Vox Super Beatle Distortion/Fuzz Germanium - Build Report

[LucifersTrip]

I finally got around to making the distortion section from the 1966 Vox Super Beatle V1141 into a fuzzbox.
http://www.voxshowroom.com/ct/amp/us/beatle/Beatle-front.jpg

Here's the distortion section pulled from the schematic. Again, very similar to a Fuzz Face:


The original was made with NPN silicon transistors, but I wanted to make mine germanium.

I chose 2 transistors that were near perfect for a germanium Fuzz Face. 2N526 (hfe=80) and 2SB165 (hfe=100).
When placed in a FF, these will get 4.5V on Q2's collector at 8K.

These are PNP, so polarities are all reversed.
Since this is Ge, the 220pf is not needed to "soften" the sound.

In this circuit I got 4.5V with Q2 collector R at 2.5V. I adjusted Q2's emitter R until it sounded best (1.8K). As with the FF, I had to raise the 82ohm till it sounded just right..170ohm, then re-adjusted the collector R to 4.5V.

It's an excellent fuzz with not as much thickness or mushiness as the Fuzz Face, probably due to the smaller input cap...

It sounds decent from ~ 3.5V (5.7K) to 4.5V (best, 4.7K*) to 5.5V (3.7K), so I used a 3.7K cutoff with a 2K pot.

*exactly as original schematic (by accident), but adjusted the 82ohm and 1K to get there.

Here's my final version.

[R.G.]

The Thomas Vox Super Beatle is IMHO a vastly underrated amplifier. The sound is good, and there's a LOT of it.

The distortion is a clear descendant of the Fuzz Face, and almost duplicates the Vox Distortion Booster.

There are so many near misses in the Thomas Vox stuff that almost made them the standard instead of Marshall. All it takes is one fatal flaw. 

[LucifersTrip]

The Thomas Vox Super Beatle is IMHO a vastly underrated amplifier. The sound is good, and there's a LOT of it.

The distortion is a clear descendant of the Fuzz Face

yes...though, were they both actually introduced in 1966?

and almost duplicates the Vox Distortion Booster.

Are you referring to this one? I was planning that shortly..
http://fuzzcentral.ssguitar.com/schematics/deluxedistortionbooster.gif

There are so many near misses in the Thomas Vox stuff that almost made them the standard instead of Marshall. All it takes is one fatal flaw.  icon_wink

horseshoes & hand grenades...

[Electric Warrior]

The Thomas Vox Super Beatle is IMHO a vastly underrated amplifier. The sound is good, and there's a LOT of it.

The distortion is a clear descendant of the Fuzz Face

yes...though, were they both actually introduced in 1966?

and almost duplicates the Vox Distortion Booster.

Are you referring to this one? I was planning that shortly..
http://fuzzcentral.ssguitar.com/schematics/deluxedistortionbooster.gif

From what I heard the Distortion Booster (v816 would be the right one) was introduced in late '65. It might have been the first fuzz based on that topology, but we can't say for sure. I know the Sola Sound Tone Bender "MK1.5" was available by February '66. Can't be certain when it was introduced, though.
The Fuzz Face was introduced in fall of '66 and was obviously based on the "MK1.5". The circuits are nearly identical.

[Mark Hammer]

Do keep in mind that the circuit in the amp was a circuit in an amp.  In other words, it was not simply receiving a normal guitar-level signal such as a pedal might.

Naturally, the sound will be somewhat different from a Fuzz Face because of that.

[R.G.]

Actually, the distortion in the 1141 was in front of the amp. It was stuck in front of the first preamp by a relay. It was after the 68K mixing resistors, and that may have contributed some effective lowering of gain as we now do with resistors in front of a Fuzz Face. This version ran from nominally +10V, and was closest to the operation of the external distortion booster.

The 1143*6 model put a slightly modified version after the first preamp, and used both N and P channel JFET switching. It ran from a lower supply voltage; but it was fed from a 100K/100K divider, indicating that they liked the 50K source impedance as well as lowering the input drive.

