AMT SS-11 Clone

[spoontex]

Hi,

I want try to build a clean two channel's rack preamp based on AMT SS-11, but using ecc82 as a output stage buffer, instead a jfet like the original. Anybody can help me if I do something wrong? or avoid something?

Thanks!

[iainpunk]

why do you want to use a tube for the output buffer? a Jfet is smaller, cheaper, has better headroom, better linearity, is alone in its package instead of coming per 2.... and its a buffer, tubes don't really add that '''tube sound''' when acting as a buffer anyways.

R4 (3M) can be omitted, as can C2 (22n), since the tone stack blocks DC anyway and those 2 components only serve that purpose, since the cutoff frequency is 3-ish Hz, which is way below audible.

cheers

[antonis]

At what voltage you intend to work ECC82..??

[PRR]

https://www.diyaudio.com/community/threads/amt-based-buffer-preamp.383035/#post-6939702

[spoontex]

why do you want to use a tube for the output buffer? a Jfet is smaller, cheaper, has better headroom, better linearity, is alone in its package instead of coming per 2.... and its a buffer, tubes don't really add that '''tube sound''' when acting as a buffer anyways.

R4 (3M) can be omitted, as can C2 (22n), since the tone stack blocks DC anyway and those 2 components only serve that purpose, since the cutoff frequency is 3-ish Hz, which is way below audible.

cheers

This way it's better?




R4 and C2 are in the original schematic.

[spoontex]

why do you want to use a tube for the output buffer? a Jfet is smaller, cheaper, has better headroom, better linearity, is alone in its package instead of coming per 2.... and its a buffer, tubes don't really add that '''tube sound''' when acting as a buffer anyways.

R4 (3M) can be omitted, as can C2 (22n), since the tone stack blocks DC anyway and those 2 components only serve that purpose, since the cutoff frequency is 3-ish Hz, which is way below audible.

cheers

The fact that I prefer a tube buffer is because for me is simple build. This will be a two channels preamp, so I have the 300v rail the heaters rail and an ecc82 tube act as a buffer, one triode for each channel.
It's a stupid idea?

[antonis]

Hasn't PRR answered you there..??

[spoontex]

Hasn't PRR answered you there..??

Yes... sorry... :icon_redface:p

[iainpunk]

why do you want to use a tube for the output buffer? a Jfet is smaller, cheaper, has better headroom, better linearity, is alone in its package instead of coming per 2.... and its a buffer, tubes don't really add that '''tube sound''' when acting as a buffer anyways.

R4 (3M) can be omitted, as can C2 (22n), since the tone stack blocks DC anyway and those 2 components only serve that purpose, since the cutoff frequency is 3-ish Hz, which is way below audible.

cheers

The fact that I prefer a tube buffer is because for me is simple build. This will be a two channels preamp, so I have the 300v rail the heaters rail and an ecc82 tube act as a buffer, one triode for each channel.
It's a stupid idea?

ow, when doing a 2 channel and having one tube as two buffers isn't a bad idea, if it were one channel, id go with the JFET.

cheers

[spoontex]

why do you want to use a tube for the output buffer? a Jfet is smaller, cheaper, has better headroom, better linearity, is alone in its package instead of coming per 2.... and its a buffer, tubes don't really add that '''tube sound''' when acting as a buffer anyways.

R4 (3M) can be omitted, as can C2 (22n), since the tone stack blocks DC anyway and those 2 components only serve that purpose, since the cutoff frequency is 3-ish Hz, which is way below audible.

cheers

I'm trying to learn about tubes, it's a new world for me. PRR send me a suggestion about the CF. That I'm very grateful. But reading the Merlin Blencowe book, the chapter about the CF, I'm design this one. It's correct?




What are the differences between this one and the one that PRR suggest me?

And you say me that C2 and R4 aren't necessary. So, it's the same with C8 and R11? Are necessary?

Thanks a lot!

[antonis]

What are the differences between this one and the one that PRR suggest me?

Grid bias..

If you want to deal with tubes, you better reckon them as MosFets rather than JFETs..

[iainpunk]

why do you want to use a tube for the output buffer? a Jfet is smaller, cheaper, has better headroom, better linearity, is alone in its package instead of coming per 2.... and its a buffer, tubes don't really add that '''tube sound''' when acting as a buffer anyways.

R4 (3M) can be omitted, as can C2 (22n), since the tone stack blocks DC anyway and those 2 components only serve that purpose, since the cutoff frequency is 3-ish Hz, which is way below audible.

cheers

I'm trying to learn about tubes, it's a new world for me. PRR send me a suggestion about the CF. That I'm very grateful. But reading the Merlin Blencowe book, the chapter about the CF, I'm design this one. It's correct?




What are the differences between this one and the one that PRR suggest me?

And you say me that C2 and R4 aren't necessary. So, it's the same with C8 and R11? Are necessary?

Thanks a lot!

c8 and r11 both serve a purpose

R11 works in conjunction with the volume to reduce the maximum level, and C8 blocks DC from flowing through the volume control ruining the bias.
the volume control is the element dissipating the DC to 0v.

cheers