Vox or Lightning Preamp

[johngovan]

Which preamp has higher headroom? Is it the matchless with parallel input stage or the vox with extra gain stage in the output section of the preamp?

[pdf64]

How are you defining ‘headroom’?
The term tends to get used by guitarists to mean the inverse of ‘gain’.

[johngovan]

How are you defining ‘headroom’?
The term tends to get used by guitarists to mean the inverse of ‘gain’.

Louder cleans before the edge of breakup.

[pdf64]

How are you assessing ’louder’?

Are you referring to breakup at the input stage itself, or just anywhere along the amp’s signal path?
Note that for a non master volume amp, or a master volume set to max, as the signal level is increased from 0, the first point at  distortion will occur is almost invariably at the output valve grids.
Occasionally, if the output load impedance is higher than normal, it’ll be the output valve anodes, eg JTM45.

[jordan86]

Which preamp has higher headroom? Is it the matchless with parallel input stage or the vox with extra gain stage in the output section of the preamp?

I don’t think either of those in their stock form are known for clean headroom. If that’s what you seek, you probably need to find a different circuit to copy or tweak them from their stock arrangement.