8-string Alt tuning help.

[KB5]

So I stumbled upon a stupid cheap ESP B-208FM 8-String. I am checking it out on Wednesday and hope to strike a deal and take it home. I want to tune it to drop D and tune the octave strings on the D and G down A and D respectively. I'm planning on Kalium Hybrids as they are my favorite stings lately. Any suggestions on string gauges?

To clarify tuning:
Dd
Aa
Da
Gd

 

[KeithAlanK]

Going off the gauges for GHS's 8 set, then thickening the E to drop-D and copying the lowered octaves you specify I get:
Dd: .100/.050 or .110/.055
Aa: .070/.035
Da: .055/.035
Gd: .040/.025

This is just a guess, but a logical starting point.
Ask Kalium what they recommend based on the above so that your tension is balanced.
They know stuff.

 

[ixlramp]

I assume you know what gauges you want for DADG, so to choose the 4'octave' strings:
Useful rules derived from physics:
2 strings at equal tension an octave apart will have gauges in ratio 2:1.
2 strings at equal tension a fifth apart will have gauges in ratio 3:2.

However thinner strings don't need as much tension as fatter strings because they have less mass and are therefore less prone to floppiness, so it's possible to make the 4 'octave' strings a little looser than the others if you want to. You can see some 8 string sets do this.

Why not use the Kalium tension chart to choose gauges?

 

[KB5]

Thanks guys! I didn't know Kalium had a tension chart. The ratios make perfect sense, I just hadn't thought that that far into this. The hive delivers again.