john curl said:
A ground plane gives a good 0 Volt reference, but what do you think about the capacitance between the different (audio)tracks to this ground plane? For Teflon boards it might not be a problem, but the dielectric in FR4 is not that good.
Also, if the positive rail, the negative rail and ground were planes, they would form capacitors.
Rolv-Karsten
OK, I knew that as far as the CTC designs are concerned. I thought maybe you had done it on your previous designs and had picked up an interesting thing or two over the years.john curl said:
Thanks, Mike.
Michael, I refer you to p186 of 'Noise Reduction Techniques in Electronic Systems ' 2'nd edition by Henry W. Ott Figure 6-23 "Experimental results of tests to determine magnetic field attenuation of conductive sheets in near field." For example.
You might read up on it sometime. Of course, it will not block a DC field like a magnet.
You might read up on it sometime. Of course, it will not block a DC field like a magnet.
john curl said:
Sorry I did neither conclude nor ask your opinion. 😉
I do mostly digital designs myself, and here ground and power planes are mandatory. Care has to be taken with bypassing capacitors etc etc. But as long as the gates switches when the should, and care is taken with ground planes, return paths, etc. Also, with the fast rise times of modern digital IC outputs, traces must be considered as transmission lines. All this is quite well known.
But when designing analogue circuits, especially for audio, I would believe care must be taken. For example, if audio traces are placed close to a ground plane this will give a capacitance to groud. And albeit a small capacitor, a capacitor with FR4 as dielectricum is probably not a very good capacitor for high end audio. But with Teflon this capacitor could be a rather But personally I would be careful with audio tracks close to a voltage (+ or -), I would prefer that the audio traces are closest to ground.
Best regds
Rolv-Karsten
Hi, John,
I read carefully what R-K Ronningstad said... If I remember fine, the crosstalk was your first enemy in Audio... With some 2.2 resistor in the JC-2 power supply path that Mark Levinson put in order to have some degree of protection to the Darlingtons...
IMO, the problem that R-K puts is in the same league : does, in your experience, the capacitance between PCB tracks degrade the crosstalk far enough to be audible (even if barely or not measurable).
And further, in the same direction as R-K, are the Teflon boards such better value that you choosed to have them in the Blowtorch ? All engineers I spoke with said that Teflon is worth at very high frequencies, but are unimportant at low frequencies... (and that the procedure to make Teflon involves such nasty odours that production is quite low Hence the price...). And if I read right, the Blowtorch is only 350 Khz bandpass... So, no HF...
Did I (we ?) missed something from the PCB material quality piint of view ?
Jbaudiophile
I read carefully what R-K Ronningstad said... If I remember fine, the crosstalk was your first enemy in Audio... With some 2.2 resistor in the JC-2 power supply path that Mark Levinson put in order to have some degree of protection to the Darlingtons...
IMO, the problem that R-K puts is in the same league : does, in your experience, the capacitance between PCB tracks degrade the crosstalk far enough to be audible (even if barely or not measurable).
And further, in the same direction as R-K, are the Teflon boards such better value that you choosed to have them in the Blowtorch ? All engineers I spoke with said that Teflon is worth at very high frequencies, but are unimportant at low frequencies... (and that the procedure to make Teflon involves such nasty odours that production is quite low Hence the price...). And if I read right, the Blowtorch is only 350 Khz bandpass... So, no HF...
Did I (we ?) missed something from the PCB material quality piint of view ?
Jbaudiophile
Most inputs here, criticising the Blowtorch design, are half-baked assumptions. Folks, you must understand that we have been using ground planes in our circuits for 25 years. Dick Marsh was first to introduce me to ground planes, but my Vendetta and CTC associate and my personal friend, Carl Thompson, is an expert in this field. He has worked for Intel, HP, and many other firms on fast, difficult, complex layouts. Decades ago, he used a 1 million dollar computer, now he uses an advanced PC to do the layouts. We have NOT used FR-4 except for power supply boards for the last 25 years as well. The working impedances are so low that the slight added capacitance is not very important.
