• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

EL509 (JJ) or PL519?

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Ears are very subjective test devices. I see that the amplifier must perform well both at listening test but also at measurements. Otherwise it is not Hi-End.
Can you measure the distortion levels ?
Free test programs that utilize the PC or laptop are available if you have not any yet.
 
I have tought myself SPICE last weekend to play around with the schematics. I found out that there is no real reason for the buffer stage to be grounded. In my schematics R5 draws almost a wimpy 30mA and consumes 7.5W, the screen grid draws about 8-15 mA. This means that the buffer needs to provide 38mA at zero signal and at least 45mA at max. I realized that R5 can be removed because the screen grid of the power tube consumes enough current to keep the buffer going. The buffer stage now only consumes the current that the screen grid draws, and we save about 20 watts of unused energy.

I think that a single ECC82 triode could be capable to provide the current needed for the screen grid, thus you can use two JJ ECC832 tubes to reduse the amount of tubes. Simulations confirm this, however I still have try this in the real world.

The power supply that I am currently using allows me to parallel the end tubes and gives me a B+ of 360 volts. My OPTs are 2.5k primairy.

So in short, drop R5, R6 and one ECC82. Then connect the cathode of the remaining ECC82 directly to the screen grid of the power tube.

Feel free to drop me a PM.

Sounds very very interesting !
Good idea to start some experiments with high g2-gm tubes.
 
Hi folks!

After three months my power transformers are almost done so I should be able to start building my mono blocks really soon.

In the mean time I have been playing around with this amplifier and I have now settled for a very nice, KISS approved, circuit. You can download the circuit here: http://www.hostpalace.nl/meuk/Update.pdf

My goal was to experiment a lot and to end up with a relative cheap amplifier. That goal has been reached, I am now able to drive the screen grid with only half a ECC82 tube, without going into distortion. In my circuit I have used an ECC823 because I wanted to play around with this two faced tube, of course it can be replaced with a ECC82 and a ECC83.

I suspect that good quality parts (tubes, trannies, R's, C's and L's) for a stereo amplifier would only cost €400. I will soon find out because I intend to build a stereo version as soon as possible! The costs can be even lower by using SS rectifiers and dropping the sepparate bias supply.

I have finished one channel and I am test running it right now. It performs very well so far, however the tubes are brand new and it's only running for about two hours so I have to re-judge the amp as soon as I have build a stereo version
 
Just for another data point, I did a screen driven SE amp using the 6CD6GA, a middle-of-the road sweep tube (20W Pd). Like Tubelab, I used a mosfet source follower to drive the output tube screen grid. However, instead of a triode, I used a 6JC6A pentode for the input stage. I used Hammond 125ESE transformers tapped at 5000:8, with some global feedback. The result was a surprisingly listenable little amp that raised a few eyebrows at Burning Amp 2008. I dubbed it "Miz Piggy", as all the iron crowded on the top deck made it kinda heavy. I had a place of honor in my living room for about a year. A search for "6CD6GA Enhanced Triode" will turn up the thread with some schematics and a pic or two, if you're curious.

I was thinking of doing a follow-up amp with more authority using the 6P45S and better output iron, but the project is stalled on the drawing board for now. I second other folk's view that a little negative bias on the control grid (instead of just tying it to ground through a resistor) may be useful to get a little more stable bias point using the EL519 or 6P45S. I wouldn't use as much negative bias as Danielak did, but would start with about -6V (3 green LEDS would do the trick).
 
Sorry. I thought that you are developing a hi-end amplifier, but it seems that I am mistaken.

Personally, I think thats a VERY harsh comment!

The final judge is how it sounds to the listener!

Numbers derived from analysis while good maybe for alterations to improve the on-paper 'quality' may in fact, Hurt the percieved sound....:rolleyes:

I have neither tested the distortion of any amp I have made, and neither am I interested in doing so, all I know is, They sound good....:D
 
The final judge is how it sounds to the listener!

Yes, this is true. The final evaluation is listening test. However, the designer or constructor of the amplifier is not the best person to carry these tests out.
Listening tests are objective only when those are done with several listeners.

Before listening test the (hi-end/HiFi) amplifier must also perform well in several tests. ( linearity/distortion, frequency response, hum, noise etc. etc.)

If the developer does not have the required test equipment or the correct attitude to appreciate this part of design process, the hi-end desing will not be created, exect by coincidence.


Besides that, High-End is the very antithesis of Do-It-Yourself.

I disagree. DIY amplifier can have extremely high performance.
Would you please give your arguments.
 
Of course a DIY construction can measure very well! But, no matter what, it will never be High End.
I think you should use the term "High Fidelity"
High End means to me a company selling hype to deaf old men with lots of money to spend. Or people that listen with their wallets.Magazines that in every single test state that "this CD/amp/cable/ can challenge equipment costing double the money"
So what you and me make, it can never be called High End.. Hi-Fi, sure. It is funny, though, that people are eating the whole hyperbole and like to put a "high end" sticker to DIY.

You do are not a company. You do not have a marketing department. You do not make products. You do not sell to people trying to impress their (male) colleagues from the bank. = You have nothing to do with High-End.

Or maybe you do have a company making "boutique" amps. I don't know you. Nothing personak, anyway
 
High End means to me a company selling hype to deaf old men with lots of money to spend. Or people that listen with their wallets.

I read this as High End means nonsense to you, or at least mainly negative aspects.

To me High End simply means well designed product that also performs well in all ways.
To create such product one does not necessarily need a "company" or marketing department.
Instead one needs design skils, good equipment and correct attitude.
 
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Instead one needs design skils, good equipment and correct attitude.

I´ve been following this thread thinking about building something out of the PL519 i have.

Now the conversation starts to sound like a past midnight catfight.

I have basic skills,tools and will let others be the judge of attitude.

But i really enjoy the contraptions i put together.

NO-FI, LO-FI or HI-FI.

Here´s something for you to sabre down.

An externally hosted image should be here but it was not working when we last tested it.


Bad caseing no audiotubes enough sand to make SS amp
 
I´ve been following this thread thinking about building something out of the PL519 i have.

If you have four of those tubes, then I suggest you to build a PP-amplifier (pentode connected). With Ub of 450 V, Ug2 = 150 V (stabilized) and RL about 2k to 3 k this gives some 120 W to 160 W with low distortion and good sound.

I have built a prototype and have the tested schematic.
 
my dear artosalo, you are describing High Fidelity, in the true sense of the word. "High End" is a coined term to describe ultra expensive and "exclusive" looking equipment. It did not exist 15 years ago, I think. You see what I mean?


flatheadmurre : My contraptions are Lo-Fi so far... But that thing! :eek: Looks like a luxury coffin for a dead toroid!
 
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