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Old 9th Jan 2007, 11:34 am   #21
oldeurope
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Smile Re: making an audio output triode...

Quote:
Originally Posted by cathoderesistor View Post
Great work, Darius.
Have you carried out any distortion analysis? Power Triodes produce mainly
2H ofcourse.
No, not jet. But the graph is the same like the propagated in the data book for the ECC82 multipled by (B+1)
Hi I just tested both systems of an used Telefunken ECC82 in parallel and the BU4525AXPH/10. I get the same characteristics as 22 triode systems or eleven ECC82 in parallel. I am going to use Uplate=250V platecurrent=100mA Ugrid=-11,5V s=25mA/V or a bit more micro=17 Rout=1KOhms.
This is the triode I was ever searching for...
So R cathode =120Ohms HT= 270V Transformer Primary/ secondary = 16 for 8 Ohms speaker load.

Darius
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Old 10th Jan 2007, 8:26 am   #22
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Default Re: making an audio output triode...

Will the thing still distort like a triode though, when overdriven? I asked someone else about this and they said it will clip hard because of the transistor, not like a triode at all?
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Old 10th Jan 2007, 10:36 am   #23
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Smile triode output current is multipled, triodemultipler

Quote:
Originally Posted by Merlin View Post
Will the thing still distort like a triode though, when overdriven? I asked someone else about this and they said it will clip hard because of the transistor, not like a triode at all?
Hi Merlin
No, it will of course not clip hard. The ECC82 is made (B+1 times "stronger")At the moment I am calculating the output transformer. Hope it'll be finished next week and I can make some screenshots from the oscilloscope.

Darius
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Old 10th Jan 2007, 10:56 am   #24
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Default Re: making an audio output triode...

Sounds good. When you test it, can you please push it towards clipping and show some photos of the waveform?
By the way, here's some explanation from someone else: (I don't know who to believe!)
"There is nothing in that circuit to set the tube current to a reasonable bias point on the curves, so what you get depends on the beta of the transistor. So you get some undetermined tube characteristic cascaded with with the current to voltage characteristic of a transistor, which has never sounded good as an audio amp. If you overload it, you get the clipping of a transistor."
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Old 10th Jan 2007, 12:11 pm   #25
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Default Re: making an audio output triode...

Darius,

You bad mad man, you'll have the light bulb police come round wanting to replace the lamps on your avatar with fluorencents next.

Peter.
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Old 10th Jan 2007, 12:25 pm   #26
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Default Re: making an audio output triode...

Hi Darius,

Very interesting, very interesting indeed...
Quote:
Originally Posted by Merlin View Post
When you test it, can you please push it towards clipping and show some photos of the waveform?
I'll second this, I'd like to know what happens when this circuit is driven hard... well, as an electric guitarist I would be...

Kind regards, Kat
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Old 10th Jan 2007, 3:24 pm   #27
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Smile Re: making an audio output triode...

Hi Merlin,

"There is nothing in that circuit to set the tube current to a reasonable bias point on the curves,"

The resistor in the emitter does, the emitter is the kathode of the new triode arrangement.

"so what you get depends on the beta of the transistor."

Right, it is triode current multiplied by (B+1) . This is what I want!

"So you get some undetermined tube characteristic cascaded with with the current to voltage characteristic of a transistor,"

No,the emitter resistor is multipled by B to the base. I want to use 120 Ohms, so the kathode of the ECC82 has a 1200 Ohms biasing resistor.
The bipolar transistor is not much interested in voltages. I just testet the triode driving transistor versus EL84 at 60mA plate current and changed the plate voltage between 150V and 250V. The current change was 5mA for the EL84.
I disconnected the triode plate from the collector and used the triode plate as g2 and the collector as plate. The current change at 60mA was only 1mA!

Conclusion, the transistor output cares less about the plate voltage than a good pentode.
There is no current voltage charactertistic of the transistor depending in the output resistance of the triodelington arrangement.
The triode makes the input voltage to current change, this current is multiplied by the transistor. That is all.

"which has never sounded good as an audio amp.

?

"If you overload it, you get the clipping of a transistor."

The clipping of the transistor takes place when the collector emitter voltage goes below say 0,5V. In saturation. But in this circuit you can not pull down the collector that much. It will go down to 50V (expected value in my application) because the triode can not handle high currents at low plate voltages. (This makes the triode output characteristic.)

Hi Peter,
I am not replacing a valve here, I am making it stronger.

Hi Kat, at the moment I have much work here. Hope to get waveforms next week.
Please note: Guitar amps are using pentodes. The sound of a pentode amp is very different from a triode. Triodes have a build in negative feedback via space charge. Pentode (and transistor) amps do often have an electrical negative feedback. This sounds different. Pentode amps with strong negative feedback are clipping like a transistor amp. Most transistor amps are using emitter followers. Pentode amps are using the plate output. Some vintage transistor amps are similar build like a pentode amp, means collector output via transformer. They sound more pentodelike. The knee in the output graph of a pentode is much bigger than the knee of a transistor output graph. This makes a softer clipping in a pentode amp, but it is much different from a triode.

Kind regards,
Darius

PS: Please tell me if you don't understand my germanenglish...
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Old 11th Jan 2007, 9:20 am   #28
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Default Re: making an audio output triode...

What you say about clipping makes sense, I can see how the triode prevents the Collector-Emitter voltage going below about 50V. This is good news (I build guitar amps too), so the triode can still draw grid-current if the grid goes positive!
A few guitar amps do use triode power valves, and that's why I'm interested in seeing the clipping wave forms. This could be very useful for a small size, low power guitar amp, or for driving a spring-reverb tank. I'd also like to try making a small HiFi amp using this mehtod, for a Laptop for example.