Many of you have not looked up info on shielding properties of aluminum. You should, before you make comments.
Many of you have not looked up info on shielding properties of aluminum. You should, before you make comments.
John, thanks!
Sorry for putting such a plain question, it wasn't my intention to annoy you, with that book in your collection obviously you surely have the facts! Actually I intentionally put my question that way because I wanted some explanations, but I see afterwards my previous question should have bean better constructed, once again I'm sorry for that!
I know theres Eddy current losses in aluminum, maybe it's not enough for 50/60 Hz but probably your box is enough thick for higher frequencies.
How thick is the BT box?
Cheers Michael
Sorry for putting such a plain question, it wasn't my intention to annoy you, with that book in your collection obviously you surely have the facts! Actually I intentionally put my question that way because I wanted some explanations, but I see afterwards my previous question should have bean better constructed, once again I'm sorry for that!
I know theres Eddy current losses in aluminum, maybe it's not enough for 50/60 Hz but probably your box is enough thick for higher frequencies.
How thick is the BT box?
Cheers Michael
john curl said:
John, sorry if you feel my comments as critisism of your design. It was more general comments/question regarding layout and use/no use of ground planes. Maybe I should not have posted it here as it was a more generel post than on your Blowtorch preamp. I do not know much about this design, so I am not in a position to critisise at all.
Thanks for the comment about the slight added capacitance, BTW.
And I agree with you on the use of aluminium.
RK
John...
John, this thread seems to be much more about theory and execution than actual results. I am not an engineer (shades of Richard Nixon!...sorry in advance to the non-Americans for the reference), and therefore really can't participate in the highly technical discussions. I will, however, offer my impressions of how the thing actually sounds.
I have had the Blowtorch for precisely 4 days now and can say that, in my system, it is without reservation the finest preamp that I have ever heard. It is completely without self-noise and timbral accuracy is extraordinary - fully the equivalent of any of the best tubed units. Bass pitch definition is outstanding, of course. Most astonishing is the ability to sculpt 3D images in space. I suspect that this characteristic is strongly related to the astounding resolution and to the extremely quiet background. All in all, the Blowtorch simply reproduces music on a higher plane than anything else in my experience.
John, this thread seems to be much more about theory and execution than actual results. I am not an engineer (shades of Richard Nixon!...sorry in advance to the non-Americans for the reference), and therefore really can't participate in the highly technical discussions. I will, however, offer my impressions of how the thing actually sounds.
I have had the Blowtorch for precisely 4 days now and can say that, in my system, it is without reservation the finest preamp that I have ever heard. It is completely without self-noise and timbral accuracy is extraordinary - fully the equivalent of any of the best tubed units. Bass pitch definition is outstanding, of course. Most astonishing is the ability to sculpt 3D images in space. I suspect that this characteristic is strongly related to the astounding resolution and to the extremely quiet background. All in all, the Blowtorch simply reproduces music on a higher plane than anything else in my experience.
JC, one question please...
Could you please offer your opinion on the possibility of driving my JC1s with very long (6-7m) balanced interconnects from the Blowtorch? This is not something that I HAVE to do, but is an option. Thanks very much in advance.
Could you please offer your opinion on the possibility of driving my JC1s with very long (6-7m) balanced interconnects from the Blowtorch? This is not something that I HAVE to do, but is an option. Thanks very much in advance.
Geophysicist:
Thank you for posting your impressions. It would be great if you could take a photo or two (or as many you wish 🙂 ) of the BT interior (preferably at a higher resolution than at the official site). A pic of the power supply would be also more than welcome. This discussion has stalled a bit and I believe I'm not the only DIYer here who would appreciate some fresh hands-on info instead of talking in circles.
Regards,
Milan
Thank you for posting your impressions. It would be great if you could take a photo or two (or as many you wish 🙂 ) of the BT interior (preferably at a higher resolution than at the official site). A pic of the power supply would be also more than welcome. This discussion has stalled a bit and I believe I'm not the only DIYer here who would appreciate some fresh hands-on info instead of talking in circles.
