Stupid Amp - Fender Princeton Chorus

[unixfish]

For some reason, since I got my Tele, my amp has been acting up. At first I thought it was the new guitar, but I have since noticed that the ground buzz happens even when the guitar is not plugged in - as long as I have a cable plugged in, it buzzes. Turning the guitar volume down does help (?) when my Tele is plugged in.

I plugged in a steel shank cable - it buzzes. Grab the steel shank of the guitar end, it stops - even without a guitar plugged in. Sometimes it's bad, sometimes it's barely noticeable. Odd. It never seems to do this with my Strat, though. I sometimes leave it plugged in with the volume up while I work - the buzz comes and goes.

I tore it apart today, hoping to find a loose ground or something. The input jacks are the circuit board mounted enclosed in plastic jobs, so nothing I can adjust. I did not find anything obvious on the circuit board.

Putting it back together, I forgot to check how to hook up the speakers (white/black plus/minus). No biggie - off to the internet for a check. I stumbled on some videos of people playing this amp - so I checked them out for fun / reference.

OMG - every Princeton Chorus on YouTube sounded a LOT better than mine. Sure, it had the same trashy overdrive, but the amp sounded a lot "fuller" and the chorus was thick and vibrant. If I turn my chorus depth up to 10, I get what they got on about 3. So, Chorus circuit - not good.

The reverb on the videos was also a lot fuller than mine as well. I get a decent bit of reverb on 10, but they were getting the same amount on about 4 or 5. Reverb circuit - not good.

So, let me think. I've had that puppy for - holy [deleted], 27 years. I don't ever remember being overrun with thick chorus or reverb, though. I guess when you buy a first amp, never play anyone else's, and keep it forever, you never really know that it never really worked properly.

I am in the market for a new amp, but I never really noticed how bad mine is / has gotten / always has been. A few videos were cell phone shot in a garage, a few were more professional - they all sounded better than mine through my laptop plugged into PC desktop speakers. On one video, the player was playing very slow runs, letting the notes ring out to hear the chorus; I can do that - so it was not some slinger shredding where it's beyond my abilities to get a sound.

I don't think this is even worth trading in - OK, maybe I can get $25 or $50 for it, and not have to leave that boat anchor at the curb.

Getting back into playing, because I enjoy it, and finding out how bad my gear is - and how much my old Strat is out of adjustment. I new the amp was just OK at best, but yikes - it's not even what it was supposed to be.

Easy solution, right? Just spend money.

 

[Cleeve]

Clean it up real nicely, take some nice pictures, slap it on craigslist, say you're selling to fund a set of Claves.

 

[unixfish]

...I'm pretty sure a set of claves would sound better. More resonance, better attach.

That is one thing my FPC does well - harsh, "metallic", brittle pick attack with no warmth.

 

[unixfish]

I.E. "that amp sounds so cold, you can use it to air condition your house in the summer!"

 

[soulman969]

After 27 years I guess it's time to retire it to wherever old SS amps go. I did own one in the far distant past and it was probably "the" home practice amp to own back then and Fender sold a ******* load of them. Mine only lasted about half as long as yours has before I sold it for $100 to someone else who wanted a home practice amp.

I think I paid around $270 for mine so $170 net cost for about 12 or 13 years of use seems like a bargain now. You probably paid around the same for yours so you're at about $10 per year for amp rental. Time to buy a new amp ya' cheapskate! LOLOL (just kidding)

Hell, take it over to a Goodwill store and take a tax write off for the donation @ half what you paid for it. You'll probably save more in taxes than the amp is worth.

 

[jazzguitar]

OMG - every Princeton Chorus on YouTube sounded a LOT better than mine. Sure, it had the same trashy overdrive, but the amp sounded a lot "fuller" and the chorus was thick and vibrant. If I turn my chorus depth up to 10, I get what they got on about 3. So, Chorus circuit - not good.

The reverb on the videos was also a lot fuller than mine as well. I get a decent bit of reverb on 10, but they were getting the same amount on about 4 or 5. Reverb circuit - not good.

I don't think this is even worth trading in - OK, maybe I can get $25 or $50 for it, and not have to leave that boat anchor at the curb.

Not sure whether you ever liked the sound of your amp, but the Princeton Chorus was quite popular among jazzers.

When my local club announced there was a certain budget to finally buy a club amp I volunteered to check for amps in that budget and kept looking out for a Princeton Chorus (they then all sold for more than 150 Euros, the equivalent of (at the time) $200. The search ended when one guitarist offered to donate his spare Peavey 112 which I find horrible but better than lugging one's own each other week).

So maybe, some cleaning does the trick! On the other hand, maybe you will be happier with something new ... ?

Just my 5 cents ....

 

[mudbelly]

Don't forget about the Princeton Chorus's big brother the Ultimate Chorus. This was a successful line for Fender. I have the Ultimate and while it's not my cup of tea my son uses it and when I sit back listening to him play it always sounds good.

 

[unixfish]

Found a simple solution to get a bit more time out of the old, tired gal - input 2.

Nowhere near the buzz noise. For some reason, there is a lot more reverb and chorus on this channel (?) It tames the harness of the overdrive a bit.

Still not a good amp, but passable for a while. Things just sound "better" on the lower input channel.

And no, I have not idea why I have not tried that all these years. It must be the years of the Strat where things sound muddy if the tone is not on 10, the volume is not on 10, and you are not using the high signal input. The Tele is such a different beast.

