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Old 5th October 2008, 11:42 PM   #31
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Location: Hartford
Quote:
Originally posted by oldeurope
http://www.tubecad.com/2008/09/blog0149.htm

"Like the citizens of New Orleans, I expected much worse. The Big-Easy folk never bore Hurricane Ike’s full wrath; nor did I get the storm of angry e-mail against which I had braced myself, in the wake of my recent Ultrapath blog. In fact, not one reader complained. Instead, I received several e-mails with subject lines along the following lines: “Ultra-pathetic” and “Ultra-waste-of-time.” The sentiment was the same in all of them: “Thank God. I thought I was alone."
I generally think TCJ is pretty good, but I think that's a really disappointing article. First, he analyzes a circuit that he calls an Ultrapath,

Click the image to open in full size.

but which isn't.

Then he analyzes an actual Ultrapath circuit, about which he sets up a straw-man argument, and says the circuit is terrible. The straw-man, in this case, is that the Ultrapath has poor PSRR. Of course, we all know it has poor PSRR and requires some real work on the power supply, but the article assumes we all have noisy power supplies, and that the circuit is thus a poor choice.

He leaves out that the signal path is shortened, that there are less caps in the signal path, that Western Electric used this circuit in their repeater amplifiers, and that lots of reasonable people actually like it. And, I think it is worth noting that beneath the letter entry where he, using the time honored journalistic method of finding someone to say what you want to say, declares the U-P to be “Ultra-pathetic”, he tries to sell his own circuit boards. This is, of course, fine, but worth noting. Anyway, as I say, a disappointing article.
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Old 6th October 2008, 04:54 AM   #32
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Join Date: Mar 2004
Location: Medford, MA
Default On going commercial....

The only people who seem to have a viable business are the
specialized parts builders: namely, the transformer winders, and
from what I know, some of them do it on the side because they
are independently wealthy from other ventures, or, they have OTHER
electronics business that they do. Look at Hammond, look at Edcor,
they clearly win at this game because they have diversified customers
in related markets to keep them going. The audio transformer business is a side-line that keeps their reputation high, and provides from some interesting variety of workload for their design team and their manufacturing teams.

TubeCAD was AWESOME for its analysis... For an science guy like me, tubecad was a set of "case studies" in how to trade off design constraints to certain requirements.

The Solid State side of the game is quite interesting... Despite
how "anti-sand" people are: There are some terrifically well-thought
out op-amp chips out there, as well as some very exciting A/D and D/A stuff. Ontop of that, it's now entirely possibly to do highly adaptive
digital processing and equalization - because you can get processor
chips like SHARC that can pump out GFLOPs for $20.00.

The problem with digital is its IMPOSSIBLE to use current production chips... They are all SMD and require very highly specialized soldering tools. Further, some of these things are so fast, they require very specialized layout on PCBs. The chips are cheap, but
they are no longer accessible to kitchen-table builders ; not unless
you are willing to pay hundreds of $$$ for small qty PCB fab and
then try to solder them up by hand.


-- Jim
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Old 6th October 2008, 06:49 AM   #33
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Join Date: Jun 2007
Quote:
Originally posted by dsavitsk
I generally think TCJ is pretty good, but I think that's a really disappointing article. First, he analyzes a circuit that he calls an Ultrapath,

Click the image to open in full size.

but which isn't.

Then he analyzes an actual Ultrapath circuit, about which he sets up a straw-man argument, and says the circuit is terrible. The straw-man, in this case, is that the Ultrapath has poor PSRR. Of course, we all know it has poor PSRR and requires some real work on the power supply, but the article assumes we all have noisy power supplies, and that the circuit is thus a poor choice.

He leaves out that the signal path is shortened, that there are less caps in the signal path, that Western Electric used this circuit in their repeater amplifiers, and that lots of reasonable people actually like it. And, I think it is worth noting that beneath the letter entry where he, using the time honored journalistic method of finding someone to say what you want to say, declares the U-P to be “Ultra-pathetic”, he tries to sell his own circuit boards. This is, of course, fine, but worth noting. Anyway, as I say, a disappointing article.
Regardless of what the Ultrapath actually is and , what Broskie said had to do with referencing the cathode capacitor to B+ instead of ground. In all of these cases he is correct.

Please elaborate how the signal path is shortened, or how there are less caps in the signal path. I believe you are incorrect, although I would love to be proven wrong here.
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Old 6th October 2008, 07:09 AM   #34
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Join Date: Mar 2008
Thumbs up Forming a local circuit ...

Quote:
Originally #33 posted by dsavitsk


...

