John Curl's Blowtorch preamplifier

Status
Not open for further replies.
Jump to Latest
#12,944
SY said:

The whole "linearizing a dielectric" has more than a whiff of pseudoscience. The patent's complete lack of backup data and the frank confession that the explanation for the effect that's not demonstrated could be total BS is something of a clue.
Click to expand...

Patents are not necessarily bound by current science. Deforest's patent on the vacuum tube reflected a bad understanding of its operation, something that Armstrong capitalized on later. Identifying a technique that makes an improvement in something and describing enough for a "practitioner in the art" to duplicate it is enough for a patent.

The trick has been "borrowed" by several others who have been successful selling cables using variations on it. I get good results with it. I have not had the incentive to do a double blind test or figure out how to really do one, but its not important to me.

There is literature on the issue of biasing capacitors and distortion. It makes a big difference in some cases.
 
#12,945
Lots of things are sold with no actual function other than in the mind of the user.

It's OK to not understand the mechanism of an effect, but when the explanation is hooey AND there's no data presented to show the existence of the effect, you'll have to pardon me for being somewhat cynical and believing that it's all a marketing exercise and an abuse of the patent system. It's analogous to a patent on a means of shielding against N-Rays. Now, if you actually have some real data, I'm all ears, so to speak. But I'd also wonder why it wasn't presented in the patent...

I guess I don't understand the analogy you draw to capacitor biasing (presumably, electrolytics), either from a dielectric physics or an equivalent circuit view.
 
#12,947
Now, if you need to buy M&C, then it will only cost you about $150 for a new copy. I thought it was out of print, since it is more than 15 years old, now. I also thought that the authors had donated the contents of their book to online, so that their students could study low noise design affordably and easily. No such luck.
 
#12,949
john curl said:
Just like how doctors use their obscure terms amongst themselves, and leave the rest of us out.
Click to expand...

If it makes you feel better, it's likely just small talk in latino about the color of your underwear and how much you'll be ripped for. :clown:
 

Attachments

  • latty.jpg
    latty.jpg
    54.7 KB · Views: 361
#12,950
janneman said:
......The ONLY reason to have balanced signal levels is to be able to get twice the signal amplitude from a given supply voltage(s)............
Click to expand...
Only reason? If you balance everything, from source circuit (phono pre, DAC, etc) through the power amp, there are some more quite good reasons.

You get a much lower modulation of the supply rails, therefore less demanding about "regulation factor" of regulators....better PSRR of the same circuit.....you can get away with components which have lower brakdown voltages....."symmetric" (on + and -) modulation of the rails in a power amp.....etc,
Just some ideas.

OTOH, I agree that balancing an unbal signal in the output stage of a source/preamp just for sending it out though a balanced interconnect (and, perhaps, unbalancing it again on the RX side) is not that clever.

Don Catino (C) Jacco
 
#12,954
john curl said:
I just checked on the M&C book and it does not have up-to-date fets listed.
Click to expand...

H & H does? We were thinking of inviting Dr. Hill to speak at our technical conference. Their book does have at least one glaring error, though it is a little esoteric.

Van der Ziel is the god of noise, but I hesitate recommending him to the casual reader.
 
#12,955
Van der Ziel wrote books for audio researchers, not typical engineers. He derived the equations initially, but we don't need to know how he did that and can still design low noise input stages.
The next level of low noise design is: 'Noise in Electronic Devices and System" by M.J. Buckingham. However, it is an advanced text and mostly useful to specialists in low noise design. It does show that there is much more to low noise fet design than simple formulas often imply, especially with 1/f noise.
 
#12,956
zinsula said:

Only reason? If you balance everything, from source circuit (phono pre, DAC, etc) through the power amp, there are some more quite good reasons.

You get a much lower modulation of the supply rails, therefore less demanding about "regulation factor" of regulators....better PSRR of the same circuit.....you can get away with components which have lower brakdown voltages....."symmetric" (on + and -) modulation of the rails in a power amp.....etc,
Just some ideas.

OTOH, I agree that balancing an unbal signal in the output stage of a source/preamp just for sending it out though a balanced interconnect (and, perhaps, unbalancing it again on the RX side) is not that clever.

Don Catino (C) Jacco
Click to expand...


OK, you have a point, balancing those signals *might* have a beneficial effect on the power supplies. But it may also have no effect, with those small signal currents.

I did say that balancing the signals in a balanced connection has no positive effect on the hum & noise supression of the balanced connection, and I stand by that.

Jan Didden
 
Status
Not open for further replies.
Top Bottom