Regards,
Milan
Hi Milan,
Why would someone take apart a brand new, expensive item and possibly void the warranty? I'm sure Geophysicist is perfectly happy not knowing exactly what is in the box for now.
For us, many hints and good discussions from John himself. More than you get from some designers! If you bought one, that would save you at least that much in development time. 😉
I couldn't help but notice that John does not sell this as a kit.
-Chris
Why would someone take apart a brand new, expensive item and possibly void the warranty? I'm sure Geophysicist is perfectly happy not knowing exactly what is in the box for now.
For us, many hints and good discussions from John himself. More than you get from some designers! If you bought one, that would save you at least that much in development time. 😉
I couldn't help but notice that John does not sell this as a kit.
-Chris
JC1s
Certainly, but please make sure that you take my comments in context. I have auditioned them extensively only in my own system, and have heard them in two others (one of which was Bob Crump's driving his Rockports).
My speakers are Sound Lab A-1s, which present an unusual and difficult load. I was having difficulty finding a satisfactory amp to drive them. My last amp before the JC1s, and the one which had done the best job up to that point, was the Rogue Zeus, a huge, heavy 6550-based tube. You can see that here if you're not familiar with it:
http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1130505439&view
I REALLY need to update those photos. A lot has changed!
Anyway, it was clear that 1) the Zeus was running out of power on some music, even with 225 watts (pentode mode) on tap, and 2) just like every other transformer-coupled tube amp in existence, bass definition was not up to par with the best solid state designs. I had heard through a Sound Lab owners group that the JC1s drove the speakers beautifully. In particular, a Sound Lab dealer here in the US called Brian Walsh was a strong advocate. Not too long afterwards, Bob Crump sadly passed away. Bob's brother asked one of Bob's friends (also an audio dealer) to sell off his gear for the benefit of his estate. I purchased his JC1s. I found out afterward that Bob had modified this pair a bit (silver wiring and IEC connector is my understanding), but I have no way of knowing the exact effects vs. stock form. Perhaps John has a better idea on that.
Anyway, sorry for the long preamble. The JC1s - once again, in my system - have all of the positive attributes of the best solid state gear, with few, if any, of the negatives that often come with territory. Let me put this in perspective. I have not owned a solid state amp in nearly 20 years. The JC1 is the first to lure me away from the very real strengths of well-designed tube gear. System synergy no doubt plays a major role. These amps sound as though they were designed to drive Sound Labs.
Having said all of that, when I first placed the JC1s into my system, my reaction then - as now - was "that is truly excellent". On the other hand, placing the Blowtorch in the system provoked a reaction more like "somebody please pick my jaw up off of the floor because I simply can't move". In other words, the JC1s were not quite as revelatory as the Blowtorch. What does that mean? Well, possibly that the contrast between the Aesthetix Janus and the Blowtorch was much larger than that of the Zeus and the JC1s. I tend to discount this, as I believe then as now that the Janus is a very fine preamp. More likely, I think, is that CTC was required to build to a reasonable price point. Who knows what the outcome might have been if cost had been no object, as with the Blowtorch. And quite a cost it would have been, I imagine!
The short answer for those who have skipped down to this after becoming bored with all of the preceeding: I think the JC1s are superb, not only as value for money, but under any criteria.
Certainly, but please make sure that you take my comments in context. I have auditioned them extensively only in my own system, and have heard them in two others (one of which was Bob Crump's driving his Rockports).
My speakers are Sound Lab A-1s, which present an unusual and difficult load. I was having difficulty finding a satisfactory amp to drive them. My last amp before the JC1s, and the one which had done the best job up to that point, was the Rogue Zeus, a huge, heavy 6550-based tube. You can see that here if you're not familiar with it:
http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1130505439&view
I REALLY need to update those photos. A lot has changed!