He leaves out that the signal path is shortened, that there are less caps in the signal path, that Western Electric used this circuit in their repeater amplifiers, and that lots of reasonable people actually like it. And, I think it is worth noting that beneath the letter entry where he, using the time honored journalistic method of finding someone to say what you want to say, declares the U-P to be “Ultra-pathetic”, he tries to sell his own circuit boards. This is, of course, fine, but worth noting. Anyway, as I say, a disappointing article.
Thanks for your post, dsavitsk.
The 'signal path' goes from input to output.
Forming a local signal (current) loop in the output circuit is the most important aspect here.
I think this is what you wanted to point out. See the red loop link.


Kind regards,
Darius
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Old 6th October 2008, 10:04 AM   #35
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Join Date: Mar 2008
Default #33

Quote:
Originally #33 posted by Cauhtemoc

Regardless of what the Ultrapath actually is and , what Broskie said had to do with referencing the cathode capacitor to B+ instead of ground. In all of these cases he is correct.

...
Hello Cauhtemoc

Please note that there is no need for a cathode capacitor.
The "ultrapath cap" is the last smoothing cap.
Conventional "ultrapath" SE schematic

Quote:
Originally #33 posted by Cauhtemoc

...
Please elaborate how the signal path is shortened, or how there are less caps in the signal path. I believe you are incorrect, although I would love to be proven wrong here.
See post #34

Kind regards,
Darius
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Old 6th October 2008, 11:08 AM   #36
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Default Re: #33

Quote:
Originally posted by oldeurope
Please note that there is no need for a cathode capacitor.
The "ultrapath cap" is the last smoothing cap.
Call it what you like, but the "ultrapath cap" you speak of is nonetheless a cathode bypass capacitor, it just connects to B+ instead of ground.

Quote:
Originally posted by oldeurope
See post #34
What the "ultrapath cap" does is to move the B+ capacitor from the output loop to the input loop, so while the output loop becomes shorter, the input loops becomes longer. It is very possible that this is preferable sonic wise, but the signal path is nonetheless the same length, and there just as many capacitors included.
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Old 6th October 2008, 01:43 PM   #37
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Default #36

Hello Cauhtemoc,

Please have a look at the schematic in #35
The cathode is grounded,
the input loop does not become longer.

Do you need a simplified schematic for better reading?

Kind regards,
Darius
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Old 6th October 2008, 08:39 PM   #38
tomsyl is offline tomsyl  United States
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Join Date: Mar 2005
Location: Hawaii
Default Aactually, I am just Watson's dog.

Quote:
So blogs made after my thread post are useful to prove my motives? You got me there, Holmes! What detective work!
I've followed TubeCad regularly, and have seen a similar level of quality throughout. Perhaps the trolling remark was off-base, in which case I retract it. But I simply haven't seen the decline in quality there that you have. IMO it continues to be one of the best sites on the net for tube fanciers; if there's someplace like it only better, I hope someone will let me know.
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Old 6th October 2008, 08:57 PM   #39
tomsyl is offline tomsyl  United States
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Join Date: Mar 2005
Location: Hawaii
Default About the Ultrapath

First, I've had the opportunity to meet Jack Elliano twice, talk to him (actually, listen to him) at length and see his workshop; I think he is a brilliant guy w/r/t transformers, of which I've bought several. (He also rebuilds Ampex tubed tape recorders.) And in fact I did buy the Ultrapath iron from him and built a unit. At his recommendation, the power supply is on a separate chassis because the output transformers are extremely susceptible to hum.

We all know that Broskie is a fanatic when it comes to PSRR, thus the Aikido. I spent an inordinate amount for those big HV caps in the Ultrapath design, and will say that the result (assuming the preamp is nowhere near an AC line cord and the PS is a foot or more away from it) is very good, handily beating a jury-rigged circuit built on the MFA luminescence linestage plans. But . . . three other preamp designs (the Berman one from Sound Practices, an 801 running into an SE output trans from Magnequest, and a very simple choke-loaded 26 design with about seven parts) all sound as good or better, and only one of them has a transformer output. So from my own personal experience, the Ultrapath is not the ne plus ultra that some describe it as being.

The final comparison will be the Aikido to the Ultrapath; I bout a 5687-based kit but haven't had time to assemble it yet.
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Old 7th October 2008, 06:58 AM   #40
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Join Date: Jun 2007
Default Re: #36

Quote:
Originally posted by oldeurope
Hello Cauhtemoc,

Please have a look at the schematic in #35
The cathode is grounded,
the input loop does not become longer.

Do you need a simplified schematic for better reading?

Kind regards,
Darius
If the cathode is grounded, the ultrapath capacitor comes in parallel with the B+ capacitor, and is effectively just another B+ capacitor.

The schematic above is very messy, please post a simpler version if you have one.
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