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50k potentiometer on P90 on acoustic guitar?? Hellppp


Manni

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Hey guys, At the moment I am "upgrading" my acoustic guitar with a p90 pickup and a piezo disc, I was researching potentiometers and I really wanted to find something like the mid frequency control on my EQ distortion pedal, I found out the pot was a C50K pot, I later found out these are usually only used for active pickups, nevertheless I was wondering how this pot would affect the sound of a passive pickup?

p.s I understand what a C50K pot is and I've realised the one in my pedal is "stacked" and I was wondering if this also affected the sound, and what the wiring for it is.

Thank you:cool03::D

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OK, Manni, my first concern: P90 in an acoustic guitar. I love P90s and I love acoustic guitars (hence my moniker), but they're not so good together. P90s are magnetic pickups, designed to use with steel strings with a high ferrous metal content. Typical acoustic strings are not that. They might not (probably won't) drive a magnetic pickup very well. My opinion, there are much better ways to amplify an acoustic guitar.

 

I'll await your reply to that before I launch into a potentiometer rap (no, don't use a 50k pot with a P90).

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Welcome to HCEG Manni. You've got some good advice so far, let me add a couple of comments

 

First, I hate to see anything invasive done to an acoustic guitar - poking holes to mount transducers or pots. There are good systems designed to be installed in acoustic guitars that work pretty well and they are pretty easy to install.

 

Second, as Dano says, electric guitar magnetic pickups work best with strings that are designed for them. Acoustic strings do have ferrous cores and there are mag pickups that will work with them if that is a sound you want - these tend to be the sound hole bar pickups (which are nicely non invasive). Lots of good choices here. If you put nickle strings on an acoustic you will compromise its acoustic (and the piezo) sound

 

Third, piezo pickups can either be under saddle types which work fine but have their own distinctive sound (do I hear a quack?). In my opinion the best are the three little piezo dots that glue to the bottom of the bridge plate - K&K is the main brand altho there are clones.

 

Forth - all of the above pickups can be installed as passive or active units - if they are passive then you need some external pre amplification, a DI box or other sound shaping. On board active involves a battery and some electronics - manufactures just put a big barn door in the side (very invasive), most others try to hide something in the sound hole. You will get some signal shaping but mostly preamplification. BTW don't use one manufacturers pre amp with another's pickup (I specifically ask K&K this, they said it might not be balanced)

 

Fifth - if you decide to run two pickups you can blend them on board but best to bring both out separately. Don't just drill a hole in the side and mount a couple of jacks - either put them thru the end block or reinforce the side. If you put the hole in the end block use a tapered reamer - you can damage your guitar with twist bits or a step bit.

 

I'll let Danoacoustic explain why different values of potentiometers (and capacitors) are used with different pickups, but I will echo the opinion that 50K is the wrong choice.

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^^ What he said. And again, Welcome to the insanity! :wave:

 

The P90 will not pick up most of the strings, unless you change over to electric strings. Which in turn, changes/ruins the acoustic tone.

 

If using under the saddle dots, like Freeman suggested, don't be cheap. Those $9 ones from China on eBay, sound crappy at best. AND they NEED a preamp to sound halfway decent. Spend the money, and get the K&K like Freeman suggested.

 

The 50K pot for a mid range control.... nope, ain't going to work. You are looking at a powered circuit, your pedal, and thinking it would work in a passive setting. Uh huh. There is a passive alternative, using either an inductor coil, as in the Gibson L6S wiring, or using a "Q Filter" from Bill Lawrence.(Which I've used in my Gibson L6S.) You could also go with a passive bass and treble circuit, similar to what G&L and Reverend does, but I wouldn't cut 3 or more holes in an acoustic's top to do so.

 

The P90 likes a 250K pot,, really likes a 330K pot, and grooves out wildly on a 500K pot. A 50K would strangle it.

 

I know it sounds as if we are stomping on your dreams, but we are just trying to save you from 1) ruining a possibly decent guitar, and 2) saving yourself a headache.

 

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I type by the biblical method (seek, and ye shall find),so I was waiting to add more. Freeman and badpenguin are not only better typists than I am, they both also know a lot about this stuff, Manni, so listen to 'em.

 

Active vs passive was mentioned. This is the crux of the biscuit when it comes to 50k pots. Sound off if you want to hear more.

 

badpenguin, you know of a good source of bulk 330k pots? Quality ones.

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Can I first say thank you so much to everyone for replying, and I really mean that. This community is very welcoming and helpful. I have taken your advice in and will henceforth not ruin my guitar 😂 instead I will use one piezo disc and mount on the treble side of the bridge, I have heard a few demos of this and I am amazed by the sound quality, I am a very thrifty guy and hate spending too much money in stuff I don't need or is not worth it in my opinion so thank you so much again for that.

I did however see a demo on YouTube of a P90 on an acoustic, and was impressed by the sound quality, I also liked the appearance but that was not the main attraction for me picking that pickup. Here's the link:

​The acoustic guitar I was planning on doing this to is a very old Fenix by Young Chang I got it for free from my old school as they seemed it broken due to a few major cracks and dents, this couldn't have been further from the truth for its playability and all I needed to do was clean it and put a new set of strings on. Anyway my point is that I don't really mind drilling a few holes into it and I realised this anyway as I was planning the whole modification.

