So reading on renaissance flutes, it seems that they were played so that they were a fifth apart. Usually A, D and G were played together. I guess I found it interesting because in ITM it seems that instruments are usually are an octave apart. Is this always the case for ITM, or has it been tried? Or am I missing some basic music theory that would explain why it is not possible?
Not that it would sound right, just curious.
You’re referring to flutes pitched in keys separated by a 5th, not harmonies in parallel 5ths, right? Just as renaissance recorder consorts were pitched in C and F (or G).
I think what you’re missing is that renaissance part music is polyphonic or homophonic. When you have different part lines (soprano, alto, tenor, etc.), you want instruments that can comfortably cover the tessitura of the different voices, which different sized / pitched instruments make possible.
ITM, on the other hand, is essentially monophonic, where playing in octaves is considered the same as unity. In this model, instruments pitched identically or in octaves make more sense.
I don’t know.
A what and a who? I really have to do some research I guess.
I think I understand, but why does not everyone play (blank) instrument if this is unity? (I mean a fifer wants a drummer, but it is mutual, not unity).
So an A flute playing the same as a D flute would it sound horrible, or sound like a cord?Just a couple of weeks ago, I accidently played a simple song in D while the rest of the folk group was playing in G. It sounded OK through most of the song except for a couple of notes. I’m not sure all songs would work as well.
I guess I don’t understand which notes clash?
C D E F G A B
G A B C D E F#
the ones he screwed up? 
You’re thinking like a fifer, there, I.D.10-t. 
As you have already learned from experience, an ITM session or performance group typically isn’t a band in the monolithic sense applied to a fife-and-drum corps or a GHB band. With certain exceptions, no one I know of in the ITM world wants to do that, in any meaningful sense. It’s egalitarianism’s other side of the coin: either you’re equal in that all play the same yoke, like a fife band, and there’s unity - one hopes - in that, or you’re equal in that all traditional instruments are welcome, like a session, and there’s unity - one hopes - in that, too. Speaking from the ITM side of things, a group of 12 banjos, say, would be interesting and maybe even cool for one go, but otherwise pretty uninteresting at best, and at worst just plain bizarre (if you could even get 'em to all match each other note for exact note, and that’s another thing!). The norms and tendencies of the ITM tradition itself are worthy of acceptance at face value. It’s how we roll. Me, I like the multilayering of timbres and slightly imprecise unity. It’s a matter of one’s personal taste. Nothing wrong with experimenting, but you always know when something’s a traditional evolutionary dead end.
If you want supreme, precise unity in performed ITM, then you might better enjoy listening to recordings of the big name céilí bands. They’re pretty darned tight. But that’s a special discipline, not a standard for all and sundry within the tradition.
You would have something akin to organum.
Hmm … It does sound like you’re thinking of playing harmonies in parallel fifths. 
Again, the purpose of having consort instruments pitched in different keys/ranges is to cover different harmony part ranges, not to play in parallel. Think of vocal/choral music. You wouldn’t want to hear The Messiah performed by an all-men’s or all-women’s chorus. Sopranos and altos, tenors and baritones - each sings the part that’s most comfortable for their own vocal range (tessitura). And the harmonies are deliberately written to take advantage of the different ranges.
Since harmony playing is not an issue or characteristic of monophonic ITM playing, having instruments in different ranges is no advantage. Melodies are played in unison or in octaves, which are perceived as unison. (The psychoacoustics of why octaves are perceived as unison and not harmony is an interesting but different question.) Of course, parallel octaves can add some texture. Whistles playing an octave up, or fiddling in octaves as is done sometimes in Northern (e.g. Donegal) tradition.
As for parallel fifths … As Nano says, you’re talking something like organum or medieval plainchant. Which would just sound spooky or weird in ITM. It’s not a matter of “clashing”. In theory, fifths are the “next most perfect” harmony to octaves. But parallel harmonies are just not a part of the tradition.
I’ve heard the A-whistle-with-D-instruments parallel playing thing done for kicks, but it definitely wasn’t a traditional result. RenFesty, sure. Best to keep it there, IMHO.
One time I played a B whistle in parallel to the tune some folks were playing on their D-compass instruments. Nothing like true organum at all, but it was pretty funny. And most gnarly. 
Here’s a jiggered version of my Mouse in the Mug whistle clip in parallel 5ths.
Gnarly! 
But quaintly pleasing enough on its own merits, I have to admit. I could see it as an interesting part of a track - ONE track - on a CD, but putting aside the idea of small doses of pushing the envelope for art’s sake, if I had to hear that approach throughout, I’d want to go out and kill something for sure.
Thanks for that, I know it isn’t trad, mostly just curious, and learned a few things on the way. Really it amazes me the differences in playing styles. Looking at the tunes, there are crossovers between American fife music and ITM. I always thought it would be neat to hear some one like David Migoya (who has done both) play the same tune in the different styles. Hard Ds, rhythm, dynamic range, gutturals, tonguing, ornamentation, which instruments are used etc. are all parts that make up the over all sound, and I wouldn’t mess with it, but I do get curious about such things. I still don’t fully understand the unity thing, and how the bodhrán fits into it all, but I don’t need to to know what is accepted and what is not part of the tradition.
Hmm. Not sure I understand what you mean by that, exactly. But when you ask “why” questions, the details of a tradition will inevitably come up. Sometimes “this-and-such is the tradition” is the best answer you can get.
What I meant to say is understanding is nice, but sometimes you just need to know the rules to follow.
Sorry, just to clarify … What do you mean by “the unity thing”?
The way it has been used here, it seems to mean a monophonic, yet multi-instrument group cohesion among participants. It seems unique in a way, and I really don’t understand how it developed.
Not trying to insult tradition, I think I will try to expand my statement.
I understand why pips are on a playing card, the numbers are a more recent thing thanks to education.
I understand the use of cowrie shells in of Pachisi, they were a randomizing device easily available.
I think I understand why the flute is used and the ornamentation that is used for it.
I think I understand the origins of mouth music.
I can play poker without knowing what a pip is, etc. I do not have to understand, just know the rules.
I do not understand this idea of unity, where it came from, or what it is.
I have heard bands that play different parts, and all attack the first note at the same time. They were all part of the same sound, removing one would have kicked a leg out of a three legged stool, but they were playing different parts by different rules, in a different style.
I played in the key of D, not C. It was the C# that was the note that sounded wrong. I never figured out why it was wrong, but it was not pleasing to the ear.
Crap, how did I mix that up? Denny should have caught that.
Missed a quip, din’t he?
too hot…try again next week 
No, you’re still right. Because …
Actually, D against G gives the same perfect 5th intervals (or their perfect 4th inverses) as G against C:
D E F# G A B C#
G A B C D E F#
C# against F# is a perfect 4th/5th like the rest. So, in theory, no more clashy (or less weird) than the rest.
But if the song/hymn was harmonized with classic V7 - I cadences, the leading tone in D (namely C#) would clash badly with the flat dominant-7 C-nat of the V7 chord in G (D F# A C-nat). So maybe that’s what you were hearing.