smoking-amp said:
From $4 to $10 on ePay, but I'm trying to find a direct supplier since I speak their language.
The GU50s are cheap - the audiophools haven't discovered them as of yet. I've been tempted to buy some, but I probably have enough tubes to keep me busy for the next couple of years. It's easy to succumb to "hackers greed" and buy yet another box of tubes, especially as there's no feminine restraining presence around the place.
I looked up the GU50 when it was first mentioned here. It is an interesting looking tube. Thanks for the offer, but I don't see myself getting to them any time soon. I have a bunch of RF type tubes to test, including some cool looking Amperex twin triodes with gold pins. They have been sitting on the shelf for a couple of years now.
Yeah, I can't say no to to cheap tubes either, and I have purchased about $300 worth of tubes in the past month. At the same time I am paying rent on a warehouse that contains about 50,000 tubes (down from 100,000).
I have a lifetime supply of cool ideas, but a limited supply of time in which to actually try them. Recent events in my life remind me that the time we all have left is finite and not always accurately quantified. I picked 3 projects that I should get to in the next 6 months, and all of the tubes that I recently purchased are intended for these projects. The glowing sweep tubes are all to teach myself all I can learn about screen drive. All of the experiments will wind up on my web site. The low voltage output tubes are all for "super tube" hybrid experiments. Many of the stuff that I can't possibly get to is being sold off.
Well, I sold the 4-1000's that I was saving for a headphone amp on Ebay. The buyer wanted to build the mother of all CB linear amplifiers. I still have a bunch of 833A's. I have already documented my idea for a 200 watt SE guitar amp, but I don't see myself ever building it. That didn't stop me from collecting all of the parts though. The prototype sounded pretty awesome.
The 6BQ6GA's that I tortured earlier are available from Stan at the Tube Center for $3 each. This is the regular price and there are plenty in stock.
I found about 10% of the ones that I got to be gassy. They test good on a tube tester, but glow brightly in an amp. Plan for this on first power up. Stan did not ask for them back, and is sending replacements, so I plan to make em glow. One arcs really good (bright purple sparks inside)!
I have 20 more of them on the way for future experiments. I will report on them when they arrive. The good ones can deal with 20+ watts of dissipation without glowing and make 100+ watts in a screen drive amp. I also got 20 more of the $0.98 regular 6BQ6's from AES while they are still on sale. These are just too cheap to pass up.
I found about 10% of the ones that I got to be gassy. They test good on a tube tester, but glow brightly in an amp. Plan for this on first power up. Stan did not ask for them back, and is sending replacements, so I plan to make em glow. One arcs really good (bright purple sparks inside)!
I have 20 more of them on the way for future experiments. I will report on them when they arrive. The good ones can deal with 20+ watts of dissipation without glowing and make 100+ watts in a screen drive amp. I also got 20 more of the $0.98 regular 6BQ6's from AES while they are still on sale. These are just too cheap to pass up.
Wow, My pathetic little collection can be listed on less than two pages. 😀 I have found that being broke helps me resist quite nicely. 😉
So true, and a good reminder.
Looking forward to digesting those pages
Another interesting topic. It occurs to me that low voltage output tubes fit nicely into another area of interest to me. That is modification of HT receivers for tube output sections. If one had an output tube that played well at about 70V B+ one could rip out the power amps and replace the mains output with nice little PP stages and tube buffer the decoded outputs for the other channels for use with external amplifiers.
Of course that would only work with the better units not the micro slimline junk that seems to be the rage these days. Gotta have some acreage in there.
Russian 6S19P (cheap and common on Ebay), or American 7233 (rare and expensive) are both 9 pin miniature triodes capable of working well at low voltages. The 6AS7G, or GA, 6080, 7236, 5998A, 6336A, and 6528 are octal dual triodes that also work below 100 volts. Of course you won't get 100 watts from these guys like the solid state amps gave.
The third project that I am working on involves these tube types. I already have plenty of all of them except the 6528, and they are just too expensive to consider.
I placed an order from AES for a few more tubes last Monday. It takes a week for them to get here. They arrived today. I am not sure what's up out there. There was one 6W4 in my last order instead of a 6W6, which they replaced in this order.
When I placed my first order for some 6BQ6's ($0.98) I asked if they had any 6BQ6GA's. They replied that they had none and that they had plenty of 6BQ6GTB's which they would ship. I got 10 and they were all good. I ordered 20 more this time. I received 2 6BG6GA's (no relation to a 6BQ6) and 18 6BQ6GA's (the fat boys that I had asked for the first time). Most of the 6BQ6GA's were in plain white boxes, and didn't look to good. Several had very little getter left. Three had brownish looking tiny little getter spots left. I have never seen this in a tube that was not used. No, they don't work, very low current, weak distorted output. This pair managed 15 watts at 27% distortion.
When I placed my first order for some 6BQ6's ($0.98) I asked if they had any 6BQ6GA's. They replied that they had none and that they had plenty of 6BQ6GTB's which they would ship. I got 10 and they were all good. I ordered 20 more this time. I received 2 6BG6GA's (no relation to a 6BQ6) and 18 6BQ6GA's (the fat boys that I had asked for the first time). Most of the 6BQ6GA's were in plain white boxes, and didn't look to good. Several had very little getter left. Three had brownish looking tiny little getter spots left. I have never seen this in a tube that was not used. No, they don't work, very low current, weak distorted output. This pair managed 15 watts at 27% distortion.
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I ordered 24 6CB5's. When I placed the order, their inventory management system told me that there were only 23 left in stock, would I accept them. I said yes.
I got a phone call several hours later stating that they really only had 8 in stock. OK, send them. When the box showed up today, there was only 7. There are 4 Sylvanias, and 2 RCA's that resemble the others that I have. And there was this old RCA. It looks too cool. Did RCA really make this? Where can I find 3 more?
I got a phone call several hours later stating that they really only had 8 in stock. OK, send them. When the box showed up today, there was only 7. There are 4 Sylvanias, and 2 RCA's that resemble the others that I have. And there was this old RCA. It looks too cool. Did RCA really make this? Where can I find 3 more?
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tubelab.com said:
Looks kinda like a KT88 with a plate cap. Very cool!
I recently picked up a few GE 6BQ6GTB's, a couple 12BQ6GTB's, and a couple 12DQ6B's. I was going to try AES for some 6BG6GA's. Did you ever test any 6BG6GA's in your Simple SE?
Jeff
Yup, that's an RCA. They are the original 6CB5. I have a few from years ago (keeping them) and lots of the later A version. They were used in at least one of the old Dukane amplifiers. This number has been one of my favorite outputs for years. Notice the left tube has a smooth plate.tubelab.com said:
Victor
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They look really nice, the 6CB5 G (or ST) bottle. I am curious if I will receive some of those bottle types among the 20 pieces ordered about two weeks ago.
Erik
Erik
Looks like the plate from a 6146.
I played with 807's, 1625's, 6L6GA's and 6BG6's in test amps before the Simple SE came to be. They are all the same tube internally. All the ones that I had were 1950's vintage. They work well but the maximum ratings don't leave much margin. Plate glow will occur at just over 20 watts on some tubes. I sold the large lot of these tubes that I had.
The 6BG6GA's that I received from AES are a much later design. The plate structure looks like a 6L6GC. The textbook ratings for a 6BG6GA is 20 watts. Some Sylvania 6BG6GA's were made with 7027A internals that can handle 35 watts. These look like something in between those extremes. The unique pinout of a 6BG6 makes it difficult to test in a Simple SE, but I may test these since they are here. It is much easier to simply plug a 6L6 type tube directly into the Simple SE. Every 6BG6 variant has a 6L6** (or 7027) equivalent.
My current experiments are centered arroung screen drive. I doubt that the 6BG6 will work in that mode.
tubelab.com said:
Seems redundant at this point, given that you have tested them in other amps and know what to expect. Initially, I was going to try some of the Phillips/ECG versions in my PP EL34 amp with the adapter kits.
I'm also interested in your screen drive experiments.
Thanks,
Jeff
The "super 6BG6GA" sold by SND is one of those odballs from the end of the tube era. Sylvania and Phillips stuffed whatever they could into the glass to fulfill contracts. The SND version is a 7027A in a 6BG6GA bottle. I have verified the 35 watt plate capability, so it should work well in a Simple SE, though I didn't have time to try them. A friend brought me a pair of the SND tubes with adapters to put in a guitar amp thay had an appetite for 6L6GC's. They are still alive. Most 6BG6GA's have 20 watt plates and 350 volt screen grids, and a good 6L6GC will kick their butts. Unfortunately it is hard to tell what you have without testing.
i agree but why do you waste money in junk toobz with such a stock by hand 😕 An octuple PP of 807 would be effortless loud enough 😀 Pierretubelab.com said:
For most of my listening I use a Tubelab SE with 45's. I have another one with 300B's and a Simple SE with KT88's. Notice that they are all SE amps.
I have this affliction (mental illness?) that compels me to build unusual things (not all tube related). I like to build things that haven't been done before. Often I take them apart as soon as they are built. I have been infatuated with SE tube amps for a while, but I have to do something different. For now I will do some P-P tube stuff (and a few digital thingies).
I could do a P-P amp with a bunch of 807's or 1625's. I thought about it several times. I had about 100 1625's still in their military packaging from WWII and a box full of 807's. After storing them for a few years I realized that I would likely never build that amp (it just didn't interest me), and would never use it if I did. I sold those tubes. An octuple (or less) of 6CB5's in screen drive would qualify as "different".
Quantity doesn't mean much. I got most of my tubes for free. They were mostly loose and unsorted military surplus, and odd voltage TV tubes. In my (somewhat warped) mind if I sell off the stuff that I will never use and use the money for tubes and transformers that I will use, while reducing the sheer volume, I come out ahead.
Sherri and I have a goal of reducing the "stuff" volume by half (and cutting the rent in half) by the end of the year. Health issues have made that unlikely.
tubelab.com said:
Ha, I know I have somewhat of the same affliction........specially if you ask my fiancee LOL.
NIck
Would someone mind posting a basic screen drive schematic? I've been reading this thread off and on, but I'm not quite sure what I am reading about.
Thanks
Thanks
Here's a pretty classic one.
http://www.davidberning.com/support/ea230
The scheme I've used over the past 20 years or so is pretty similar, but with MOSFETs (in my case, IRF820) as the driver rather than the cathode followers shown.
http://www.davidberning.com/support/ea230
The scheme I've used over the past 20 years or so is pretty similar, but with MOSFETs (in my case, IRF820) as the driver rather than the cathode followers shown.
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