I've already sent a message to v4lvelover (who is probably busy this holiday season) and I like to have different opinions and different points of view on a "problem".
I bought a few EL84 amp PCBs from him and two of them will be in EL84, but I have an idea for two of the others.
In my archives, I got my hands on a pair of opt 6k6s from Piemme (EI68004) and I have a few 6aq5 / el90s in stock (you see where I'm going with this...
I asked him if apart from the lower B+, the bias to modify, the sockets to replace, if there were other modifications to make to the diagram to make it work with 6aq5 and 6k6 opt.
I also answer before being asked the question, yes the opt have multiple secondary 4/8/16 ohm and they are rated at 20/25 w.
thanks in advance .
I bought a few EL84 amp PCBs from him and two of them will be in EL84, but I have an idea for two of the others.
In my archives, I got my hands on a pair of opt 6k6s from Piemme (EI68004) and I have a few 6aq5 / el90s in stock (you see where I'm going with this...
I asked him if apart from the lower B+, the bias to modify, the sockets to replace, if there were other modifications to make to the diagram to make it work with 6aq5 and 6k6 opt.
I also answer before being asked the question, yes the opt have multiple secondary 4/8/16 ohm and they are rated at 20/25 w.
thanks in advance .
I think if you plan to adapt a circuit to different tubes then you need to use a tool like LTSpice to model the circuit before and after the changes to evaluate the new component choices yourself.
There is standing on the shoulders of giants, and there is delegating.
There is standing on the shoulders of giants, and there is delegating.
I stand on the shoulders of giants for many things and when I don't know, I ask the giants.
very honestly, I take your sentence very badly.
In the real world I spend my time helping people, I also help here to the extent of my knowledge and I rarely ask for help.
You do not need to use LTSpice. Just the datasheet curves and Ohm's law should be enough.
LTSpice is a very helpful tool, and I use it a lot. But it is not strictly necessary by any means.
Huggygood,
The EL84 Pentode tube, and "Sister" 6BQ5 Beam Power tubes are rated:
300V Plate and Screen; 12 Watts plate dissipation (And should be the same 12 Watts for Ultra Linear and for Triode Wired operation modes, in order to keep the tube temperature the same. (the control grid "gets" lots of that heat from the screen and plate).
The 6K6 Plate rating is 315V, but the Screen is Only rated for 285V in Pentode and Ultra Linear Modes.
In Triode wired mode, the screen is rated for 315V, along with the plate.
The plate is rated for 8.5 Watts in Pentode mode; and only 7 Watts in Triode Wired mode.
The 6AQ5 Plate and Screen are only rated for 275V.
The Plate is rated for 12 Watts in Beam Power mode, but Plate + Screen are only rated for 10 Watts in Triode Wired mode.
Obviously, the 6BQ5 Beam Power tube is the easiest to Tube Roll into an EL84 socket.
They are so similar, that some Manufacturers Dual Labeled them as 6BQ5/EL84; even though in the beginning the EL84 was Only a Pentode;
and in the beginning the 6BQ5 was Only a Beam Power tube.
Have Fun!
The EL84 Pentode tube, and "Sister" 6BQ5 Beam Power tubes are rated:
300V Plate and Screen; 12 Watts plate dissipation (And should be the same 12 Watts for Ultra Linear and for Triode Wired operation modes, in order to keep the tube temperature the same. (the control grid "gets" lots of that heat from the screen and plate).
The 6K6 Plate rating is 315V, but the Screen is Only rated for 285V in Pentode and Ultra Linear Modes.
In Triode wired mode, the screen is rated for 315V, along with the plate.
The plate is rated for 8.5 Watts in Pentode mode; and only 7 Watts in Triode Wired mode.
The 6AQ5 Plate and Screen are only rated for 275V.
The Plate is rated for 12 Watts in Beam Power mode, but Plate + Screen are only rated for 10 Watts in Triode Wired mode.
Obviously, the 6BQ5 Beam Power tube is the easiest to Tube Roll into an EL84 socket.
They are so similar, that some Manufacturers Dual Labeled them as 6BQ5/EL84; even though in the beginning the EL84 was Only a Pentode;
and in the beginning the 6BQ5 was Only a Beam Power tube.
Have Fun!
Yes, and apologies to @huggygood if my original comment was a bit waspish.
It is a lot easier I think if one starts with a straw man and presents that for criticism.
The danger is that the original author makes their recommendations and either other people criticise the original author or the suggestions are suboptimal.
I find if I try to create a straw man for discussion I am already a lot further along the path to understand the criticism.
And we all want criticism, otherwise why post ideas?
As mentioned above, I asked the designer for his opinion and I received a response that I cannot publish here because I do not know if it is a joke or if he is serious.
@OldHector
@OldHector