1976 Princeton Reverb sounds flabby sometimes, punchy others

[mickrhodes]

It's a great amp that I absolutely LOVE, all stock save for a Celestion Gold speaker. I've had it out three times in recent weeks for outdoor socially distanced jams, and once it sounded spectacular (on a porch with a wall behind it and a metal patio roof; once last night on my drummer's driveway just sitting out on his lawn, where it sounded sorta 'eh' but was okay; and a third time on that same driveway, not on the lawn, where it sounded weak, flabby and farty. I can't figure this thing out! I'm thinking it may have something to do with having a wall behind it and a roof overhead, but all three were outdoors, same guitars, same settings, etc. I am perplexed! Anybody have any ideas? If it's not my theory, is it possible that amps can sometimes get too hot or something and start sounding crappy? I've also had this same experience with a Victoria 5112. Thank you in advance for your input, TDPRI peeps. Mick.

 

[corliss1]

Welcome!

Sure, I think amps that I know and love sometimes sound epic, and sometimes not. Depends on the day, and that's why we have variety

First thing people are going to ask, including me, is has it ever been serviced? If not, it's a reliability time bomb waiting to happen, and that could be related.

 

[wabashslim]

Could be an undersize extension cord isn't up to the job and you're not getting 120v to the amp. I'd measure the voltage at the point where everything's plugged in & running. And if using a generator - watch out - those outlets are notorious for putting out nothing that resembles A.C. as we know it.

 

[Burning Fingers]

Having done my share of outdoor gigs I would say that any type of roof , fence , hard floor etc for sound to bounce off makes an amp sound better than being totally in an open space.

A lot of what we hear indoors is sound reflecting off walls ,floors and ceilings...the energy is contained within the room, but when outdoors with nothing for it to bounce off, a lot of the sound disappears into the universe without reaching our ears..so we turn the amp up to get more volume and end up with a farty lower end as the power supply struggles.

For indoor gigs I use my little 15 watt 5E3 amp or Princeton amp but for most outdoor gigs I need my 100 watt Seymour Duncan convertible amp to make up for the lack of sound reflection/containment...and that's just for "onstage" sound...the amp is also mic'd and put through the PA for out-front sound.

If your amp was on the driveway and facing the grass then the grass will have soaked up some of the sound...when it was on the grass the nearby driveway could have been bouncing the sound.

I imagine your amp sounded best with the wall behind it , the roof over it and a porch floor under it.

The only times I have had problems with amps due to heat was when the amp was about to fail due to an internal problem ... a resistor couldn't handle the heat stress and eventually let the smoke out or a thermal fuse built into a power transformer failed on a 43C day.

 

[uriah1]

Ya, floor, proximity to walls, etc, etc..it al matters
with open back amps. Get a gamma isolation riser
maybe

 

[Boreas]

It Is all about the space it is being played in - or on. Open air and on a lawn, probably the worst acoustics for tone. Even a Fender Twin could fart out. But another thing to try if you are not getting the tone you want is to either set the amp on a sturdy box and/or tip it back 30 degrees or so - so that it points toward ears instead of feet.

 

[schmee]

I'm surprised you can get it to sound good outdoors at all. I love Princetons, but find they can get a bit farty even in a small club. Outdoors changes the game with amps a lot. I suspect it's an SPL thing. Wide open spaces reduce the sound pressure level a ton. One thing Princetons are very susceptible to is getting farty with an OD in front. Just a bit too much gain on the OD and it's suddenly nasty.
Is it possible you had that going on? or the Gain on the OD was nigher than normal?

OTOH, I sometimes experience an amp like a Deluxe getting farty on the third set in a club after sounding fantastic the previous set... I've come to the conclusion that it's my ears or it's all in my head...!

 

[mickrhodes]

I'm surprised you can get it to sound good outdoors at all. I love Princetons, but find they can get a bit farty even in a small club. Outdoors changes the game with amps a lot. I suspect it's an SPL thing. Wide open spaces reduce the sound pressure level a ton. One thing Princetons are very susceptible to is getting farty with an OD in front. Just a bit too much gain on the OD and it's suddenly nasty.
Is it possible you had that going on? or the Gain on the OD was nigher than normal?

OTOH, I sometimes experience an amp like a Deluxe getting farty on the third set in a club after sounding fantastic the previous set... I've come to the conclusion that it's my ears or it's all in my head...!

Thanks! No, no overdrive on just straight in mostly. I did have a clean boost on for a bit but that made it worse so I just disengaged. I'm gathering from all the great responses that it's just a outdoors thing, with nothing for the sound to bounce off of. Makes sense. I think next time I'll set it up on a chair or something and see how that goes. Thanks again!

 

[mickrhodes]

Welcome!

Sure, I think amps that I know and love sometimes sound epic, and sometimes not. Depends on the day, and that's why we have variety

First thing people are going to ask, including me, is has it ever been serviced? If not, it's a reliability time bomb waiting to happen, and that could be related.

Hi and thanks. Well, strangely, I haven't yet had this amp serviced, which is always my go-to when I get a new (old) amp. This one was completely stock down to the tubes, with never a screw turned. It was a second owner deal, and had been sitting unused for about 6-8 years. I cleaned the tube sockets and de-oxed the pots and turned it on and it was fantastic! I did end up trying a few different preamp tubes that I have sitting around here and ended up changing a couple. Other than that, no service needed it appears. It's quiet and sounds marvelous ... except on a lawn!

 

[mickrhodes]

Welcome!

Sure, I think amps that I know and love sometimes sound epic, and sometimes not. Depends on the day, and that's why we have variety

First thing people are going to ask, including me, is has it ever been serviced? If not, it's a reliability time bomb waiting to happen, and that could be related.

