Well, that ought to clear it up for Duaine... '-] David Ilvedson, RPT Pacifica, CA 94044 ----- Original message ---------------------------------------- From: "Dean Reyburn" <dlr at reyburn.com> To: pianotech at ptg.org Received: 11/14/2009 6:42:54 AM Subject: Re: [pianotech] ETD stretch vs pure (octaves) >RCT's Octave Tuning Style (OTS) numbers 1 through 9 are simple to use, but they >are not like a simple volume control, not at all. >The numbers are a very high level representation of a complex, aural based tuning >algorithm. RCT's tuning algorithm actually adapts itself to each piano as needed, >without changing OTS numbers, but changing the OTS number will vary the stretch >as needed. >For example, OTS 4 (a middle of the road stretch which works on most pianos) >targets a 4:2 octave plus about 1/3 bps between A3 and A4, and a 6:3 octave plus >1/4 bps between A2 and A3. However if the double octave A2-A4 is greater than 1 >bps, then the two single will be squeezed in to fit. If too much squeezing is required >(such as small, high inharmonicity pianos), RCT enforces a single octave minimum, >effectively making the A2-A3 octave into a 4:2 octave. Tuning above A4 and below >A2, RCT does it's best to use the same style as was required for that piano in the >midrange. >That's a simplification but you get the idea. Higher OTS numbers target more >stretch, lower numbers less stretch. The user changes the stretch depending on the >situation, piano, room, or whatever the tuner's or listener's ears require. >RCT's OTS 1 attempts pure single octaves using the most prominent octave type >(2:1, 4:2 etc...) for each part of the piano. OTS 7-8 will give you pure fifths and >12ths but with a controlled significant amount of beats in the octaves and double >octaves. >If the tuner wants to (for example) combine a one stretch in the midrange with >another type of stretch in the bass or treble, RCT's Custom Equalizer tool lets the >user adjust the stretch in each octave. Custom EQ uses octave type markers for >4:2, 6:3, 2:1, 4:1, 8:1 etc... for beat speeds readouts, the adjustment is done >visually on a set of sliders that looks like a graphic equalizer. >Hope that helps, >-Dean Reyburn, RPT >On Nov 13, 2009, at 5:48 PM, Porritt, David wrote: >> Do these OTS numbers correspond to any partial scheme (i.e. 4:2, 6:3 etc.) or are >they just numbers like on a volume control? >> >> dp >> >> >> David M. Porritt, RPT >> dporritt at smu.edu >> >> From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On >Behalf Of Rob Mitchell >> Sent: Friday, November 13, 2009 3:49 PM >> To: pianotech at ptg.org >> Subject: Re: [pianotech] ETD stretch vs pure (octaves) >> >> This has long been a point of confusion for me. Smaller pianos typically have >higher inharmonicity, requiring more stretch in the octaves in an attempt to match >the higher partials. And yet on RCT, the higher OTS (Octave Tuning Styles) are >recommended for bigger pianos. We had Karl Lieberman out a couple of weeks ago >and I think he recommended using OTS 7 or 8 on Steinway D's. >> >> I'm assuming OTS 8 has more stretch in the octaves than say OTS 4. Do I have >this backwards or am I missing something else? >> >> Rob >> >> Mitchell Piano Service >> (415) 994-1030 >> www.mitchellpianoservice.com >> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >~~~~~~~~~~~~~~~~~~~~ > RPS, Inc. contact: <http://www.reyburn.com/contact.html> > Dean Reyburn, RPT > 2695 Indian Lakes Road web page: <http://www.reyburn.com/> > Cedar Springs, Michigan, 49319 USA > Sales & support: 1-888-SOFT-440 (or 616-340-7277) Fax: 616-696-8121
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