Myths, Legends and the Mojo of the Dallas Rangemaster

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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noelgrassy
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Post by noelgrassy »

Dai your two hints are even more cryptic though I suspect you actually know the fellow's identity.

1} Don Cornelius was the MC of Soooooooul Train.

2} Is that a quote from Planet of the Apes?


3} How about ODB from Wu Tang Clan?
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dai h.
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Post by dai h. »

ODB? ol' dirty bastard? lol

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Post by DougH »

I don't know why everyone is being so cryptic. Just google "toneman" and you'll find it.
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dai h.
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Post by dai h. »

:shock: CIA for you! :lol:

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Post by schemripper »

Getting off the whodunnit for a minute... :lol:

I've seen a couple of references to this mod- firstly at the now departed Plate To Plate site, but also referred to at Fuzz Central.

The quote from Fuzz Central is "I have added a reverse-biased Germanium diode between the base-emitter junction of the transistor to offset the effects of temperature variation on the transistor." Their modded schematic (with the usual anti pops, power filtering etc) can be found here.

Ignoring different component values for a sec- what is the opinion of those well versed in the black arts of using a 1N34A to stabilise the Ge transistor? Is the theory sound?

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Post by R.G. »

schemripper wrote:Getting off the whodunnit for a minute... :lol:

I've seen a couple of references to this mod- firstly at the now departed Plate To Plate site,...
Ignoring different component values for a sec- what is the opinion of those well versed in the black arts of using a 1N34A to stabilise the Ge transistor? Is the theory sound?
Depends. The theory is that putting one reverse biased junction from base to emitter will suck out an amount equal to the leakage through the reverse-biased collector-base, and thereby keep the transistor from amplifying the leakage current. Good theory.

But it depends on whether the suck-out junction has the same leakage as the collector-base. While I guess any compensation is better than none at all, I suspect perfection will depend on how close the suck-out junction really is. The problems are that
(1) diode and transistor junctions are optimized for different things (leakage per unit area will be different)
(2) diode and transistor junctions are different sizes (area will be different)
(3) thermal impedance into/out of the devices will be different (metal case vs glass, cooled primarily by the leads)
(4) history will be different for the two junctions; soldering and age change germanium junctions.

So, yeah, compensation is nice, and some is better than none; but expecting perfection is going to be disappointing. I suspect that different instances will work better or worse depending on the things above.

I've recently discovered H.L. Mencken's quotations. One that comes to mind here is this:
For every complex problem there is an answer that is clear, simple, and wrong.
And he didn't even address the answers that are near-misses or "not quite".

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Post by DaveKerr »

What if you have a mittful of cheap Russion Ge transistors, find a couple that match leakage pretty well, and use one as a diode? Not that you'd want to use that approach if you've got some of those NOS mojo-laced transistors sprinkled with unobtanium...
... multiple LFO waveforms (saw up, saw down, triangle, square); a more flexible envelope with attack/release controls as well as inverted envelope. I am afraid it will have more knobs than the TGP annual convention - frequencycentral

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Post by Octopus1992 »

I use a Ac126 in my, made it last month or so, and even with this crazy weather in my town it works really fine, tried 2 ac126 both perfect, and tried 2 2SB324, not so what I wanted, more mids, but a little muddy.

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Post by Octopus1992 »

for shure, it's a bit high powered, can't denny, but that's what I like in it. C'mon, it's just one, even I can tweak it to be a little lower gain :applause: , but instead, I want to make it sound a little more gainy, just that extra something.

I've put a 7 position switch to choose the firt cap, 2n2, 3n3, 4n7, 5n6, 10n, 27n, 47n, and one simple switch for the the last cap to choose a 10n or a 100n.

Got me some crazy sounds, the 2n2 is realy thin, didn't had the chance to try it with a les paul or other fat sounding guitars, only strats and teles, and it gets really funky and strange, can't really describe it.
On the other hand, the 47n sound killer, with lots of bass, and some kind of fuzzy.

Will post dome pictures as soon as fix my freaking camera or get other one :whappen: :thumbsup

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Post by R.G. »

DaveKerr wrote:What if you have a mittful of cheap Russion Ge transistors, find a couple that match leakage pretty well, and use one as a diode? Not that you'd want to use that approach if you've got some of those NOS mojo-laced transistors sprinkled with unobtanium...
It gets a little abstract when you try matching them.

