Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum 6:3 and 8:4 bass octaves

I've always used the default 6:3 octaves in the bass in Tunelab, but today switched to 8:4 on a couple of grand pianos. I understand that 8:4 gives a little more stretch in the bass. I liked the way the bass sounded. Really clear and the octaves seem cleaner too. I understand that 6:3 octaves are the preferred octave type, as far as the PTG, but are there times when one should deviate from that? If so, how does one know?

Since I know we both use TuneLab, I look at the tuning curve adjuster, switch the ratios and see how the curve looks. That may be a little easier on the Pocket PC version, which I use, because the iPhone and Android version are zoomed in closer and therefore the curve looks kinda crazy. On the Pocket PC version it's zoomed out and the two lines look smoother. Pocket PC also has an option where you can have another ratio layered on top of what's currently being used so you can see how they compare. I've also been using the 8:4 ratio in the bass sometimes and also try out the 4:2 ratio in the upper register but be careful, for some reason there are times I go to it and the curve flattens out! I don't know why. But anyway, make sure the curve looks somewhat "normal" when you switch them.

Thanks for the reply Scott. Here are screen shots from my phone of a Baldwin Grand I worked on today. One with 6:3 and the other with 8:4. Could you explain a little more of what you mean using these two pictures? The only change I see is on the bottom on the deviation curve...I'm still not sure I exactly what that is.

Hi Ryan,
I have a tendency to tune a slightly narrower sounding bass, especially when I stretch as much as possible up the register. I used to stretch the bass where there'd be too much rolling - seemed to create a bit of drama, but overall did not sound correct. There is a balance, for sure.

Seems to me one of the contributing factors as to how much stretch to apply can include the piano's scale, size, type, and mainly your mind's ear after you set your bearings.

Glen

Are you aware that you can display alternate bass and treble octave curves? I have my PPC version set to display both 6:3 AND 8:4 octaves in the bass, and seeing them both together, can compromise between the two.

Mark

In the bottom read-out the bass has disappeared so that means it's gone lower that the screen will show. Try pinching the screen to change the zoom or scrolling down so you can see it. Anyway, as I've observed on mine the 8:4 octave is stretched lower so that would account for it disappearing.

As far as what's best to use, I guess that's up to you. Experiment! These days I usually tune the bass section mostly by ear anyway using TuneLab as a general guide, especially on a pitch raise. I've found that I tend to tune the bass tighter or narrower than TuneLab usually calculates on spinet pianos. It just seems what sounds best to me. On better scaled piano I tend to follow TuneLab in the bass.

Ok, thanks guys. That makes sense. So if I understand probably stick to 6:3 on smaller spinet pianos and maybe save 8:4 for larger grand pianos? What about 4:1 & 4:2 in the treble? I have noticed sometimes, mostly on spinets that I don't like the speed at which some of the 3rd are beating. Mostly in about the 6th octave.

As far as experimenting with the bass, say I tune a piano's bass in 6:3 and then want to retune using 8:4, how far up the scale does this apply? In other words, at what point on the piano does it switch to 4:1 or 4:2?

I guess after doing this for a few years now, I'm starting to listen more and not just accept what Tunelab is telling me. My problem is, I can hear what I don't like, I'm just not always sure how to fix it.

Enter the problem with ETD's.. tuning a 6:3 bass is no more 'right' than tuning an 8:4 bass. Thinking about it this way will take you farther away from trusting your own sense.

I'd really recommend tuning without looking at the machine for awhile. You'll know where to tune various sections of the pianos because the most important partials will stand out and demand to be noticed. Sometimes those change in my experience over as little a distance as eight notes. Individual notes always differ in small amounts.

Small pianos like a more conservative bass in general. Large pianos can demand 12:6 in rare cases. The transition in the treble is important. I find myself switching from what I listen to in the treble around the fifth octave. Below there, the smaller intervals demand alignment.

