PRS 635JM vs 635JM “S” - Specs and Resonance Curve

gpdb

Guitar Pickup Database
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May 13, 2022
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It felt incredibly wrong cutting my own USA Silver Sky’s pickup out to do this, but hopefully it will provide some value to everyone! I posted these images to my instagram account, which is why they have the "swipe" icon.

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Hopefully the images come up - if not, here's a data table with the information:
DC ResistanceMagnet TypeInductanceResonant Frequency
635JM6.43KAlnico 52.33 H3.9kHz
635JM "S"7.45KAlnico 52.72 H3.5kHz

In summary, the pickups aren't worlds apart, but they are noticeably different. You'll hear a bit more clarity and brightness in the 635JM, where as the 635JM "S" is going to have a bit less of that and be a bit smoother. Neither is better or worse, it's just preference. As to the physical characteristics, the 635JM's cover has a much more beveled edge across the top, and also is straight across on both sides with the leads underneath. The 635JM "S" has the same trapezoidal bottom as most strat pickups. Both pickups are wax-potted. The magnet stagger is also different, which makes sense due to both guitars having a different radius. Lastly, the 635JM "S" has some metal inserts in between each of the magnets, which is exactly what Dimarzio does with their "virtual vintage" pickups. This increases inductance, which could account for part of the higher inductance of the pickup, the other being the hotter wind. The 635JM pickup doesn't have these inserts as far as I can tell.

As a final interesting note - the 635JM "S" shares a very similar resonance curve to the Seymour Duncan Alnico II Pro strat pickup. If you have any other specific questions I can answer, I'll try to respond with what I can. I plan to do an audio test of both pickups in a neutral guitar so the differences can be heard in a consistent test.
 

CVS

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Thank you for sharing. I like the way yu presented the results. Very easy to understand- and I like the idea of doing it in a neutral guitar. Hopefully the results are the same in terms of brightness vs smoothness
 

gpdb

Guitar Pickup Database
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May 13, 2022
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20
Thank you for sharing. I like the way yu presented the results. Very easy to understand- and I like the idea of doing it in a neutral guitar. Hopefully the results are the same in terms of brightness vs smoothness
Thank you, I appreciate the positive feedback. I'm still trying to figure out how to present this data, I'm trying to do more of this on my instagram (@guitarpickupdatabase). Yeah I'm very interested to hear it as well. I have a bunch of other single coils so I'll be able to compare both of to others too.
 

CandidPicker

Building For A Better Future
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This is good info folks can use when selecting a variety of pickups. The resonance plot intrigues me. Did you perform a side-by-side frequency test and plot the results, or find your data elsewhere? Although it doesn't really matter that much, I'm wondering if perhaps you did the test yourself, or if someone else did...congrats in advance if the work was yours. And commendation for the nice presentation. And thanks again for making it easy to read...
 

gpdb

Guitar Pickup Database
Joined
May 13, 2022
Messages
20
This is good info folks can use when selecting a variety of pickups. The resonance plot intrigues me. Did you perform a side-by-side frequency test and plot the results, or find your data elsewhere? Although it doesn't really matter that much, I'm wondering if perhaps you did the test yourself, or if someone else did...congrats in advance if the work was yours. And commendation for the nice presentation. And thanks again for making it easy to read...
Thanks! I performed the tests myself, using my personal Silver Sky’s pickup and a 635JM “S” I purchased off of reverb. I send a signal sweep through a drive coil that’s connected to an oscilloscope. That plots out the voltage that the pickup produces from 100Hz to 10kHz. That voltage is converted to dB, which gives you a representation of how that pickup reproduces sound. This is a loaded plot, which means I performed the test with a load that represents 2 x 250k pots and a guitar cable’s worth of capacitance, so this is a good prediction of the sound you will hear. I also have unloaded plots for anyone that’s interested. As far as the pictures I posted, I did all of that too.
 

CandidPicker

Building For A Better Future
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Jan 26, 2019
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4,639
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NW Connecticut, USA
Thanks! I performed the tests myself, using my personal Silver Sky’s pickup and a 635JM “S” I purchased off of reverb. I send a signal sweep through a drive coil that’s connected to an oscilloscope. That plots out the voltage that the pickup produces from 100Hz to 10kHz. That voltage is converted to dB, which gives you a representation of how that pickup reproduces sound. This is a loaded plot, which means I performed the test with a load that represents 2 x 250k pots and a guitar cable’s worth of capacitance, so this is a good prediction of the sound you will hear. I also have unloaded plots for anyone that’s interested. As far as the pictures I posted, I did all of that too.
Congrats! Electronics isn't my personal strong suit, but you're well on your way towards making a name for yourself. That's commendable! You might consider building a separate website (www.wix.com has free ones) which might showcase your work. Best wishes! Always good to see technical charts that can help guitarists with their choice of replacement pickups!
 

gpdb

Guitar Pickup Database
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May 13, 2022
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20
Congrats! Electronics isn't my personal strong suit, but you're well on your way towards making a name for yourself. That's commendable! You might consider building a separate website (www.wix.com has free ones) which might showcase your work. Best wishes! Always good to see technical charts that can help guitarists with their choice of replacement pickups!
Funny you should mention, I actually have a website at guitarpickupdatabase.com. I’m going to add this type of data too, but currently I have all the public specs for every major pickup model in an easily filterable table, so you can compare specs really easily. I’d appreciate if you’d check it out and provide feedback!
 

Broseph

PRS Fren
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'Merica
Great info!

I wish PRS gave detailed info on their products. The store’s details leave A LOT to be desired. It would be great to have sound clips. Basic measurements of products like width of tuner posts, etc.
 

gpdb

Guitar Pickup Database
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May 13, 2022
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Great info!

I wish PRS gave detailed info on their products. The store’s details leave A LOT to be desired. It would be great to have sound clips. Basic measurements of products like width of tuner posts, etc.
I fully agree, I wish the pickup manufacturers would provide this data. It seems that most have access to it and use it, there's just not standard for how to do the graphs. If everyone came together to decide on a standard they could do it, but that's more or less what I'm trying to do.
 

Tom Bradovich

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Jul 24, 2021
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What a great website you have! Especially liked the ability to sort by desired sound and that you give us the choice of emailed results or proceeding by clicking next. Very nice job.
 

gpdb

Guitar Pickup Database
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May 13, 2022
Messages
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What a great website you have! Especially liked the ability to sort by desired sound and that you give us the choice of emailed results or proceeding by clicking next. Very nice job.
I appreciate that! Any feedback you have would be helpful for me to make it better. It’s still early but I’m continually adding comparisons on my Instagram and I’ll be writing more articles and reviews on the website. And I’m also working on making the quiz better, but I like how it works so far. My first major goal is to create a space where every pickup option is available, so there’s no more searching endlessly for something super specific, you could just filter and find every option.
 
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