 Watt burst.
From 36 Watts to 46 watts or 47.5 watts, it seems those are probably into very hard clipping.
The schematic seems to indicate that global negative feedback is used.
The best that a single ended 805 amplifier can do may be different than that, I am just quoting what is written on the schematic.
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You could draw a loadline on the plate characteristics.
And from that get an estimate of power available less OPT losses.
And the D%. The Amperex data sheet for the 805 has what you need. 🙂
The raw DF exclusive of the OPT can be read straight off the data sheet.
And from that get an estimate of power available less OPT losses.
And the D%. The Amperex data sheet for the 805 has what you need. 🙂
The raw DF exclusive of the OPT can be read straight off the data sheet.
Vaiable feedbck on this amplifier.
Koichi Shishido 805 amplifier : 3 dB overall feedback. 45 Watt output at 6 % distortion. 15 Watt at 1% distortion.
V3. 805 anode 800V 135 mA 4.5dB cathode feedback
interstage transformer: turns ratio 1:0.8
V2. 6L6GC triode connected anode 320V 30mA, cathode 90V
V1 12AU7 anode 70V 5.5mA