Shocking Side-by-Side Test of Fender Amps

[rintincop]

I did a long and careful side by side today at Guitar Center with three re-issue Fenders:

• The Princeton 65 Blackface LTD in red wine with a 12" Jensen and 15 watts (35 lbs)
• The Princeton Custom '68 with its stock 10" Celestion and 15 watts (34 lbs)
• The Pro Jr. IV tweed with its stock 10" Jensen and 15 watts (15 lbs)

I highly recommend you do the same! Do not go by reputation.

The '65 was a distant 3rd place for jazz, it couldn't keep up with the push of my playing dynamics through its 12" speaker , the tone was sort of thin and sounded as if too many "mids" were missing. I had the store staff assure me it was operating normally.

The Pro Jr. was the warmest, nice clear and present mids, but the '68 was bigger sounding with a classic silverface Fender Reverb-ish. Think Twin silverface.

The '68 and the Pro Jr. both had better push in terms of translating dynamics through their speaker behavior. They had "push". I used my P90 pickup Epi Casino guitar. I had another guitarist with me and he came to the same exact conclusions.

I have owned blackface Fender amps: a 60's Super Reverb, a 60's Deluxe Reverb, and actual 1968 silverface Princeton Reverb and a blackface 60's Vibrolux Reverb. I have used and heard many vintage silverface Twin Reverbs.

I've been around, here was my rig in 1970:

[KirkP]

Most of the tonal difference between the two Princetons is undoubtedly due to speakers.

Fender says the ‘65 Limited has a Jensen C12Q. Here’s Jensen’s published frequency response. Note the midrange dip and abrupt treble boost.



Fender says the ‘68 has a Celestion Ten 30. It’s obviously much smoother.

I’m not sure how well frequency response charts translate to desirable tone for electric guitar, but my engineering instinct is to choose a speaker with as smooth a response as I can get, then use tone controls or pedals to dial in. If a speaker’s response has an abrupt jump somewhere it can be pretty much impossible to dial it out. This approach has worked well for my last couple of speaker purchases.

[rNeil]

I've done the calculation and construction of straight forward through complex multi box hi fi speaker, sealed and ported, subs too.

Given a choice between those curves for a guitar, no way I'd think of the first one. Right through the heart of the frequencies we want, you have that wide and fairly deep depression.

I don't understand something here.

Neil

Sent from my SM-G930V using Tapatalk

[rintincop]

Jensen P12Q speaker, according to G.C.'s website, not C12Q in the Princeton LTD wine red at G.C. Perhaps no difference really. Anyways, both have the mid range scoop and the big spike thereafter.

The '68 also has a bass boost in the circuitry, one reason they call it the custom. It uses a 10" Celestion.

P12Q | Jensen Loudspeakers

[cosmic gumbo]

What was shocking about the comparison? Did you expect that 12" alnico Jensen to sound the best? I wonder how a new stock 65 Princeton 15w with the 10" Jensen would have compared? That 68 Custom is only 12w.

[KirkP]

Looks like P12Q is basically the same speaker with alnico instead of ceramic. That response might work fine for rock and country, but probably not for me.





One 12” speaker I’ve gotten a lot of use of is a Jensen Tornado. But I must turn the bass knob low to tame that bump around 150 Hz.



I also like the Eminence Red White and Blues. There’s a bump in the treble, but it never seemed too bright. I think that’s because the treble quickly drops off-axis.



None of those amps have 8” speakers, but here’s the Eminence Beta 8A for reference. I got one this week for a small ported amp and am pleased with its smooth response. It’s not intended for an open back cabinet though.

[christianm77]

When I did a side by side of the 65 and the 68, I actually thought I preferred the 68 until i tried the 65 again about half an hour later. I bought it.

That was a stock unit with a 10” Jensen I wasn’t crazy about and replaced.

The 68 has less headroom. Even the 65 didn’t have enough when I started gigging it. Then I replaced the speaker with something more efficient and it’s just great, keeps up with fusion drummers no sweat.

