Weird issue with Fender Princeton '68 Reissue ?

**Fred Archtop** · 04-26-2016, 02:20 PM

Dear fellow jazz guitarists,

Something wierd happening here. Ultimately I have tried a Fender Princeton 68 reissue, to get along with my archtops. I'm a Fender guy.

Nice amp all in all, but...After extensive trial in the shop I notice a clear buzz when playing a Bb on the lower E string (less pronouced with surrounding A & B notes, no buzz with Bb played in upper octaves). Here comes the owner of the shop, a good friend of mine. He hears the problem just like me, tries to figure out where it comes from, takes out the front, tighten the screws, sits on the top. There is nothing to do, the buzz is still here.

We agree it must be a crappy model, not my lucky day, and we decide that he'd better order another one from Fender and send the buzzy one back to them. Except this buzz, the amp works just fine with my guitars.

A couple of days later, my friend gets the new model (while still having the other one). We unpack the new amp together and....exactly same problem appears with this second one. No way to figure out easily where the buzz comes from. It's internal to the amp, no obvious parts vibrating while I play this Bb.

Ok, so either I am really unlucky or someone else could well have pointed out the same kind of problem with this model. The amps are now back to Fender. No news from them for the moment.

Thanks in advance for your hints and tips.

Fred

PS : maybe I should consider becoming a crash tester for Fender ? Alternatively I could keep on playing but without using the lower Bb note.

**Jabberwocky** · 04-26-2016, 02:40 PM

To help isolate the problem, could you plug the amp into an extension cabinet, bypassing the integral speaker? If there is no Bb resonance, then it might be the speaker or its baffleboard.

Check that all valves are properly seated and non-microphonic by tapping them gently with a pencil or chopstick.

**Fred Archtop** · 04-26-2016, 02:45 PM

Thanks Jabbs,

No microphonic issue. Fender already sent a pair of premium valves and we tested them in the shop. Same prob. I guess you're right, most probably coming from the internal speaker/baffle. But on 2 successive models in a row...damned !

**Jabberwocky** · 04-26-2016, 02:55 PM

I don't know, Fred. Maybe get a pine cabinet for it from TAD or a new speaker like a hempcone Eminence L'il Buddy. I don't know if the output transformer is the same undersized one in the 65 PRRI. The "bass fart" is a known issue with the PR combo.

But I'd first plug it into an extension cab to see if the issue jumps over. If it does, it is the amp.

**Fred Archtop** · 04-26-2016, 02:57 PM

Thanks for you help ! I will.

**vinnyv1k** · 04-26-2016, 05:46 PM

I had the same problem with a Tone King Imperial amp. It only did it playing a Bb also but on any string. I replaced the preamp tubes with ones of higher quality (NOS) and a spec'd phase inverter tube and it fixed it. It only did it playing a Bb note and really had me scratching my head. Weird.

i have heard of a lot of QC issues with the Fender '68 series amps. The '65 series seems to have a better track record.

**D.G.** · 04-26-2016, 05:54 PM

I ALWAYS remove the back panels on BF amps. You'll get rid of a source of many, many buzzes and rattles this way. Of course, this does expose the tubes to possible damage, so be careful transporting it!

**Greentone** · 04-26-2016, 09:34 PM

If _any_ frequencies are going to give you trouble, they are generally going to be 6th string Bb or 6th string B. Consider, those notes are, respectively, 117hz and 123hz. They are right around the octave of the 60hz frequency of the alternating current, which the power supply is filtering to a great, but not perfect extent. I doubt that there is a resonance with the cabinet or some component in the amplifier. Rather, I suspect that the power supply is not perfectamundo. Read, the dual-rectifier tube is a 5AR4 tube of new origin. Frankly, there is no such thing, IMO, as a _true_ 5AR4 except those NOS tubes made before 1980-something. The rest are some kind of crazy 5U4g or 5y3gt tube made to pretend to be a 5AR4. In my experience, they just don't do the job of the _real_ 5AR4 tubes of yore.

I recommend getting a NOS GE, RCA, Mitsubishi 5AR4 or hanging the moon and using a Mullard GZ-34 rectifier. You won't regret it, even though you will spend good money on the tube. The tube will last and last and last.

Please excuse me for sounding like Mr. No-it-all.

**snoskier63** · 04-26-2016, 09:36 PM

I'm not sure if construction is similar, but I have had two GB Hot Rod Deluxe amps. The first one arrived with screws loose, and even had several completely out and sitting at the bottom of the cabinet. I got everything put together and securely tightened, and the subsequent buzz was horrible. On most everything! I returned it, and eventually I bought a second one from Reverb. It was listed as a store demo model in New condition, so I was hoping it was in perfect working order. I can't be happier with this one! It has only been about 6 weeks, but it's been great so far.

**gggomez** · 04-26-2016, 10:45 PM

Greentone, man that is such a boss picture, is it inferred that you recommend this upgrade for all new princetons? Does it create any difference in tone?

**Fred Archtop** · 04-27-2016, 01:14 AM

Thank you all for these valuable info.

Greentone: people at Fender-France suck ! You know better their product issues then themselves. I'm gonna contact them.

Thanks a bunch again.

Cheers.

