John Curl's Blowtorch preamplifier part III

[PMA]

To me, CB's experiment is technically flawed. The only valid part, for me, is a cable analysis, which anyone with some skills and knowledge may make in the simulator.

2nd, I am afraid, that some here, though unintentionally, are supporting, through their hypothesis, black magicians and snake oil sellers in this thread. Thus, to me, such hypothesis should be supported by experiment results or link to a scientific literature. In case that the findings are secret and may not be disclosed, then please do not talk about them.

 

[picowallspeaker]

And that is only the first section in the analysis, the part I would consider bog standard. As I mentioned to Demian, I've no clear engineered approach yet for actually measuring the non linear time variant full frequency span impedance variations on a fully hard music driven device..that is where the real brainstorming is needed. Sine waves need not apply.

 

[Max Headroom]

The cables were the M2.2 and M2.4. This was 1997 or 1998. We used a Caddock power film resistor, 100 Ohms. MP850 I think. It was imbedded in thermal epoxy inside the big aluminium shells even though it would never get stressed. Finding a review may be hard. Monster was not taken seriously in high end circles even then.

The rationale was that virtually all speakers are inductive at high frequencies (even electrostatic speakers). Terminating the cable at around its characteristic impedance (100 Ohms) would move that HF impedance back to a more normal Z and reduce/eliminate reflections at high frequencies as well as improve stability. it did seem to have the desired effect of a different (better) sound pretty much everywhere it was used. We can touch on the marketing side of that issue but its not nice to point out so much human frailty. . .

Thanks, so you did what I'm doing and for the same reasons/reasoning.
There are plenty of reviews mostly all positive, I found one 2/5 review which seems unusual.

Dan.

 

[chris719]

The name is Monster. I am surprised it got a star at all. It could only get a worse review if it were branded Bose.

 

[Zung]

The cables were the M2.2 and M2.4. This was 1997 or 1998. We used a Caddock power film resistor, 100 Ohms. MP850 I think. It was imbedded in thermal epoxy inside the big aluminium shells even though it would never get stressed. Finding a review may be hard. Monster was not taken seriously in high end circles even then.

The rationale was that virtually all speakers are inductive at high frequencies (even electrostatic speakers). Terminating the cable at around its characteristic impedance (100 Ohms) would move that HF impedance back to a more normal Z and reduce/eliminate reflections at high frequencies as well as improve stability. it did seem to have the desired effect of a different (better) sound pretty much everywhere it was used. We can touch on the marketing side of that issue but its not nice to point out so much human frailty. . .

Thanks, finally some actionable info, will try that!
It looks like this guy is custom made to your specs, isn't it? Or would the cermet introduce some unholy effect?

 

[scottjoplin]

2nd, I am afraid, that some here, though unintentionally, are supporting, through their hypothesis, black magicians and snake oil sellers in this thread.

And then there are those that lurk silently (most of the time, though interjecting occasionally to stir the pot if too much reason seems to be prevailing) in the shadows, listening, picking up titbits dropped by the unwary conjecturer later to be used as fodder for FUD buyers in BS marketing blurb.

 

[Max Headroom]

To me, CB's experiment is technically flawed. The only valid part, for me, is a cable analysis, which anyone with some skills and knowledge may make in the simulator.

2nd, I am afraid, that some here, though unintentionally, are supporting, through their hypothesis, black magicians and snake oil sellers in this thread. Thus, to me, such hypothesis should be supported by experiment results or link to a scientific literature. In case that the findings are secret and may not be disclosed, then please do not talk about them.

Your high bias open-loop amplifier is essentially immune to return energy and induced/picked up RF energy, most production NFB type amplifiers are not so immune to delayed return energy or external energy input (RF ingress).

You should try your test on a mid-fi Panasonic/Pioneer/Yamaha etc integrated amp to be more representative of real world conditions before making blanket conclusions.
At present your findings apply only to your test system.

Dan.

 

[scottjoplin]

There is no Voodoo left in loudspeaker development.

