Intonation on a quasi-quirky PT6

[horto008]

Here goes:

I have an old PT6 - old as in it was made right before the moniker PT6 was given to the horns but after the PT5. It's been my baby for the last 5 years or so, and when I bought it, I was told it was a PT6 prototype. According to my trusted horn repair guy, it has the largest lead pipe and receiver he's seen on a horn - the receiver for a Yamaha YBB321 will fit inside the lead pipe of my horn. My PT50+ fits in the receiver almost up to the end of the shank, and my GW Diablo pretty much sits inside the receiver up to where the cup begins. The pipe and receiver on the other PT6's I've seen IS MUCH smaller. I would state the measurements if I had them.

My question is whether the giant pipe could be causing the horn to have some interesting intonation quirks. Most every note centers well (including the low register), but the tuning on many of them takes some effort.

Examples:

Low Eb (one line below staff) is sharp (one inch adjustment), but the Ab's around it are spot on.

F (bottom of staff), Bb (3 lines below), Bb (fourth line), Bb (top of staff) are all right in tune with each other; F (second line) is WAY sharp and requires almost a 2 inch adjustment.

As far as open pitches, the G (5th line) is in tune with ALL of the C's I can play. The high G (second space) is WAAAY sharp.

ALL the pitches (Ab, A, Bb, etc.) above G are spot on up to high F.

I have tried my best to listen where the horn seems to center the notes while working with a strobe tuner. Now i'm trying to figure out if there are any reasons the horn would have these quirks -- at least any i might be able to fix.

Any advice?


From the "But I got a great deal on it" archive,
brad h

[poomshanka]

I bought a PT-6 from Bob Tucci back in '94, and wanted to try a smaller leadpipe on it to chew some of the "bacon fat" out of the sound (how Bob put it). He had the factory do a smaller leadpipe, pretty well finished off/smoothed out, and with the lead left in it. I took it out to Robb Stewart to put on the horn.

Definitely put some "zing" back into the sound. The intonation with both pipes was pretty solid, so I don't know what effect a smaller leadpipe might have on your particular horn's intonation. The only thing I'd recommend, however, is that if you order a new pipe, ask that the factory smooth it out, and that they leave the lead in it. It'll make it easier for a repair guy to adjust to fit your horn.

...Dave

[Adam C.]

Brad, you just described all of the intonation tendencies of my PT-6P.

I have no advice that Martin didn't already give, except maybe using 4 for the middle G and 2-4 for Gb. Really changes timbre, though, so I'd go for 1-2 and 2-3 if possible.

My PT-6 (rotor) at work has only the Eb/Ab descrepancy- 6th partial is much better. Bottom range also requires less adjustment.

[Adam C.]

The intonation tendencies on my horn are generally the same whether using a Laskey 30G or 30H, PT 48, 88, Shilke Helleberg II, or Conn Helleberg.

I believe it's a tendency of the model itself.

[horto008]

Ok. sorry for the long delay, here's a pic of the mp on the receiver. I will try to get another of the connection of the receiver to the actual lead pipe (and the pipe). Just to describe it, the lead pipe is almost exactly the same in diameter as the receiver - you can feel it on your fingernail, but measuring it would be very difficult; it's less than 1/32 of an inch difference.

<img src="http://69.73.61.13/tuba%20pic.jpg">

note: trying to serve this from apache on my home box..firewall is being stubborn, so forgive me if it is slow and you occasionally receive the imfamous red X.

[horto008]

No, I told them what horn/size it was going in....this is at the heart of the issue i was talking about anyway, my PT50+ goes in nearly as far as the GW.