High Powered 3cx300a1 Tube Amp

[Nixie]

LOL! Liquid cooked $50K 3CX300A1 audio amp. I'm guessing it's some sort of flourinated fluid. Interesting way to get rid of the blowers...
http://www.vongaylordaudio.com/product_html/productviewuni.htm

Now pair this tube with a Berning/ZOTL-type output impedance conversion... XD

 

[astouffer]

Looks kinda fake... Von Gaylord? Where is the liquid anyhow? Looks like a glass chimney and nothing more.

 

[Nixie]

It's real, just not filled in that photo.

http://www.vongaylordaudio.com/products.htm
Also mentioned here:
http://www.6moons.com/industryfeatures/ces04/ces04_12.html

 

[multi]

Came across this old thread; I built a monoblock amp class A using the 3CX300A for 40 watts.
I used a two computer fans running slow so no huge noise. The plate resistance is only 450 ohms compared to the Western electric 300b of 700 and the GEC KT88 of 670 to 800 ohms so I has very good damping factor with not much feedback.
Very easy to make a small box to cover the tubes!!
I use speakers sensitivity close to 100DB or more so don’t need lots of power, but can’t see what the problems would be to get at least 100 watts from the 3CX300A.
I wonder if BlackUnikorn who started this thread ever made an amp using the 3CX300a ?? Hard to imagine he would have!!


3CX300 Plate resistance 450 ohms
KT88 Plate resistance 670 to 800 ohms.
300B Plate resistance 700ohms

 

[PRR]

....can’t see what the problems would be to get at least 100 watts from the 3CX300A.

Sounds optimistic for SE?

SE Triode rarely gets 25% efficiency. 300W Pdiss suggests "only" 75 Watts output. 3CX300a may do a little better at (obscenely) high voltage and high-ish THD. Not 100W clean.

Re-posting my image which was lost to the sands of time....

 

[multi]

I am not a fan of Single ended have made single ended amps sound pleasant but prefer push pull, would never try a 100 watt SE.
Phil

 

[Kay Pirinha]

Well, this is your very personal opinion (which I tend to follow, btw). But does it help to answer the original question?
Best regards!

 

[multi]

Push pull 3CX300a

I found these push pull circuits by Bob Danielak.
The 660 volt version is 100 watts Bob claimed 200 watt at 850 volts, but considered is not worth it as the output transformer is so big and expensive.

 

[PRR]

...Bob claimed 200 watt at 850 volts...

There's easy 400 Watts at 1200V-1500V, fix bias, and a higher load Z. And significant fan.

As I said 15 years ago: a herd of glass tubes can make that power level, with less-insane voltages and incredibly low winding impedance (good for bandwidth). Use 6L6 or EL34 and if one dies, you can get a replacement on a Saturday night at the local rock shop; or run without at ~80% power. At $300/pop and very-very few sellers, locally/widely available 6L6 again sounds like a fine deal... $600/pair for 3CX300a1 vs ~$560/16 for glass bottles. Hammond sells a 280W OT which could be doubled-up if you really want more-more-more.

 

[multi]

PRR
Of course you are correct best to use KT88’s or el34’s, 4 x KT88 can get close to 200watts.
Even the 3cx300a Push pull I built is crazy for just 40 watts, I paid $47 dollars each for the 3CX300A. Can get close to 40 watts with triode connected KT88’s.
Builders on this site use lots of crazy Tubes like 833’s single ended; at least the 3CX300A does not need thousands of volts. 100 watts at 660 volts is not too bad.
Have lots of 4CX350A’s bought from an auction.
PRR, I read on another site you wrote of the 4cx; OR run it Triode. Rp is near 250 ohms. G2 and Plate should be limited to 400V. Looks like 65 Watts output in 2KCT load.
I recently had to modify a Jadis amp with 8 X KT88 the box was full of soot from the number of times the resistors had burnt up no wonder with one meg on the grids so even multiple tube amps can have problems if not properly designed.
Is fun to try different tubes if you have them.

Phil