Need a little help wiring a Yamaha preamp

[irishluck]

Hello,
I have an older acoustic/electric Yamaha LW5C with a built in preamp, 9v power supply and pickups, all wired to a strap button input instrument jack.
The guitar was given to me years ago and I never had much use for the electronics until recently, I recieved an Acoustic AG30 amp. It sounds great with active electronics, but I plugged in my passive "sound hole" Dean Mearkley ProMag pickup and it had to be cranked to 10 just to hear it. I was thinking of buying a preamp.
Then I looked down at my guitar....
It had all I needed right there, the preamp, the power supply, the pickups, it's just missing the 3 wires from the preamp to the ring, tip, and sleeve connectors of the cable input jack. One is red, one white, and one bare.
Is there anyone who would know how I could figure out which wire goes to what pin? I found an old stereo that has a a 3-pin connector that fits in perfectly. I just need to figure out the way that it's wired.
Here are a few photos, that's the input on the back left, and I guessed I'd just post photos in case someone could identify it. All the research I've done only comes up with that it's a "System 34" preamp for Yamaha guitars.
Any help/ideas/suggestions are much appreciated!

[newey]

irishluck-

Hello and Welcome to G-Nutz2!

Unfortunately, I don't have an answer for your question, I've never fooled around with one of those preamps (yet). But hopefully someone will be along. . .

Ordinarily, the ring connection is used to cut the battery. Perhaps you can see something on the circuit board, where those connections are wired to the board?

[ashcatlt]

First of all, the jack in the guitar (which connects guitar to amp) is an output.

Second, the easy way to find out is probably to just make sure it's got a good battery in it and temporarily short two of the termainals together. If the led comes on, then the other one is the tip. If the led doesn't come on, disconnect the wires and try the other pair. If that doesn't work, try the other pair. Once you've determined which one is the tip (the one which is not involved with lighting the led), the other two are pretty much arbitrary, since they'll be the exact same thing any time a cable is inserted.

So that gets you out of the preamp to the amp, right? Have you figured out how to get that ProMag to (and through) the preamp?

[irishluck]

Well, I bought a Presonus TubePre for all the other acoustics I have that don't have onboard preamps, and i'm stuck with using the soundhole  pickup.So that's why I got the preamp, for the Yamaha I posted about I just got all the parts I need in the mail today and will wire it up tomorrow. I use the soundhole pickup for acoustic bass and banjo also. I just got The Presonus POS today and was excited to see how well it worked. It got nothing but rave reviews. I must have gotten a dud. It hisses and hums and makes it unuseable. I don't touch the "tube" setting at all. It's all the way down. And the only way to reduce the hum is to touch the endpin jack. But it's plugged into a grounded outlet. So I don't know what the problem is. Touching anything still doesn't fix the hissing. I take the Presonus out of the picture and run it straight to the amp, hum and hiss are gone. When it's pluggd in to the preamp, the louder I turn up the gain, the louder the hiss. I have to turn it down so much for a quiet signal it's not even worth keeping. I'm so frustrated with it I want to throw it out the window. I'm so tired of junk. Seems like I have to return something at least once until I get something that works as advertised. Getting tired of poorly made crap with no quality control at the factory and having to spend so much time trying to get it to work, only to find out it's not working properly, and return it. Seems like it happens to me 99 percent of the time lately. I thought this was going to sound good. Everyone recommended it for the price range I am  working with. I should have just thrown $100 in the trash. But I guess I'm taking the scenic route...ending up at the same place anyway.
Any ideas/comments would be greatly appreciated.
I'm so close to chucking this POS in the trash where it belongs.

[ashcatlt]

Woah dude!
Step away from the ledge.

This kind of issue is kind of difficult to diagnose from across the internet, and especially when it's just from a frustrated rant like that.

Honestly, though, I think the fact that the noise goes away when you touch the endpin is a good sign and indicates that it's not really the preamp that's the problem. Frankly, the problem is you, or at least the noise that your body makes/transduces from the world around you. In an actual electric guitar, or an acoustic-electric that's actually intended for a pickup, there will always be a wire from the bridge or something else which conducts to the strings and connects them to the "ground" at the jack sleeve. This accomplishes the same thing you did when you touched your endpin - shorts your noise before it can get to the amp. Unfortunately, those soundhole pickups by their very nature just can't incorporate that kind of thing. They're meant to be quick and easy and temporary and "good enough" in most cases. Why it doesn't seem as noisy through the amp is about anybody's guess. All I can say is that noise is by definition random and hard to predict.