Biggest headache with it - noisy reverb circuit and still too scooped even after the speaker swap.

I don’t think trying an amp in a shop tells you everything unfortunately.

I knew another guy who plays a 68 and it sounds lovely with a vintage 125. He has more of a Bill Frisell tone.

[Longways to Go]

Hey Christianm77,

I had a '65 PRRI a couple of years ago and when I first took it home I had noise problems with the reverb too. Turns out the RCA plugs on the reverb tank weren't making very good contact. I twisted them around a bit and voila -- problem solved !!! Might be worth a shot

[Little Jay]

When I did a side by side of the 65 and the 68, I actually thought I preferred the 68 until i tried the 65 again about half an hour later. I bought it.

That was a stock unit with a 10” Jensen I wasn’t crazy about and replaced.

The 68 has less headroom. Even the 65 didn’t have enough when I started gigging it. Then I replaced the speaker with something more efficient and it’s just great, keeps up with fusion drummers no sweat.

Biggest headache with it - noisy reverb circuit and still too scooped even after the speaker swap.

I don’t think trying an amp in a shop tells you everything unfortunately.

I knew another guy who plays a 68 and it sounds lovely with a vintage 125. He has more of a Bill Frisell tone.

Princeton Reverbs have no mid pots, but a resistor of 6.8k. This acts like mid pot fixed on 2/3rds (Fender uses 10k for their mid pots in Black/Silverfaces), but that’s actually still pretty scooped. Replace the resistor with 10, 15, 20 or even 25k for les mid scoop (a £0.75 mod if you can do it yourself). Or even better, replace it with a 25k pot (that you can put in the back, or sometimes one of the inputs is sacrificed). Makes it a hell of a lot more versatile!

Noisy reverb in what way? You have noises like hiss and hum?

[John A.]

I don't find that result shocking -- the PR is more scooped sounding because of its tone stack (BF with a resistor instead of a pot, as Little Jay says). The 68 custom and the Blues/Pro Jr have tone stacks that are based more on Tweed amps and are more mid range-y. If you turn down the bass and treble knobs on a PR, this has the effect of reducing the scooped character and boosting the mids, but it will still have a brighter sound than a BJ/PJ or a 68 Custom. I have a SF PR, with a Jensen C10Q. With the bass and treble turned down, it's not scooped sounding and has a very full, warm sound, with a touch of classic Fender shimmer. It took me a while to figure that out.

I think some of what you're hearing may also be the sound of a 12 vs a 10. 12's tend to be more directional, so when you're closer to them they tend to sound more ice-picky than 10s; their "sweet spot" tends to be further away from the amp.

But ultimately taste is taste. If you like the PJ more, so be it. When I was amp shopping, I played a BJ, a PRRI, and a SF PR side by side. All sounded good, but slightly different from each other. I can't remember whether I've ever tried a PJ, but I've played through a bunch of BJ's on gigs and at jams. I think they're great. I somewhat prefer the tone of a PR, and think the vintage (non-PCB) construction is better, but would be perfectly happy with any of the above.

John

[christianm77]

Princeton Reverbs have no mid pots, but a resistor of 6.8k. This acts like mid pot fixed on 2/3rds (Fender uses 10k for their mid pots in Black/Silverfaces), but that’s actually still pretty scooped. Replace the resistor with 10, 15, 20 or even 25k for les mid scoop (a £0.75 mod if you can do it yourself). Or even better, replace it with a 25k pot (that you can put in the back, or sometimes one of the inputs is sacrificed). Makes it a hell of a lot more versatile!

Noisy reverb in what way? You have noises like hiss and hum?

It serves as a good reminder not to use reverb :-)

[KirkP]

Princeton Reverbs have no mid pots, but a resistor of 6.8k. This acts like mid pot fixed on 2/3rds (Fender uses 10k for their mid pots in Black/Silverfaces), but that’s actually still pretty scooped. Replace the resistor with 10, 15, 20 or even 25k for les mid scoop (a £0.75 mod if you can do it yourself). Or even better, replace it with a 25k pot (that you can put in the back, or sometimes one of the inputs is sacrificed). Makes it a hell of a lot more versatile!

