#1
My primary amp, is a jcm 800, the two channel version. I can play a telecaster into it and the cleans are great, but when I my gibson lp studio with sd 59's in the bridge... its muddy mids city , the middle position is only ok, and the neck with an sd antiquity sounds great. But I primarily use the bridge position. The tech that worked on my amp told me that anything with humbuckers wouldn't do well on this amp's clean channel. I'm wondering if there is a way around this... Would the right P90 in the bridge help at all? Or is the amp the problem? Don't get me wrong, I really enjoy my 800, however I enjoy playing a lot of cleans and I'd like to start being able to play my gibson again.
Last edited by andyhatescrass at Sep 26, 2013,
#2
It's probably just the amount of output. Turn the bridge volume down and see what you think. You can also lower the pickup to see if that helps.

If you have the channel volume high and the master volume low on your amp you should reverse those, too. If you've got a lower gain preamp tube like a 5751, 12AT7, etc., try that in V1, should help a lot. That's a very common tweak for clean tones out of amps like yours with low headroom.

The SD 59 is a perfectly good bridge pickup for cleans, so if it's not working for you it's either because it's not set up optimally, or your rig just doesn't like that pickup.

On the other hand: I just want to make sure you're aware of all of your options before spending a bunch of money on a new pickup. You can probably get it sounding good with some tweaking. However, a nice P90 would be a great upgrade and might fix your issue entirely. I'd suggest trying all of those tweaks first.
#3
I know this is going to sound REALLY stupid, but have you messed around with the Volume or Tone knobs on your bridge while playing clean, because honestly that makes a total difference. The '59 is in the vintage output range for humbuckers meaning its probably one of the best for nice delicious clean tones. I use a set of Seymour Duncan SH18's in my Les Paul Traditional and the cleans it gets on my Marshall are perfect, but I do have to roll back the volume and tone appropriately. I think your problem was the tech you were talking to, a P90 could clean things up but not by much as a P90 will be close to the same output of a SD '59 if all else fails I would invest in a EQ pedal to clean things up even more rather then a pickup swap if you are happy with whats in there.
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#4
I'm not sure how a p90 will help when p90 outputs tend to be broadly similar to paf humbuckers.

i'd try rolling your volume down on the guitar, as colin suggested. if it's too dark like that, consider adding a treble bleed cap to the volume controls (or maybe try 50s wiring).
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#5
Quote by Roc8995
It's probably just the amount of output. Turn the bridge volume down and see what you think. You can also lower the pickup to see if that helps.

If you have the channel volume high and the master volume low on your amp you should reverse those, too. If you've got a lower gain preamp tube like a 5751, 12AT7, etc., try that in V1, should help a lot. That's a very common tweak for clean tones out of amps like yours with low headroom.

The SD 59 is a perfectly good bridge pickup for cleans, so if it's not working for you it's either because it's not set up optimally, or your rig just doesn't like that pickup.

On the other hand: I just want to make sure you're aware of all of your options before spending a bunch of money on a new pickup. You can probably get it sounding good with some tweaking. However, a nice P90 would be a great upgrade and might fix your issue entirely. I'd suggest trying all of those tweaks first.


Admittedly, I havent tried lowering the pickups or the low gain pre amp tube. However, I've gone somewhat in depth and swapped speakers, tried playing it through different cabs and even adjusted the bias to see if it running cooler would help. Nothing really gets rid of the unpleasant mids so I feel like my rig really doesn't like the pickup as you suggested . I'll give lowering the pups a shot soon.
#6
Quote by Dave_Mc
I'm not sure how a p90 will help when p90 outputs tend to be broadly similar to paf humbuckers.

i'd try rolling your volume down on the guitar, as colin suggested. if it's too dark like that, consider adding a treble bleed cap to the volume controls (or maybe try 50s wiring).


Hmmm. I never realized this. I have been thinking about upgrading to 500k pots and taking out the circuit board in this guitar for a while. While I'm at it, I could do the 50's wiring. I'll keep this in mind.
#7
Quote by andyhatescrass
Admittedly, I havent tried lowering the pickups or the low gain pre amp tube. However, I've gone somewhat in depth and swapped speakers, tried playing it through different cabs and even adjusted the bias to see if it running cooler would help. Nothing really gets rid of the unpleasant mids so I feel like my rig really doesn't like the pickup as you suggested . I'll give lowering the pups a shot soon.

You can swap speakers and cabs and bias until you're blue in the face but if the problem is the interaction between the pickup output and the preamp, none of that will do anything.

Quote by Dave_Mc
I'm not sure how a p90 will help when p90 outputs tend to be broadly similar to paf humbuckers.

Higher resonant peak, no phase cancellation, wider dynamic range. Not lower output per se but less muddy given the same output, and often a little friendlier turned down.

Quote by andyhatescrass
Hmmm. I never realized this. I have been thinking about upgrading to 500k pots and taking out the circuit board in this guitar for a while. While I'm at it, I could do the 50's wiring. I'll keep this in mind.

