Blackface Bassman AB165 Overhaul

We can get your blackface Bassman 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, bias power tubes, tighten all pots, jacks, switches & transformers, and give the entire circuit an exam. 

A full electrolytic recap is required in original amps. 

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!  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.

Shop rates are $100/hour plus parts.  A typical complete silverface overhaul takes about 4 hours, and tends to average around $500-$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 does not include the price of a full re-tube if needed or desired. 

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 ‘standard’ blackface Bassman AB165 amps include:

AB165 to AA864 Conversion:  This is the Bassman version of the ‘blackface mod’!  The AB165 Bassman has its own wacky phase inverter, feedback loop, bias circuit and output section.  CBS took over Fender on Jan 5th, 1965, so this circuit from Jan 1965 (AB ‘1/65) may very well be a post Leo CBS design! 

This mod converts the AB165 to ‘classic’ blackface specs.  This is the same phase inverter, bias and output circuit found in the AA864 Bassman, AB763 Super Reverb, Twin Reverb, Deluxe Reverb, etc.  It makes a HUGE improvement in tone and performance, giving a much richer sound that is much more musical, with much more clean sustain and a more ‘open’ feel.

Tweed Preamp in the Bass Channel:  We convert the first (normal) ch to a tweed preamp!  The tweed preamp mod in the normal channel is an excellent option and a great voicing.   Thicker tone with more midrange emphasis and lends itself towards earlier breakup.  It gives you another whole tone option at your fingertips, and still full-on classic Fender!   Sounds great for both guitar AND bass!!

If you do the AA864 conversion and the Tweed Preamp conversion in the bass ch, we can keep ALL of the blue molded caps in place!!  We just trade the ones from the phase inverter with the ones from the bass ch tone stack – it’s really almost too good to be true!  And the end result is nothing short of magical…

AA165 Bassman:  The AA165 circuit is actually extremely rare to come across.  There are a LOT of AB165 circuits with the AA165 tube charts on the cab… you (or I) need to look at the circuit itself to determine if it’s a real AA165.  If you do have a real AA165, it already has the ‘classic’ AA864/AB763 phase inverter, bias circuit and output stage!  The only mod we might recommend would be the Tweed Preamp for the bass ch to add another vintage Fender flavor to the amp. 

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

I do need to point out that a relatively new 'condition' has been popping up quite a bit lately, where the steel chassis are 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!!  

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 at all!