Mandolin Has "Chorus" Effect After Reintonation

[kennethmclaughlin]

I sent my mandolin (Rogue RM-100A) into the shop to have the nut lowered and intonation reset, but now that I've got it back its got a really bright and metallic tone that I'm not a huge fan of. It almost sounds like the mandolin has a built in chorus effect.

I linked an example of me playing below, and you can particularly hear it on the A string. The only cause I can think of is I switched from light to medium gauge strings. I don't think any nut changes or reintonation caused it.

I'm curious if anyone has thoughts on the cause and how I can revert this back to a cleaner, more traditional mandolin tone.

https://streamable.com/s5pjz

[ProfChris]

I think I'm only hearing the chorus effect on the open strings - is that right?

If so, the most likely cause is the offending string not sitting properly on the base of the nut slot. As it vibrates it hits the base of the slot in different places, thus changing the note slightly.

The thicker strings might be the cause, if they bind towards the bottom of the slot. The remedy is a little work to broaden the base of the slot.

If you also hear this on fretted strings then it's likely to be a similar problem at the saddle, with the strings sitting high in the slots there.

[kennethmclaughlin]

Thanks for the reply. It is audible on fretted strings, but not as noticeable. I think the cause may be the slightly thicker gauge strings sitting higher in the saddle notches.

[FLATROCK HILL]

It's hard to tell for certain by that video alone, but here's what might help:

Gently stretch those new strings a bit. When they're settled in... tune it up. Tune one string in each chorus with an electric tuner. Tune the other string in each chorus by ear to the string you already tuned. For instance, when you've got one of your 'A' strings tuned, tune the other 'A' string to that one. Start by tuning it slightly lower than it needs to be and slowly bring it to pitch. You'll hear an oscillation that gradually decreases in frequency and it will stop when the two strings are matched.

This might be useless advice. Then again, it might help.

[Roger Moss]

Are the strings binding at all when you tune up or down? That would evidence tight nut slots. Otherwise you might try going back to the light strings to see if that helps.

[Bertram Henze]

The A course just sounds out of tune to me, i.e. like wet tuning taken too far. Once you got both open strings in exact unison, the question is are fretted notes on the A course in exact unison, too? If not, then research would start at the nut as mentioned above.

[pops1]

When setup it was most likely setup for the string gauges that were on it. Changing to heavier strings may make the nut slots too tight.

[MikeEdgerton]

Weave a piece of leather or cloth through the strings behind the bridge and in front of the tailpiece. Does it go away?

[FLATROCK HILL]

The A course just sounds out of tune to me, i.e. like wet tuning taken too far.

(I didn't want to just come out and say it.)

[Drew Streip]

That's not even "wet" tuning. That's simply an out-of-tune mandolin. Tune your A strings to the exact same (correct) pitch and record again.

I assume if you can change strings you can also tune them. All three other courses are correct. If the A strings are making that sound open and fretted, it's just out of tune.

[Willie Poole]

Tune the A string so that both sound alike and then go up to the 7th fret and see if they still sound together, if not the most likely problem would be the nut slots are not the same depth so when you press down on the strings one of them is being stretched a tad more than the other,,,This is quite common when someone other than a person with mandolin set up experience works on a mandolin...

That video tells me that the mandolin is not in tune from the get go...

Willie

[Mark Gunter]

Interesting problem, and interesting responses. I hope you get it figured out, in my limited experience such problems can be a devil to solve.

I had a similar problem on one. That crazy "chorus" effect, especially on the A course. I'd tune the A chorus to unison, then when fretting it would be out of unison. I figured the problem had to be either with the nut slots or the bridge slots, so I made adjustments numerous times with no success. I'd tune "out of unison" to try and find a happy medium between open and fretted notes, and of course there is no satisfaction with that if you want it to sound right.

After months of making micro adjustments, and having the strings wear the slots through a lot of playing, I suppose, the issue finally resolved. I never was really able to just solve it and be happy all at once.

Better luck to you.

---------------

Another thought: Since you've paid for a setup, I think you should return to the shop and let the luthier fix the problem.

[pops1]

I didn't listen to the recording, but if it was just set up and then heavier strings were put on the change in A string diameter may be enough to stick in at least one nut slot and make the A's out of tune with each other. Especially if it wasn't doing it before the setup;.

[Mandoplumb]

Was the one who did the set up a mandolin man, slots in the nut and saddle MUST be EXACTLY same depth in the pair and must ride on front of said nut and saddle. Not so critical on guitar.

[Rob Meldrum]

Email me at rob.meldrum@gmail.com for a free copy of my ebook on how to set up a mandolin. I used three different Rogue mandolins as testbeds while writing the book and they all turned out great. I think the others are right, the nut slots were probably not cut correctly. Either the slots are set for light gauge strings and your medium-gauge strings are binding, or the slots were not angled properly (down and away from the fretboard).

Read the ebook and check out your setup. The fixes are easy!

Rob

[allenhopkins]

The "chorus effect" you're getting is the vibrational interference between two A strings tuned slightly differently, IMHO.. You get the same "vibrato" from "wet"-tuned reed instruments, e.g. Echo Harp harmonicas; the slightly different sound wave patterns from the two strings interact to produce a "wobbly" effect, since the peaks and valleys of the sound waves sometimes coincide, sometimes oppose.

If you accurately tune the strings, then get some kind of unwanted "vibrato," I'd look to see if you're getting sympathetic vibrations from the portions of the strings above the nut, or below the bridge, as Mike E suggests above.

To my ears, this has little to do with set-up or string gauges, but is a function of slightly "off" tuning. Break out the electronic tuner, would be my advice.