Don't see the point in either of those things. There should be 500K pots in there already, and Gibson uses good stuff. The circuit board is fine, no reason to change it unless it's in your way or it's broken.
#8
Quote by Roc8995

Don't see the point in either of those things. There should be 500K pots in there already, and Gibson uses good stuff. The circuit board is fine, no reason to change it unless it's in your way or it's broken.


Somewhat off topic, but I measured the pot values a few months ago and the volume pots measure around 250 and the tone pots around 500. Is 500k what I really need though? I've read that 300/350k pots are better for p90's and in my case, for cleans.
Last edited by andyhatescrass at Sep 26, 2013,
#9
500k will have a bit more output but will also be brighter and often clearer. So it depends on what the issue is. You can try both, they're not that expensive, but that setup is fine. A bit odd that they're using 250 on the volumes though, usually you'd want 500k for humbuckers. I wouldn't be surprised if switching to 500 across the board made an improvement.

Just thinking of this now: when's the last time you got new tubes in your amp? Any chance your preamp tubes are getting tired?
#10
Quote by Roc8995
500k will have a bit more output but will also be brighter and often clearer. So it depends on what the issue is. You can try both, they're not that expensive, but that setup is fine. A bit odd that they're using 250 on the volumes though, usually you'd want 500k for humbuckers. I wouldn't be surprised if switching to 500 across the board made an improvement.

Just thinking of this now: when's the last time you got new tubes in your amp? Any chance your preamp tubes are getting tired?


Tubes are less than 6 months old. A few of the pre amp tubes are older (2 years at most). I doubt they are the issue.

Do the $12 Gibson pots really sound better than the $2 alpha pots or the $5 CTS ones? I'm guessing its just because it says gibson....
#11
The $12 Gibson pots are the $5 CTS pots

Well, not exactly. Gibson used CTS pots for a long time, and fairly recently started using "Gibson brand" pots which are actually very nice custom spec. I suspect CTS makes them, they look very similar when you take them apart. CTS' standard pot recently switched to a cheaper nylon shaft, which isn't as good as the old-spec brass shaft that Gibson still uses, but you can still get brass shaft CTS pots at many online stores. I'd just get those, they're very close to the Gibson ones and a Gibson pot sure isn't worth twice the cost of the standard CTS pot.

2 years might actually have worn out your preamp tubes depending on what they are. A lot of the production tubes just don't last very long. Sovteks and EH only last me about 2 years. JJ, Shuguang, Tung-Sol have lasted me a bit longer but really it seems like you're just not going to get 5 years out of most of these new preamp tubes. Might want to pick up some new ones, you should always have spares around anyway and they're not getting any cheaper.
#12
Quote by andyhatescrass
Tubes are less than 6 months old. A few of the pre amp tubes are older (2 years at most). I doubt they are the issue.

Do the $12 Gibson pots really sound better than the $2 alpha pots or the $5 CTS ones? I'm guessing its just because it says gibson....


Personally i find bournes to be my favorite, CTS have been good for me as well.
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#13
I think I'm just gonna go for 500k pots on the volume knobs and take the pcb out while I'm at it. So any 500k pot will work? Should I also consider new tone pots even though they measured out to 500k?

This one is cheap and will ship fast...

http://www.philadelphialuthiertools.com/electronics/pots/cts-500k-guitar-potentiometer-fine-spline/

It would work for the two volume pots correct?

I'd like to try a new wiring without the pcb. I see a bunch of stuff about 50's wiring being popular....

Given how I want the guitar to sound, which wiring scheme and capacitors would be best?
#14
You need long shaft pots. If it doesn't say, they're short.

50s wiring only changes the sound if you use the tone controls, a lot of people are parked permanently on 10 and then say it doesn't do anything. If you don't use those controls, just try both. You only have to move a few wires, you can do it in five minutes and see which you prefer. I like the 50s wiring with a treble bleed cap.
#15
Exactly what kind of treble bleed caps do I need?

I can only find that they are supposed to be a value of .022 ... Do I want .022uF or .022mfd?

http://www.philadelphialuthiertools.com/electronics/capacitors/orange-drop-capacitors-022mfd-200v/

.022mfd


http://www.stewmac.com/shopby/item/1281?utm_source=google&utm_medium=shopping&utm_campaign=2013-09-gp&gclid=CNP3s7mH7LkCFQqe4AodnGQAlw

.022uF
#16
^ to a certain extent I think it's personal preference. That being said, there are some rules of thumb as well as to which values you should use. There are also a couple of different circuits you can use for it- cap alone, cap and resistor in series, cap and resistor in parallel. Again, it's partly personal preference, partly about tailoring it to your exact pickups etc.

Colin will know way more than I do about this, so probably wait until he answers you.

Quote by Roc8995
(a) You can swap speakers and cabs and bias until you're blue in the face but if the problem is the interaction between the pickup output and the preamp, none of that will do anything.


