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previous: Lee Glenn I know that there are mods to switc... -- 1/4/2000 5:32 PM View Thread

Re: Can I use anything besides EL84s?

1/4/2000 7:35 PM
Re: Can I use anything besides EL84s?
It would be good to know what voltages are on the present EL84s, and the plate current. You'd then know what could be expected performance of other tubes (assuming you can mount them) without drastic circuit mods or power supply mods. Maybe the stock power transformer can't handle much more heater current, anyway. 6V6s would use less than EL84s, but 6L6s would draw a little more (another 0.3A for the pair).  
Please correct me if I'm wrong, but I think this .22 Cal amp is run fixed bias. The EL84 needs relatively little negative bias voltage, compared to other commonly used output tubes. Depending on which alternate tube you select, the bias voltage supply would need some modification.  
Offhand, a 6V6 would be the closest in operating voltage requirements, and have a similar output power as EL84 under those conditions. EL34s & 6L6s, when run at lower plate voltages, need to run considerable plate current to achieve decent power output (and they need a greater drive signal, too). You may be able to run the present EL84s or some 6V6s in cathode bias, for a different response character.  
What sonic characteristics might you be looking to change? Have you tried other brands of 6BQ5/EL84 tubes, or are you only listening to the good ol'sovteks? Messed with different preamp tubes yet? They color the sound, too. Try some of the simple stuff before major surgery.