P90 Cover Question - Metal vs Plastic

Basher

Long story short(ish):

 
I have an Epiphone Casino ('97 Peerless Korean). I've had the guitar setup and modded and I love the look and feel.
The original pickups were terrible, very high output and muddy, so I had them rewound giving a lower output. This improved things a bit but the guitar still sounds dull, particularly the neck pickup. I've even tried experimenting with magnets - the neck now has an Alnico II/V combo.

Thinking the problem might be the metal cover. I've just recorded a quick comparison (just some open chords and a brief single note line). In each case, the UNCOVERED pickup plays first and is panned left the COVERED pickup follows and is panned hard right. The recordings are run through identical amp/eq sim settings (Amplitibe Fender Twin model)

Casino P90 Neck comparison - uncovered vs covered

To me there's a world of difference. The uncovered pickup (while noisier) has much more top end. It's noisier (covers shield noise I think) and louder too (this might be a difference in playing but I tried to use the same force each time). The covered pickup sounds very dull in comparison.

So, eventually, here are my questions:

1. Do other people hear the same difference, or has this guitar finally driven me insane?

2. Would replacing the metal pickup covers with plastic ones keep the same treble content as an uncovered pickup or would this still attenuate the high frequencies to some degree?

Sorry for the long post but this has driven me mad for a year or two. I have other guitars with humbucker, P90 or single coils and the Casino is easily the dullest/boomiest sounding. I realise that some of this is the hollow body resonance but it still seems extreme. I can't get plastic covers to replace the metal ones as the Casino neck dogear has narrow string spacing. I would probably need to buy a complete replacement set, which I'm happy to do but want to be as sure as I can that it is the metal covers causing the problems.

Thanks for any thoughts/opinions.

OilCityPickups

Any metal cover ... even nickel ... messes with eddy currents and filters off treble. End of story. I like a nice shiny cover as much as the next man, and am happy to fit them to pickups for customers ... but there is always a trade off. The problems occur when you start with overwound pickups as fitted to a Casino.
The other problem I have discovered from dissecting several Casino pickups ... is that they use 43awg (instead of 42awg used in a proper P90) in order to fit all the wire onto smaller than standard bobbins. This means you can't really rewind them with the 'right' wire, as it won't all fit! 43awg wire can lack treble in some winds ... particularly machine ones with no scatter ... so the problem is pretty much unresolvable with those bobbins.

GuitarMonkey

Wow, there is a huge difference. It's like all the treble is attenuated by the cover.

If you want plastic covers you can buy without holes and drill to match the bobbins. 

http://r.ebay.com/Gvy9ya

To line up the holes, stick metal and plastic back to back with double-sided tape and drill through the holes in the metal cover.

You might need to adjust the height with spacers.

PS yes, plastic will be 100% magnetically transparent.

ChrisMusic

Unless I am talking from the same sanatorium, you don't need to worry about being the only one to hear that difference in pickup tones between chrome and uncovered, it is marked, even more than I would have expected.  The uncovered tone is OK but still not in "great P90 territory" to my ears though.  There is better tone to be had IMHO.

Plastic is electrically and magnetically inert so a good choice for covers, and used to accompany Gibson's P90s for a reason, even if people don't like black plastic covers in general, there is an accepted precedent here.

edited* in the light of GuitarMonkey's wisdom in later comments:

I had heard that the pickups in the Casino were different, but then Epiphone were an entirely separate company when the Casino was launched** initially developed (maybe*), so the originals may have been an Epiphone take on the P90 design rather than the Gibson one.  I assume there was some precedent in Epiphone designing them slightly differently.  Thanks to Ash for the clarifications on the differences, nuggets of wisdom, as always.

If it were me, I would be checking whether a "normal" P90 is a realistic option.  Worth a chat with Ash.  Good luck, and keep us updated please.   

I am not sure how relevant all this article is, but the Wildcat is Epiphone with chrome P90 covers and presumably the wiring is of a not dissimilar length in total, is the wiring enough to make a significant tonal difference ?   I guess it will partially depend on the interaction with the pickups resonant frequency, hopefully Ash or ICBM or someone more knowledgeable on the specifics can advise further.  (So it may be that the wiring is less of an issue with a different pickup spec is what I am guessing)

Check this article out anyway

http://www.award-session.com/pdfs/Epiphone WildKat Tone Mods.pdf

GuitarMonkey

ChrisMusic said:

I had heard that the pickups in the Casino were different, but then Epiphone were an entirely separate company when the Casino was launched, 

FWIW, Gibson bought Epiphone in 1957, prior to the Casino being introduced. The Casino was almost identical to the Gibson ES-330, made on the same production line and was sold through non-Gibson dealers as a cheaper alternative.

