Gibson maestro fuzz tone issues

[olddawg]

If they are germanium transistors you should have .3v across a forward biased emitter/base junction. If you don’t the transistor isn’t conducting.

[J M Fahey]

If they are germanium transistors you should have .3v across a forward biased emitter/base junction. If you don’t the transistor isn’t conducting.

That´s the textbook case but as you see the transistors are conducting, even if apparently no or wildly insufficient bias

* Q1 is passing 110uA (which is fine) even with meager 100mV bias

* Q2 is passing 666uA even with meager 60 mV bias.

* Q3 is passing 170uA .
It shows 2 "impossible" readings:
a) impossible 500mV bias
b) which we do not know where it comes from, since there is no resistor to feed base current from -2.9V rail to Q3 base ... which to boot is grounded through a 10k resistor

The explanation for all these anomalies is that germanium transistors are lossier than an oxygen tank with exhaust tube "covered" with a handkerchief.

Imagine invisible internal resistors connecting Collector to Base and you will be near enough.

OK, now that we solved the DC problem, let´s test the AC/functional side.

The howl means the Fuzz pedal is healthy and has (lots of) gain, let´s tame that.

Please do the tests suggested in post #16 and post results

[olddawg]

That´s the textbook case but as you see the transistors are conducting, even if apparently no or wildly insufficient bias

* Q1 is passing 110uA (which is fine) even with meager 100mV bias

* Q2 is passing 666uA even with meager 60 mV bias.

* Q3 is passing 170uA .
It shows 2 "impossible" readings:
a) impossible 500mV bias
b) which we do not know where it comes from, since there is no resistor to feed base current from -2.9V rail to Q3 base ... which to boot is grounded through a 10k resistor

The explanation for all these anomalies is that germanium transistors are lossier than an oxygen tank with exhaust tube "covered" with a handkerchief.

Imagine invisible internal resistors connecting Collector to Base and you will be near enough.

OK, now that we solved the DC problem, let´s test the AC/functional side.

The howl means the Fuzz pedal is healthy and has (lots of) gain, let´s tame that.

Please do the tests suggested in post #16 and post results

Yeah.. I guess.. there is always some alchemy going on with old germanium transistors. Don’t see them much except it old fuzzes, Rangemasters, and the occasional vintage car radio restoration. I had a Rangemaster clone at one time that was usable.. but even as a kid in the early 70s.. these legendary boxes, fuzz faces, etc, never seemed to live up to their reputations.

[J M Fahey]

I had a Rangemaster clone at one time that was usable.. but even as a kid in the early 70s.. these legendary boxes, fuzz faces, etc, never seemed to live up to their reputations.

Oh,if you use them on their own, they are cheesy.

"brushing shoulders" fames from being used by KILLER very creative Guitar players, and for the exclusive use of driving a Plexi or AC30 balls to the wall slamming tjem with 20X the signal they expected.
What you hear is pure power tube distortion, driven by a guitar *boosted* 20 to 40 dB preamps ... which sometimes also distorted on their own, but that´s not the point.

A few famous players used fuzz or raw distortion pedals (think MXR Dist+ or Big Muff and the odd Fuzz) into clean amplifiers and sound was ghastly ... think Rolling Stones, some American Rock bands in the late 60´s or the buzzy "Jerry Garcia" sound.

As a free sample, here´s a record from our early Argentine Rock music, 1969.
They are using all the "proper" stuff: Gibson 335 into a 100W Plexi and 2 x 4x12" , probably Greenbacks ... but also some nasty Fuzz (most certainly Germanium based) and the marshall used "clean" .
Surprisingly the background guitar has quite an acceptable crunch but the lead Guitar sounds like a mosquito on crystal Meth.

[olddawg]

But of course.. still the old pedals were always hit and miss... even old VOX wahs. I tried most at some point or another... probably the worst was the “Fender Blender” (which I don’t think was germanium) imho, which people seem to be falling themselves over lately. AND.. amp performance varied as well. I always wrote it off as 20% tolerance randomness and the vagarities of germanium devices.