Bingo!
Here's a tutorial on the classic Fender (and Marshall) tone stack.
GM Arts - Guitar Amplifiers
It includes examples showing how each control knob affects the frequency response when the other two controls are set to 5. I've extracted them below.

Mid control - There's always a mid scoop (or notch) around 500-600 Hz when the treble and bass are set to 5! That scoop is centered on notes on the top E string.


Treble control - It does what it should, but with the mid control at 5 you always have a mid scoop.


Bass control - Again, it does what it should but look at the mids.


After seeing these plots and running a few of my own, I decided on the following process for Fender tone stacks:
1-Start with T-min, M-max, B-min
2-Adjust the volume knob to desired level
3-Turn the bass knob up until the bass and mids seem about the same level. Usually I end up around 2 or 3.
4-Turn the treble knob up until highs seem on the same level as mids and bass. This can vary greatly depending on acoustics of the room.
5-At this point I might consider reducing the mids knob a couple of notches. With the treble and bass controls near zero, the mid knob begins to act more like a volume control, so if I dial back the mids I must bring up the volume control to compensate.
On my Twin Reverb this resulted in a gut-punching tone. (Unfortunately, it's now in a closet waiting for me to diagnose a fault.)

[christianm77]

I think 2 band EQ would be OK then if I changed that resistor from that info

[KirkP]

You can run your own calculations on the Tone Stack Calculator (for Windows):
TSC

Here are some I did just now, setting the mid control to 10 for each run and making very small adjustments to treble and bass:

T & B set to zero:


T & B set for the flattest response possible:


T & B set to 1:


T & B set to 2:


If you've never tried settings like these, you might be surprised. If you don't have a mid knob you can only get there by changing out the mid resister for a higher value (10K or higher).
With a tweak to capacitor values you could also move the center of the mid scoop to a different frequency.

[Longways to Go]

I gave up on my PRRI because of the 2 knob EQ. Got a Rivera Venus 3 instead and haven't looked back. It has a super flexible EQ, but not near as good a reverb. But I'm much happier with this amp.

Half of the charm of the PRRI is the luscious long tank reverb + great tremolo. A touch of each gives that amp an amazing dimensional sound. They have a super rich sound, but there is a piece missing for me. I have a rock & roll buddy who is crazy over his. He now owns 3 !! A 65', a 68' and one with a 12" speaker!!. Crazy but true.

[KirkP]

It serves as a good reminder not to use reverb :-)

I love a touch of spring reverb, but most are too bright. I’d like a treble control for the reverb channel. That might be achievable without a mod simply by connecting a small project box with an R/C circuit between the spring tank and the amp.
[Edit- With a couple of RCA-phono adapters I could put a cheap 7-band EQ pedal in series with the reverb return. If I do I’ll report back.]
I have one amp with a reverb dwell control. I really like that too, but it does require a mod.

[christianm77]

I love a touch of spring reverb, but most are too bright. I’d like a treble control for the reverb channel. That might be achievable without a mod simply by connecting a small project box with an R/C circuit between the spring tank and the amp.
I have one amp with a reverb dwell control. I really like that too, but it does require a mod.

Yeah a little reverb is sometimes a necessity (I'm trying to get used to having no reverb as my bassline) - the PRRI has FAR TOO MUCH of it for me. Another mod, perhaps.

[David B]

Hi Christian,

You might like to take a look at the valve sets from Watford Valves. He offers a range which can reduce the gain, give a little more headroom and tame reverb. I have the -30% gain set in my '65 Deluxe Reverb.
See: Watford Valves product search :: princeton

Also a regular application of WD40 contact cleaner to reverb tank leads, valve sockets and inputs can help with noise.

[John A.]

