Quickie as tube buffer...hum

[4krow]

Wait a minute  wate a minite wade a mininight, The quickie as a buffer? could it get closer to that just by changing to a tube with less gain?

[earwaxxer]

Hey Greg! - I wondered how long it would take for you to chime in! A 'buffer' is not much different than a preamp. Take the volume control out. Or, were you more interested in my new years eve 'escapades'?

[4krow]

All I gotta do iz read the front page iffn I wan't ta knoe yer beeswax.

  Now, I think that a buffer will have zero gain as opposed to a pre-amp. I still put volume controls on mine to fine tune the input going to my integrated amp. Sure, it adds cicuitry, but even so I like the results.

[Jim R.]

Greg,

Have you tried just jumpering out the volume control on the integrated and using it as a straight power amp with the quickie in front of it?  May be worth a try.

-- Jim

[earwaxxer]

ok true - I guess a preamp and a buffer are different in that a pre has gain, but they both, ideally, 'improve' the sound. Its amazing to me how many ways there are to do thing. With digital, even more possibilities.

[4krow]

Jim, I have tried that, but because the sensitivity of my integrated is quite high, I use the volume control on the buffer to adjust input gain if you will. This allows me to have a greater degree of rotation on my amp's volume control. I know, I could have adjusted that within the integrated itself, but this was is more adjustable and immediate..

[galyons]

Every added component degrades the fidelity.  Pots are some of the worst offenders.  Have you considered reducing the sensitivity of the Quickie or integrated amp with high quality resistors?  A pot is just a variable resistor.  Cheap pots are more expensive than good resistors. Every pot eliminated is, generally, a good thing. Just measure the Quickie's or the integrated amp's pot resistance at the desired level and replace with similar value high quality discrete resistors.

Extraneous pots would be like adding soda pop to a barrel strength single malt instead of a splash of pure water!!!!

Cheers,
Geary

[4krow]

I like soda pop, and so I am sticking with this arrangement....for now. I have beat the OCD gene into submission. " walk away very slowly, and don't turn your back"

[proud indian]

Extraneous pots would be like adding soda pop to a barrel strength single malt instead of a splash of pure water!!!!

Cheers,
Geary

Well, I got one better. There was this guy at a party who insisted on having Glenlivet with tonic water!!! Maybe he thought it was Gin.

[earwaxxer]

'A pot in your hand, is worth two in you Scotch'....

[4krow]

Ok, back to topic. Quickie as a buffer. I'm hard headed when it comes leaving the volume control in the Quickie, but I am asking how might it be possible to lower the gain of the Quickie.

[underdawg]

I would think the easiest from electronics perspective is add a resistor at the rca out or in to step the gain down.You can try input if you device is 2 plus volts otherwise put on the rca outs. Just my 2 cents.

[4krow]

No doubt, adding a resistor to the input would do the trick, but I am thinking there is a way to decrease the gain of the circuit itself, perhaps adjusting filament voltage? I don't know

[Paul Joppa]

The gain of the tube is set by its internal geometry. You can however load it down - the stock plate resistor drops the gain 6dB from a very high load (PJCCS or plate choke). Using an even smaller plate resistor than the stock 4K would do the following:

1) increase distortion

2) reduce peak output voltage

3) reduce gain

4) reduce output impedance

5) increase plate current (i.e. reduce battery life)

The distortion and plate current effects are not large, so there's no real reason not to try them. The peak output will go down with the gain, so it's probably not an issue either - if you want very low gain, you probably don't need very much output! Worst case you'll have to restore the original configuration.

[4krow]

Paul, THAT was the question I was trying to ask, thank you. I just don't have enough knowledge to know how to phrase my questions sometimes. I will consider using your answer when the new Q 1.1 arrives. Thanks