Any 8X El34 amps here?

[Bernardduur]

To me it looks more like input protection for the FET.

Cheers,
Albert

PS: I have an old "LAY Power Block" lying around with 10 x EL34
Haven't opened it up yet. IIRC it has an ECC81 LTP inverter.

Could be! It'll add some compression when the signal gets too hot or even clips it.

[Alf]

Imho I think this circuit was designed for playing (or passing) a clean signal, so who wants clipping at the front then ?

I would remove it .

What is the inductance of the choke ?


Alf

[Bernardduur]

Imho I think this circuit was designed for playing (or passing) a clean signal, so who wants clipping at the front then ?

I would remove it .

What is inductance of the choke ?


Alf

The signal has to be higher then the threshold of 1.4V to get clipped; in this setting it'll protect the FET. I'd rather use an end to end diode setting with one end to ground, one end to V+ as it is normally done.

Can't read inductance here; no Henry on my DMM

[Bernardduur]

Question:

I've seen most amps work with simple caps to ground as power supply filtering.... now this amp has bleeder resistors over em. What is the advantage of that?

link to pic

[black_labb]

bleeder resistors discharge the caps after power off so they dont stay at high potential for long periods of time.

[Bernardduur]

I found in a good source that they are also used as ways to get both caps the same load so not one is quicker then the other. Makes the 'new' value (2 caps in series) more stable.

My question is more on the soundwise; how is it compared to the standard cap to ground? I think I'll swap em for 47uF caps as I can get em in the right voltages pretty easy.

[harry]

can anyone explain that to me? i've always wondered why.

surely two identical capacitors would have the same resistance?


is it just because the resistance of the capacitors is low, so resistance in wires etc. would affect the potential divider that's created by the capacitors?

[black_labb]

can anyone explain that to me? i've always wondered why.

surely two identical capacitors would have the same resistance?


is it just because the resistance of the capacitors is low, so resistance in wires etc. would affect the potential divider that's created by the capacitors?

not sure exactly, but probably an issue with tolerances. the caps may age differently or have different temperatures when set up. putting resistors in parallel with them ensures that there isn't a problem

[Bernardduur]

not sure exactly, but probably an issue with tolerances. the caps may age differently or have different temperatures when set up. putting resistors in parallel with them ensures that there isn't a problem

Great!