I find that people apply words like "scooped" "warm" "shimmering" etc. to sounds differently. I find it a lot easier to get what people are talking about via a reference to something specific. Anyway, as a point of reference, here's a quick and dirty bit of noodling through my '78 Princeton Reverb with a Jensen C10Q. Settings here are:

V: 2.5 (it's hard to tell from the recording , but it's pretty loud)
B: 2
T: 2
R: 2.5

On the guitar, the volume is wide open, and the tone control is turned down to about 6.

To me, "scooped" means "a lot of bass, a lot of treble, not much mids." I don't hear this as scooped. I hear it as somewhere between even and warm, with a fair amount of mids and presence (upper mids). The high E is kind of thin/bright, but this is guitar is strung with round wounds, 10-46, and that's mainly were that thinness comes from. I hear the high end has having a shimmering quality. The reverb strikes me as fairly subtle (but if I turn it up even a little more it's pretty surf-y). How do you guys hear this, not the recording or playing quality (both of which are casual, to put it mildly) but the in terms of the vocabulary like tubby/scooped/warm/thin?

John

[KirkP]

I find that people apply words like "scooped" "warm" "shimmering" etc. to sounds differently. I find it a lot easier to get what people are talking about via a reference to something specific...

I use adjectives like warm and bright for a general impression, but I don’t find words adequate to describe tone. The descriptions of tone in guitar and amp reviews are pretty much useless to me. After all, there about six octaves between low E on a guitar and the highest frequency most guitar speakers can produce, and another two or more octaves of human hearing. The frequency response of your end-to-end signal can have lots of peaks, valleys, spikes, and notches between those extremes. There are too many possible variations for adjectives to describe.
Generally, I can get along with a wide variety of frequency responses from bright to dark as long as things vary smoothly from one end to the other. I generally dislike notches or spikes in frequency response no matter where they occur in the spectrum.

[Little Jay]

Yeah a little reverb is sometimes a necessity (I'm trying to get used to having no reverb as my bassline) - the PRRI has FAR TOO MUCH of it for me. Another mod, perhaps.

Yes another mod! ;-)

Change the 1M yo ground resistor in front of the reverb driver tube to 500k! Less reverb in a good way.....

You can also experiment with the 1M resistor and 10pF bypass cap for darker sounds.



Trouble is, while these mods cost you only £2 in parts, they take time. And tech labour time is costly..... So it’s only cost efficient if you can do it yourself... but it’s lots of fun! I changed my Fender Blues Deluxe that way into a boutique sounding amp! (I get heads turned in awe from other guitartists when they hear that amp - and here’s me thinking it’s my playing..... ;-)

But please know how to avoid a 500 volts DC shock before you open up an amp!

[Little Jay]

Oh and a well meant advise from David B on the contact spray, but those can leave a sticky goo-y substance behind, especially WD40 (which is a ‘multi spray’), better use a dedicated spray for electrical contacts and use it sparsely. But if you just unplug and plug the RCA-connectors a couple of times and turn them a bit you’ll clean the contacts just the same!

[KirkP]

Oh and a well meant advise from David B on the contact spray, but those can leave a sticky goo-y substance behind, especially WD40 (which is a ‘multi spray’), better use a dedicated spray for electrical contacts and use it sparsely. But if you just unplug and plug the RCA-connectors a couple of times and turn them a bit you’ll clean the contacts just the same!

David B was referring to the WD40 Specialist Contact Cleaner. I don’t know how it compares to other contact cleaners, but it’s not plain old WD40.

[KirkP]

Change the 1M yo ground resistor in front of the reverb driver tube to 500k! Less reverb in a good way.....

Replace that resistor with a pot and you have a dwell control. But replacing the resister with a lower value is a great suggestion if you know are willing to experiment and won’t need to adjust it later.
Then at a tone control pot to the output of the reverb to dial out the surf and I’d be happy. Or if you don’t mind a fixed tone setting, add resister and capacitor to the reverb output.

[Little Jay]

David B was referring to the WD40 Specialist Contact Cleaner. I don’t know how it compares to other contact cleaners, but it’s not plain old

Ah didn’t know that! I normally stay away from anything that says WD40... :-)

But good to know they have a dedicated spray for electronics!