Now, in your somewhat-more-permanent installation, you do have the opportunity to do something about it. Others here might have some idea of how to do it more or less properly, though it might take a little surgery. Me, I'd probably take a relatively fat solid-core wire, strip enough from the one end to span all 6 of the strings and the other end enough to wrap around the threads on that jack. Probably have to take the strings way loose and jam that wire in on the peghole side of the saddle, just run the wire over the top. Maybe duct tape it down for good measure. But that's me.

All that said, I really hope you don't expect this preamp to make it sound super awesome. Most of those soundhole pickups are "meh" at best, and there's kind of nothing you can do about it even with a lot of eq and compression. No preamp alone is going to fix that unless you really want to just distort the heck out of it, and then only if you actually like the sound of your preamp melting down. The "tube" feature probably won't make much difference unless you do that either. A preamp is to make whatever you feed it louder, period. If that thing doesn't sound good to begin with, making louder usually doesn't help.

[irishluck]

Ya, I understand he soundhole pickups aren't the best, but what about my acoustic bass with built in pickups? Why does that make the same exact sounds? And also my electric guitar with humbuckers that is as quiet as a mouse when run directly to my amp? But when I run it through the preamp - whoa....it's horribly noisy. It's supposed to work on vocals, acoustics, electric guitars and basses, and even recording drums. So why would I bother with it if it makes guitars noisy, that are normally very quiet straight to the amp?  What's the purpose of this thing then? Serously? What is the benefit here?
It makes the same noise with all instruments I've plugged in.... Strat, a P-Bass, a Jazz bass, an acoustic bass, and my two acoustic guitars. And I took my P-bass to a luthier and watched him add the wire to the bridge, and that is still noisier running through the preamp. So that seems like a waste of time to do with all of my instruments if it's not working to reduce the unwanted noise while using this preamp. Seems like throwing good money after bad. I have several amps and instruments, never had this issue until I got this preamp. Everything is very quiet. I just got this because I got a great deal on an acoustic amp, and realized I'll need to boost the signal for my acoustics. And when I found this Presonus it boasted how great it makes everything sound. That is B.S. It makes every instrument that sounds just fine without it, sound like turd.
I can run my electric though a 100 watt 2x12 Peavey that will shatter my windows if I turn it up too loud, and it has less noise when cranked up than running it through the preamp and keeping the amp at a much lower level. It seems all it does it boost noise.If I want volume I can just tuen up the gain on my amp and it remains quiet, but add that preamp and it all changes. It does increase the volume (which I don't need on electric, but only tried it as a test) And it seems as if the tube does absolutely nothing at all.  I turn it all the way up (and the tube pot has a lot of loud and scratchy noise just turning the dial, so much noise it puts the VU meter past clipping by just turning the dial!) and it sounds exactly the same as when it is all the way down. In the manual it says the tube drive setting will go from subtle to extreme. It's subtle alright, at every setting from 0-10. I'm not looking for distortion, I just think that this is defective if the tube drive doesn't do anything at all, in any situation with all of my instruments. Wouldn't you agree that is a bit odd? Why have the tube drive if it does nothing at all?
I even played the acoustic and electric while turning up the tube gain and asked my wife who knows nothing about this stuff if she notices ANY difference in the sound when I crank the tube, and the answer was no. She has no bias here, just a second opinion from someone with no vested interest in this. I can't hear any difference, I'm really not expecting it to make anything "sound better". That isn't why I got it at all. I got it simply to boost the signal of the acoustics to a decent level so I don't have to crank a 50 watt amp up all the way just to hear it.  But it's just not working as it should. If all my gear....5 amps, 2 acoustics, an acoustic bass, 2 electric basses and 2 electric guitars sound just fine until I put this crapper in the loop, I don't see anything besides that being the problem. If I get rid of it, problem solved. I plug it in, and wow....what a difference, in a bad way. So if a preamps purpose is to make what I feed it louder, why does whatever I feed it sound awesome on my other amps, and sound noisy and hissy through the preamp, even when run at a lower volume? That pins it down to the preamp.  Really, I put my electric guitar into my super loud amp, fire the amp up, and it's so quiet that I can't even tell the amp is on until I pick a string, and it's loud when I do! ALL of my instruments are super quiet while plugged into all of my amps, and again, the amp is on and turned up loud, plugged into all of my guitars/basses and cranked pretty loud. It's not the guitars if it can do that without the preamp, and when the preamp is introduced into the loop, it's just unuseable. No setting on the preamp sounds ok unless the gain is turned way down to 2 or 3. And that's uselss in my opinion.

