John Curl's Blowtorch preamplifier

Status
Not open for further replies.
Disabled Account
Joined 2004
Well said, John !

Your own Dennesen JC-80, that is a close cousin of the Blowtorch one, is very tricky indeed and took me several days to be understood fully... ! Caps have their own sonic colourations (you demonstrated it several times), and I have been targetting your own works from mid-80's... So, I understand why you went DC offset correction... and that (perhaps...) Otala is getting some points back in your own reflexion ...

With the notable exception from a couple guys on the forum (Elso, SY, Darry, and a few others (for them, I beg your pardon, guys !)), seems to me that no one has been innovative or input trading... Nor explicative or input seeding...I am in Europe, and perhaps taht we won't ever see a Blowtorch here, but it is here a very hard challenge to have an attempt to "double think" on your design... and a great fun too because of friends ideas fun discuss (and fight !!!!) around it... Can't you think that it is possible ? Just email me back...

Hope that the CES convention was a full success ! Only beeing sad with Bob, who sadly passed week ago... Juts keep care... We need guys like you.

jbaudiophile
 
JB, of course, you are on the right track. On this thread I saw, at first, only criticisms and complaints about a design that is quite serious and successful.
I don't easily give away everything that is important, because I still make a living from designing these products. However, many of the criticisms made of the unit are silly, in my opinion.
 
Its not because the well known designer posted in here that I write my positive impressions with this picture, its just that I’m very pleased to see a wiring topology which doesn’t care to please the eyes of a punctual house cleaner, and which disregards rulers and T-squares ;-))
I especially liked this curved silver input connectors to selector wiring.
I would be very pleased though to learn if it is a 1mm one-ply pure silver wire that is used, as I presumed.

Regards,
Thalis.
 
John, yes, many of the criticisms look patently silly to me, but they arise from people who 1) either cannot afford top-end products (hence, isn't that machined aluminum such a waste of money) or 2) think topologies and components have no or little sonic signature (hence, isn't that machined aluminum such a waste of money).

I, for one, have always appreciated what you've said on these forums. Yay John, and keep up the inspiring work!

:D
 
John Curl
"JB, of course, you are on the right track. On this thread I saw, at first, only criticisms and complaints about a design that is quite serious and successful.
I don't easily give away everything that is important, because I still make a living from designing these products. However, many of the criticisms made of the unit are silly, in my opinion."

It's just like for AKSA, whose owner makes a living : discussions about aspects of the technical conception are impossible, any questions raised are considered as irrelevant or silly criticisms. Are some threads of this forum just reserved to admiration and endless lauding ? It's nice to get money by selling and/or conceiving products but I don't know the aim of their commercialy involved authors in being present on such a forum if they don't expect some design related questions. Happily for me, I've already had positive returns about the points I raised in my previous posts.


Serengetiplains
" [...] cannot afford top-end product"
Air is more sonically innocuous than teflon and I still can afford air.
I saw a photo with Bob Pease using it.

" [...] components have no or little sonic signature"
Golden watches with diamonds give time with a signature : the pleasure to know its price when seeing it.


~~~~~~ Forr


§§§
 
Forr, you're assuming your quippy quotes account for all variables gone into whatever John's design choices you care to criticize? Maybe, just maybe, some sonic, aesthetic, practical or regulatory consideration may have guided a given choice which you, or other criticizers, may not, on first or even further glance, appreciate? Part of the bother, that irks me at least, is just how patently sure some people are when they spout.
 
C'mon now,

Just look at the way it is wired... forget about circuit design. It may be a good circuit, I wouldn't care to find out, but the wiring is all about appealing to the "rich and confused". This is about reaping "old money". "New money" is seldom that foolish.
 
poobah said:
... the wiring is all about ...

Poobah, how do you *know* what you assert? Maybe, just a little smidgen maybe, the wiring is not *all about* (= about nothing else whatever) what you say it's about? The wire, for instance, looks silver, which is an excellent sonic choice in my books, but maybe not yours, which is to say it might smidgenly appeal to not only looks? Just a wee bit maybe?
 
What I know (and many other's) is this,

1. The wiring has large loop areas... this is bad... any magnetic field wandering along just found a nice playpen.

2. The "solid billet aluminum" chassis will do nearly nothing to prevent the intrusion of magnetic fields.

3. The amount of voltage induced in these loops is probably insignificant... why then is the resistance of copper wire significant... and please don't bring up "sonic" sheep dip.

4. The style of wiring leaves much to be desired for another less obvious reason. Who would want to repair this? Of course it's made out of the finest cryogenically abused devices that will NEVER fail. One benchmark of quality products is serviceability.

This is frustrating when you consider that if they chose to use copper wire; maybe they wouldn't have been so inspired to scrimp on every inch of it.

This is as bad as St*** Nug***'s "Holophonic" $1500 power cords.... puleeeze!
 
Ex-Moderator
Joined 2005
That is a really well done piece of equipment! If you take notice of the marking on the volume dials it would seem as though the unit is actually resting on it's top in the photo and the bottom panel is the one that is removable so the enclosure looks seamless when it's upright.

For the price I would expect to see the pots and switches placed closer to the inputs with shafts going to the front panel, but hey I don't plan on buying one either :) Still, it's quite pleasing to the eye and I'm sure to the ear as well.
 
BWRX said:
For the price I would expect to see the pots and switches placed closer to the inputs with shafts going to the front panel,

Well, it seems like the switches and pots are mounted directly to what is left out of that aluminum block. Maybe there is a reason for that. If shafts to be used, they might affect the sound the same way as the famous $500 wooden knob "improves" the sound of the pot.

Besides, placing the switch directly at the inputs, saves only few feet of the silver wire, signal still needs to be routed to the boards and to the pots, and placing the pots directly on the front panel was certainly not coincidential.

I checked the inside of Placette passive preamp. Even although it is passive unit, the box is well damped and a lot of effort went into decoupling a tiny board with resistors and relays from the chassis (with sorbothane pads).

Anybody noticed how RCAs are mounted?
 
Upupa Epops said:
he's really great man

Damn right !
Someone who has been succesfully designing audio circuits for some 35 years is a true legend.
Stuff like the JC1, JC2, JC3 and the awesome ML2's.
And continues with JC80, Diva, Parasounds and CTC's !!
I'd say that is great, someone like that has a reason for doing the Blowtorch as it is.
Only trouble is how to tickle it off his lips.
 

Attachments

  • sota_head_amp.jpg
    sota_head_amp.jpg
    37.4 KB · Views: 8,826
Status
Not open for further replies.