The input preamps on the Thomas Vox stuff didn't have much gain. The signal level after the incoming preamp was kept quite small for all of the signal stages. So the distortion boosters were running from very close to guitar level even in the 11x3*6 models.

[Mark Hammer]

As always, I yield, every so begrudgingly, to the facts.

(Stooopid facts...grumble grumble) 

[cthulhudarren]

Intriguing!  Personally I prefer the UK SS amps that the Beatles used.

[R.G.]

Intriguing!  Personally I prefer the UK SS amps that the Beatles used.

A lot of people do. However, there are many points where the Supreme/Conqueror/Defiant are very similar indeed to the Thomas Vox Beatle.
- both have power amps using a driver transformer and a stacked output stage
- the tremolo on both is nearly part-for-part the same
- both keep signal levels quite low up to the mixer before the power amp
- the S/C/D power amps use no feedback, the Thomas Beatle uses a little

Frankly, I suspect most of the perceived difference is in the speakers, ease of fixing the UK versions (techs will talk down the Thomas stuff any chance the get 'cause they're hard to work on), and perceived snob appeal of Vox made in the UK.

[LucifersTrip]

for reference, here's the full v1141 schematic:

http://elektrotanya.com/PREVIEWS/63463243/23432455/power_amps_vegyes/vox_super_beatle_v1141.pdf_1.png

[LucifersTrip]

That's pretty funny,...I just realized now after recently finishing one that the Colorsound One Knob Fuzz is a direct copy of the Vox Super Beatle distortion section.

 

The only difference is the 4.7K in the Super Beatle as apposed to a 2.2K in the One Knob, which would make sense since Q2's collector voltage is 4.5v & 7v*, respectively

* http://www.diystompboxes.com/smfforum/index.php?topic=51351.5;wap2

[DavenPaget]

That's pretty funny,...I just realized now after recently finishing one that the Colorsound One Knob Fuzz is a direct copy of the Vox Super Beatle distortion section.

 

The only difference is the 4.7K in the Super Beatle as apposed to a 2.2K in the One Knob, which would make sense since Q2's collector voltage is 4.5v & 7v*, respectively

* http://www.diystompboxes.com/smfforum/index.php?topic=51351.5;wap2

It's 2.2K in the super beatle and 4.7k in the one knob ,
yeah , they didn't even bother to change anything else .

[LucifersTrip]

It's 2.2K in the super beatle and 4.7k in the one knob

i think it's the other way around...

[DavenPaget]

It's 2.2K in the super beatle and 4.7k in the one knob

i think it's the other way around...

OOPS . Probably got it wrong because i am drunk 

[LucifersTrip]

It's 2.2K in the super beatle and 4.7k in the one knob

i think it's the other way around...

OOPS . Probably got it wrong because i am drunk 

excellent!!! now pull out a good fuzz and wake the neighbors!

[zombiwoof]

The Thomas Vox Super Beatle is IMHO a vastly underrated amplifier. The sound is good, and there's a LOT of it.

The distortion is a clear descendant of the Fuzz Face

yes...though, were they both actually introduced in 1966?

and almost duplicates the Vox Distortion Booster.

Are you referring to this one? I was planning that shortly..
http://fuzzcentral.ssguitar.com/schematics/deluxedistortionbooster.gif

From what I heard the Distortion Booster (v816 would be the right one) was introduced in late '65. It might have been the first fuzz based on that topology, but we can't say for sure. I know the Sola Sound Tone Bender "MK1.5" was available by February '66. Can't be certain when it was introduced, though.
The Fuzz Face was introduced in fall of '66 and was obviously based on the "MK1.5". The circuits are nearly identical.

Actually, as I understand it the first fuzz was the Maestro FZ-1 ("Satisfaction" fuzz).  It was made to duplicate the sound of a channel on a board in a Nashville (?) studio that was going bad, a guitar player plugged into it and got a great distorted sound that was used on a record.  Then every guitar player there wanted "that sound", but they eventually got the board fixed and someone had a pedal made to emulate that broken channel sound.  The accurate story is on the net somewhere, but it's an interesting read.

Al