**Fred Archtop** · 04-27-2016, 01:23 AM

Thanks for this documented info Mr Greentone. I'm in France, and in Europe we have 50 Hz/230 V AC-DC, not 60 Hz like in the USA. Should this make a difference ?

Best to you.

**Little Jay** · 04-27-2016, 01:54 AM

Read this, this might be your problem: http://billmaudio.com/wp/?page_id=438

**Greentone** · 04-27-2016, 08:56 AM

50 hz might make the buzz something else.

say, in Fender's defense: if I were producing amps I would put the same tubes in that they do. There isn't a commercial alternative. Nobody makes rectifier tubes that are as good as the old ones because solid-state rectifiers eclipsed tubes for such applications. In guitar amps, however, there is an audible difference. Tube rectifiers are imperfect. When they are called upon to provide more current, there is a voltage sag that compresses the audio signal. That compression is cool.

only small amps...50 watts or less...use tube rectifiers. So, it is a subset of a market for electronic devices that yet need tube rectifiers. The entire amp market isn't that big...and is mostly solid state. So, rectifier tube development and production boiled down to only bomb proof computer applications (diode logic circuits) until the Cold War ended.

more or less, there hasn't been a gz34/5ar4 tube produced in 40 years. It isn't Fender's fault. Their business model doesn't support resurrection of rectifier tube manufacture, or sourcing $200 NOS tubes that will not be surely available. However, we can always buy a NOS tube. A good rectifier will last the life of the amp.

again, no beef with Fender here. They are making some of the best amps anywhere.

**Fred Archtop** · 04-27-2016, 11:20 AM

Thank you Mrs. Little Jay & Greentone !

**Max405** · 04-27-2016, 12:08 PM

Originally Posted by Greentone

If _any_ frequencies are going to give you trouble, they are generally going to be 6th string Bb or 6th string B. Consider, those notes are, respectively, 117hz and 123hz. They are right around the octave of the 60hz frequency of the alternating current, which the power supply is filtering to a great, but not perfect extent. I doubt that there is a resonance with the cabinet or some component in the amplifier. Rather, I suspect that the power supply is not perfectamundo. Read, the dual-rectifier tube is a 5AR4 tube of new origin. Frankly, there is no such thing, IMO, as a _true_ 5AR4 except those NOS tubes made before 1980-something. The rest are some kind of crazy 5U4g or 5y3gt tube made to pretend to be a 5AR4. In my experience, they just don't do the job of the _real_ 5AR4 tubes of yore.

I recommend getting a NOS GE, RCA, Mitsubishi 5AR4 or hanging the moon and using a Mullard GZ-34 rectifier. You won't regret it, even though you will spend good money on the tube. The tube will last and last and last.

Please excuse me for sounding like Mr. No-it-all.

Originally Posted by vinnyv1k

I had the same problem with a Tone King Imperial amp. It only did it playing a Bb also but on any string. I replaced the preamp tubes with ones of higher quality (NOS) and a spec'd phase inverter tube and it fixed it. It only did it playing a Bb note and really had me scratching my head. Weird.

i have heard of a lot of QC issues with the Fender '68 series amps. The '65 series seems to have a better track record.

You guys amaze me with all your knowledge. Not only did you both diagnose the problem, but you also also recommended direct fixes, down to the brand of tube. Incredible. Thanks, Joe D

**vinnyv1k** · 04-27-2016, 12:55 PM

Combo tube amps are vibration torture chambers but we all love that sweet tube tone. SS amps can come close but no cigar.

**Fred Archtop** · 04-28-2016, 09:09 AM

Just got in touch with the amp tech yesterday. Seems to be a vibration of the speaker on the baffleboard triggered by Bb only.

You are all of tremendous help ! Thanks a bunch.

**asedas** · 11-15-2018, 03:20 AM

I will continue on that. Have exactly the same pb - I'm in EU as well. Princeton 65 Reverb, lower E string, note A/Bb/B and you have the buzz :/ Was this vibration of speaker at the end or sth else?

**stevo58** · 11-15-2018, 10:54 AM

To isolate a mechanical vibration, take a cardboard tube (like one from a roll of paper towels) and listen while someone else causes the buzz, moving it around the amp until you locate the source.

Most likely it will be the baffle against the cab, the speaker against the baffle, or the back panel against the cab.

Steven

**Fred Archtop** · 11-16-2018, 03:03 AM

Originally Posted by asedas

I will continue on that. Have exactly the same pb - I'm in EU as well. Princeton 65 Reverb, lower E string, note A/Bb/B and you have the buzz :/ Was this vibration of speaker at the end or sth else?

As for me, I gave up the idea of buying a Princeton after I tried a 3rd model with the same issues. Finally, I went for a Deluxe Reverb '65 reissue.

**KirkP** · 11-16-2018, 01:13 PM

When diagnosing a buzz in a combo amp try plugging the speaker into another amp placed a couple of feet away. If the cabinet still buzzes, you’ll know it’s not a microphonic component in the amp.

I had a mystery buzz in a new tweed-style combo a few years ago. To diagnose it, I pushed on various parts of the cabinet while playing the note that produced the worst buzz to see what locations changed the buzz or made it go away. I determined it was the top of the rear panel buzzing against the cabinet frame. As an experiment, I loosened the screws, slid a guitar pick into the gap, and retightened. Problem fixed! I intended that to be a temporary fix, but years later that pick is still there, doing its job.