John Curl's Blowtorch preamplifier

[anatech]

Hi Steve,

How 'bout something like this?

...
Yep, I like that.

Let's let the marketing guys worry about how the concepts are used. I like these definitions that clear up these discussions. Since some circuits are bound to have "Degenerative Feedback" apart from what is inherent in the device itself, this seems to clear things up. A little honesty can now come out as these terms are good enough for our purposes.

Hi Nelson,

Does anybody here have any good ideas on a coherent way to

I think that between you and Steve, it's nailed. Only marketing types may have issues with this.

I'll bet Bob Carver could give these terms a confusing spin. 😀

-Chris

 

[john curl]

The problem is that you people are more concerned with how feedback is defined, rather than what negative feedback does to audio quality. If you would just try different forms of feedback, all else being comparatively equal, you might find that many of your previous assumptions do not hold up.
This is why the Blowtorch preamp was designed, initially. It is a test bed for a number of 'outrageous' concerns, including global negative feedback. This is much like a race car on a test track. We compete with other 'race cars' such as made by Ayre and Pass Labs. Sometimes one of us wins, often we tie, but we usually match most of the competition at the very least, even when compared to efforts that cost much more money to produce.

 

[anatech]

Hi John,

The problem is that you people are more concerned with how feedback is defined

That's not true. In order to keep from going around in circles, a common definition helps us speak the same language. No marketing, just "tech talk".

This issue of definitions just came up, so here we are. Now we can all continue because we will use the same terms.

-Chris 😉

 

[PMA]

The problem is that you people are more concerned with how feedback is defined, rather than what negative feedback does to audio quality. If you would just try different forms of feedback, all else being comparatively equal, you might find that many of your previous assumptions do not hold up.
This is why the Blowtorch preamp was designed, initially. It is a test bed for a number of 'outrageous' concerns, including global negative feedback. This is much like a race car on a test track. We compete with other 'race cars' such as made by Ayre and Pass Labs. Sometimes one of us wins, often we tie, but we usually match most of the competition at the very least, even when compared to efforts that cost much more money to produce.

The problem is that you are quite often self-concentrated and you underestimate another people.

I can agree on some of your thoughts. Like different "kind of feedback", based on experience with output stage out of GNFB, or preamp without GNFB. On the other hand, I am not sure if this experience may necessarily be generalized.

Regarding comparisons, it is difficult to do them virtually on 7000 miles distance. I have made comparisons with Pass products and frankly speaking, they are no sound reference for me. I can say similar about Ayre. I have never heard JC1. But the reviews are not only enthusiastic. Contrary to Stereophile review, this one:

http://www.hometheaterhifi.com/volume_11_3/parasound-jc1-amplifier-8-2004.html

shows reservations and problems. So, how to argue in long distance communication?

 

[anatech]

Hi Pavel,

Contrary to Stereophile review, this one:

I am stunned. 😀

Did you read this entire review? I made it through with great effort. This reviewer represents the audio industries hope for survival.

The reviewer also outlines how unimportant John's (and everyone else's) design efforts are in comparison to some power cords, an iffy amplifier (the power conditioner) and some interconnects. I wonder if these cables and AC power products were tried with components like "SoundDesign" or "Lloyds"? Might be an earth shattering discovery here. The quality of the AC supply may be the only important thing there is. Inexpensive zip cord prevented these cost effective products from attaining their peak performance.

-Chris

 

[Magura]

Hi Pavel,

I am stunned. 😀

Did you read this entire review?

I was fortunate enough to head straight for the conclusion...and after reading his conclusion, I didn't feel any need to read the rest 😀

Magura 🙂

 

[PMA]

Hi Chris,

it is again difficult to assess. According to our experience, good power conditioner (large isolation transformer + filters) brings significant sound improvement. Some components are more dependent on AC mains purity and some less, and it makes difference between them. So?

 

[anatech]

Hi Magura,
LOL!
No, you didn't.

I was struck with morbid curiosity. I had to see how far down this review went...... I lost sight of it myself!

Having a product cooed about in this way must be embarrassing. There is a certain target market this will reach though. Still ......

-Chris

 

[PMA]

If you look at spectra, they contain high levels of mains frequency residuals and its multiples. This can be done much better, and this may indicate to extreme AC mains purity dependence.

 

[anatech]

Hi Pavel,
I agree with you.