The collector-emitter leakage is the collector-base leakage times the hfe at that low current. If you're connecting a reverse diode to the base of an active transistor, you want to subtract the collector-base leakage, not the collector-emitter leakage of the compensation transistor.

So you need to measure the collector-base leakage of the active device, then find another with a close-enough collector-base leakage, not the amplified collector-emitter leakage. That's a bit different, but easy to test for. You just measure current through the device with the voltage across the collector base, emitter open.

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Post by DaveKerr »

Damn, that's a clear enough explanation even for someone with my hillbilly-level understanding of this stuff - thanks.
... multiple LFO waveforms (saw up, saw down, triangle, square); a more flexible envelope with attack/release controls as well as inverted envelope. I am afraid it will have more knobs than the TGP annual convention - frequencycentral

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Post by R.G. »

DaveKerr wrote:Damn, that's a clear enough explanation even for someone with my hillbilly-level understanding of this stuff - thanks.
I come by it naturally. I grew up in a small town in the northeast corner of Oklahoma where the Arkansas Ozark mountains overlap. We had people living in the hills back in the creek valleys in unpainted board houses and moonshiners who'd shoot first and ask questions later. So hillbilly electronics is a compliment to me. Thanks! :D

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Post by DaveKerr »

While I grew up in Massachusetts, it was in the hills in the Western part of the state. Bare feet and rope belts were a big part of my summer as a child.
... multiple LFO waveforms (saw up, saw down, triangle, square); a more flexible envelope with attack/release controls as well as inverted envelope. I am afraid it will have more knobs than the TGP annual convention - frequencycentral

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Post by Electric Warrior »

Electric Warrior wrote:It's quite obvious that it's not a factory schematic. Whoever drew it misidentified the caps for resistors - guess why :mrgreen:
There's basically two versions: The early ones have an OC71, 0.0082 Siemens styroflex cap at the output, a brown Hunts cap at the input and two 50µF Electrolytics. The later OC44 version has 25µF Electrolytics (though some come with mixed 50/25 values - 50µF is always at the bottom of the terminal strip afaik) and tubular ceramic caps of the usual values.
The emitter resistor varies a bit, as it was used to set the bias. Most have 3k9. I have photos of some with 4k7 and 3k7.
The pot was usually audio taper, though there are some with linear taper. A few might have come with a 20k pot, but I'm not entirely sure about that.
Turned out they started with OC44s, used OC71s for a while and switched back to OC44s again.
The early OC44 units have 50µF electrolytics, a brown hunts cap for input and the Siemens styroflex for output. Some have 22k pots.

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Post by Greenmachine »

I just built one of these with an OC71 and it sounds like it's doing what it's supposed to; however, I used an 82k resistor in Rb1 to lower the collector voltage to -7.12v. Originally, it was at -7.8v with Rb1 at 56k.

Do these voltages sound correct to any of you? I'm trying to get the most out of this circuit.

Collector: -7.12v
Base: -1.17v
Emitter: -1.09v

Thanks.
"[Y]ou want sketchy, dude? I breadboard on a door." -- RnFR, 2011
"This amp is freakin loud, like crazy, I'm going to kill pets loud." -- mich, 2011

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Post by kaycee »

I'd just use the voltages as a guide and use your ears to judge. I tune them by ear using a trim and them measure for the fixed resistor. I find that I prefer a lower voltage, @6v. The Keeley Java Boost has a 500k and 100k trim inside and its nice to dial it in using those.

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Post by Greenmachine »

Thanks. You're right about using the ears. I would like to know if these voltages are in the ballpark or not though.

Cheers
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Post by peps1 »

Anyone got a wiring diagram for terminal strip build?
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Post by vot »

Please, sir!
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Post by azrael »

Greenmachine wrote:I just built one of these with an OC71 and it sounds like it's doing what it's supposed to; however, I used an 82k resistor in Rb1 to lower the collector voltage to -7.12v. Originally, it was at -7.8v with Rb1 at 56k.

Do these voltages sound correct to any of you? I'm trying to get the most out of this circuit.

Collector: -7.12v
Base: -1.17v
Emitter: -1.09v

Thanks.
seems good to me.

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