 

[sbpark]

SS amp have caps that need to be replaced, just like tube amps! 27 years sounds like it may need a service and cap job. Probably not worth it though.

 

[Ringo]

" input jacks are the circuit board mounted enclosed in plastic jobs, so nothing I can adjust. I did not find anything obvious on the circuit board."

A lot of modern PCB board amps that have the input jacks soldered directly, the jacks can cause problems over time, as you noted nothing to adjust inside the sealed jack, it's probably just worn out. Another thing to check is the solder joints on the PCB, you could try reflowing them but
since the 2nd jack works, I'd bet the problem is the first input jack.
If you like the amp other than that issue, try replacing the first input jack , some guys use a regular 1/4" jack and run wires to the PCB for more durability.

 

[teleplayr]

I would try re-flowing the solder joints on the 1st channel (like Ringo mentioned) before going through the hassle of replacing it. If you have buzzing on that channel and not the second chances are it's a grounding issue.

If you have a multi-meter check the connection between the solder pads of the jack and the next closest component to make sure you don't have a broken trace.

I lost count of how many of those surface mounted jacks I replaced/repaired when working at a service center.

One thing that helps with the surface mount jacks is to run a bead of silicone along the joint between the jack and PCB, it will add some extra strength.

Changing it to a regular 1/4 input could possibly help, but make sure you have enough space to do it when the amp's re-assembled.

 

[unixfish]

Caps. Never thought about that. This has the tall upright ones - not the "laying down in series" caps like on tube amps.

Caps and an input jack would cost - well - not worth bothering. They amp is probably only worth $100 in good condition. I only kept the amp because it sounds decent at low volume - I would need a good pedal to get decent overdrive. If I'm spending that money, I'm getting a new amp.

I still cannot believe I did not think about caps. I saw them when I took it apart, and it just did not dawn on me.

 

[syrynx]

At 27 years old, every spring tension electrical connection in that amp is bound to need cleaning.

Here's a copy 'n' paste of a text file I post here frequently:

Your hitherto faithful amplifier has betrayed you. It's working, but not well. Maybe it's cutting in and out. Maybe the volume has dropped significantly, or drops and then comes back to normal intermittently. Maybe it's making noise-- perhaps an irregular, static-like noise, perhaps a continuous white or pink noise, perhaps a sound that doesn't originate from your guitar and only shows up on certain notes. Maybe it's distorting, and not in a good way. Maybe it's a mixture of two or more of these unpleasant malfunctions.

The first step I would take, because it's the quickest, the easiest, the least expensive, and the most likely to address the problem, is to clean and re-tension all spring tension connections in the amp.

Even in a very simple amp-- a SF Champ-- there are 31 (yes, thirty-one) spring tension connections. The more complex the amp, the more spring tension connections there are. Some are extremely unlikely to cause either the noise or the intermittency (the power switch, the fuse holder, the speaker jack).

But many of the others-- the connections in the input jacks, the pot wipers, and the connections between the tube pins and the sockets-- are HIGHLY likely to be point-contact semiconductor diodes at this stage in the amplifier's history.

Metals oxidize over time, in the presence of, er, oxygen. Oxidation is speeded up by heat, which amplifiers generate. Put a metal point in contact with a thin film of metal oxide, and you get a diode. This ain't new, and it ain't high tech; such diodes were in use long before there were electron tubes.

Diodes are really good at two things: Rectifying (making AC into pulsating DC) and generating noises: Burst noise, Flicker noise, and Shot noise.

What you thought was a pure tube amp is almost certain to have a whole flock o' semiconductor diodes you didn't know were there. Make 'em go away, and the noise and intermittents will probably go away as well. Make the metal oxides go away, and the diodes go away. Caig's aptly-named DeoxIT is highly regarded by many in these forums, and I've used it with very good success.

Our TDPRI brother Billm has a good tutorial on cleaning and re-tensioning tube sockets on his Web site. Our other forum brother andyfromdenver covers servicing input jacks, cleaning pots, and re-tensioning tube sockets in his Service Diary: Silver Face Fender Champ Fun!. Really, you should read the whole thread.

 

[keithb7]

Dump it. Hey your old Strat must be tired and wore out too. I could take it off your hands.

 

[jtees4]

I may have missed it, but did you try it with different cables?

 

[Johnny Cache]

Just my 5 cents ....

How does that convert into USD?

 

[Mark N]

I just picked one up locally for a couple hundred bucks and it surprised the hell out of me...I don't like the OD channel...I use it clean with pedals in front. It's perfect for the practice space.

 

[unixfish]

Is that a Baja in your avatar?

Mine would be OK as a pedal platform if it were healthy. To get it healthy would cost $200 to $300, unless I tried to do it myself. I'm out of practice with a soldering iron, and I would probably melt the board.

For $300, I could spend another $29 and get a Mustang III brand new.

My Princeton Chorus needs the pots cleaned, a new input jack, caps, and probably some other love as well. It is 27 years old and has never been serviced. It's an original red knob.

Fix the amp, buy some pedals, and I have spent $500. Yeah, no.

I think I just need a different direction here - but if you found a healthy one, it is a good practice amp if you have the "stuff" to put in front of it.

Agreed - the OD channel is artificial and crappy sounding.

 

[unixfish]

...probably not a Baja in the avatar? I think the Baja has more black around the edges with the 'burst finish. At least mine does.

 

[Mark N]

That is a MIM Esquire that I put a black guard on...I don't have it anymore. Sold it. I have a blonde one now.