Tannoy HPD-315A Crossover

This article is about the crossover for my HPD-315 driver units.

Original schematic

The original crossover scheme is depicted here, this includes the switches for Energy and treble roll-off. A lot has been said about the original components, among the wise words are, that the coils should be used in a new crossover, to sustain the 'original' Tannoy sound.

Original schematic

However, I am very reluctant to interfere with the original crossover while experimenting, due to the fact that I actually enjoy the current sound immensely. Therefore I plan to build a new x-over from scratch to test out different parts, alhough I'm not going all-in budgetwise (as in Duelund or Jensen parts) but will stick to low-key parts like Jantzens.

New crossover

The following crossover schematic was created by Dan Cramer; it substitutes the regular switches using a value of inductors which equals the Level / Level setting of the original crossover switches.

Dan Cramers schematic

Dan implemented it like this, with a lot of Jensen coils and caps:
Dan Cramers implemented crossover
One variation of this, is to use a cap of higher value (6.8uF instead of 4.7uF) as the primary capacitor on the HF part; according to Hans Hilberlink of the Tannoy website, this should bring the sound closer to the sweet and open midrange of the old Tannoy Monitor Gold speakers.


I intend to test it and see what I like best; should I end up discovering that the types and make of the caps really do have a major influence on the sound, I could end up simply replacing the most important caps of the original crossovers.

Component list per crossover
16.8uF 800V 2%CapacitorJantzen Silver Z-cap
26.8uF 800V 2%CapacitorJantzen Superior Z-cap
13.3uF 800V 2%CapacitorJantzen Superior Z-cap
11.5uF 800V 2%CapacitorJantzen Superior Z-cap
14mH 5% rdc-0.09 10% wire-1.6CoilJantzen C-Coil
12.2mH 5% rdc-0.10 10% wire-1.4CoilJantzen C-Coil
1.7mH 3,870Ohm 0,30mmAir CoilJantzen C-Coil
222R 10W 5%ResistorJantzen Mox Resistor
210.0R 10W 5%ResistorJantzen Mox Resistor
21.0R 10W 5%ResistorJantzen Mox Resistor
24.70R 10W 5%ResistorJantzen Mox Resistor

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