Your English is ok so far!
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Old 11th Jan 2007, 10:06 am   #29
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Default Re: making an audio output triode...

Quote:
Originally Posted by Merlin View Post
What you say about clipping makes sense, I can see how the triode prevents the Collector-Emitter voltage going below about 50V. This is good news (I build guitar amps too), so the triode can still draw grid-current if the grid goes positive!
A few guitar amps do use triode power valves, and that's why I'm interested in seeing the clipping wave forms. This could be very useful for a small size, low power guitar amp, or for driving a spring-reverb tank. I'd also like to try making a small HiFi amp using this mehtod, for a Laptop for example.

Your English is ok so far!
Hi Merlin,
what is a spring-reverb tank?
If the thing sounds good, I'll make selected transistors for the triode multipler and high quality output transofrmers available.

Darius
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Old 11th Jan 2007, 11:41 am   #30
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Default Re: making an audio output triode...

Spring-reverb is an effect used in guitar / organ amplifiers. It uses a metal box (tank) containing a number of springs stretched from one end to the other. At each end the springs connect to a transducer. You drive one end with a signal (from a small power valve or power transistor).
Natural vibrations in the springs cause phase shift and delay of the signal, which is picked up at the other end. Then you mix it with the "dry" audio signal to give an echo or reverb effect.

Nice transformer! It must be great being able to make your own!
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Old 11th Jan 2007, 2:13 pm   #31
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Default Re: making an audio output triode...

Quote:
Originally Posted by Merlin View Post
Spring-reverb is an effect used in guitar / organ amplifiers. It uses a metal box (tank) containing a number of springs stretched from one end to the other. At each end the springs connect to a transducer. You drive one end with a signal (from a small power valve or power transistor).
Natural vibrations in the springs cause phase shift and delay of the signal, which is picked up at the other end. Then you mix it with the "dry" audio signal to give an echo or reverb effect.

Nice transformer! It must be great being able to make your own!
Ah, spring-reverb is called "Hallfeder" here. Thanks for explaining.
Darius
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Old 18th Jan 2007, 5:27 pm   #32
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Smile Re: making an audio output triode...

Good evening, at the moment I am doing some mechanical work. It takes some days to show you some screenshots from the oscilloscope.
Kind regards,
Darius
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Old 19th Jan 2007, 3:17 pm   #33
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Default Re: making an audio output triode...

Quote:
Originally Posted by cathoderesistor View Post
Great work, Darius.
Have you carried out any distortion analysis? Power Triodes produce mainly
2H ofcourse.
Hi cathoderesistor
Yes, I did. It is an ECC82 triode miltipler by eleven. Increasing the cathodetesistor makes the 2H good visible in a sine wave on the oscilloscope.
At the moment it is all free wireing on the workbench. I finished the output transformers and I am making the big coil between the electrolytics. I don't know the name for them.
Kind regards,
Darius
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Old 19th Jan 2007, 4:05 pm   #34
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Smile test

Some screenshots from the oscilloscope...

Darius
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Old 21st Jan 2007, 7:28 pm   #35
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Default Re: making an audio output triode...

Quote:
Originally Posted by oldeurope View Post
I am making the big coil between the electrolytics.
I think you mean the "choke".

Why did you wrap metal around the valve sockets?

I would like to see some more photos of the 'scope with the triode being heavily overdriven (very heavily!)

Great workshop by the way- I am jelous!
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Old 22nd Jan 2007, 5:20 pm   #36
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Default Re: making an audio output triode...

Quote:
Originally Posted by Merlin View Post
I think you mean the "choke".

Why did you wrap metal around the valve sockets?

I would like to see some more photos of the 'scope with the triode being heavily overdriven (very heavily!)

Great workshop by the way- I am jelous!
Hi Merlin,
I will take some more photos with the ECC82 with 22K in parallel with a choke loaded stand alone and the triodelington arrangement with 2K Ohms and choke, soon.
The attached pic showes why I weaped the metal around the valve sockets.
Darius
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Old 24th Jan 2007, 9:50 am   #37
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Default Re: making an audio output triode...

Quote:
Originally Posted by oldeurope View Post
The attached pic showes why I weaped the metal around the valve sockets.
Oh but I like those sockets the way they are to start with!
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Old 29th Jan 2007, 11:15 am   #38
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Smile The work goes on...

Quote:
Originally Posted by Merlin View Post
Oh but I like those sockets the way they are to start with!
Hi, do you have the screeningcans for this kind of sockets?
Kind regards,
Darius
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Old 29th Jan 2007, 7:27 pm   #39
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Smile first test for the triodelington

I made a first test. I am very happy. Next is the mainstransformer. It must make 300V DC at the first 100uF electrolytic and the 6V3 AC for the heaters.
What is the correct spelling triodemultipler or triodemultiplier?
Kind regards,
Darius
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Old 29th Jan 2007, 11:51 pm   #40
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Smile Re: making an audio output triode...

Fantastische Arbeit, Darius. entschuldigen Sie bitte mein Deutsch.

Hi Darius, I hope you will excuse my opening in my poor German (my Grandmother was German, so I hope you will excuse me!)

Very impressive
And you wound all of the wound components yourself.

Looking at the scope shots, looks like mainly third harmonic distortion?
What are the HF and LF breakpoints?
How does it respond to square waves?

Impressive lab you have there, any chance of some pics, please? (In another thread to keep the mods happy!)
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