ChrisMusic

ChrisMusic said:   I had heard that the pickups in the Casino were different, but then Epiphone were an entirely separate company when the Casino was launched, 

@GuitarMonkey said:   FWIW, Gibson bought Epiphone in 1957, prior to the Casino being introduced. The Casino was almost identical to the Gibson ES-330, made on the same production line and was sold through non-Gibson dealers as a cheaper alternative.

Oops, my bad.   I thought it was before.  Thanks for correcting that.  My education continues  

Do you know why the pickups were different in both size and spec ?  It seems an unnecessary complication just for a minor differentiation in product.  (and one that most of us are blissfully unaware of, until it surfaces as a tone issue like now)

GuitarMonkey

ChrisMusic said:

Do you know why the pickups were different in both size and spec ?  It seems an unnecessary complication just for a minor differentiation in product.  (and one that most of us are blissfully unaware of, until it surfaces as a tone issue like now)

Apart from the covers, original Casino and ES-330 pickups are the same.

It's the Far East manufactured ones that are annoyingly different.

ChrisMusic

Cheers GuitarMonkey, that makes more sense.

Well apart from why they changed size and spec when manufacturing in the Far East, some inscrutable Asian decision making no doubt.  Just doesn't seem logical to either me, or my inner Spock.

GuitarMonkey

Gibson P-90s use imperial measurements (1 15/16" e-e) and I imagine that the Koreans used metric measurements?

ICBM

A bit late to this, but...

What GuitarWeasel, ChrisMusic and GuitarMonkey said.

You're not the only one, there is a big difference, and plastic covers will sound the same as no covers.

I like metal covers on some pickups (sorry Ash! ), but they do definitely alter the tone - more with some pickups than others, and also dependent on the metal type and thickness of the cover. In my opinion, the 'softer' the magnetic field, the bigger the effect - eg Alnico II pickups are affected more than Alnico V, and ceramic least. A P90 also has a pretty diffuse field due to its construction. A thicker or brass cover has a bigger effect than a thinner or nickel one. I could be wrong but I think Epi Casino covers are plated brass - they're definitely very thick though.

Basher

Thank you for the responses. Glad to see that it's not just me that hears a "night and day" difference! I realised that there is an ongoing debate about humbucker covers attenuating treble but my little experiment reveals such a marked difference for this particular dogear P90 that I was quite shocked.

Thanks to @TheGuitarWeasel for explaining about the wire and other internal doodads. What's interesting is that the current pickups are, if anything, underwound. I've checked the specs from the rewind, and it was 8000 turns of wire (not sure what gauge), alnico 3 magnets and 1018 steep polepiece screws. That gave a DC resistance of approx 7k (I measured it at 6.66k). I've since replaced the magnets with, IIRC, an alnico 2/5 pair supplied by Ash for experimental purposes.

@ChrisMusic - I was aware of the Wildcat tonal problem but even if the Casino was similarly afflicted, it's since been rewired with good quality pots, switches and caps so I've removed that from the equation. Actually, what you said earlier is also interesting in that I've owned a few P90 guitars (Yamaha TVL, LP Junior Special and a 56 reissue Goldtop, which I still have) and all sounded completely different to the Casino. Much more chime and jangle, particularly on the in-between settings that's almost completely absent on the Epi.

@GuitarMonkey - I had thought about trying the "drill yer own" method but when I looked (probably a few months ago) those blank covers were no longer for sale (and hadn't been for a while). I can't believe that I forgot to check again! I might pick up a set and try them.

Have just re-read the comments made by @ICBM and I think you might have explained my earlier thoughts about why a P90 might be more susceptible to tonal changes.

I'm still unsure as to the next step. Clearly I need to lose the metal covers but I'm tempted to go the whole hog and just buy new, plastic covered, pickups. 

Am I missing something or are these, cheap as chips, options too good to be true?

MATCHED PAIR ARTEC ALNICO 5 P90 DOG EAR PICKUPS

They seem to have the narrower neck spacing (48mm) and a vintage output of 7.8k although they don't specify any difference between neck and bridge which makes me suspicious. Like I said, they seem a bit too good to be true at that price.

