Apologies in advance, but I have to ask what this is

[Mark Hammer]

The tune is called "Wheels" by the String-Alongs.  But there is a subtle effect in there that I'd love to be able to identify.  Not strong enough to be a Leslie.  Not tremolo.  Is it the vibrato from a Magnatone amp?

[Kipper4]

Certainly sounds like a vibrato effect.
I couldn't find much info on them except this

http://www.superoldies.com/pettystudios/stringalongs.html

Sorry I'm not much help.

[samhay]

from: http://www.superoldies.com/pettystudios/stringalongs.html

"Jimmy Torres, whose guitar played through his Magnatone amp was the group's focal point..."

[PEPPER!]

I think you're right.  Here's a guy with a Magnatone 440 and the sound is very close - the vibrato kicks in at around 25 seconds:

[thermionix]

I've worked on a couple Magnatones (forget the model, look kind of like suitcases) that had stereo power amps, I think 2x 12" speakers, and the vibrato was only on one channel.  Sounded amazing, one of the best vibratos I've ever heard.

[Kipper4]

Well spotted Sam

http://celebrityinbend.blogspot.co.uk/2005/09/jimmy-torres.html

[Mark Hammer]

Well alright!  I gotta make me one of those.  Thanks, fellas.

[StephenGiles]

I had an Ampeg amp around 1965 (ET1) which had that effect,
https://reverb.com/item/1389679-1962-ampeg-et-1-echo-twin-vintage-2x12-tube-guitar-amplifier-reverb-tremolo-jensen-c12r-speakers/similar

never used it though because by that time we were doing British R & B - which for the younger generation was this!!  https://www.youtube.com/watch?v=JMGzymLICl0

Oddly enough, BBC6 Radio rebroadcast this superb performance from 1964 in glorious 320kbps digital stereo last month. You can hear probably Vox vibrato in Mona.

[Mark Hammer]

I always thought that was tremolo in Mona.  The very thought of Bo Diddley being played with vibrato....perish the thought!

[StephenGiles]

Of course it's tremelo!

[brianq]

It's Vibrato- most Magnatones had it, straight tube vibrato with the help of some varistors. Btw Bo Diddley exclusively played thru a Custom 280 as did Buddy Hollie. Danelectro amps also have a similar vibrato sound. hope this helps

[Kipper4]

Check out the magnavibe threads Mark. Unless you want a tube vibe.