Hi All,
In one of my 200 unfinished songs I ended up having a section in Fm which I want to connect to another section in Bm. This is essentially a tritone modulation (moving between 2 keys that are maximally apart in the circle of 5ths).
I want to write a sorta bridgy riff that implements that modulation smoothly in 4 or 8 bars.
So… what are your favourite chord progressions for a tritone modulation in 4 or 8 bars? Bonus points if they sound “rock” if ya know what I mean!
Cheers 
One possibility is to tritone substitute your dominant chord in Fm and use that as a pivot chord to change keys, as it will be the dominant chord of the new key.
Other possibilities include two successive modulations by minor thirds using diminished chords, or three wholetone movements.
My immediate thought was to use the bII/Neapolitan, which I think is the same thing? Something like Fm - Gb7 (lol) - C7 - Fm - F#7 - Bm. (My jazz theory is weak, I’m going off common-practice theory classes from over a decade ago)
Also, what about using chromatic mediants? Fm - Dbm - Dbm7b5 - F#7 - Bm or something like that. It’ll sound very “black metal” but that can be fun.
Yep, same thing.
Cool idea, I like it.
Hey, can you guys recommend a good source for learning modulation techniques/theory?
It’s been a couple of decades since my eduction and I need to brush up and learn more!
The dim7 substitutes V7b9 for key of F minor are the same as for B minor (and F major, and B major):
Edim7 Gdim7 Bbdim7 and C#dim7
All four of those chords can function as V7b9 for all four of those keys.
I’d feel silly throwing out chord progressions without knowing the melody or anything else about the piece, but in addition to playing around with the above, or the expected F#7 to Bm or C7 to Bm stuff (or A major to Bm, or C major to Bm) consider this expansion on the descending minor thirds concept:
parallel major of F minor is F major
relative minor of F major is D minor
parallel major of D minor is D major
relative minor of D major is Bm
writing harmony that goes from key of F minor to key of F major is probably more familiar to you.
Then to go from F major to D minor …then D minor to D major, then D major to B minor.
example of concept, half measures each:
Fm Dbma7 Eb Edim7
Fsus4 F(major) C/E A7/C#
D(major) D/C# D(7)/C A#dim7
if you want to get there more quickly, could be something like
Fm Dbma7 Eb Edim7
F Dm Edim7 F#7b9
Bm
Thank you all for the input on this!
I came up with the following “solution” (I think?), which avoids the classical cadences (those that rely on dominant chords (I also think!)).
This is because in this piece I wanted to avoid any hints of neo-classicality, and instead go for more of a “nostalgic 80s-90s videogame music about spaceships and stuff”
The arrangement is a work in progress, but the progression is more or less like so:
Fm, Ebmaj, Bbmaj/D, Dbmaj, Fm,
then some back and forth between Emaj and Bb maj (both with the sharp 4), then finally back to Bm.
Now, I know am writing all these chords, but maybe another way to see it is just a melodic riff that somehow gets there,. I think I convinced myself I don’t hate this, but let’s see what I think in a couple days 
Not sure how useful a very subjective response is, but I like this solution! I think it modulates well and does a good straddle between logical or traditional vs creative/interesting.
In terms of naming it I’m not sure I’d call that a Bb major with a #4 to get to the Bm. I hear it more as an E “lydian” figure, then a run from the diminished scale; D F E Ab B Bb (B Bb trill). Since the bass just plays along with the guitar there, my ears/head can’t really reduce that to a chord symbol but it’s equally a E7b9#11 as it is a Bb7b9#11 ; the six notes are arpeggios of either chord.
Could also think of that as enclosure to the E (whole step below, half step above) then same enclosure to the Bb/A# . Interestingly, the E and A# are the tritone within the V7 dominant of Bm, F#7. So I think that helps with the ‘logical’ part of the sound, that the E and A# are unstable in key of Bm, and the A# is the leading tone up to B.
Also cool that it’s not from the typical diminished scale that would resolve to Bm (the one that would have F#7b9 and A#º7 in them) but a Bb7 to Bm as VII7 to i isn’t unheard of either.
Anyway, always a bunch of ways to dissect something after-the-fact. Big picture thanks for sharing the process and result here, cool to see this work out as smooth as it did.
My 6 year old son walked by while I was playing it. I asked him if he liked it and he said “yeah”. He’ll definitely say when he doesn’t like something. So that’s uh…something 
FWIW I like it too. Cool how it’s not ‘predictable’ on a first listen.
I dig it, sounds kinda wild. Vaguely reminded me of Ron Jarzombek.
That’s so cool! I learned something today thank you 
I’ll gladly take both
And thank you too! Will check him out, always good to be exposed to new sounds!
He’s remained relatively obscure, despite having decades worth of output - just a bit too odd for most shred consumers, I imagine. Some of his projects worth checking out are Spastic Ink and Blotted Science, and his solo album Solitarily Speaking of Theoretical Confinement. His brother is a pretty beastly drummer, too, who’s played for Fate’s Warning and others.
Thanks everyone for the discussion, this is what the whole tune ended up like
Tabs [the tritone modulation section is around 1:37 or bar 73]:
SSSSOOOO Awesome!!!
(some more character to make validation happy)
Nice work, makes me want to play streets of rage, or shinobi 
Thank you so much, that’s mission accomplished for me then
99% of my writing is based on classic videogame nostalgia
Very cool! I like the grin/grimace around 2:13 when you nail the fast run, haha.