My findings tend to show that this is more a failure of power supply and amplifier design than it is a required accessory. If the power supply in your product has been executed properly, I would think the extra resistance over a direct mains connection would be more of a problem for higher powered amplifiers. For signal level stuff this is a non-issue.

Now, power cables? I have never once heard an improvement in all my years. Not unless the originals were arcing due to damage.

We are saying the same thing I think. I accept that many power supplies are poorly designed and that these conditioners would help in those cases. When a piece of equipment is properly designed I don't think a power conditioner would be a positive addition. In all fairness, our power is very good where I live.

-Chris

 

[Variac]

I thought that PMA was mentioning that review as a negative one,

Here are some quotes .... "Listening to the Parasound Halo JC 1 monoblocks is a thrilling experience....... Anyone who is in the market for better amplification, has good power conditioning and enough power cables, and can afford to spend $6,000 would be nuts not to give these monoblocks a home audition. In three words: they are fabulous.

If that's reservations , I don't know....
It seems to me embarrassingly positive. More positive, I'd say than the Sterophile review which was also very very positive as PMA states.

The biggest problem seems to be a hum, that the author admits pre-exists in his system...

EDIT : OK I do see the power supply issue, but the author is still pretty over the top...

 

[anatech]

Hi Pavel,

If you look at spectra, they contain high levels of mains frequency residuals and its multiples. This can be done much better, and this may indicate to extreme AC mains purity dependence.

Very delicately put sir. 🙂

This was my point, but you put it so nicely!

-Chris

 

[PMA]

Hi Chris,

our experience is such that sound of ANY power amplifier (including very well known products) and audio system as a whole has been improved by a good power conditioner. This conditioner must contain isolation transformer.

 

[anatech]

Hi Variac,

Here are some quotes .... "Listening to the Parasound Halo JC 1 monoblocks is a thrilling experience....... Anyone who is in the market for better amplification, has good power conditioning and enough power cables, and can afford to spend $6,000 would be nuts not to give these monoblocks a home audition. In three words: they are fabulous.

Yes, however the quote is out of context now. The rest of the text is very telling.

It seems to me embarrassingly positive. More positive, I'd say than the Sterophile review which was also very very positive as PMA states.

Well .......... yes. It's embarrassing. The reviewer stated a number of things that had to be done in order to make those amplifiers sound even listenable. The journey for these amplifiers to be made acceptable was long and torturous. That was one of the points I tried to make also. If I were John, I would not be too happy with the list of accessories required to make these sound good. The reviewer's story is good at explaining why the audition was not well received at first. So, one wonders, what is the real truth?

I am positive these are good sounding amplifiers John. Please do not read into this that I am commenting on the equipment. I am commenting on the review. Drivel.

-Chris

 

[PMA]

Hi Variac,

I assume that everyone of us can read the whole review and make his own opinion. It can be misleading if we only quote one or two individual sentences.

 

[Zen Mod]

reviewers...............

well, most of them .......

but also

designers.............

well,most of them .......



hey - both breeds lousy almost as technicians

 

[anatech]

Hi Pavel,
Interesting findings.

I would think a direct connection for the amplifiers and isolation for the signal level stuff would do it. This would break leakage currents that might be at the bottom of the issue. AC mains noise issues ought to be eliminated in the power supply of the equipment in question.

Does this make any sense, or am I barking up the wrong tree?

-Chris

Edit: Hi Zen Mod,

hey - both breeds lousy almost as technicians

Hey! I resemble that remark! 😉

 

[Zen Mod]

.......... AC mains noise issues ought to be eliminated in the power supply of the equipment in question.



...........

................

but you know that they never are , at least not in anything below Rohde Schwartz engineering quality

EDIT:

Hey! I resemble that remark!

I know

 

[PMA]

Hi Chris,

according to my experience this is one of not very well explored fields (the mains issue), and I do not want to make any simplified conclusions. I am not sure if only leakage currents and signal isolation transformers are the solution. They have their issues as well.

We are pretty OT here 😀

 

[anatech]

Hi Zen Mod,

I know

And I know you know. You know?

Hi Pavel,

according to my experience this is one of not very well explored fields (the mains issue), and I do not want to make any simplified conclusions.

Yes, I think so too. That and our electrical systems are different enough so that what is important where you are may not be where I am - if that makes any sense. I'm thinking the higher voltage vs th higher current.

We are pretty OT here

Yes we are. Thank you for reminding me. It is loosely related as far as the practical noise floor is concerned. (That's my out!) 😀

-Chris