Blackface Princeton Overhaul

We can get your blackface Princeton Reverb sounding and performing better than it ever has.  As part of the standard maintenance/tune-up service, we clean all pots, jacks & switches, clean & re-tension all tube sockets, test all tubes, tighten all pots, jacks, switches & transformers, and give the entire circuit an exam.  

Shop rates are $100/hour plus parts.  A typical complete blackface overhaul takes about 3 - 4 hours, and tends to average around $400 - $700 for the full treatment, depending on selection of certain components - NOS or new production carbon comp resistors, tube condition, etc.  This estimate allows a new preamp tube or two, but the lower end does not include the price of a full re-tube if needed or desired. 

A full electrolytic recap is required in original amps. This includes the bias cap, cathode bypass caps in the preamp, and replacing the power filters.  The original PR has a 'cap can' housing four separate power filters.  The modern can replacements don’t meet our standards for tone and performance - they sound terrible, are unreliable, and are often way out of spec.  We replace the cap with individual power filters mounted inside the chassis.  We prefer to completely remove the can in order to achieve this in as neat and secure a manner as possible, but the original can may be left in for looks if absolutely necessary.   

As part of the service we dial in the blackface circuit (called blueprinting) - certain key components are replaced if out of spec. 

The original blue ‘molded’ signal caps are some of the best caps ever made, regarding tone, performance, and longevity!  If you are fortunate enough to have these in your PR (about a 50% chance) those stay in!!  If your amp had those caps removed for some unfortunate reason, we can restore the circuit using Jupiter Condenser ‘vintage tone’ series signal capacitors.  These sound remarkably close to the original blues.  

Many Princeton Reverb amps did not have these blue signal caps, but sonically inferior brick red caps.  If this is the case, a Jupiter signal cap upgrade will do wonders to improve the tone while keeping the integrity of the original circuit!

We replace certain resistors that do get noisy over time such as the plate resistors in the preamp, bias board resistor, and power drop resistors in the power supply.

Please keep in mind that CBS era Fender used low quality carbon resistors from mid 1967 - 1969, not the high quality Allen Bradley carbon comp resistors used both before and after this block of time (I suspect they found a huge surplus lot at a very low price).  These resistors are almost always WAY out of spec, tend to be noisy, and break very easily when being removed.  If you have a 1967 - 1969 Fender, you will need to have the majority of these resistors changed in order to ensure your amp will be electronically stable and sound as good as it can for years to come!   This does add both time and parts cost to the service estimate.

If you choose to keep you blackface amp circuit dead stock, we are more than happy to oblige!  However, there are some folks who like to get a little more variety from their blackface amp.  Again we are happy to oblige!  These are minor mods, easily reversible if you ever want to return the amp to stock, original condition.  We WILL NOT drill your blackface amp for a mod, so don’t ask ;)

The popular mods in blackface Princeton Reverb amps include:

Sexy Vibrato:  This mod allows a much slower range on the vibrato speed knob!  Fast stays fast, but the slow end gets considerably slower.  We also make the vibrato effect have a deeper range of intensity.  You get deeper vibrato effect available on the knob.  VERY useful and players love this mod.  If you’re a vibrato fan this is highly recommended.

Adjustable Bias:  This easy mod brings your Princeton to another whole level.  The PR has a fixed bias circuit, but the bias is determined by a single resistor and not adjustable!  This is different from ‘cathode bias’ circuits that bias themselves.  With the tremendous range of current draw in tubes these days, being able to properly set your bias is vital for proper performance!! We often find power tubes running very cold or very hot with the standard Princeton reverb fixed bias resistor.  We add a mini bias pot allowing the bias to be properly adjusted no matter what 6V6 tubes you install.  No drilling!

Standby Switch: Another very useful mod.  We convert the obsolete ground switch (with a grounded three prong power cable installed) to a standby switch!  Very handy and increases tube life.

Power Tube Resistors: Another great feature that extends tube life.  The Princeton Reverb amps were built to be affordable student model amps, and some cost saving practices were implemented as a result.  Resistors were left off of the power tubes.  These resistors act as buffers and improve the operating conditions of the power tubes themselves, making them much more 'comfortable' in their operating conditions.  All larger Fenders are fitted with these resistors.  Minimal change in tone (if any), these resistors are more of a performance enhancer.  

A speaker upgrade is also a BIG step towards better tone.  The original speakers were 'ok' back in the day (keep in mind that Fender did offer a JBL upgrade at additional cost). These original speakers often sound flat and dull now (some 50 years later)!  We use Fat Jimmy Vintage Series speakers in our shop.  They pair incredibly well with vintage Fender amps and really help bring a dull amp to life! Highly recommended!

I do need to point out that a relatively new 'condition' has been popping up quite a bit lately, where the steel chassis is oxidizing enough to interfere with the ground connection between the chassis and bronze grounding plate under the tone pots and input jacks.  I've been needing to remove, polish and clean the plate and chassis and apply contact enhancer before re-installing. This adds about an hour of labor, but it has been literally eliminating hum and other noise issues that may persist after a basic servicing. 
We ARE talking about 50+ year old amps after all!!  

We like to send the player back a blackface amp that blows away the tone & performance of the amp that was sent in!

After an overhaul, your amp will be good to go for a very long time circuit wise.

Current turnaround time is approx 30 business days.

Please reach out if you have any questions!