can't find valve art tube - and glowey tube pic

[wicked1]

I've got a pair of the valve art 300b-98c titanium mesh plate tubes, and was just looking for another pair. I can't find them anywhere. Last year a few vendors had them, and a lot more 300b's. Now the selection seems to be slim. Have some tube manufacturers gone out of business, or something?

and, here's a photo of my amp w/ those tubes.

[Ty_Bower]

Really nice looking amp. The layout reminds me of the Tubelab SE, but I thought the board didn't lend itself well to under chassis mounting. That's an awfully fine looking rectifier, too. Is it GZ37?

[tubelab.com]

The layout reminds me of the Tubelab SE, but I thought the board didn't lend itself well to under chassis mounting.

I started building an under deck Tubelab SE almost a year ago, then things got hectic, and that amp never got finished. I went through all of 2008 without building a single amplifier! I promise not to let it happen again. Other builders have figured out ways to mount the Tubelab SE under deck.

The secret of an under deck Tubelab SE is to make socket extensions similar to the old "socket savers". This lets you build the board in the normal fashion but raise the tubes up about 1 and a half inches to be flush with the deck.

There are some excellent photos of wicked1's and akirasugai's amps in the Photo Galery thread, including detailed photos of the socket extensions. I made my extensions out of brass tubing from a hobby shop with no housing. See page 93, posts #2307, 2308, 2309, 2312, 2314,2315,2316. Page 94 post # 2350 shows wicked1's amp.

As to the 300B tubes, I read a story on this forum I believe that the Shuguang factory has found that there is more money to be made in street lighting than vacuum tubes. The Sino 845 and 211 has gone extinct already.

[wicked1]

Hi, thanks for the comments!
There are a couple of better (better angle, more light) pictures of my amp a page back in the photo section.
It is indeed a tubelab SE. (Thank you, George!)
I also used brass tubes to make the extensions for my input tubes. Basicly, bringing them to the height of the output tube and rectifier sockets. My resistors are on top of the PCB, and my caps are on the bottom. The IC's are also on the bottom of the PCB w/ their heatsinks. The 5pin ic is connected via very short jumper wires from the top of the board, so that it can lay flat.

Last night the 5pin ic, 5v regulator, shut down from overheating. I guess I need a better heatsink now that it is closed up in a case. I was happy to see it was the auto shutdown of the IC, rather than having blown my tubes or something!

And I'm really sad to hear these tubes are probably not being made anymore. V.A. had 3 or 4 different 300b's on the market. I was hoping I'd be able to try different tubes over the years. Now it looks like we've only got a few choices on the market for 300b's, and maybe only one inexpensive option.

Rectifier is a 5u4g, cheap one, too. I was getting far too much voltage from my Hammond pt, and the 5u4g brought the voltage down about 20 volts.

[kevinkr]

According to a well placed source the Shuguang factory that made 845/211 was badly damaged in last year's earthquake and while tube production has recommenced the 211 and 845 are not amongst the types currently being made. No idea if and when they might be available again.

AFAIK Valve Arts tubes are not made by Shuguang, and other vendors like TJ are still in full production. I do see Shuguang 300B listed on eBay regularly.

The 211 unfortunately is another matter, just when I decide to design and build an amplifier around 211 they become unavailable.. I will have to rethink that..

[Ty_Bower]

Originally posted by kevinkr
...the ??? factory that made ??? was badly damaged in last year's earthquake...

Didn't the same thing happen a few years ago, affecting computer processor or memory prices?

[tubelab.com]

Last night the 5pin ic, 5v regulator, shut down from overheating.

If mounted in a closed box a fairly large heat sink is required to stop the thermal shut down. My original Tubelab SE worked fine with the small heat sink specified in the parts list with 45 and 300B's, until I mounted it in the small Lexan box. I added a heat sink that I liberated from the Pentium chip in a junk computer and all is well.

AFAIK Valve Arts tubes are not made by Shuguang

I don't have any real information except that I bought a box of bulk Chinese EL34's about 2 years ago. 25 tubes in the carton, each bubble wrapped in a white box. Several were branded "Valve Art" and the rest "Sino". All are of identical construction. The tube dealer said that the carton was as delivered from his importer, and other cartons of EL34's contained a similar mix. This could be a case of "copycatting" or creative relabelling.

[rcavictim]

Originally posted by kevinkr


The 211 unfortunately is another matter, just when I decide to design and build an amplifier around 211 they become unavailable.. I will have to rethink that..

Anyone with the fire dept will tell you that it is a lot easier than you might like to think to get a 211 at your location.

But seriously...Aren't 211 and 845 so similar that the 845 would quench your thirst? Use an 845 to put out your 211 as it were?

[kevinkr]

Originally posted by rcavictim


Anyone with the fire dept will tell you that it is a lot easier than you might like to think to get a 211 at your location.

But seriously...Aren't 211 and 845 so similar that the 845 would quench your thirst? Use an 845 to put out your 211 as it were?

Unfortunately no.. Plate resistances, and mu are quite different and it appears that the 845 is equally affected by the cessation of production at Shuguang. They aren't interchangeable and the 845 requires a great deal more drive voltage and may not be as amenable to A2 operation either. I was also contemplating the possibility of a 2 stage design which because of the 845's low mu is almost impossible to implement with the prospect of any reasonable amount of output power. (The required driver voltage swings at my target power level would be over 300Vpp, compare that to about 110Vpp with the 211 and you see what my issue is.)

I have one set of good used GE VT4C and can probably get more at relatively great expense, I can possibly get a set of TJ 211 which have considerably lower plate current and voltage ratings and cost over $400 a pair new. Alternately I could (re)consider the GM70 which sounds good and can be had for less than $40 each and is currently relatively plentiful. Practically speaking I should consider bi-amping my system and using my 300B amp to drive mid horns and horn tweeters, and a new power amplifier with about 30Wrms for the bottom end.. Or I can just learn to live with the current max clean SPL level my Onkens deliver with 8W per channel.

[rcavictim]

Originally posted by kevinkr


Unfortunately no.. Plate resistances, and mu are quite different and it appears that the 845 is equally affected by the cessation of production at Shuguang. They aren't interchangeable and the 845 requires a great deal more drive voltage and may not be as amenable to A2 operation either. I was also contemplating the possibility of a 2 stage design which because of the 845's low mu is almost impossible to implement with the prospect of any reasonable amount of output power. (The required driver voltage swings at my target power level would be over 300Vpp, compare that to about 110Vpp with the 211 and you see what my issue is.)

I have one set of good used GE VT4C and can probably get more at relatively great expense, I can possibly get a set of TJ 211 which have considerably lower plate current and voltage ratings and cost over $400 a pair new. Alternately I could (re)consider the GM70 which sounds good and can be had for less than $40 each and is currently relatively plentiful. Practically speaking I should consider bi-amping my system and using my 300B amp to drive mid horns and horn tweeters, and a new power amplifier with about 30Wrms for the bottom end.. Or I can just learn to live with the current max clean SPL level my Onkens deliver with 8W per channel.

As far as I know, "211 in progress" is fireman's radio code for a fire. Just a (apparently) failed attempt at a joke.

I wonder if the 805 might do for your needs then? As you say the GM-70 is available. I'd like to grab some of those for future experiments but the money is needed elsewhere. The high filament voltage is going to be a possible hum issue with them I think unless you go DC heat with an automatic polarity reversal system per play (to extend cathode life), or excite it with an ultrasonic power oscillator (AC heat above the amplifier passband).

How much SET power are you trying to achieve?