Slight tremolo in cut?

[mischmerz]

Fellow trolls:

After re-arranging my equipment over the last few days, I ran the first test cut today and noticed a slight tremolo, almost like a "special effect", especially noticeable in the higher frequency spectrum. Any idea where to look for the culprit?

Michaela

[EmAtChapterV]

It's speed variation - make sure the idler wheels on your Rek-O-Kut are absolutely 100% clean. I had this when I accidentally got a fingerprint on one. It's especially problematic on piano music or any other instrument with long extended notes.

[mischmerz]

It's speed variation - make sure the idler wheels on your Rek-O-Kut are absolutely 100% clean. I had this when I accidentally got a fingerprint on one. It's especially problematic on piano music or any other instrument with long extended notes.

Thanks for the hint. Will clean everything and try it out.

Michaela

[Bahndahn]

I don't know the machine and I cant really help with the problem, but for clarity for you and future readers I want to disambiguate one thing:

Tremolo is defined as: low frequency amplitude modulation. The volume gets louder/softer/louder/softer etc.

Vibrato is defined as: low frequency pitch modulation. The 'pitch' wobbles/continuously oscillates subtly.

Which are you experiencing?

[chris-zwarg]

I don't know the machine and I cant really help with the problem, but for clarity for you and future readers I want to disambiguate one thing:

Tremolo is defined as: low frequency amplitude modulation. The volume gets louder/softer/louder/softer etc.

Vibrato is defined as: low frequency pitch modulation. The 'pitch' wobbles/continuously oscillates subtly.

Which are you experiencing?

This isn't the most common definition of the two terms I'm afraid! For classical singers at least, the difference is rather that "vibrato" is intentional while "tremolo" is a defect. In singing (and in most non-electronic musical instruments), the effect is always a combination of AM and FM.

I'd bet however that the recording defect Michaela describes is FM caused either by a slipping/deformed idler (as has been suggested) or by a defective motor. With old asynchronous 78rpm motors, the problem is usually the centrifugal governor - mostly the leather/felt pad is worn and dried-out, or there is just a drop of oil missing.

[mischmerz]

I don't know the machine and I cant really help with the problem, but for clarity for you and future readers I want to disambiguate one thing:

Tremolo is defined as: low frequency amplitude modulation. The volume gets louder/softer/louder/softer etc.

Vibrato is defined as: low frequency pitch modulation. The 'pitch' wobbles/continuously oscillates subtly.

Which are you experiencing?

I didn't know that. So - I am experiencing "vibrato" Thanks for clearing that.

Michaela

[mischmerz]

Thanks a lot, you pinted me in the right direction. I ffound and fixed the problem. Turns out that the 33 rpm idler wheel was missing its top retainer ring allowing it to travel upwards and (slightly) rubbing against the platter. We manufactured a felt spacer lubed it added a new (wider, plastic) retainer ring and the problem disappeared.

Michaela

[Bahndahn]

Chris, I'm going to try to sway you for the sake of discussion! I come in peace.

This isn't the most common definition of the two terms I'm afraid! For classical singers at least, the difference is rather that "vibrato" is intentional while "tremolo" is a defect. In singing (and in most non-electronic musical instruments), the effect is always a combination of AM and FM.

It certainly may not be the most common definition, but it is correct. People are not often 'fundamentalists' about their "FX" terminology.

The human voice is the only exception I can think of, and the combination of AM and FM is a sort of byproduct of both the imprecision of human voice control and expressivity.

In other acoustic instruments, the definition holds true: vibrato on the bowed instruments is induced by the rocking of the finger back and fourth on the fingerboard [at the 'stop' location]. This is a frequency modulation.

An electroacoustic classic vibrato effect is found with the "Leslie" [horn portion, Leslie 122, 147 etc. models] speaker where the doppler effect is employed to achieve frequency modulation. The lower-frequency speaker baffled however, induces AM primarily but it is not the defining feature of the Leslie sound.

Tremolo, i.e. commonly used with the mandolin, is a continuous 're-picking' of the string - this may be extrapolated as an amplitude modulation.

Etc.

Here is the some disambiguation via the wikipedia page on vibrato:

Screen Shot 2015-09-19 at 1.48.21 AM.png

Pardon the tangent, folks!

[Bahndahn]

In singing (and in most non-electronic musical instruments), the effect is always a combination of AM and FM.

You know, I see what you are saying here. To produce tremolo in any non-ideal apparatus that is wind driven, frequency will always inevitably change subtly too. Therefore, it is [mostly] safe to say that the effect is always a combination of AM and FM in and wind-driven acoustic apparatus.

[Bahndahn]

But its not finished yet....

Tremolo in classical music notation is the rapid changing between notes, where frequency and amplitude are both a modulation