Procees of elimination narrows it down to one thing from every test I put it through, with all instruments, amps and cables. It's the preamp.  And I have one bass with active EMGs, and I did exactly what the manual said to do with active pickups, and still, crap. Again, I already love the way they all sound, I'm not looking for it to make them sound any better. I just wanted to use the preamp to boost my acoustic signals but that's worked out to just be a waste of time and money. And I don't really want to fix things that aren't broken. Getting rid of the preamp solves the problem, in every situation I threw at it. Obviously adding the wire ground doesn't help. My P-Bass proves that. I can't blame the soundhole pickup either. Granted it doesn't sound "great" but there is no unwanted noise until I run it through the preamp. So there's a real common factor in all the tests I did that added unwanted hiss and hum, and that common factor was....you guessed it...the preamp. I know this sounds repetitive, and there's no way around that if you want all the facts. That's why I know it's the preamp. It was the only thing that added noise in every situation.  

I'll just run my acoustics through my non-acoustic amps and deal with it. They don't produce the clarity from an acoustic guitar like the acoustic amp does since there is no tweeter, but at least the noise doesn't make me so frustrated I unplug and go do something else.

Sorry for the rant, but if you want to know all the information you can about everything I've tried to do with this to make it work, I needed to write all of this. And if I come across as frustrated it's because I am. Very frustrated, and rightfully so. It took instruments and amps that sound great on thier own, sound worse, and I paid $100 for that?  I don't see any benefits from the preamp, and I don't see any solution here besides just not using it. If anyone can read this and can come up with anything I can do to fix this, I'd sure love to hear it!!
Thank you

[ashcatlt]

So you got this thing to go between the guitar and an amp? I'm not sure that's really the intended purpose, but there isn't a good reason it shouldn't work. The fact that it goes away when you touch the endpin on the acoustic, but not when you touch the strings on your other instruments is a bit confusing, and perhaps just a red herring.

I'm wondering now if it's maybe a ground loop between the preamp and the amp itself, but then the thing says it takes 16VAC power input. You said it's plugged into a grounded outlet, but does the wallwart actually have three prongs? If it does, this might be the issue. Really, even if it isn't, it can sometimes happen. Are the amp and preamp plugged into the same pair of outlets or better yet the same power strip? If not, try that. If that doesn't help, you could try running a relatively thick wire between the two chassis. If that doesn't help, you could try actually lifting the shield connection at the amp end of the instrument cable between the two devices.

If none of that works, look into the return policy from wherever you got it.

[irishluck]

Yes, it is certainly one of it's intended purposes. Without scanning the manual or quoting it, I simply took a photo of the box. Couldn't be more clear that you can go from guitar > preamp > amp. The photo is very simple and clear that can and is intended to be used exactly in that way.
I'll try running a wire, thank you for the idea
And yes they are plugged into the same strip. And no, it does not have three prongs, just the two with the larger prong on one side.
Aside from the unwanted noise, I'm just baffled on why the tube gain doesn't do anything at all. Seems kinda strange to me. Seems like it's not working properly since that should do something. I've read so many reviews and nobody mentions the tube gain not working. The closest I can come to anything about the tube is that it won't really give you a tube sound like a tube amp, but that's more of a comment on the lack of warmth when compared to a real tube amp....but nothing I could find where anyone said that the tube gain doesn't do anything at all.
Arrrghh, I was supposed to be having fun with this, not spending the day troubleshooting. Sigh....that's why my username is what it is. And I registered under that name *before* I had any preamp problems. I really have bad luck with gear. Even if it's brand new. I always get the comment from techs or tech support "that's weird, I've never seen this before!"  It's some sort of curse I have! lol
Thank you so very much for your responses and help!  If I seem frustrated, it's the gear problems that are getting me down...I certainly don't intend to direct my frustration at you, and I hope you aren't taking it that way.  I don't know any musicians where I recently moved to and have to rely on the kindness from helpful people like you on the internet. I stayed up until 1am last night trying to figure this out. Drives my wife nuts!!

Attachments:

[irishluck]

Well, nothing seemed to work. I probably have to blame the wiring in this old house. It was built/wired around 1950. I've had some noise issues here and there before. Which is why I had my P-Bass grounded to the bridge. None of my other electric basses or guitars had much unwanted noise. My strat has a little, but it's very minor. It has single coils, so I just figures that was the reason, because my Ibanez electric has dual hubuckers and is super quiet. So the preamp is just boosting the faint noise that's already there, but not nearly as noticeable until I turn up the gain on the preamp, therefore turning up the unwanted noises. I've never really gotten into amplification with my acoustics until I got this deal on this amp. Then one thing led to another and I spent way more money than I thought I would have to.
I still think it's defective due to the tube not working, But it's getting returned anyway, it's already packed up and ready to go back.  I've spent all day with it and it sure drains all the fun out of playing. I'd much rather play guitar then troubleshoot for hours ad hours....and hours, with no positive results. Seems nothing helps the problem.
Weird thing...totally off topic, maybe someone could shed some light on. I have an Acoustic brand AG30 amp, and recently tried the Acoustic AG15. And the 15 watt is louder than the 30 watt. Why would that be? I remember readng somewhere that just because an amp has higher wattage doesn't mean it is louder. I didn't quite understand why that is, but now see that it is true. Any idea why that is? They do have the same exact size speaker in them. But you would think 30 watts would be louder than 15???
Anyway, thank you very much for the suggestions. I think I'm beating a dead horse at this point. But thank you!!

