I'm currently building a small power amp using an ECLL800 and this schematic (only the ECLL800 part, no feedback):
http://www.jogis-roehrenbude.de/Verstaerker/ECLL800-Schaltung.jpg
The amp generally works but I only get about 1V RMS @ 8 Ohm with quite heavy clipping. The anode voltage is about 280 V and the voltage above the cathode resistor (180 Ohm in the linked schematic) is about 5.5 V, so the current through each tube is about 15 mA. This is less than specified in the schematic but I think should rather lead to crossover distortion than early clipping.
When measuring the anode voltages it can be seen that, although the anodes are at about 280 V, the maximum voltage swing is about 15 V RMS and clipping at top and bottom, resulting in the output voltage of said 1V RMS.
I tried two different tubes and also two different output transformers. The output voltage is a bit different with different parts but it generally is around 1 V RMS.
Anyone any idea what might be at fault here?
Thanks,
Chris
http://www.jogis-roehrenbude.de/Verstaerker/ECLL800-Schaltung.jpg
The amp generally works but I only get about 1V RMS @ 8 Ohm with quite heavy clipping. The anode voltage is about 280 V and the voltage above the cathode resistor (180 Ohm in the linked schematic) is about 5.5 V, so the current through each tube is about 15 mA. This is less than specified in the schematic but I think should rather lead to crossover distortion than early clipping.
When measuring the anode voltages it can be seen that, although the anodes are at about 280 V, the maximum voltage swing is about 15 V RMS and clipping at top and bottom, resulting in the output voltage of said 1V RMS.
I tried two different tubes and also two different output transformers. The output voltage is a bit different with different parts but it generally is around 1 V RMS.
Anyone any idea what might be at fault here?
Thanks,
Chris