Hi and thanks. Well, strangely, I haven't yet had this amp serviced, which is always my go-to when I get a new (old) amp. This one was completely stock down to the tubes, with never a screw turned. It was a second owner deal, and had been sitting unused for about 6-8 years. I cleaned the tube sockets and de-oxed the pots and turned it on and it was fantastic! I did end up trying a few different preamp tubes that I have sitting around here and ended up changing a couple. Other than that, no service needed it appears. It's quiet and sounds marvelous ... except on a lawn!

 

[mickrhodes]

Could be an undersize extension cord isn't up to the job and you're not getting 120v to the amp. I'd measure the voltage at the point where everything's plugged in & running. And if using a generator - watch out - those outlets are notorious for putting out nothing that resembles A.C. as we know it.

Thanks! Not using a generator but am using a Furman SS6B 6 Plug Surge Protector in between the amp and the wall. Never had any problems with these though.

 

[mickrhodes]

Having done my share of outdoor gigs I would say that any type of roof , fence , hard floor etc for sound to bounce off makes an amp sound better than being totally in an open space.

A lot of what we hear indoors is sound reflecting off walls ,floors and ceilings...the energy is contained within the room, but when outdoors with nothing for it to bounce off, a lot of the sound disappears into the universe without reaching our ears..so we turn the amp up to get more volume and end up with a farty lower end as the power supply struggles.

For indoor gigs I use my little 15 watt 5E3 amp or Princeton amp but for most outdoor gigs I need my 100 watt Seymour Duncan convertible amp to make up for the lack of sound reflection/containment...and that's just for "onstage" sound...the amp is also mic'd and put through the PA for out-front sound.

If your amp was on the driveway and facing the grass then the grass will have soaked up some of the sound...when it was on the grass the nearby driveway could have been bouncing the sound.

I imagine your amp sounded best with the wall behind it , the roof over it and a porch floor under it.

The only times I have had problems with amps due to heat was when the amp was about to fail due to an internal problem ... a resistor couldn't handle the heat stress and eventually let the smoke out or a thermal fuse built into a power transformer failed on a 43C day.

Thanks!

 

[mickrhodes]

Ya, floor, proximity to walls, etc, etc..it al matters
with open back amps. Get a gamma isolation riser
maybe

Thank you!

 

[mickrhodes]

It Is all about the space it is being played in - or on. Open air and on a lawn, probably the worst acoustics for tone. Even a Fender Twin could fart out. But another thing to try if you are not getting the tone you want is to either set the amp on a sturdy box and/or tip it back 30 degrees or so - so that it points toward ears instead of feet.

Will do. Thanks!

 

[schmee]

Thanks! No, no overdrive on just straight in mostly. I did have a clean boost on for a bit but that made it worse so I just disengaged. I'm gathering from all the great responses that it's just a outdoors thing, with nothing for the sound to bounce off of. Makes sense. I think next time I'll set it up on a chair or something and see how that goes. Thanks again!

Yeah, mostly an outdoor thing. However, even a clean boost changes the amp, anything the boosts in front pushes it harder. It seems to be mainly a Princeton thing and I am not sure why. Maybe it's the odd ball phase invertor, although to me that's what make a PR so good compared with other BF styles.. It can be a great thing for some tones, not so great for others.

 

[mickrhodes]

Yeah, mostly an outdoor thing. However, even a clean boost changes the amp, anything the boosts in front pushes it harder. It seems to be mainly a Princeton thing and I am not sure why. Maybe it's the odd ball phase invertor, although to me that's what make a PR so good compared with other BF styles.. It can be a great thing for some tones, not so great for others.

Yeah, I suspect you may be right ... I LOVE this amp, which is weird because for years I've been chasing that perfect blackface PR amp (I've had several!) and just stumbled onto this one locally thinking I'd sell it, make a little dough, and keep searching. But this one surprised me and sounds so much better than any other PR I've owned. It has a little bit of the tweed sag going on, which seems like an accident or some sort of sorcery, because it shown't, but there it is. I think that's what sold me. It's a hybrid sounding amp really: still stiff and twangy when needed, but when I crank the volume knob on my guitar (it loves my Jr. ... p90s in general) it gets all Neil Young on me. Spectacular! But not on grass ... ha!

 

[BobbyZ]

Since its untouched make sure the fuse is the proper rating. Hopefully that'll blow before the power transformer goes up in smoke, that stuff really stinks! If not a new PT is only like 80 bucks, not a big deal. When that happens change the cap can and the rest of electrolytic capacitors too. Because oddly enough weak, flabby and farty is exactly what weak filter caps sound like. . . . . .

 

[mickrhodes]

Since its untouched make sure the fuse is the proper rating. Hopefully that'll blow before the power transformer goes up in smoke, that stuff really stinks! If not a new PT is only like 80 bucks, not a big deal. When that happens change the cap can and the rest of electrolytic capacitors too. Because oddly enough weak, flabby and farty is exactly what weak filter caps sound like. . . . . .

Thanks!

 

[archetype]

Assuming that you have the anp cranked because you're outdoors, have you turned the bass down?

The amp may be perfectly fine, but it's a Princeton Reverb circuit. IIRC the PR circuit increases the amount of bass, not just the volume of bass, as you turn the volume up. Lots of people who play their DR dimed run the bass on 2, 1, even 0. The OD probably makes the bass effect worse.

 

[Phrygian77]

Where did you have the bass set? That circuit doesn't roll off as much low-end as the bigger amps that have an LTP phase inverter.