Blackface Amps

Are these the most popular amps of all time? Probably anyone has even a casual interest in amps would not have heard of the Fender Blackface line. Starting in 1964 and in constant production through the 70's and up into the 80's when the handwired amp was finally abandoned for the lure of the robotic assembly line versions.

While I tend to try to give a little background on all the amps I build, there is so much written about the Blackface amps and so many other amps are always compared back to them, that for once I will cut it short and just so you an example or two.

I have built many of the different models of the Blackface line. I have also used them as springboards for amps somebody wanted that was never actually built by Fender. I have owned several, still do. I have restored them, modded them or just tuned them up for folks.

Perhaps the Deluxe Reverb is the best place to start. The same basic circuit used in the Deluxe with changes for other tube types are found on many other Blackface models. Put 2 6L6 tubes in this and add four 10" speakers and you get a Super Reverb. Add two more 6l6 tubes and two 12" speakers and you have a Twin Reverb. Or put it in a cabinet with a 15" speaker and you get a Vibroverb. So much of the basic circuit is common across the line. Its almost like they were designed to make a similar sound and take advantage of component sharing to make money. What a concept.

There is no denying however that they sound fantastic. Sweet, sparkly clean tones. Huge deep reverb and nice tremolo(vibrato) as well. Push them hard and the power tubes breakup in a unique way to the Blackface line. By this time, Fender had pushed the voltages in the Deluxe Reverb to over 475 volts and gotten 22 watts out of them. Compare that to 350-380 volts for a Tweed Deluxe and about 15 watts. More voltage gives them more clean headroom- also more trips to the tube store for new power tubes.

Here are the 6 preamp tubes of the deluxe amp. Also you can see the small reverb transformer between the tubes and the classic "doghouse" cover over the power circuit capacitors right behind the preamp tubes. There are 9 total tubes in a Deluxe reverb. Gets expensive to retube one of these.

 

 

 

 

 

The front panel on the bench showing the reproduction chassis and faceplate I like to use. You can see the tone controls, reverb and tremolo controls. You can also see my old radio shack soldering station that has been layed to rest- it died a noble death in the line of duty.

 

 

 

 

Here is the other end of the chassis. You can see the normal channel inputs and the Vibrato channel inputs. Since the normal channel on the Deluxe (and the other Blackface amps of the same ilk) have a normal channel that mimics the vibrato but with no reverb or tremolo, it does not get used much. I altered the normal channel in this amp to be more like a Tweed Deluxe and I dug deep into my stash of vintage components and installed the same Astron capacitors the tweed line used. They are those big yellow guys on the left side. I also used a famous "Blue Mallory" capacitor in there as well. Is there an audible difference? I honestly could not tell but since I originally built this amp for my own personal use, I decided to try them and see.

You can also see the input and output jacks for the foot pedal switches that control the reverb and vibrato effects along the back wall of the chassis.

 

One more picture of the insides. Lots of wires but still beautiful in a geeky amp guy kind of way. Its important to keep lead dress correct to avoid noise issues. This particular amp was mated with a 1966 12" Fender CTS alnico speaker and it sounded wonderful. It was sold ($1300) after I built my Brownface Vibroverb - that is a screaming good deal on a Vintage correct handwired amp. I will not make one again for that price, but pretty close.

 

 

 

 

 

 

This amp is a custom variation of a Fender Bassman circuit but only the normal channel and adding a full treble, mid and bass tonestack and a Master volume. In addition, I included a switch to change the voicing from a Fender style to a more Mashall Style preamp. Then it was built into a Princeton Reverb chassis and I got a custom faceplate with all the controls named properly.

 

 

 

I do not usually take progress shots of building an amp, but I just happen to have taken some of this one. This picture shows the heater wiring having just been put in. The power and standby switch, speaker jacks and output transformer connections made.

 

 

 

Here are the power tube sockets wired with the heater circuit and the leads to the output transformer twisted together and in place. Since this was a Princeton chassis and the Bassman power transformer is huge by comparison, I have to do a lot of metalwork to open the mounting hole up to fit it into its new home.

 

 

 

Another angle on the heater wire circuit

 

 

 

 

Shot of the back of the chassis. You can see the 3 external bias points I installed so that bias can be done with the chassis in the cabinet. The bias pot can be seen above them.

 

 

 

Here is the eyelet board being populated prior to mounting inside the amp. I designed the circuit myself by modifing the Fender circuit to the customers specs and design requirement. Then I layed it out and built the board by hand. Old worldcraftmanship still lives. All in all this was a very cramped build. The chassis size was really too cramped for the Bassman circuit and all the power supply capacitors it requires. I spent a lot of time debugging this amp and being clever with placing all the parts in the chassis. Oh well, it was a learning experience- I learned not to to one like this again.