(b) Higher resonant peak, no phase cancellation, wider dynamic range. Not lower output per se but less muddy given the same output, and often a little friendlier turned down.


(a) +1

(b) I guess... though IME humbuckers, if anything, often have a tighter bass than p90s which are often loose on the bass.

I still say swapping for something with a broadly similar output and a broadly similar EQ curve (not identical, as you correctly pointed out, but within the same ballpark) is likely to have little more beneficial effect than the stuff you said in (a).

Quote by Roc8995

50s wiring only changes the sound if you use the tone controls


I thought 50s wiring was supposed to retain a little more treble when the volume control was turned down as well? Admittedly, that's based on what I've read rather than personal experience
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Quote by K33nbl4d3
I'll have to put the Classic T models on my to-try list. Shame the finish options there are Anachronism Gold, Nuclear Waste and Aged Clown, because in principle the plaintop is right up my alley.

Quote by K33nbl4d3
Presumably because the CCF (Combined Corksniffing Forces) of MLP and Gibson forums would rise up against them, plunging the land into war.

Quote by T00DEEPBLUE
Et tu, br00tz?
Last edited by Dave_Mc at Sep 27, 2013,
#17
I wouldn't use orange drops, they're too big. They're good for tone caps but not practical for treble bleed. Get a handful of tantalum or ceramic caps around 100 picofarad and see what you like. In my Les Paul I use a 100 and a 120 pF cap for treble bleed. Here's my wiring:

#18
Quote by Roc8995
I wouldn't use orange drops, they're too big. They're good for tone caps but not practical for treble bleed. Get a handful of tantalum or ceramic caps around 100 picofarad and see what you like. In my Les Paul I use a 100 and a 120 pF cap for treble bleed. Here's my wiring:



Where would the pickups/pickup selector/output jack wires be in your diagram? I am somewhat new to reading schematics still.

Could I use the capacitors and connection between the vol and tone pots that you suggested and for everything else refer to a schematic like this?

#19
Pickup hot wire goes to the non-grounded outer lug on each pot (right side on my diagram there), wire to the selector switch goes to the middle lug. Here's a similar diagram that has those connections added:

It's just missing the treble bleed caps, and doesn't use the grounding setup that I drew out. Tying all the pots together like that isn't strictly necessary, but I like to do it.

I am not sure what your last sentence means. Are you asking if you can use another schematic and just insert my changes in? You can certainly do that if you have another diagram you like.
#20
Why does everyone think the solution to everything is a pickup change.
I have the same amp and have never had a distorted sound come from the clean channel. Roc talks the most sense in his first post, I run mine with the master on full and my clean channel rarely goes over 2 or 3 even when gigging. Every guitar I've ever played through mine has always sounded super clean, even cheap Epiphones. Rolling the volume back on an all tube amp will clean up the sound but the clean channel on your amp shouldn't be driving tubes on the clean channel?
The only things I can think of are to try turning the bass down slightly, I've alway found humbuckers to come through very bassy if its too high, I suppose this could cause distortion, roc also suggested lowerin the pick up, I'd try this also.
If neither of those things work if could be a speaker in your cab, perhaps try another cab if you can or take your amp to another tech for a second opinion, there could be something wrong with the amp?

I suppose the other question is, does this guitar sound like it through other amps?
Last edited by Delboyuk_01 at Sep 28, 2013,
#21
Quote by Roc8995
Pickup hot wire goes to the non-grounded outer lug on each pot (right side on my diagram there), wire to the selector switch goes to the middle lug. Here's a similar diagram that has those connections added:

It's just missing the treble bleed caps, and doesn't use the grounding setup that I drew out. Tying all the pots together like that isn't strictly necessary, but I like to do it.

I am not sure what your last sentence means. Are you asking if you can use another schematic and just insert my changes in? You can certainly do that if you have another diagram you like.


Never mind my previous question. Just a few more before i go ahead with this...

Would I be able to substitute .02 mfd caps for the .015 and .022 uf caps in your diagram that you drew up?

Also where exactly should I ground these 3 points?

Last edited by andyhatescrass at Sep 28, 2013,
#22
It'll be fine.


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#23
Just be careful - some people use "mfd" to signify millifarad, and some mean microfarad. I would not suggest using a .022 millifarad cap.
#24
From having the pcb in it, things seem to be set up differently in this guitar. The wire for the bridge pickup had some heat shrink around it. When I peeled it back, I found this: one wire splitting into two wires with a solder joint in the middle. Im guessing its like this in the neck wire too. Should I extend the wires or go ahead with grounding these wires?

Last edited by andyhatescrass at Oct 1, 2013,
#25
That looks normal to me, I'm not sure I understand the question. If you don't need to extend the wire, don't extend the wire. That silver braiding is the ground/shielding element, you solder it to the back of the pot to ground it.

#26
I actually soldered the green wire to the pot and the bigger black wire to the lug. Will that still work the same?
#27
Is the green wire connected to the silver braid? It will work if it is, can't see if that's the case there.