universal high-gain pre-amp useful ?

[Bigun]

Once you decide to go to the trouble of building a phono-amp you have a nice high gain low noise amplifier. If you make the RIAA correction filter a feature that can be disabled the same amplifier could then be used for other purposes. I was thinking - it could be used to boost the signal from a current-output DAC using a small valued resistor ? It could be used to boost the signal from a tuner front-end ?

Anybody thought of making one nice pre-amp serve multiple purposes like this ?

 

[DF96]

It could be used to boost the signal from a tuner front-end ?

No. A tuner front-end produces IF, not audio. Once you get audio from the detector or discriminator it only needs low gain amplification. So no need for a high gain audio amp in a tuner.

 

[TNT]

I like your way of thinking. I see use for one in at least 2 or 3 different situations inc. mic amp.

//

 

[sreten]

Hi,

A typical old use without RIAA is a mic input, with other EQ a tape head input.

Its a poor choice for a DAC or any other line level input. However you can
make the line level amplifier part of a 2 stage RIAA EQ for the bass boost.

rgds, sreten.

 

[TNT]

Hi,

A typical old use without RIAA is a mic input, with other EQ a tape head input.

Its a poor choice for a DAC or any other line level input. However you can
make the line level amplifier part of a 2 stage RIAA EQ for the bass boost.

rgds, sreten.

DAC case was: "boost the signal from a current-output DAC using a small valued resistor"

//

 

[Bigun]

Its a poor choice for a DAC or any other line level input.

I was thinking when used to make a hybrid-DAC i.e. not to amplify the line-level output of an off-the-shelf unit but if I made my own DAC or 'hacked' into one. For example, there are some relatively affordable DACs on eBay and you know how us DIY folk like to hack things that work perfectly well to start with. A high gain pre-amp along with a low value resistor makes for an I-V converter.

 

[fdegrove]

Hi,

@Bigun:

Not every valve is happy with a low value grid resistor but a 6DJ8 would do.
Years ago I mentioned in passing that my headamp for MC cartridges would happily double as a I/V convertor stage for a DAC.
And it does. 😀

It can even be built as a balanced I/V should that be required.

I'm even considering using EC86s iso ECC88s but that's another project entirely.....
So many parameters to balance..........

Cheers, 😉

 

[Bigun]

Not every valve is happy with a low value grid resistor but a 6DJ8 would do.

What's not to like about a low value grid resistor - are you worried about those high gm tubes oscillating ?

 

[fdegrove]

Hi,

Sorry, meant grid leak resistor.

If you're smart you can do without grid stoppers most of the time really.

Cheers, 😉