See George's #2 post relating to the Simple SE and cathode feedback: http://www.diyaudio.com/forums/tubes-valves/115697-simplese-amp-multiple-taps-cathode-feedback.html
jeff
No, it's negative feedback. It's about the shortest possible feedback loop that includes the OPT. It works wonders with some OPT's and does nothing with others, and can even make things worse in a P-P amp if the OPT had a lot of asymmetry.
I used the same formula today with the 8 year old that worked well last month with the 10 year old. Rent out the community pool for 3 hours, get 10 pizzas from Pizza Hut, let a bunch of 6 to 10 year olds play a game of "drown grandpa." I spent half an hour walking around in the pool with 4 to 6 of them hanging all over me.
I went digging in my "storage unit" (a derelict mobile home adjacent to the house) and found 5 hamfest quality 6GE5's. I will buy most any sweep tube at a hamfest subject to the following criteria. A loose tube without a box that I don't have a bunch of, but don't really need, that looks OK, must cost $1 or less. A "NIB" sweep tube, that looks like it hasn't been used, $2 if I don't really need it, $3 to maybe $5 if there are several, all look the same, and something that I know to be useful. I have collected hundreds of sweep tubes over the years doing this, some for as little as a quarter each.
I know that there are some 6AV5's and some 12AV5's in there too, but I didn't have time to search for them.
There are at least 5 different versions of the 6LW6 in two different bottle diameters with different sized winglets.
The 6LW6 is rated for 40 watts of plate dissipation. The skinny version without the winglets will start to show red plate in the 50 to 55 watt range. The fat bottled version with the small winglets starts to show red in the 60 to 65 watt range. There are two versions in the large bottle with huge wings. The biggest version doesn't show red until over 90 watts.
Today marked the first time that any tubes have glowed in this new house......they were 6GE5's. I had 5 X 6GE5's that were "NIB".
Out of 5 tubes there were 3 different constructions. There were two RCA branded tubes that were made by RCA, An RCA branded tube that was made by GE, An RCA branded tube that was made by Sylvania, A Sylvania that was made by Sylvania. All appeared new.
I had discovered a breadboard that I had made in Florida that had 6GF5's in it (tiny sweep tubes) It was set up for dual drive (G1 and G2 driven simultaneously). I remember having problems with it, but I hooked it up and tried it. There was a lot of distortion and getting equal currents between the two output tubes seemed impossible. The current wandered all over the place.
The 6GE5 has exactly the same pinout as the 6GF5 so I plugged in the pair of RCA tubes. The breadboard worked flawlessly. The idle current was easy to set and stayed put where I set it. The board made 50 watts into a 6600 ohm OPT with 450 volts of B+ at 2% distortion. Cranking the audio generator to max produced about 75 very distorted watts. No hint of redness, screen grid glow or other anomalies were seen. SO.....
MORE POWER.....I have 450 volt caps in the board, and the power supply is already set on 450 volts, so I put my 8 ohm load on the 16 ohm tap to give the tubes a 3300 ohm load. More power? OH YEAH, I get 90 watts at 2% distortion, and 99 watts at clip.....
OK, I'll bump the voltage knob up to 475 for just a minute to see what happens. I get 100 watts at 2.5% distortion. A minute turned into 5 just to see if......yes, there is a pale red glow on the plates. OK, I have reached the limit of the 6GE5.........but wait....there's more......
The Sylvanias have the big boxed plate like those killer 6AV5's had, so crank em up. 108 watts at 2.5% distortion, not a hint of glow after 10 minutes at this power level. Diming the audio oscillator produces 120 watts of pure square wave.......I turned off the power before I blew up any caps......450 volts remember. My meter reads 476 volts.
Note that this was an existing breadboard with a unique dual drive circuit. I would expect that a conventional G1 driven 50 WPC amp with these tubes, or the 6AV5's would be easy. Best bet would probably be an OPT in the 4000 to 5000 ohm range with about 450 volts of B+ and 150 to 175 volts on the screens. Alternatively you could use a 3300 ohm OPT with less B+.
Pictures:
#1 the "lab" in March
#2 the "lab" yesterday
#3 the "lab" today
#4 6GE5 in the hot seat
Out of 5 tubes there were 3 different constructions. There were two RCA branded tubes that were made by RCA, An RCA branded tube that was made by GE, An RCA branded tube that was made by Sylvania, A Sylvania that was made by Sylvania. All appeared new.
I had discovered a breadboard that I had made in Florida that had 6GF5's in it (tiny sweep tubes) It was set up for dual drive (G1 and G2 driven simultaneously). I remember having problems with it, but I hooked it up and tried it. There was a lot of distortion and getting equal currents between the two output tubes seemed impossible. The current wandered all over the place.
The 6GE5 has exactly the same pinout as the 6GF5 so I plugged in the pair of RCA tubes. The breadboard worked flawlessly. The idle current was easy to set and stayed put where I set it. The board made 50 watts into a 6600 ohm OPT with 450 volts of B+ at 2% distortion. Cranking the audio generator to max produced about 75 very distorted watts. No hint of redness, screen grid glow or other anomalies were seen. SO.....
MORE POWER.....I have 450 volt caps in the board, and the power supply is already set on 450 volts, so I put my 8 ohm load on the 16 ohm tap to give the tubes a 3300 ohm load. More power? OH YEAH, I get 90 watts at 2% distortion, and 99 watts at clip.....
OK, I'll bump the voltage knob up to 475 for just a minute to see what happens. I get 100 watts at 2.5% distortion. A minute turned into 5 just to see if......yes, there is a pale red glow on the plates. OK, I have reached the limit of the 6GE5.........but wait....there's more......
The Sylvanias have the big boxed plate like those killer 6AV5's had, so crank em up. 108 watts at 2.5% distortion, not a hint of glow after 10 minutes at this power level. Diming the audio oscillator produces 120 watts of pure square wave.......I turned off the power before I blew up any caps......450 volts remember. My meter reads 476 volts.
Note that this was an existing breadboard with a unique dual drive circuit. I would expect that a conventional G1 driven 50 WPC amp with these tubes, or the 6AV5's would be easy. Best bet would probably be an OPT in the 4000 to 5000 ohm range with about 450 volts of B+ and 150 to 175 volts on the screens. Alternatively you could use a 3300 ohm OPT with less B+.
Pictures:
#1 the "lab" in March
#2 the "lab" yesterday
#3 the "lab" today
#4 6GE5 in the hot seat
Attachments
So far it's just a little piece of my big dream for a new lab.
In Florida everything (lab, construction, listening room, and some storage) was all stuffed into a 10 X 10 foot room. Now I have a 1500 square foot basement. There will even be a gym in here. I also have a 850 square foot mobile home next door for storage.
The financial situation has made a big turn in an unfavorable direction, so I have been building my lab for near zero budget. I am now working on my third workbench and so far I am still under $100 total. I took today off from the table saw for some tube time. I think it's the first this year, although I may have plugged in something back in January in the other house when it was too cold to work outside.
Wait just one minute............tubelab DIDN'T blow something up in his new lab on the first day?!?!?!?! JK 😉
I would say the results for the 6GE5 are good indeed. Hopefully you can try and hook em up to the SE boards for triode operation. Probably a pain in the butt because of the different sockets. Vinylsavor seemed like he is pleased with the results he got in triode operation.
Thanks tubelab for all the work you do in the "lab"! It will be cool to see it when it's all finished, I bet you are excited. 🙂
I would say the results for the 6GE5 are good indeed. Hopefully you can try and hook em up to the SE boards for triode operation. Probably a pain in the butt because of the different sockets. Vinylsavor seemed like he is pleased with the results he got in triode operation.
Thanks tubelab for all the work you do in the "lab"! It will be cool to see it when it's all finished, I bet you are excited. 🙂
Unfortunately the last experiment (not involving 6GE5's) blew both mosfets on the driver board. I wired something up wrong, and both mosfets are now shorted. I'm not exactly sure what went wrong yet.
I need more, and better light in that basement. I grabbed both LED light sticks in our local Walmart last week, but one didn't work. Road trip tomorrow to another Walmart to get more. 4 foot LED light stick, 1850 lumens, 19 watts, $25. 4 or 5 more should be about right.
I can't do conventional G1 drive experiments until I get the dead power supply fixed. Autopsy revealed that one of the 1960 vintage electrolytics has spilled its guts. They probably all need replacement. It was left in the unheated storage building last winter.
Nice to see glimmers of life in the new tubelab lab.. 😀
The luxury of space, I have about 1/4 the space and it is shared with a small machine shop and listening area as well as my lab space; so I am envious indeed! 😀
Will check out the LED light sticks as I need more light, want to replace 40+ yr old fluorescent fixtures with LED equivalents as well.
Sorry to hear about the finances, this is a big long term worry here too. Hopefully that resolves in a positive way soon.
The luxury of space, I have about 1/4 the space and it is shared with a small machine shop and listening area as well as my lab space; so I am envious indeed! 😀
Will check out the LED light sticks as I need more light, want to replace 40+ yr old fluorescent fixtures with LED equivalents as well.
Sorry to hear about the finances, this is a big long term worry here too. Hopefully that resolves in a positive way soon.
I wish I could work out again but my spine is not too happy, I have chronic pain and nerve damage due to L5-S1 issues, I feel like cutting my left leg off (for those with sciatic nerve issues know about this). I lost a lot of my muscle mass, I now only weigh 135lbs @ 5'9", I used to be 155lbs. I feel like a wimp now :/
I would look like a bean pole standing next to tubelab, dude is ripped!
Tubes should be here tomorrow. I can't wait!!!!!!!!!
I would look like a bean pole standing next to tubelab, dude is ripped!
Tubes should be here tomorrow. I can't wait!!!!!!!!!
I've been thru this as well, although the sciatic pain only lasted for a couple weeks, due to a disk protrusion between L4 & L5. This is a very common area for people to have issues. No chance of getting your problem fixed?
jeff
Been dealing with it for a couple years now, I do have an appointment soon with a neurosurgeon. I don't really want surgery.
If you want to be pain free, you may not have a choice. I've talked to a couple of people that have had back surgery recently. They were up and about the same day, without much pain, so obviously back surgery has evolved quite a bit.
jeff
I went to the Walmart store in Triadelphia and got two more light sticks, all they had. Tested both before leaving the store, both worked. They are NOT listed on Walmart.com, even if I plug in the number on the box. It says Great Value 4 foot LED Shop Light on the box and the number is 73992/GV. The UPC code is 81131 08032. They don't seem quite as bright as the typical 4 foot shop light with two 40 watt tubes, but they only eat 19 watts.
Thursday morning I will be heading out on a 3000 mile road trip. I should pass a Walmart or three on the way. I'll get more. Our basement currently uses ELEVEN 75 watt incandescent bulbs for light....825 watts. Most of this is turned to heat which must be removed by the AC system for about half the year. Winter basement heat will be GLOWING TUBES, not light bulbs.
Health care is the big hitter. The promise of retiree health care evaporated, Cobra runs out next month, and the ACA is neither. $950/month for insurance that will never pay out ($10K deductible, no prescription coverage) or $1450/month for coverage with a $6000 deductible. No government subsidy this year due to a severance payout in January, but maybe next year......
Daughter, husband, and their 4 kids moved here to live in the house that we were planning to sell. He makes $16/hr so we are subsidizing them too.....planning on delaying social security until age 66 (3 1/2 years) but that may not be possible.
Still have a few kilobucks put aside for the lab buildout from selling tubes, parts, amps, and my collection of "stuff" that I didn't want to move.
I brought some equipment from Florida, and got a few things free from Sears with "shop your way" points after dropping $6K on appliances for the new house. I bought a 2 year membership in a run down 40 year old gym when I got here. It has 11 months left, so the gym will be the last thing built, although it's kinda hard to find the motivation to go there when it's -10 degrees outside. I go at 7AM to avoid crowd.
It's usually my right leg, sometimes the left, or both.
That's where my BAD disk is, but there is another damaged disk, I don't remember which one.
We all watched Evel Kinevel as kids and tried to emulate his stunts on bicycles, but it was a stupid bike trick about 10 years ago that did my lower spine in. There was an old bridge over a canal that was on my daily bike ride route. There was about a 18 inch gap between the bridge and the rock road on the bank that I routinely jumped. I was out riding when I spotted a huge solid state integrated stereo I someone's trash, so I grabbed it under one arm, and headed across the bridge......and crash. I managed to walk home, and return with the car for my bike and the stereo. Oh, I did fix the stereo and gave it away after using it to blow up some 6X9 car speakers.
About a day later the pain, numbness, and instability started, and later that day, my right leg just collapsed while walking across the street. No matter how much I tried, I could not stand up. Within an hour I was in the ER.
A week of drugs and immobility later I could walk...slowly. Physical therapy slowly restored my mobility, but my exercise routine would be changed forever. No more squats or ANY exercise that puts a compressive force on the spine. No more back jarring bike rides in a bent over position, I got a recumbent, and eliminated mountain bike riding, and any kind of jumping. I started taking mandatory breaks from the computer at work every 2 hours, usually with a lap or two walk around the complex (about a mile). I still have numbness and pain if I don't keep moving.
I have lost about 30 pounds of muscle mass in the last 12 years.
!
For most of my life I was a SKINNY guy. At age 17 I weighed 130 pounds at 6 feet tall. By age 40 I had made it to 145 pounds. At age 47 they put the gym in at the Motorola plant where I worked and said it was FREE! It was then that I figured out that I was capable of packing on muscle.
At age 50 I weighed about 205 pounds with a single digit body fat percentage. After the crash I stabilized at about 190 due to the change in exercise routine. Since moving here, I have again stabilized at about 175 pounds. Mostly due to lack of calories.
Picture is me at age 25....beanpole....yeah
Attachments
BEANPOLE!!!!!!!! Hahahaha 😉
I guess I have hope yet.
I think I will make a trip to walmart and see if they have some lights too. My little workshop has two 100 watt incandescents that could be replace by something more efficient. Hopefully Kevin left me some in this area
I guess I have hope yet.
I think I will make a trip to walmart and see if they have some lights too. My little workshop has two 100 watt incandescents that could be replace by something more efficient. Hopefully Kevin left me some in this area
I finally looked at the instruction sheet that came in the box with the Walmart light. It says "FEIT Lighting" Plugging that name into Amazon brings up a few hits. It seems that FEIT manufactures several house brands in Taiwan.
One of the lights shown on Amazon says "Imported by Costco" and several reviewers say that it sells for about $35 at Costco. It appears to be a two tube version of the Walmart light. The light and wattage numbers are double the WM version. This may make the Costco version a better deal. There is no Costco in this area though, and the Costco in Florida was such a zoo that we let our membership expire years ago.
http://www.amazon.com/Feit-Electric...439297146&sr=8-1&keywords=feit+led+shop+light
Just to let you guys know--The usually 'out-of-stock' 6HJ5 is available from Vacuum-Tubes.net at $4 each--They have 700 Raytheon 6HJ5 in stock. Its a 24W P-Diss tube.
How do the make, Raytheon measure up on average....?
I had sent them a message a few days ago, and hadn't heard back till just now.....
How do the make, Raytheon measure up on average....?
I had sent them a message a few days ago, and hadn't heard back till just now.....
That's good news. It appears that Raytheon may have made all the 6HJ5 tubes. They were the designers that registered it. I have several brands here, and they are all identical in construction (except there are 2 positions for getters) and all have "LYFA" etched on the bottle. I would say their quality level is quite good. (they are well known for military equipment)
The 6HJ5 tube has a plate equal or bigger than the usual 6L6GCs. Runs on 6.3 V for the heater. No plate cap. (all the bigger sweep tubes have plate caps) Suitable for very linear g2 drive as an option. I would say this is the most desirable DIY sweep tube around, and the price is right. George gets amazing audio Watts out of them. (more than 6L6GC)
21LG6 is also similar to the 6HJ5, but with a plate cap. Same price.
The 6HJ5 tube has a plate equal or bigger than the usual 6L6GCs. Runs on 6.3 V for the heater. No plate cap. (all the bigger sweep tubes have plate caps) Suitable for very linear g2 drive as an option. I would say this is the most desirable DIY sweep tube around, and the price is right. George gets amazing audio Watts out of them. (more than 6L6GC)
21LG6 is also similar to the 6HJ5, but with a plate cap. Same price.
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