Lower output EL84 or subsitute?

[samdjr74]

Hi All,

I have a smaller low watt single EL84 amp. It sounds pretty good but it's still on the loud side to crank it. I know that JJ has the EL844 but I haven't heard a lot of good things on that tube. I also heard that EL86 or 6CW5 might help as well. I'm open to suggestions.

Thanks,
Sam

[Markusv]

Sam

I have two el86 amps and they still are very loud. Not much less than a el84

I suggest you look at some of the smaller tubes (miniature)
RJ on the forum has built some - perhaps you can search for the thread
I think its caled a mini rocket?

[backpack]

6973 are pretty cool tubes for lower output.

[M Fowler]

Decrease the preamp tube to 12au7.

[samdjr74]

Thanks guys, I'll look ino the other trheads.

I have tried a few other preamp tubes and I think I did drop a couple 12au7's into it but I'll need to double check.

[harryk]

I have used a pair of 6AK6 tubes in push pull configuration successfully. They give some 2-3 W output with low plate voltages like 280 V. To get higher rail voltages ( app. 320 V) for preamp, I use VVR technology to control output power but also to reduce power tube plate voltages. You can use VVR to both minimum and maximum voltages easily.

[Andy Le Blanc]

I remember looking into 6aq5, the plate dissipation is 12w but the plate V
is less than 300, good for the table top radio, but even a few watts can be loud

another thing I tried was simply putting a light bulb before the ct of a opt
current limit the power side, it actually works really well, kept the tone, half the output.

[samdjr74]

That's pretty interesting with the ligh bulb, got any layout diagrams?

I remember looking into 6aq5, the plate dissipation is 12w but the plate V
is less than 300, good for the table top radio, but even a few watts can be loud

another thing I tried was simply putting a light bulb before the ct of a opt
current limit the power side, it actually works really well, kept the tone, half the output.

[harryk]

I tried also a pair of 6AQ5/EL90 tubes for a 5F6-A Bassman amp I made but that sound was not what I was after. I replaced those 7-pin miniatyre power tubes with real 6V6GT:s and it was a huge improvement soundwise. If you want to control output power, one easy way is to use power scaling/VVR for it. I have put VVR to many diffrent tube amps successfully.

[Andy Le Blanc]

someone posted a light bulb attenuated amp they saw at a amp show

I got to noodling on the bench just see how it was possible and thats all it was

put a light bulb, try different wattage's, and a socket, in series between
the PS and the ct of the opt, I think I posted about it.....

http://ampgarage.com/forum/viewtopic.ph ... ulb+ground

"samamp"

[passfan]

someone posted a light bulb attenuated amp they saw at a amp show

I got to noodling on the bench just see how it was possible and thats all it was

put a light bulb, try different wattage's, and a socket, in series between
the PS and the ct of the opt, I think I posted about it.....

http://ampgarage.com/forum/viewtopic.ph ... ulb+ground

"samamp"

Cool, I've seen light bulbs used as current sources to bias output stages in lieu of big heatsinks in single ended mosfet amps.

[Andy Le Blanc]

I was surprised at how well it worked.

To think you blew all that dough on attenuators and put holes in your
amp modding it for vvr, when all you needed was 5$ at the hardware and a
couple bits of wire...