I hope Planet10 doesn't listen to you or some happy muddy footed fairies will find themselves in the dole queue.

 

[Max Headroom]

The name is Monster. I am surprised it got a star at all. It could only get a worse review if it were branded Bose.

Demian and Richard were involved, are you saying that their work is crap ?.

 

[chris719]

Demian and Richard were involved, are you saying that their work is crap ?.

No, why would you even come to that conclusion?

The rating is bad because of preconceived notions due to the brand name. Monster did not have a warm welcome among the Hi-Fi elite as I remember it.

 

[Max Headroom]

Thanks, finally some actionable info, will try that! It looks like this guy is custom made to your specs, isn't it? Or would the cermet introduce some unholy effect?

You don't need anything like 100W rating but as I suggested it is worth to experiment with resistor type......I found the shunt resistor chemistry to be important, really important and no more than 5W rating is required for music signals. I found CF to sound artificially 'nice' but but not accurate. I have no idea of the chemistry of the MF 0.6W I am using for now, but I do way prefer it to CF or ceramic WW which is another sound again. You might need to do some measuring to establish the characteristic impedance of your cable, I think close matching is important.

Dan.

 

[PMA]

Band aids only work with wounded - poorly designed or flawed equipment. Otherwise they are not needed.

 

[Max Headroom]

Last time I checked AC theory the word was that transmission lines must be correctly terminated or else ringing and resonances will occur. So who has equipment that is perfect in the audio band with reactive loads, and also has perfect RF immunity?

 

[Zung]

You don't need anything like 100W rating but as I suggested it is worth to experiment with resistor type......I found the shunt resistor chemistry to be important, really important and no more than 5W rating is required for music signals.
I found CF to sound artificially 'nice' but but not accurate.
I have no idea of the chemistry of the MF 0.6W I am using for now, but I do way prefer it to CF or ceramic WW which is another sound again.
You might need to do some measuring to establish the characteristic impedance of your cable, I think close matching is important.


Dan.

Thanks for saving me $15.
Sadly, any "real" experiment will have to wait until the fall. They want us out of the appartment to rebuild the crumbling walls, no doubt designed by some subjectivists/unbelievers.

So who has perfect equipment in both audio band and RF ?.

PMA!!!

 

[chris719]

Nothing like the blind leading the blind.

What is "RF" anyway? Where does your leaded power termination resistor begin to look inductive? Is this supposed to be about preventing reflections, minimizing RF ingress, or both?

 

[Zung]

Nothing like the blind leading the blind.

What is "RF" anyway? Where does your leaded power termination resistor begin to look inductive? Is this supposed to be about preventing reflections, minimizing RF ingress, or both?

We're talking about chemistry, no physics involved. Please respect the isolation of genre!

 

[PMA]

Where does your leaded power termination resistor begin to look inductive?

As soon as or even sooner than the cable reflection frequencies do occur .

We're talking about chemistry, no physics involved. Please respect the isolation of genre!

Please do not forget about quantum physics.

 

[Zung]

Please do not forget about quantum physics.

Of course: living in Geneva means we're all literally sitting on top of the world's largest particule accelerator. We all live and breathe quantum!

 

[scottjoplin]

I think the objectivist of speaker world is Earl Geddes.

Perhaps, IIRC he says job done?

 

[johnego]

Floyd Toole or Sean Olive. Just about everything can be measured of speakers, and these measurements correlate one on one with preceived qualities. There is no Voodoo left in loudspeaker development.

Objectivists with good ears equal subjectivists. Speakers or amps are no different; people talk about numbers without knowing its relationship with perceived sound. In speakers, as I said, because of the so many compromises (being usually the weakest link) things are more audible than in amps (even 1dB response matters). Ask yourself this: given (contrast) impulse responses of speaker A and speaker B, can you tell which one is which in blind test? Or look at the impedance of speakers. Given a speaker with flat impedance, can you tell which is it in a blind test?


Troels Gravesen is among speaker builders who explicitly admits the missing correlation between measurement and quality. This has nothing to do with technology. It is because someone can't hear so he doesn't know.