• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Advise on SE amp

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
N

Narside

Member
Joined 2017
Tom1973 said:
Hi Narside,

If your current 3,5 watts is barely enough, then you might want to aim for more then the 5 watts you mentioned. On paper it is almost a 50% increase in power, but subjectively it will be a lot less. If a lack of power is really your issue than I think you will be a lot happier when you aim for ~12 watts. This could be achieved by using a pair of 6V6 in push-pull.

Power output of a 2A3 in SE is also around 3,5 watts and would be ruled out based on your power requirements.

Regards, Tom
Click to expand...
You're absolutely right. That's why i'm planning to build new speakers with high sensivity next after my amp.
 
N

Narside

Member
Joined 2017
Eli Duttman said:
I would never use a wimpy 12AX7 section to directly drive a UL mode power tube. A DC coupled (to 'X7 plate) ZVN0545A source follower changes the calculus.

A triode wired 6V6 will give a 2A3 a good run for its money, sound wise. The 2A3 wins hands down over the 6V6 operating UL or pentode, but a UL/pentode 6V6 produces more power.

A reasonable attempt to have your cake and eat it too is building with a UL/triode mode switch. Triode is more refined, but less powerful. UL is more powerful, but less refined. Choose the mode depending on the material being listened to. Assuming speakers of sufficient sensitivity, triode will be very nice with a string quartet or small jazz combo.

BTW, once a buffering FET "sits" between 'X7 section voltage gain block and "final", there is (IMO) no good reason for eschewing "fixed" bias.
Click to expand...

Eli, thank you for this information. Very useful for me.
 
RajkoM

RajkoM

Member
Joined 2009
This amp has my friend. Little different PSU, but not much.
It sounds great.
 

Attachments

  • EL84-DC-2A3.GIF
    EL84-DC-2A3.GIF
    25.3 KB · Views: 305
M

musical noise

Member
Joined 2004
PRR said:
How many do you need? 6C6 sells for $8, which means there must be thousands of Golden Age 6C6 in a warehouse somewhere.

If you are going to make thousands of amps, you want to confirm how many will be around. If you are just building for yourself, a lifetime supply (4? 8?) is not expensive.
Click to expand...

I also agree with this.

This is awesome and very simple except 6c6 is produced no more
Click to expand...

Also look into 6SJ7 and 6J7 as substitutes. These are equivalent tubes to the 6C6, the difference being the glass - straight T-9 vs. ST shape. All fairly easy to find and affordable.
 
GoatGuy

GoatGuy

Member
Joined 2012
RajkoM said:
This amp has my friend. Little different PSU, but not much.
It sounds great.
Click to expand...

Nice and simple. Front end EL–84 delivers what, about 40× gain or so. I like that it doesn't have cathode bypass caps on the '84. Linearizes that tube a lot. So with up to 2 V input gives ± 80 volt at the 2A3 grid. Since its floating at 157 V, that's easily within its range of non-clipping. 2A3 mu is low enough that there's not significant gain; the (475 - 200 = 275) working volts on the final will be swinging near (but again, not past) saturation.

And… if one were "in the mood", you could fairly easily convert to push-pull, all "class A" too. Different output transformer of course. But sweet none-the-less. Also, I like the CLCLC power supply: It'll get the job done.

Just kind of curious - is the output really 475 B+ on the supply? I'd have thought that with CLCLC you'd get closer to 533 B+ volts.

GoatGuy
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom