tube fanatic
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Posts posted by tube fanatic
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If you don't mute the preamp, but simply turn the volume all the way down, do you still get the popping? Also, is the popping present if nothing is connected to the amps' inputs? Popping at turn off is often related to arcing in the on/off switch which is, of course, amplified and carried through to the speakers. The fix is quite simple if you find the popping bothersome.
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The photo didn't attach- will try again later!
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Some pictures of the arrangement you are currently using would be very helpful in coming up with a workable solution.
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We "old timers" who have been in the tube amp design field for 50 or more years have long realized that a practical design goal is a flat frequency response between 35-40 Hz and 13-15 kHz! Extending beyond that range is usually inaudible to most listeners and adds greatly to the cost of the required output transformers. Some may disagree with this philosophy, but my experience has demonstrated its validity. Good luck with your quest though!
Maynard
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Does the preamp use a solid state or tube rectifier? If the latter, putting the phono board above the preamp board would subject the components to fairly excessive amounts of heat which is not a good idea (and would also restrict the ventilation of heat generated by the rectifier.) Also, rectifiers such as a 6X4 would require very tall standoffs for the phono board since the tube is around 2.5" high. So, the point is that it isn't a good idea to stack them in that fashion. Otoh, if you can place the phono board under the preamp board you may be ok as the 12AX7s generate very little heat. And the enclosure needs to be very well ventilated of course. Good luck!
Maynard
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There's no need to spend a fortune on a multimeter. Autoranging types are abundant, and are worth having since you won't have to select the measured range. MCM electronics has quite a few of their Tenma brand meters which are very reliable and about as good as anything else out there. Fluke is fine also, but probably not worth the additional expense.
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I heard this group for the first time yesterday. Kids didn't have that kind of talent when I was that age! The strange part is that I live only about 10 miles from them................
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Check out this Samsung promotion. I can't believe they're using tubes in the preamp section!!! Seems like they're trying to corner multiple markets with this offering...........
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A friend just sent this. Apologies if someone else has posted it previously.........
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Regarding difficulty in soldering on some pc boards, terminals, etc., it is usually due to residues which were not removed during manufacturing. The simple and effective solution is to use a tiny amount of one of the Kester no-clean flux offerings which are available from most electronics suppliers. This type of formulation does not have to be removed after soldering and makes for a really nice super-shiny, and very electrically sound connection. We used this at the industrial power supply company on all pc board connections to ensure proper electrical contact.
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Here's another perspective on the acquisition. I had no idea that Fine Sounds also owns AR and Wadia (I don't know how the current Wadia products are, but my friend's Model 6 from 1992 can hold up against any other CD player that I've ever experienced)!
http://www.cepro.com/article/why_did_fine_sounds_acquire_mcintosh/
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And now we can have genetically engineered milk.
http://vitals.nbcnews.com/_news/2012/10/01/14173274-cow-named-daisy-makes-reduced-allergy-milk?liteAdd vaccines to the list also:
http://articles.mercola.com/sites/articles/archive/2012/10/02/vicky-debold-on-gmo-vaccines.aspx
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See also the documentary film "The World According To Monsanto".
The more time goes by, the more I am glad we didn't have children.
Another concern regarding kids is the huge number of forced vaccines they must have in spite of safety concerns being raised. Many states are eliminating conscientious objections for any reason; and schools in California may now administer Gardasil to kids in certain age groups (in spite of some frightening safety concerns) without parental notification or permission! Imagine your healthy child suddenly dying (documented with Gardasil) without your having any idea that they were given this poison. On top of that, vaccine manufacturers are totally shielded from liability (thank you Supreme Court) in the event any kind of adverse reaction occurs from a "required" vaccine. So, there's no incentive for them to turn out a safe product knowing that they can't be sued. Just lovely.................................
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In India, thousands of sheep have died after eating genetically modified
cotton plant stubble, even though grazing on nature's cotton plants is common
and produces no harm. Genetically modified corn was also implicated in
cow deaths in Germany, as well as the deaths of horses, water buffalo,
and chickens in The Philippines.Yes, and then there's the psychological side of this whole issue, particularly as it has affected Indian farmers:Issues such as this make one wonder what our politicians are really interested in. When government decides what the population will eat, and doesn't give citizens the choice simply to protect corporate financial interests (possibly their own as well? ie: activities of lobbyists like Jack Abramoff), there's something quite wrong. I won't even get into the fluoridation of municipal water supplies question as I consider that to be nothing more than the government approving the mass poisoning of the population. I believe Portland, OR just approved doing this in spite of the public being against it for the most part. Let's hope that California voters enact the legislation by a huge margin. It will be interesting to see if products sold across the rest of the country will carry the same labeling or if it will be restricted to just the one state. -
While this is about as far removed from audio as possible, it's such an important issue that it's worth knowing about:
Amy, if this violates the forum protocol, please delete it! Maynard
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Apparently more controversy for one of my all time favorite groups:
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Btw, the way the schematic is drawn, G1 and G2 are reversed. Triode operation is present here as the screen is connected at the plate end of the output transformer as opposed to the B+ end as it would be for pentode operation. Deckert does specify a 1k resistor for the triode strapping. Not exactly sure why he goes with such a large value, but possibly to keep things under better control if the screen doesn't track with the plate as it should. But, from the standpoint of controlling possible parasitics, having it there certainly can't hurt.
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How about some under-chassis photos so folks can see just how simple a tube amp can be? It might be fun to have some friends over and ask them how much power they think you're running after hearing the system! Maynard
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Sent to me by an eye doctor friend. We're all aware of potential injury to the body from airbag deployment, but this is the first I've heard about this possibility:
Case of Severe Airbag Related Ocular Alkali Injury 
While airbags have saved many lives and are clearly beneficial overall, sodium hydroxide (NaOH)
powder produced by the inflation reaction can cause significant alkali ocular injury if not irrigated promptly.
This report details a case of severe airbag related ocular alkali injury as a way to bring attention to the need for
prompt ocular irrigation following motor vehicle accidents (MVA) with airbag deployment.
A 47-year-old man was involved in a MVA with airbag deployment in a rural setting. Attention was paid to several
other life-threatening traumatic injuries; however, ocular irrigation was not performed until some six to seven hours
after the MVA. Over the course of six months, airbag-related alkali injury caused severe limbal ischemia, conjunctivalization
of the cornea, corneal epithelial defects, cicatricial scarring, haze and corneal/limbal vascularization despite amniotic
membrane graft.
Awareness of the importance of ocular irrigation following airbag deployment must be raised both in the ophthalmology and
emergency medicine communities.
SOURCE: Barnes SS, Wong W Jr, Affeldt JC. A case of severe airbag related ocular alkali injury.
Hawaii J Med Public Health. 2012;71(8):229–31.
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Yes, WAF ("wife acceptance factor") has always been a major issue when choosing speakers, among other things (an optician friend tells all of his male clientele not to make a final decision on their eyeglass frames unless their wife comes along to approve them!!!) The suggestion above to put them in the room and observe their appearance is terrific! My wife and I actually purchased the house we have lived in for so many years because the family room was perfect for K-horns from both of our viewpoints (sound for me, and appearance for her; we still have the house, but not the K-horns much to my regret!!!) Good luck, and please post with the final decision...............
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Dave, what about the situation in which a person's degree(s) actually works against them? In today's poor employment environment, where people are applying for any job they can perform, many employers will not hire someone whose degree suggests that they are "overqualified" for the job in question. I personally encountered this years ago when I applied for a part-time position with an industrial power supply manufacturer. The owner took one look at my resume, which showed a graduate degree in the optical field, and was ready to negate all of my electronics training and credentials on the basis of that alone. It was only after he pulled out schematics of a number of his designs and began grilling me that he finally relented and said he would give me a try (and was glad that he did!)
And Fjd, I agree with your assessment of the Trumpet article. As with anything, there are different ways to view the situation. Their point, however, about kids getting a useless/costly degree is well taken. I know of so many kids in this community whose parents spent (this is a very wealthy county) upwards of 150 grand or more on their kids' undergraduate education only to have them graduate and take up a "career" at the local sneaker store or supermarket.
I don't see any easy fix for the situation as it currently stands.
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This article presents an excellent overview of the college degree issues that plague our society:
I've received this publication for more years than I can remember, and their assessment of many issues has been quite cogent in my opinion.
Maynard
Tube amps popping on shut down...Arrggg!
in Technical/Restorations
Posted
No, unfortunately, Deoxit won't help in this situation. The fix requires soldering a .1 uf class X2 or class Y2 suppression capacitor across the primary of the power transformer. It will totally eliminate the problem. Where are you located? I'm in NJ and would gladly help you out with this if you're not too far away. Maynard