JJB Prestige 330 - 15mm vs. 20mm transducer?

[personatech]

Hi all,

I'm thinking of buying a JJB Electronics Prestige 330 pickup system for my Eastman E1OM. Thankfully, the Eastman's endpin hole is already drilled at 1/2" so no additional drilling should be necessary! However, I have two options: a 15mm transducer or 20mm transducer. From JJB's materials, it seems that 20mm is standard but 15mm is offered in case there's no enough room on the bridgeplate to fit the 20mm.

How do I determine which to go with? Are there advantages other than just fit for going 20mm instead of 15mm (or vice versa)?

[midwinter]

I run JJBs in several instruments (although not guitars) and I just get the 20mm ones.

[Goat Mick]

I've used the 15mm ones in 5 guitars and really like them. I haven't looked at the website lately but it used to say that the 20mm ones were for laminate tops.

[mitcher16]

This is from their website...at the bottom.
I have a Eastman E20D and I use the 15mm and it sounds fantastic.

The 15mm configuration is designed for more resonant guitars or ones with thinner soundboards. Both systems have a very similar tone but the smaller system provides a little less output than the bigger sized system. In many cases this slight difference is negated by the higher resonance of a smaller bridgeplate. As a general rule of thumb, if you have a mid-grade
or better, solid top, steel string acoustic guitar, the 15mm option is likely to be your best option.

The 20mm size is the best option for 12 string guitars as well as high-string setups. Either size can be used with or without a preamp with fantastic results.

[personatech]

Originally Posted by mitcher16

This is from their website...at the bottom.
I have a Eastman E20D and I use the 15mm and it sounds fantastic.

Thanks, this is very helpful!!

[ljguitar]

Originally Posted by personatech

Hi all,

How do I determine which to go with? Are there advantages other than just fit for going 20mm instead of 15mm (or vice versa)?

Hi p-tech

If K&K are considered, the original PURE was 15mm and overly bass heavy. In addition it didn't fit small bridgeplates. It is now recommended for 12 string instruments (and works well with them) and the Pure Mini measures only 12.5mm and is less bass prone.

I’d expect similar results from JJB.

Hope this adds to the discussion.

[Nick84]

JJB recommend the 15mm for most guitar applications. You won’t want the 20mm unless:
It’s a plywood top that isn’t particularly resonant OR
A 12 string

Contact JJB if in doubt - Jesse is very responsive. I have K&K in my Eastman OM which are smaller than 15mm. I’ve previously had 15mm JJBs in a 000 and it did the job nicely.

[Mandobart]

I've used the 20 mm pickups in all larger instrument applications - guitars, banjo, octave mandolin, mandocello, upright bass. I've installed the 15 mm pickups in four fiddles and a couple mandolins due to not much room between the edge of the f-holes and the bass bar/tone bars.

I really don't detect any difference in tone or output signal between the two sizes.

[Marty C]

Yes. I purchased a Martin D16 some years ago and had a k & k installed. It must have been an old one the luthier had in stock. I could never get the bass lowered enough during the time I had it. Really a woofy guitar. It wasn’t until I decide to take it out that I saw the two large, green disk on the outside (20mm). I later found Out these are now only used for 12 string guitars. It was a Great, clean Install but the wrong pickup. Turn the bass all way down and the treble all way up and use a thin pick - it was decent. But finger pick typically resulted in feedback.

[James May]

From the point of view of the physics of how these transducers work, disc size only affect the strength and volume of the output. Not the frequency response.

But, all things being equal, a larger disc will have a lower (stronger) impedance which CAN mean more bass. Into a given input impedance such as 1Mohm, the 3dB roll off point is usually 30Hz and below, so whether you will hear this on a guitar or not is debatable.

The main feedback frequency will usually be the chamber resonance and that is around 100-120HZ. For that, 12mm vs 15mm vs 20mm discs won't behave significantly different.

[Marty C]

Originally Posted by James May

From the point of view of the physics of how these transducers work, disc size only affect the strength and volume of the output. Not the frequency response.

But, all things being equal, a larger disc will have a lower (stronger) impedance which CAN mean more bass. Into a given input impedance such as 1Mohm, the 3dB roll off point is usually 30Hz and below, so whether you will hear this on a guitar or not is debatable.

The main feedback frequency will usually be the chamber resonance and that is around 100-120HZ. For that, 12mm vs 15mm vs 20mm discs won't behave significantly different.

Agreed, but the two larger ones are on the outside with a smaller one in the middle.