[newey]

I remember readng somewhere that just because an amp has higher wattage doesn't mean it is louder. I didn't quite understand why that is, but now see that it is true. Any idea why that is?

"Louder" means louder to one's ears, and that depends on the sound pressure level that reaches ones ears through the air. The amp's wattage is only one factor. The efficiency of the speaker is another big factor. Also, there are different ways of measuring wattage, so one has to be sure to be comparing "apples to apples" (probably not an issue if thee two are the same brand, though)

One example of this can be seen in bass amps- bass players need amps with much more power just to be able to be heard in the mix, because our ears selectively hear higher frequencies better than lower.

But if the two amps are the same brand, and same speakers, if the 15 watter is dramatically louder it suggests a problem with the 30 watter.

[ashcatlt]

Course even with all things being the same, 30 watts won't be a whole lot louder than the 15 anyway. It definitely won't be twice as loud. These things are logarithmic so that (theoretically, at least), it takes 10 times the wattage to get a doubling of perceived loudness.

Anyway, I'm sorry that didn't work out for you. Hope you have better luck in future.

Edit -

I do it for free, but if you really want to thank me, go vote! There's two days left.

[reTrEaD]

Aug 29, 2015 18:17:06 GMT -5 irishluck said:

Weird thing...totally off topic, maybe someone could shed some light on. I have an Acoustic brand AG30 amp, and recently tried the Acoustic AG15. And the 15 watt is louder than the 30 watt. Why would that be? I remember readng somewhere that just because an amp has higher wattage doesn't mean it is louder. I didn't quite understand why that is, but now see that it is true. Any idea why that is? They do have the same exact size speaker in them. But you would think 30 watts would be louder than 15???

I have a few ideas. But before we go into those, how about some perspective on power?

As Ash mentioned it takes 10 times the power to sound twice as loud. Twice the power would sound "appreciably" or "noticeably" louder. Lets take a tangent on how relative Sound Pressure Level is compared.

10x power = +10dB SPL = twice as loud.
2x power = +3dB SPL = "noticeably" louder.
Double that again ... 4x power = +6dB SPL = more noticeably louder
Double that one more time ... 8x power = +9 dB SPL = ALMOST twice as loud as the original.
So from this exercise you get a feel for the increase in loudness for these increments.

Keep in mind these relationships remain true if all other things remain equal. But let's imagine where other things might not remain equal...

1 - Different manufacturers might use different benchmarks for how they rate the power output of their amplifiers. But since we have the same manufacturer, it's not so likely one is being rated under more stringent conditions. But keep that in mind for future reference, dealing with different companies.

2  -  Difference in speaker efficiency.  A more efficient speaker will produce higher SPL for the same amount of amplifier power.  And the differences can be STAGGERING.  Difference in speaker efficiency of more than 10db is not at all uncommon for speakers of the same size.  A 10dB more efficient speaker can make a tenth of the power sound just as loud.  Wow!  But I really doubt they would use a more efficient speaker in the lower power amp from the same company.  So again, let's file that away for future use and dismiss it as being likely here.

3  -  Misleading specifications.  I can imagine a company MIGHT under-rate a stripped down amplifier so that a feature-packed amp (which uses the same power output section) looks more desirable. That could be in play here.   But if so, that only speaks to a partial cause.  If that was the only thing in play, we would expect the two amplifiers to sound equal in volume.

4  -  Input sensitivity to achieve rated output power.  If there are differences in the gain of the preamps or equalizers, they could make it necessary for one amp to see a higher amplitude input signal to achieve its rated output, compared to the other.  The "30 Watt" version of this amplifier has a sweepable midrange frequency.  The equalizer may have a lower overall gain than the one in the "15 Watt" version.  Also, the 30 has two input preamps that are summed together.  The summing network might cause some signal loss.  We'd expect the engineer would have added more gain to compensate for this, but maybe he didn't attend to this detail.

There could be other possibilities that I haven't thought of.  But that's a start.