ICBM

The bridge pickup spacing is given as 50mm so they are definitely different.

I would get them at that price - not much to lose… they look right, the construction looks and is specified right, and at worst they may need rewinding.

I'm finding it hard to believe the prices of some of the stuff coming out of China these days - eg a complete Les Paul copy for under £100, if you buy direct - but the basic quality does actually seem to be OK. How they do it, short of employing slave labour, I'm not sure.

Basher

I've been gathering some information and am hearing that the Artec P90s are OK but nothing special. 

Given this, I'm going to hold back and wait until I can afford something decent. My holy grail would be the underwound Fralin "Sean Costello" set but they're expensive when shipping/duty are factored in. It's definitely plastic covers though!

As for the neck polepiece spacing, I've been reliably informed that this isn't critical tonally so I guess it's only a problem if you want to keep the original metal covers which, given the effects documented above, I definitely don't. The picture below shows the current polepiece spacing and I think it shows that I could probably get away with anything up to about 50mm, although a tad less would obviously be better:

imalone

On the same theme, why do most humbucker sized p90s have metal covers when plastic seems more common for proper p90s?

ICBM

So they look right in humbucker guitars!

Basher

You do get odd ones that come with plastic covers. Harmonic Design Z90s:

And I quite like the ones with a metal "rim" and black interior:

I'd probably go for either of these over an all metal cover, given the choice.

57Deluxe

I like a nice wood cover...

http://www.setchellguitars.co.uk/ant/ant/bloguploads/2006/09/rosewood_p901.jpg

knuckleberryfinn

I had the same problem with my '97 Casino - and in fact the bridge pickup was horribly microphonic too, to the point where it would explode into massive screeching feedback suddenly.  I think the Korean Casinos have sensibly wound pickups (around 8K), while the Chinese ones are overwound to around 13-14K.  I was wondering what to do, but in the end I ordered some new Casino-specific dogears from Marc at Mojo, and they sound amazing.  The only problem is that you will need spacers to raise them off the body of the guitar - these dogears sit much lower than the Casino's - and to go between the dog ears of the covers and of the pickup itself (there is a 5mm or so gap).  Spacers from Allparts are too rigid for archtops, and in any case are too wide to fit in the neck position, so do as someone else on the forum did (sorry, I forget who) and make some out of neoprene.  I will be doing this when I get time - hopefully at some point in the next 20 years.

Basher

Thanks for the info @knuckleberryfinn

The originals on my '97 were about 11.5k IIRC. I know that they changed the specs and I believe later Korean Casinos have lower output pickups and a wider nut.

The key for me has been those metal covers - absolute tone-suckers! 

I've asked Ash @ Oil City and it seems that his dogears will fit (both are 11mm which is about as high as the current metal neck cover). Obviously the bridge will need a shim as this is much higher on a Casino.

Hadn't thought about Mojo. Have heard good things about them.

I seem to remember the neoprene thread and I'll search it out. I've done this before with the foam off an old mousemat but it's not easy to cut cleanly so the results were a bit ragged! I think the chap who used neoprene bought sheets of it off ebay. I guess the ideal is something dense enough to cut easily while still conforming to the arch. Interestingly enough this appears to be the material that Rickenbacker use, at least it is on my 660.

knuckleberryfinn

Basher said:

I seem to remember the neoprene thread and I'll search it out. I've done this before with the foam off an old mousemat but it's not easy to cut cleanly so the results were a bit ragged! I think the chap who used neoprene bought sheets of it off ebay. I guess the ideal is something dense enough to cut easily while still conforming to the arch. Interestingly enough this appears to be the material that Rickenbacker use, at least it is on my 660.

I'm about to use the wetsuit my son just grew out of - I'll let you know how it goes.

Agreed on the metal covers - they really do chop off the high end, and I'm a treble fiend, so they had to go.

OilCityPickups

For the record, I can supply a 47.2 mm spaced black neck dogear cover ... which may well fit the Casino neck pickup. The reason I don't make 47.2mm spaced neck P90 is that there are no commercially available bobbins available to go inside it! While I could scratch build them, that would push the cost of the pickups up substantially. Also the cover is only 5mm thick which requires modification to the dogear baseplate to allow the pickup to 'close' and ... like the Mojo pickup, it then requires a spacer to get it to the string height.
If you want a 47.2 cover to try ... I'm happy to send you one.
Ash