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Original Dallas Rangemaster from 1966


RevDavidLee

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It has been the first treble booster then. Treble boosters were widely used until circa the late 1970's and early 1980's.

 

The performance of the unit in question is debatable due to component aging. Germanium transistors were usually rated with an MTTF (mean time to failure) of 30 years. Most were discontinued during the 1980's, and NOS (new old stock) parts age through diffusion of the dopings making the chip partly n (negative) or p (positive) semiconductors. Although working on principal, they already may produce lots of flicker noise.

 

Old transistors in low-current applications like in treble boosters usually don't blow in an instant. They slowly go bad making funny sorts of crackling noises until they finally fall silent. As credited by himself, for creating the rumbling noise in the song "The Launch" from the Boston album "Third Stage" Tom Scholz used an old VOX treble booster with a transistor gone bad. This album was already released in 1986... :unsure:

 

The song doesn't play in Germany but perhaps the link works for you:

 

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It has been the first treble booster then. Treble boosters were widely used until circa the late 1970's and early 1980's.

 

The performance of the unit in question is debatable due to component aging. Germanium transistors were usually rated with an MTTF (mean time to failure) of 30 years. Most were discontinued during the 1980's, and NOS (new old stock) parts age through diffusion of the dopings making the chip partly n (negative) or p (positive) semiconductors. Although working on principal, they already may produce lots of flicker noise.

 

Old transistors in low-current applications like in treble boosters usually don't blow in an instant. They slowly go bad making funny sorts of crackling noises until they finally fall silent. As credited by himself, for creating the rumbling noise in the song "The Launch" from the Boston album "Third Stage" Tom Scholz used an old VOX treble booster with a transistor gone bad. This album was already released in 1986... :unsure:

 

The song doesn't play in Germany but perhaps the link works for you:

 

BS

 

The carbon comp resistors will drift, altering the bias of the transistor. The electrolytic caps very well may be dried up and way out of spec. The transistor itself is about the last part to fail unless you damage it with the power supply.

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BS

 

The carbon comp resistors will drift, altering the bias of the transistor. The electrolytic caps very well may be dried up and way out of spec. The transistor itself is about the last part to fail unless you damage it with the power supply.

 

Supposing there are similar components about now. How much would it cost to build one? Around the £8 mark?

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BS

 

The carbon comp resistors will drift, altering the bias of the transistor. The electrolytic caps very well may be dried up and way out of spec. The transistor itself is about the last part to fail unless you damage it with the power supply.

Yep - carbon resistors may drift or fail and take the transistor with them, and shorted caps, too. The power supply point is also important since these units didn't have any reverse voltage protection.

 

 

Supposing there are similar components about now. How much would it cost to build one? Around the £8 mark?

[biggrin] I think you are pretty close. The price may not include the housing but much better metal film resistors, and fine caps, too. [thumbup]

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Yep - carbon resistors may drift or fail and take the transistor with them, and shorted caps, too. The power supply point is also important since these units didn't have any reverse voltage protection.

Resistor drift causing the transistor to fail would be pretty damn unlikely. Not even really worth mentioning.

 

If the 47uf DC ripple cap dries out, it will usually be open, which isn't going to damage the transistor although it will obviously not be performing it's job as intended

 

Whether you use carbon comps or metal film in this doesn't really dictate the noise level. That's more down to transistor specs and biasing

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Supposing there are similar components about now. How much would it cost to build one? Around the £8 mark?

Depends how nice you want to make it. You could do it for £8 but chances are it won't sound very impressive and that's not going to include the enclosure or switch so it would be useless anyways.

 

It's not rocket science, but if everybody could slap together a perfect sounding Rangemaster for a few bucks then the market would be a lot different

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Resistor drift causing the transistor to fail would be pretty damn unlikely. Not even really worth mentioning.

 

If the 47uf DC ripple cap dries out, it will usually be open, which isn't going to damage the transistor although it will obviously not be performing it's job as intended

 

Whether you use carbon comps or metal film in this doesn't really dictate the noise level. That's more down to transistor specs and biasing

Resistors drift killing the transistor within the particular circuit would indeed be very unlikely. However, of the (only) four electrolytic capacitors gone bad I encountered through 37 years two were open, two shorted. Regardless how improbable the latter would be in general, it was not fine when it happened. The affected Al caps had always been operated within their ratings. <_<

 

Resistors' noise floor is worth considering specifically in hi-Z applications. The Johnson-Nyquist noise will determine the minimum possible noise level and always contribute to the overall S/N ratio. The transistor will add its shot noise and 1/f aka pink noise. You're right, old-school AF germanium transistors are critical herein compared to their modern counterparts.

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Resistors drift killing the transistor within the particular circuit would indeed be very unlikely. However, of the (only) four electrolytic capacitors gone bad I encountered through 37 years two were open, two shorted. Regardless how improbable the latter would be in general, it was not fine when it happened. The affected Al caps had always been operated within their ratings. <_<

 

Resistors' noise floor is worth considering specifically in hi-Z applications. The Johnson-Nyquist noise will determine the minimum possible noise level and always contribute to the overall S/N ratio. The transistor will add its shot noise and 1/f aka pink noise. You're right, old-school AF germanium transistors are critical herein compared to their modern counterparts.

Carbon comps have lower induction than metal film and sometimes it is preferable to use them because of that. Anyway the only resistor in the direct audio path in this circuit is the potentiometer

 

If you build this with carbon comps, and then replace the resistors with metal film that measure exactly the same, I can just about guarantee that you won't hear any difference in the noise level. I can tell you that I have built this with carbon comps and metal film several times, and haven't had any issues.

 

Just sayin.. Everything you've mentioned is technically true, but somewhat out of context with regards to this circuit. Germanium transistors from the 60s are still working just fine if they weren't damaged along the way. If you want to build one of these you're going to want an old germanium transistor anyways, so your comment that the transistors are past their shelf life doesn't make much sense to me.

 

Especially when you say they will make a noise from the doping breaking down.. I have literally thousands of germanium transistors that could prove this wrong for you all day long.

 

Btw, I am not suggesting that this auction is anywhere remotely close to an acceptable deal. This guy won't get 1/4 of his asking price, he is completely whacked.

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Btw, I am not suggesting that this auction is anywhere remotely close to an acceptable deal. This guy won't get 1/4 of his asking price, he is completely whacked.

 

if I had this kind of gear I think I'd be trying to flog it directly to recording studios who could then promote to prospective artists - hey we have all this 'best ever' gear available for your recordings.

At least they could write it off as a tool of the trade, and what's $10K to, say, Tommy Lee's studio for example.... that, or call Brian May's agent direct.

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At least they could write it off as a tool of the trade...

 

Not really. Just because you paid 10k for it doesn't mean you realize a 10k tax benefit, it just doesn't work that way. A transaction of Ten Grand will get you some Homeland Security attention too.

 

rct

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if I had this kind of gear I think I'd be trying to flog it directly to recording studios who could then promote to prospective artists - hey we have all this 'best ever' gear available for your recordings.

At least they could write it off as a tool of the trade, and what's $10K to, say, Tommy Lee's studio for example.... that, or call Brian May's agent direct.

Yeah but why wouldn't they just buy one for the normal (still high) going rate of 1K-2K?

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