The compromise shifts towards larger intervals (12th and 15th) in the 5th octave and above. In the seventh octave, sometimes the octave threshold is loud and demanding, other times, it is quiet and allows the piano to expand following the partial series of the voice range. You can use partial ghosting to determine the optimal points there and the limits to stretch.

The machines have no regard to limits of stretch. They see it only as a number.

Ryan, if you listened to different types of bass octaves and preferred a certain type then why can't you simply tune the bass octaves by hearing alone until they sounds sweet to you. And, then check and modify with the double octave and some other criteria such as 12th and RBI progression. Relying on those octave types alone is a risky way to tune a piano I think.

only advantage of edt there is to provide something related to double octave, 112 th and 12 +8. .... lot of beats inthe basses and we have totune beating octaves, not easy if we are not listening well

but thinking that oneor 2 partials are giving a fundamental pitch is irrealistic.
On wound strings, Ih varies with the dinamics. nothing better than ears

With the above, I totally agree. It is not really true that the PTG exam "prefers" or uses any particular type of octave. The Master Tunings are all constructed by ear only. It is safe to say that Octave 2 may well correspond to the 6:3 model but for Octave 1, it will depend on the size and scaling of the piano used in the exam. Octave 1 will be tuned for the best sound, whatever that octave type may be. That octave type may change over the span of that octave.

Therefore, I suggest that for any piano, go ahead and use the ETD default suggestion but trust your ears to improve the Low Bass aurally.

Many ETD users and the ETD manufacturer suggest starting a tuning on A0. This may be sufficient for pitch corrections or very ordinary, small pianos where refinement of the Low Bass sound is not really a priority. It has never made sense to me to start a tuning in the Low Bass because if you do, you have nothing to aurally verify. I much prefer to tune the Low Bass last, not first. I only tune the wound strings by ear as they are first of all, quite easy to hear and tune for me and the ETD calculated program, if I use one at all, is never entirely correct.

Therefore, I suggest for those who do need the ETD as a guide, go ahead and use it however you may, whether you tune the Low Bass first or last but once you have the whole rest of the piano tuned, return to the Low Bass to determine if you can improve the sound. To do that, start on or about F1 (wherever the highest single bass string is in the scale), play a single octave while holding the damper pedal fully open. Adjust slightly the note being tuned sharp and flat while listening for a blend of sound.

It may help to also play the octave-fifth, double octave, double octave-fifth and triple octave. For example, when testing F1, play together with the damper pedal held fully open, F1-F2-C3-F3-C4-F4. Adjust the F1 slightly sharp and flat until you hear the best, pleasing resonance. Do the same with each note of the Low Bass all the way down to A0.

If you tune as described above and try to analyze partial matches electronically, you may find that the octaves shift as you descend from 6:3 to 8:4 to 12:6 or that there is really no particular match at all. There has never been a PTG Exam Master Tuning event in which I was a participant that anyone ever attempted to find out what the partial match actually was because that information would have been irrelevant.

I would say, however that the examinees who have chosen to use the ETD calculated program to tune the Low Bass have always passed that portion of the exam easily, often with no errors scored at all, or perhaps only one or two 1-point errors. That is because the tolerance in that range is quite wide. The tolerance is forgiving because whether the Bass sounds "in tune" or not can be much more subjective, particularly in the lowest range.

Inevitably, when there is an electronically scored error, it is aurally verified and found to be uncharacteristic with the rest of what has been done. It is therefore, possible to actually tune the Low Bass significantly flatter than what the examiners proscribed in the Master Tuning and still pass, having each scored "error" nullified if (and only if ) the Low Bass tuning has been consistently done.

Just as with the High Treble, you may occasionally find a client who prefers a "tighter" or "looser" Low Bass than is your personal preference. Being responsive to what is asked of you is more important than imposing your own preference on the client, for sure. It can make the difference between retaining that client and not.

Once again, thank you Bill for your insight and knowledge. Very helpful.

Thank you so much Bill! I can understand that!