[Mark Hammer]

Question: are there heat sinks one can get that fit over these transistors, and if so, does that improve their relliability, or rather the biasing reliability?

[nosaj]

Question: are there heat sinks one can get that fit over these transistors, and if so, does that improve their relliability, or rather the biasing reliability?

There are I can't find any pics of the old ones I've seen in old solid state devices but here are some options
https://www.cricklewoodelectronics.c...s-and-ICs.html
This next one is similar to what I remember piece of aluminum wrapped around the transistor some had holes to mount to chassis otheres were free standing.
https://www.alibaba.com/product-deta...770237381.html

nosaj

[mozz]

The 2n270 weren't to-5, slightly smaller. I think he is using OC transistors which might be the same diameter as the old germanium output trannys such as 2sb**. They used a wrap-around aluminum heat sink.

[J M Fahey]

Question: are there heat sinks one can get that fit over these transistors, and if so, does that improve their relliability, or rather the biasing reliability?

These transistors dissipate VERY little, do the Math using around 1.5V DC and less than 1 mA , see the above currents I calculated and you´pll end up with feeble 1 or 2 milli Watts

No dissipation=no self heat rise=no need for heatsinks.

On the contrary, these transistors will happily drift all over the place with *ambient* temperature variation, and heat sinks do nothing about that.

I respect and salute innovation, and germanium transistors were a huge step ahead ... comparing to nothing at all that is, but only Silicon signalled the "coming of age" which led to current World domination and then some.

My brain explodes trying to imagine ICs and modern Digital Electronics running based on Germanium

As in: they would not exist.

[mozz]

Russians were way far ahead of the US on germanium. A lot of the Russian transistors you can buy now, date coded 70's-late 80's, have no leakage. I was also reading somewhere on germanium to start being used for computer chips, they are faster than silicon.
https://www.sciencenews.org/article/...-silicon-again

[J M Fahey]

Yes, that Science article says so ... but reading the fine print:

Germanium computer chips gain ground on silicon — again
Excerpt from the February 25, 1967, issue of Science News

Oh well

Yes, traditionally Russians (well, at least the Soviets) "junk nothing".
They go on advancing but keep old stuff working if it proved reliable in its own field.

Typical of Military thinking, I remember reading in 2002 or so about what then was the last surviving Tube Factory in USA, who "if asked" could make excellent 6L6 ... for about $60 (some $120 in today's prices) who of course could not compete with $12/$15 Russian and Chinese versions.

Their only commercially viable product at the time was a miniature "grain of wheat" sized UHF diode (vacuum tube of course) which was bought regularly in quantity by US Govt (who of course does not care about price) for dual purpose:
* detector in some USAF electronics countermeasures detector, they bought a ton of those to be used in the Iraq invasion, because Saddam´s missiles used outdated Russian electronics and the Vietnam era ECM pods were best for that.
* again detector in some Hewlett Packard or Tektronix Lab equipment which apparently was in *every* University and Govt Lab.

It was sad to see the aged "should have retired 10 years ago" Engineers, trying to keep the Factory running, and all the very dated equipment which if broke would be irreplaceable.

FWIW I once repaired Medical equipment and was amazed to find, inside Gas in Blood analyzers and Blood PH analyzers coexisting "pencil tubes" , Germanium transistor SMPS (high voltage flyback generators), silicon transistor modules, TTL logic chips and in one, early Microprocessors.

Apparently they apply the "you don´t mess with a winning team" Logic ... which in this case is very sensible.

Besides, given the red tape involved around anything Medical plus the huge possibility of malpractice attacks by greedy Lawyers, I bet that the safest course is to keep time honored and tested stuff as long as possible.
Parts cost is again irrelevant.

*Somebody* must keep all those obsolete/unavailable parts suppliers in business