Maybe. However I have a character such that once I have stated a hard fact and explained it I expect intelligent folk to listen and then head in the direction of trying to understand it with a view to casting off their misunderstandings. Once they understand then they can apply the facts solidly for their own benefit, instead of trying to do technical design while drifting around in some swirly arty-farty mind-space.
I offer factual advice to help, and if they choose to ignore it or attempt to contradict fact then I feel dissapointed that they are spreading nonsense to the potential detriment of those that follow.
However it is their choice, and I shall just have to accept their inability to understand.
It's now time for me to leave the thread and do something more constructive.
Good bye.
Why not Andy? KT88 is a great tube if you know how to use it! Attached is a picture comparing KT88 triode connected, 300B, and KT88 pentode connected with 20% of plate signal fed back to the grid. Mu of KT88 triode is 8(blue), KT88 with plate-grid feedback is 5(pink), and Mu of 300B is a little less than 4(yellow).
Attachments
omg ss! How dare you confuse science with art! Begone you demon of analysis! Get behind me, you oscilloscope-probing harbringer of audiomediocrity!
The 26 is an artistic tube that recalls the pleasant, some say easier, days of yore. Its early 20th century manufacture assures the listener of AUTHENTIC, period qualities. They have a mellow and silk glove approach, tinges of rose and lavender water waft from the speakers (horns of course) bearing the tones of Coruso on wings of angels.
Such God-caressed perfection would only be sullied by testing and the evil that would befall if a PC based analysis of its dulcit electrical signature took place would surely strip any musicality from its perfect form...
;-)
Each to their own eh - live and let live...
The 26 is an artistic tube that recalls the pleasant, some say easier, days of yore. Its early 20th century manufacture assures the listener of AUTHENTIC, period qualities. They have a mellow and silk glove approach, tinges of rose and lavender water waft from the speakers (horns of course) bearing the tones of Coruso on wings of angels.
Such God-caressed perfection would only be sullied by testing and the evil that would befall if a PC based analysis of its dulcit electrical signature took place would surely strip any musicality from its perfect form...
;-)
Each to their own eh - live and let live...
Aardvarkash - I couldn't have expressed it better myself. I have started my day in a happy mood. As we cognoscenti know, one should talk to valves and boost their self-esteem. Lack of confidence is a perrenial problem in DHTs - they realise they are part of the elderly population of valves, and like all elder citizens they crave to be useful and to feel understood. After all, the original DHTs are by now full of wisdom, having survived wars, credit crunches and man's landing on the moon. They have a subtlety that younger valves lack, despite their pentode-like virility and their constant global feedback (Facebook, Twitter..). Admittedly, they are physically handicapped - they wheeze and make funny noises and are very susceptible to airborne feedback about how they operate, and of course they aren't able to do AC like more modern valves (though some like the 300b can still manage to "get it up" with AC).
Ah well, after that swirly arty-farty mind-space I must return to the Heraclitus of soldering. Now let's see - you can't make the same joint twice and all is flow....
andy
Ah well, after that swirly arty-farty mind-space I must return to the Heraclitus of soldering. Now let's see - you can't make the same joint twice and all is flow....
andy
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Hi there - I have in fact a cunning plan. I have collected several 2E22. This DHT is in the same ballpark as the KT88 but I'm hoping it hits more home runs!
It's on the launch pad about to propel my next amp into space!
andy
DHP, you mean right?
I love screen grids, they let you do so much. If I ever make a big amp, it will use 813s.2E22 looks like a lot of fun. To get similar power out as a KT88, you will need to put some power into the grid. My take on a design would be plate-to-grid feedback (turn those pentode curves into triode-like curves) with a follower inside the loop. Are you planning on opening a new thread on your new amp? I don't want to hijack the current thread, but would love to see your plans on driving the 2E22.
Hi there!
I'm just going to use the 2E22 in boring old triode - somewhere between 350 and 400v on plate. Replacement for a 300b. I have some Neotrons which everyone says are better than the usual US ones. I also have a box of 813, which I'll use when I have figured out the DC filament supply. Either one very big heatsink or maybe a Hammond choke in the supply - Cuiffoli used that. I presume AC filaments would be a bit noisy - anybody tried?
andy
I'm just going to use the 2E22 in boring old triode - somewhere between 350 and 400v on plate. Replacement for a 300b. I have some Neotrons which everyone says are better than the usual US ones. I also have a box of 813, which I'll use when I have figured out the DC filament supply. Either one very big heatsink or maybe a Hammond choke in the supply - Cuiffoli used that. I presume AC filaments would be a bit noisy - anybody tried?
andy
DHP, you mean right?
2E22 looks like a lot of fun. To get similar power out as a KT88, you will need to put some power into the grid. My take on a design would be plate-to-grid feedback (turn those pentode curves into triode-like curves) with a follower inside the loop. Are you planning on opening a new thread on your new amp? I don't want to hijack the current thread, but would love to see your plans on driving the 2E22.
Can you show me an example of this circuit? I still stuck in the SET world.....
But have some LTSpice skills
Here is an amp I built using this principle with KT88s.
Now, if you wanted to do it with a 2E22 or an 813, the feedback network would not be able to drive the grid positive. You would need to have something (a mosfet or tube) buffer the signal at the grid so that it could be driven positive. It really isn't worth that level of effort, in my opinion because tubes like KT88 and EL34 work so well and don't require any positive grid drive.
I don't have much experience with positive grid drive but when I was researching it I really only found that the 6L6GC is the only tube (out of all the common audio tubes) that has that sort of operation in the datasheets. I don't think they were designed for positive grid operation.
I have a bunch of 5670 tubes that do show positive grid operation, I was thinking of making a headphone amp with them. FWIW.
I have a bunch of 5670 tubes that do show positive grid operation, I was thinking of making a headphone amp with them. FWIW.
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