Anyway, it was clear that 1) the Zeus was running out of power on some music, even with 225 watts (pentode mode) on tap, and 2) just like every other transformer-coupled tube amp in existence, bass definition was not up to par with the best solid state designs. I had heard through a Sound Lab owners group that the JC1s drove the speakers beautifully. In particular, a Sound Lab dealer here in the US called Brian Walsh was a strong advocate. Not too long afterwards, Bob Crump sadly passed away. Bob's brother asked one of Bob's friends (also an audio dealer) to sell off his gear for the benefit of his estate. I purchased his JC1s. I found out afterward that Bob had modified this pair a bit (silver wiring and IEC connector is my understanding), but I have no way of knowing the exact effects vs. stock form. Perhaps John has a better idea on that.
Anyway, sorry for the long preamble. The JC1s - once again, in my system - have all of the positive attributes of the best solid state gear, with few, if any, of the negatives that often come with territory. Let me put this in perspective. I have not owned a solid state amp in nearly 20 years. The JC1 is the first to lure me away from the very real strengths of well-designed tube gear. System synergy no doubt plays a major role. These amps sound as though they were designed to drive Sound Labs.
Having said all of that, when I first placed the JC1s into my system, my reaction then - as now - was "that is truly excellent". On the other hand, placing the Blowtorch in the system provoked a reaction more like "somebody please pick my jaw up off of the floor because I simply can't move". In other words, the JC1s were not quite as revelatory as the Blowtorch. What does that mean? Well, possibly that the contrast between the Aesthetix Janus and the Blowtorch was much larger than that of the Zeus and the JC1s. I tend to discount this, as I believe then as now that the Janus is a very fine preamp. More likely, I think, is that CTC was required to build to a reasonable price point. Who knows what the outcome might have been if cost had been no object, as with the Blowtorch. And quite a cost it would have been, I imagine!
The short answer for those who have skipped down to this after becoming bored with all of the preceeding: I think the JC1s are superb, not only as value for money, but under any criteria.
Milan...
I'm sorry, I have no intention of opening up the case(s) unless absolutely necessary. My curiousity of what the guts look like is satisfied by the photos on the TG Audio site.
I'm sorry, I have no intention of opening up the case(s) unless absolutely necessary. My curiousity of what the guts look like is satisfied by the photos on the TG Audio site.
Anatech,
Why ?
Perhaps because Geophysicist Blowtorch came with no Vendetta phono board, and John perhaps doesn't retrofit any... I just suggest Geophysicist to ask John first, and then the Forumers... Perhaps that some can help (hope so !).
Anyway, many of us just had a pretty good impression of John's work on the Line, but like me think that the PSU is still much more interesting : a full piece of the cake !... For sure, nothing as usual... Go back to Darry's first PSU proposals... and note the head cap position.... Then switch to TG-Labs pics... Nothing to see ?
I just admire more John's tricks.... "A very astute engineer..." said to me Bob Crump... From my early works on rethinking it, and with time goes, nothing is like the data books comment. and where I assumed the parts were... Burned my eyes to catch the missing trick and experiment with. Cloning job ? Oh, absolutely...
Will do that even with rotten pics... Perhaps that John will ever publish a book with all his tricks, as I suggested to pass him to William Sommerwerck... But doesn't planned that at the time..
Very, very, very... sorry for ! So, I have just to go my own way...
Jbaudiophile
Why ?
Perhaps because Geophysicist Blowtorch came with no Vendetta phono board, and John perhaps doesn't retrofit any... I just suggest Geophysicist to ask John first, and then the Forumers... Perhaps that some can help (hope so !).
Anyway, many of us just had a pretty good impression of John's work on the Line, but like me think that the PSU is still much more interesting : a full piece of the cake !... For sure, nothing as usual... Go back to Darry's first PSU proposals... and note the head cap position.... Then switch to TG-Labs pics... Nothing to see ?
I just admire more John's tricks.... "A very astute engineer..." said to me Bob Crump... From my early works on rethinking it, and with time goes, nothing is like the data books comment. and where I assumed the parts were... Burned my eyes to catch the missing trick and experiment with. Cloning job ? Oh, absolutely...
Will do that even with rotten pics... Perhaps that John will ever publish a book with all his tricks, as I suggested to pass him to William Sommerwerck... But doesn't planned that at the time..
Very, very, very... sorry for ! So, I have just to go my own way...
Jbaudiophile
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