Old Fender amps and modern guitars - oil and water?

[Che_Guitarra]

I've got a Jackson Dinky guitar that just doesn't gel with my DIY amps (based on early 60s Fender circuits). In my experience, this is a pretty typical outcome when you plug a superstrat into any early Fender. Notes bloom like crazy, dynamic range is non existent, and it sounds like the treble has been rolled off the amp.

Of course, Leo Fender didn't have a crystal ball to anticipate the direction of guitar specs, but i'm wondering what the weak point in the amp design is that causes this flubby response with hot pickups?  Particularly in regard to tweed, brown and blackface era combo sized amps.  Are modern pickups too efficient for older preamp circuits to cope with? Is it the raised pickup impedance? Is it their EQ voicing? Or is it sonic byproduct of speaker designs of the era?  Where is the bottleneck in the system causing this shabby response?

I'm too much of an electronics greenwood to be able to explain it away, but i'm very curious of this interaction.  After all, modern superstrats and early Marshalls gel together without much fuss, and early Marshall topology is based on tweed bassmans if i'm not mistaken.  But superstrats and early Fenders are like oil and water? 

Hmmm...

 

[critterkllr]

I rarely have an issue with a modern guitar and a vintage Fender amp. Perhaps you're expecting a different sound than what a Fender does well? The only weak point I find in some vintage Fenders are some Tweeds get cranky with humbuckers. Too hot for some. If this is the case for you, try different values on the input resistor. Since it's a clone, the mod shouldn't be an issue.

Some Fender Tweeds prefer to be cranked up high while using the guitar's volume pot to control the overall volume.

You can't really lump Tweed, Brownface and Blackface amps together. Even the models within the different generations are very different. They may be similar circuits, but the transformer specs, speaker sizes and quantity make big differences.

 

[Che_Guitarra]

I shouldn't lump them all together.  I'm more specifically referring to high-output humbucker-equipped superstrats plugged into low-watt combos such as Princetons and Deluxes.  I'll refine my observations to 6V6-based pre-'62 Fender circuits.  I've tried a whole bunch over the years and it seems the outcome is the same with any Jackson, Ibanez, ESP, or similar styled guitar.  Typically, they don't do each other great justice.

I myself use a DIY 6G2 head as my primary amp and it's pretty much the perfect partner with all the guitars I own... except the JB-equipped Jackson, but no amp can be everything.  Just curious where in the path it falls flat?

 

[critterkllr]

Yeah, this is a common opinion on early Deluxes and Princetons. I'm not a fan of higher output pickups with these amps either. What tube do you have in V1? A 12AY7 or 12AU7 is going to help with headroom if you currently have a 12AX7. I've also found the breakup to be smoother overall even with a clean boost in front.

Otherwise, google "5E3 humbucker mod" for plenty of different suggestions. You could play with different cathode bypass caps. Marshall used .68 uf and most Fenders were around 25uf. You can try some different bias resistor values. If you go with a mod like these, I'd recommend a switch to go to stock and humbucker mode.

The speaker is also very important IMO. For hotter pickups through a Tweed Deluxe, I really like a Celestion blue. It's hard to beat a vintage Jensen in an old Fender for everything else. They do get "farty" when slammed.

 

[kato]

Have you tried turning down the guitar's volume? That's gotta be worth a try.

 

[JohnRoberts]

I recall a few decades ago in connection with doing research to design an active direct box, I asked the head of guitar engineering for an output voltage spec for his hottest guitar pickups (he wound his own). He gave me one of those tilted head puppy-dog looks. "what do you mean voltage?".  So my next stop was to talk with the design engineers designing guitar amps, as surely they would understand voltage. They chewed my ear off about how the so and so pickup makers (and active built into guitar preamps) were in an arms race to get louder and louder.

I can't peg dates to this but suspect this was partially driven by the wider availability of compact rare earth magnets for higher output pickup coils.

I punted without ever getting a definitive number for max output voltage, but ASSumed that 99.9% of active preamps used 9V batteries , so that 9V supply would provide a rough max peak voltage swing target. 

I hope this helps a little, but I can imagine too much gain in the first stage of an older amp that could saturate and not deliver a clean sound under all conditions, with hot modern guitar.

YMMV

JR

 

[lassoharp]

Is it their EQ voicing?

I'm not sure if it should be considered a weak point in design - just a choice in voicing, arguably to cut mud a give a nice crisp clean tone.  The standard Fender tone control section creates a large dip in the midrange around 1K which stays there during boosting of top and bottom, and even on the amps with midrange controls.  You can easily modify the tone control values to get a different curve and remove this mid dip, at the expense of the the top and bottom curves which will change. You will get a tad more gain overall too.

I think the modern pickups are what they are, and perhaps hotter in the mids and upper mids which makes the bottom sound thin.  Try plugging one of your Fenders into a Marshall cab and see if you like that.  Marshall gets a huge chunk of their bottom response from the cab itself.  If you plug an older JCM 800 or Plexi head into a Fender cab it will sound thinner and raspier with any vintage of guitar.