Laney Ironheart Tone Control /Presence Circuit

[Mr. Lime]

I came across the Laney Ironheart schematic and recognized the funny looking presence control called "Tone".
It sits between non-inverting and inverting anodes of the PI and uses a tandem pot to blend between lowpass and a 100n Presence cap. Pots have 220k linear.
Reminds me somewhat on Hiwatt presence circuits..

Any opinions on this?
Has someone tried it out and can report how it sounds and how smooth the range is?

Laney Ironheart Presence.png

[Roe]

reminds me of the vox cut controll

[Mr. Lime]

reminds me of the vox cut controll

Completly different imo as the Vox Hi Cut connects the power tube grids and nullifies them through a cap. No ground connection is needed therefor and it only cuts highs.

The Laney control acts halfway as a usual presence to boost the top end but kills highs when turned other way round. But why do they cut highs in this position and not earlier?

[Roe]

it is better to cut treble late in the signal chain, in order to preserve detail and harmonic complexity. But bass is better removed early on in high-gain amps

[pdf64]

Thanks for bringing that tone control to light, it's a new take on things!

reminds me of the vox cut controll

Completly different imo as the Vox Hi Cut connects the power tube grids and nullifies them through a cap. No ground connection is needed therefor and it only cuts highs.

The Laney control acts halfway as a usual presence to boost the top end but kills highs when turned other way round. But why do they cut highs in this position and not earlier?

In regard of their electrical principle of operation, I think that the Vox tone control and the 'cut' side of the Laney tone control are the same; the path to 0V for cap in the Vox is via the 'other' LTP triode's plate impedance.