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GregBKC,You suggested the use of a 6CM4 as a 400mA damper diode. That number seems to be a triode. Do you recall the actual number? I've read my newest Sylvania manual and can't find any damper diode greater than 350mA.
Thanks in advance,
Stuart
"You can never go fast enough" James Taylor in Two Lane Blacktop
Follow Ups:
6CM3, 6DQ3: 400 mA. 6DQ3A: 450 mA
Thanks. Now let me see which ones are commonly available.Stuart
"You can never go fast enough" James Taylor in Two Lane Blacktop
... why just as soon as he can pull himslf away from listening to music with his new highly-improved 245 amp, now reconfigured as Low HY, Low DCR, Low C and good wiring. He uses 5U4GBs now, no more TV dampers with cathodes.
Enough already about your pet 'Low DCR' subject.By the way, the 5U4 has a MUCH higher voltage drop (54 volts at 300 ma) than a 6CM3 damper diode (10 volts at 350 mA), which is quite impressive. If low DCR is of such importance, than a damper diode may be a better choice. The rectifier is in series with the power transformer - what's the point in having a power transformer with less than 10 Ohms DCR if the rectifier has a ESR (equivalent series resistance) of 180 Ohms (54 volts / 300 mA)?
Mike, I agree with your points. But I also have to say that I find myself liking the sound of the 5u4 rectifiers, especially the older ST shaped bottles. Others are better on paper but the sucker does tone right to my ears.
Hi Russ,Sure I'll respond.
(1) Jeff Medwin IS NOT anymore just LOW DCR only !! Yes I started with low DCR, but midway last year I reported on Low C and Low HY too, with my friend's wrtings, posted under my moniker. Now, ( several weeks ago ) I was able to TRY all three together on Greg's 245 SEer, and I NOW have HEARD that my friend Dennis is correct, all three are sorely needed if ya wanna get an amp to truly boggie big time !!
(2) Look at the construction of a Damper diode versus a 5U4. The damper diode has a nice SLOW ramp up, due to its cathode, and it also has lowZ. But wait, the lowly 5U4 has NO cathode, its a filamentary rectifier, meaning it can do INSTANTANEOUS music events better than any cathode diode. Gee, don't some of us swear by filamentary triodes sounding better.... how about filamentary diodes over cathode diodes Russ??? No one ever mentions this up here.
When you get into Low DCR, Low HY, Low C power supplies, which have less storage time than everyone's conventional archaic supplies, the instantaneous respose of filamentary diodes become more of a factor, and is more easily appreciated. Conventional supplies, by comparison, do NOT serve the music, because they get it severly "out of time" and certainly "off-kilter", due to their slugishness, etc. from too high a DCR, HY and C in the design.
So Russ, buy two Triad C-40Xs from Allied Electronics, under 11 dollars each, and two 40 uF ASC oils from Mike Percy, under 13 dollars each, and LISTEN to that on your output stage. Assume VDC = 1.35 times VAC of your PT trannie, minus tube rectifier drop.
Want a lower impedance filamentary diode, how about a 5V3? For long term health and safety, avoid mercury vapor filamentaries of any type in your home.
Hope my response makes sense to you, Russ. Buy those parts I described, and keep final voltages similar !!
semiconductor diodes would be the best. They are very 'fast' and have lower voltage drop than a tube rectifier.I believe the argument for the use of directly heated triodes versus indirectly heated triodes is based on linearity, DHTs, in general, being more linear than IDHTs. This is measureable and verifiable.
A tube rectifier is a non linear device; that is, the voltage drop is not a linear function of current draw. Just look at the output voltage versus load current plots for a 5U4 (DH) and a 5AR4 (IDH). They are not straight lines. Actually, the 5AR4 is better in this respect than the 5U4. Now throw in the affect of load current on a LCLC supply that does not meet critical inductance criteria and wow!
You state," Now throw in the affect of load current on a LCLC supply that does not meet critical inductance criteria and wow! "
The important point is, LCLC supplies that DO MEET critical inductance are TOO SLOW for audio reproduction, they jumble and skew the MUSIC, are all out-of-time !!!
Don't argue, order the inexpensive parts I told Russ about and LISTEN !!And yes, Solid State diodes can be used in a world class amp MikeyB.
.
