Out go the cathode's resistor and cåp - In goes the BATTERY

[CRU JONES]

Merlinb,

So, the battery would just discharge at it's self discharge rate?

The reason Guitarist is putting the battery on the cathode is so the idle current trickle charges the battery. It seems like we could get a top off charge from somewhere.

The signal off the preceding stage couldn't charge it. Could it?

Could significant signal asymmetry charge a battery?

Maybe put a capacitively coupled rectifier in there somewhere?

Cheers,
Cru

[Merlinb]

In a grid leak circuit a lithium battery should last for years (literally). (The signal voltage would have no significant effect on it though).
I hadn't considered the trickle-charge idea.

[loudthud]

I've been looking into this subject to try building an amp with no electrolytics. An LED I measured had a dynamic impedance of about 30 ohms at 1mA. Not bad but I'd like lower. Haven't had a chance to try any other examples. I'll have to look for some high brightness types.

Another possibility is a voltage reference chip like the LM4041. The impedance is below 1 ohm up to 1KHz or so, it needs a 10uF bypass cap.

http://focus.ti.com/lit/ds/symlink/lm4041d12.pdf

[bob p]

Well, early tube amplifiers did use batteries for bias. They also used batteries for the B+, and they used batteries for the heaters. They used batteries for the whole thing. it was only later as houses were wired for power that they changed over to line voltage.

The heaters ran off the A battery, the bias battery was the C battery ( and yes it would last a lot longer than the others), and the high voltage was the B battery, which is why we refer to it as B+ today.

glad to see this post -- its's exactly what I was thinking.

when enough time passes, the old becomes new again.

[Merlinb]

. Haven't had a chance to try any other examples. I'll have to look for some high brightness types.

Of the common diodes, rectifier diodes and infra-red LEDs have the lowest impedance (I measured about 5-6 ohms at 10mA).
I think you will find high intensity LEDs have even more impedance than your red LED!

[mooreamps]

Of the common diodes, rectifier diodes and infra-red LEDs have the lowest impedance (I measured about 5-6 ohms at 10mA).
I think you will find high intensity LEDs have even more impedance than your red LED!

Doesn't make so much as a hill of beans worth of difference. What does make a difference, you have to re-cap the input and output to makes this little trick work. . I don't see you saying anything about that.....

-g

[Merlinb]

Doesn't make so much as a hill of beans worth of difference. What does make a difference, you have to re-cap the input and output to makes this little trick work. . I don't see you saying anything about that.....

That much is obvious- it's no different from having a fully bypassed cathode. In any case, that's not what Loudthud was talking about.

[Gregg]

I soldered in a few batteries (scratch the end caps, dabbed resin and added the wire to pin 3/8 and the local/star ground) and they really clear the amp up. No BS!

I never played with batteries in a guitar ampa but I have a 300B SE Hi-Fi amp and using batteries in preamp's cathode did change and clear the sound.
I'm using two AA 700mAh Ni-Cd rechargeable batteries. I tried regular batteries there and they kind of ... exploded. I had the that liquid all over the place. No such problems with the rechargeable ones though.