Input Impedance and Sensitivity Question

[Strabo]

Yep, more tube questions. I've been thinking about circuits and that can be dangerous because it's way outside my knowledge. Well, thinking is ok, putting something into practice can be dangerous.

Before I go trying my hairbrained scheme and break something here's my questions.

My amp has an input impedance of 150k which seems a little low. And, it has a sensitivity of 1.8v to hit full power which is kinda high for my SS pre.

So, my thinking is that raising the input impedance will also lower the required sensitivity to hit full power.

1. Am I on the right track?

2. Will this affect anything in the rest of the circuit?

From the diagrams, the input is shorted by a 150k resistor. The positive runs through a cap then right to the input tube, not sharing any other connections. The negative goes right to ground.

Your thoughts?

[Strabo]

Thanks for the great explination. Some day I may know enough to not be so dangerous.

After a little digging, my pre is listed as 2vrms output with a 100k load and 5k listed as a minimum load as you said.

Keep in mind I am only working in theories here. In real life I normally listen < 75db peaks, 85 if I feel like cranking things up. So in reality I have plenty of gain no matter the situation.

In theory, 2v output doesn't leave me with much wiggle room if some day I wanted to crank up a low voltage source that was recorded very quietly.

[NOSValves]

Strabo,

You should really consider picking up a tube preamp ! Chances are the SS pre isn't doing your tube amp justice. If your going to mix and match SS and tubes the reverse setup would net better results IMHO.

Craig

[tubelover]

So you do not like solid state?

[Strabo]

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On 9/16/2004 10:27:31 AM NOSValves wrote:

Strabo,

You should really consider picking up a tube preamp ! Chances are the SS pre isn't doing your tube amp justice. If your going to mix and match SS and tubes the reverse setup would net better results IMHO.

Craig

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Quit tempting me.

I haven't found an affordable tubed HT pre so that would mean spending big bucks for another piece of equipment or just dumping the HT aspect and starting over.

I'm pretty happy with what I have, for now. Just trying to learn a little bit about how it works. FWIW, I prefer the AVM-20 over the PAS-3 for two channel. Not a fair comparison, I know, but it's not a stock PAS either. The soundstage and tone are about the same but the AVM is faster and more detailed.

Maybe someday I'll scrap it all and start over with two channel but I'm not ready to make that jump yet. I've weighed the options before. If I dumped this pre for a good analog pre with HT pass through and a POS entry level AVR I'd loose more in HT then I think I'd gain in 2 channel.

For instance I'd lose the variable crossovers by channel so I'd have to add an ICBM and a crapload of patch cords, or spend more money on more Forte's to put all around the room. And, there's a user adjustable parametric EQ for the sub in the AVM-20 and that would require another piece of equipment and more cash and more patch cords.

Then again, I have only watched three movies in the last 5 months, so why have HT in the first place? Quit tempting me.

Besides, I think my source is the weakest link at the moment.