You said: "The damper diode has a nice SLOW ramp up, due to its cathode, and it also has lowZ. But wait, the lowly 5U4 has NO cathode, its a filamentary rectifier, meaning it can do INSTANTANEOUS music events better than any cathode diode."That is completely false. The fact that the cathode has a higher thermal mass and consequently higher thermal lag has no effect of the electrical performance once the cathode is hot.
Jeff, you are entitled to believe in whatever you want but please don't post "reasons" for your beliefs which have no basis.
if you do not break the glass of a Hg tube, while it is hot, it is safe. Keep them under protective cover, so you cannot accidentally break the bulb.
BTW, most tube testers have Hg rectifiers........ even portable military types where safety is paramount. The secret is not to expose them to physical damage.good luck,
I don't think its as simple as you think it is. See URL :Jeff Medwin
- http://db.audioasylum.com/cgi/m.mpl?forum=tubediy&n=102582&highlight=mercury+dennis+jeff&r=&session= (Open in New Window)
If mercury somehow leaks through the glass, wouldn't that mean that all of those old mercury thermometers out there are reading low? Ought to be able to quantify things by recalibrating an old (previously well calibrated) thermometer of know age.
Thanks, Jeff. Puts things in a new perspective.
In the lab I use microscopes that have mercury vapor lamps, to generate UV. They are in an airtight metal casing. Eventually, the %$#$@# microscope manufacturers do not even warn about the hazards of hot mercury vapors.
Placing a (user-) protective cabinet might be a solution for the experimenter......
There are loads of stories about the health effects of Mercury.
You can find out FACTS about Hg from this reprint from a medical journal:
http://www.cmaj.ca/cgi/reprint/176/1/59
In brief: Hg toxicity has devastating effects. The body gets seriously messed up. Organic Hg absorbs completely orally(and breathing the vapors, too). Inorganic Hg absorbs only at extremely low levels through the gut.
The proof for that is the inorganic Hg found in dental amalgam. That leaks continually Hg out, yet people are fine with it, even after having amalgam in their teeth for decades.
You have to be much more cautious about fish that are on the top of the food chain, like shark, tuna, swordfish. They accumulate ORGANIC Hg, and it is advised not to ea any of these more than once a week. If you are pregnant, you must NOT eat any of these fish. It can result in brain defects in the fetus. Sorry, I was lazy to look up references for these.
good luck,
Janos
...why not do some real research to support your assertions. Dennis' ramblings don't count as reaserch. Get something independent.
Hard to site other references when only Dennis has brought it up, through his direct experiences.Who did Einstein reference to when he said E=MC squared?? No one. Does that make him irrelevent?? And how many people understood it initially??
Jeff Medwin
Albert, Jeff and Dennis in the same paragraph!I believe there are some major misconceptions here. Einstein’s theories were built upon the solid work of others. His theories were also thoroughly reviewed and largely validated by his peers. And Albert wasn’t always right either. His reluctance to accept quantum theory is well documented.
Dennis’ claim about mercury migration thru glass are based on who-knows-what and appear to remain unvalidated by anyone/thing at this time. If mercury migration thru glass is an issue, it should be well documented in the scientific and industrial literature of the past century. It should also be easy to verify experimentally. Therefore, a (very) little research should be able to verify everything and be citable. Since you and Dennis make the novel claim, you and Dennis should do the research or develop the experiment that proves the claim. Publish the details of your research or experiment and others will be able to verify it independently. Without this your claim is nothing more than unsubstantiated opinion.
As an aside, realize that if what you and Dennis claim is correct and becomes the accepted truth, the fluorescent lighting industry will be destroyed, worldwide energy use will increase and global warming will be accelerated putting human existence on the brink. Who would’a thunk it?
Actually, it seems to me like you and Dennis are making all this up as you go. You also seem to be caught in the feel-good trap of believing that all ideas and concepts are equally valid until proven otherwise. Tough as it may be to accept, the ideas of some are more valid than the ideas of others.
muhahahahaha
I am in no way disagreeing with your observation that a 5U4 'sounds good'. I am just pointing out the inconsistency of pushing for the lowest possible DCR and not using a rectifier with low voltage drop as well. Maybe the 'sound' of a amplifier is not entirly related to low DCR - who knows?
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