Manny thanks again

Manni

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Also couldn't I use acoustic steel strings? I thought that might be a lot better than abandoning my approach. Nevertyeless thank you so much guys

First, welcome to the Forum. You've already gotten some excellent advice. Second, yes, acoustic strings are best on an acoustic guitar. There are also strings like DR Zebras and GHS "White Bronze" that are designed for use with a magnetic pickup. If you do want to install a magnetic pickup, your best cheap alternative is the Fishman Neo-D. If you're near a music store you should be able to buy one for $60 or so. Budget another $10-15 for an endpin jack and install it permanently. You won't have volume or EQ controls but it will sound 'way better than a P90 and anyway you have those controls on your amp.

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d I will use one piezo disc and mount on the treble side of the bridge' date='[/quote']

 

Most of the contact piezo systems have three little dots which are superglued to the bridge plate directly under the saddle. One goes right in front of the first string pinhole, one between the 3rd and 4th, one between the 5th and 6th. K&K gives you a little jig to help install and great instructions. If you try to put only one on the treble side you will loose all the bass.

 

As far as your question about using acoustic strings with a mag pickup, they will work because the core is ferrous, but they will not be balanced like nickle electric strings. If you have the ability to change each pole piece (like a 'bucker) you MIGHT get some semblance of balance, but using a mag pup that is designed for acoustic strings as DE suggests.

 

FWIW, I run a Sunrise magnetic sound hole pickup in my Weissenborn and it sounds pretty good, but I use fairly heavy strings and a plain third. That is the traditional pup for that style of guitar, I guess its just the sound I expect to hear.

 

 

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want to hear more.

 

you know of a good source of bulk 330k pots? Quality ones.

 

If 300k CTS pots are close enough...

 

https://guitarelectronics.com/cts-300k-audio-taper-volume-tone-pot/

 

 

If nothing but 330k will do...

 

http://www.pickofthericks.com/genuine-rickenbacker-330k-potentiometer/

 

 

And I agree with you Dano - 300-330k is the sweet spot for a P90 volume control.

 

 

 

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I'm going to go left field and suggest a Fishman Rare Earth soundhole pickup. It gets you close to what I think you're after, but it's easy to install, quiet and removable if you don't l like it.

 

I run a completely separate output for mine, so the piezo pickup and internal mic go to the PA, but the soundhole goes to an electric guitar amp.

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A P90 is going to hum unless you ground the strings. You'd need to solder a ground wire to a piece of copper foil placed under the bridge where the strings can wedge against the foil by the string pins. I've done this to many guitars that have standard electric pickups.

 

As far as the output. Bronze strings can have an output that is a bit uneven, but not as bad as some have posted. The cores are steel so they do pick up sound and the P90 does have adjustable poles for balancing the sound. P90's are one of the oldest pickups used by Gibson and used on many jazz boxes so they are able to get some decent sounds considering its really not the type of guitar you want to use magnetic pickups on. You'd be far better off installing a bridge Piezo and use an acoustic guitar preamp, both of which would cost you less then $10.

 

A Piezo element is $2.50 https://www.ebay.com/itm/Piezo-Under-saddle-EQ-Pre-Amp-Pickup-for-Acoustic-Guitar-braided-steel-cable-New/142131016177?epid=873475795&hash=item2117ab31f1:g:500AAOxycmBSwQI2

 

4 band preamp is $5.46 https://www.ebay.com/itm/4-Bands-Piezo-Pickup-EQ-7545R-Acoustic-Guitar-Preamp-Amplifier-Equalizer-Tuner-r/142738038766?hash=item213bd99fee:g:Wh4AAOSwb6FavIdZ

 

The pair will sound far better then those disks by the way. The preamp is really important too. If you don't want to mount it in a guitar you can simply mount it in an external box.

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I'm going to go left field and suggest a Fishman Rare Earth soundhole pickup. It gets you close to what I think you're after' date=' but it's easy to install, quiet and removable if you don't l like it. . . .[/quote']

Not as far left as you'd think. I recommended the Fishman Neo-D, which is a budget version of the Rare Earth.

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. . . As far as the output. Bronze strings can have an output that is a bit uneven, but not as bad as some have posted. The cores are steel so they do pick up sound and the P90 does have adjustable poles for balancing the sound. P90's are one of the oldest pickups used by Gibson and used on many jazz boxes so they are able to get some decent sounds considering its really not the type of guitar you want to use magnetic pickups on. You'd be far better off installing a bridge Piezo and use an acoustic guitar preamp, both of which would cost you less then $10.

 

A Piezo element is $2.50 https://www.ebay.com/itm/Piezo-Under-saddle-EQ-Pre-Amp-Pickup-for-Acoustic-Guitar-braided-steel-cable-New/142131016177?epid=873475795&hash=item2117ab31f1:g:500AAOxycmBSwQI2

 

4 band preamp is $5.46 https://www.ebay.com/itm/4-Bands-Piezo-Pickup-EQ-7545R-Acoustic-Guitar-Preamp-Amplifier-Equalizer-Tuner-r/142738038766?hash=item213bd99fee:g:Wh4AAOSwb6FavIdZ

 

The pair will sound far better then those disks by the way. The preamp is really important too. If you don't want to mount it in a guitar you can simply mount it in an external box.

Yes, bronze strings have steel cores but the pickup is designed to respond to the whole string. That means the wounds strings will have less output than they normally would. Your piezo element is $2.50 including shipping from China and your preamp is $5.46 including shipping from Hong Kong. How much of that do you suppose actually goes toward the product? You recommended crap and it will sound like crap. "Those disks" have been used and recommended by acoustic guitarists for years, many of whom prefer them to undersaddle piezo systems like yours. I'll defer to your knowledge of electric guitars but you gave bad advice based on a poor understanding of acoustic instruments.

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