Any Tube Guys Here ?

( snip all Mike's incomprehensible drivel)

** Making sense is not what you are about - is it ?

.... Phil

Reply to
Phil Allison
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Rather than explaining where you seem to think I was going wrong, you snipped all your own drivel as well.

Whatever you are trying to prove, you're doing a great job.

--
Mike Perkins 
Video Solutions Ltd 
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Reply to
Mike Perkins

** Hang on - it was MY post that you were addressing.

I have no interest whatever in discussing your absurdities.

Fuck off.

.... Phil

Reply to
Phil Allison

That is correct, the one where you snipped your own drivel.

Whatever you are trying to prove, you're still doing a great job.

--
Mike Perkins 
Video Solutions Ltd 
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Reply to
Mike Perkins

Den tirsdag den 17. juni 2014 01.33.44 UTC+2 skrev Tim Williams:

how about modulating a synchronous boost converter?

-Lasse

Reply to
Lasse Langwadt Christensen

e to tube-only application. "

Remember the thread "Single Ended Push Pull" ? Remember the thrysistor runn ing with the power oscillator and just snipping piece of voltage off of it no matter if positive or negative, and switching fo at zero crossing. I sai d I wanted to do it at 60 kHz, but now for this application which is for th e golden ears club, I want to take it to 150 kHz.

Syncheonous rectification would work fine, and it would probably work fine with pentodes art the rectifiers as well, but drive is the problem, and so is heater isolation.

MOSFETs would be great, but each would need a diode in series because of th e back diodes included on all of them.

Think cheap now, just how good does that series diode have to be ? Really. If it switches a bit slow it will not add to the dissipation of your sychro nous switch. Maybe a few milliwatts of the back diode but nothing going thr ough the really working part of it. It will add up to the total device diss ipation though, which should be watched. Temperature and all y'know. Might be more than milliwatts too, at that voltage and frequency. And I have to r emember, EVERYTHING is an antenna.

There is another aspect of this I want to bring up about design. you might call it a cheat, but you might not. It depends on a coule of things. It wou ld apply whether tis circuit is made with tubes, t5ransistors, or silly put ty. About the drive. Now THAT is something I might be able to do in Spice. Spice turned me off a bit here recently for not being able to do someting s o simple. That, I will bring it up in a new thread.

Reply to
jurb6006

An unmodulated AM carrier voltage will produce the 100 % DC voltage level after the rectifier.

Applying 100 % audio modulation to the RF carrier and the peak RF voltage will vary from 0 % to 200 % of the unmodulated carrier voltage. The 200 % voltage also means four times transmitted Peak Envelope Power (PEP).

After rectification, the AF voltage varies from 0 % to 200 % of the nominal unmodulated carrier. A capacitor will simply shift this 0 ..

200 % range to -100 % to +100 % range.
Reply to
upsidedown

With a simple bridge rectifier, you are going to get a voltage between

0 and Vmax. If this DC offset is a problem, there are ways of getting away with it.
  • Use a series capacitor on the audio side. This is practical down to say 20 Hz.
  • Use a full bridge H configuration with two PWM sources modulated by the opposite od the audio waveform. This goes down to DC.

If you really need to go down to DC, check the full bridge H-configuration.

Reply to
upsidedown

Getting some output (at least measured in dB) down to 20 Hz is not a problem for very low levels, getting something audible (measured in SPL) is a bit harder.

Getting significant (even audible) at octaves higher for the lowest string of an electric guitar is not a problem.

Getting high levels of very low frequency at very high absolute pressure (not to mention audibility) at low frequencies is very problematic, due to the high volume of air that needs to pumped. Sure a very long throw 300-380 mm woofer or an electrostat the size of the whole wall will be capable of doing it.

Otherwise, I do not understand how any miniature system is going to be able to reproduce correctly the Tchaikovsky 1812 Overture from a decent recording (down to 3 Hz) with real cannons.

Reply to
upsidedown

This is common in the "Williamson" configuration, but how much otherwise ?

Reply to
upsidedown

must. In this app the load might be on the ngative side. That is, like in a totem pole arraingement.

not sure exactly how to run this. I want maximum current and the ability to accomplish PWM at 150 kHz. I know the tubes will not be cheap of course. the reason for tubes is that I want about 5 kV output. I lso know this is insane, but so what.

I don't need to pull a Sony with this type of components for a damn open

15K resistor way in the other side of the thing. that much is fine acually, what I don't know is what to do with the screen grid.

If I lower the screen voltage from there what happens ? It has something to do with the gain. I don't want to have to pump these things with more voltage than they put out. I am already going to find T1 because it may have to take the full output voltage.

problems. I do not intend to go through what it takes to make for example this :

transformers. Count me out.

that would be no godd for this app because no output tube could handle 5 kV. tisis in the realm of a TV horizontal output. Actually more like maybe the tubes used in linears for CB radios. Well not legally, they take ten meter ham jobs and retune them a bit. (that part for our overseas folk who might not know what "breaker one nine" means)

how to most efficiently use the tube. Figure a pentod power tube like maybe a 6JE6 (??) or something like that. 6MJ6 maybe ?

anode, no node or what ? Of course I want it to conduct like all hell to keep it more efficient. At the same time I need it to switch fast and I don't need any strange ions floating around in there. (or whatever)

pulled negative from the screen voltage will it ? Or will it ?

from the locals...

Well, not all tubes can handle 5 kV; in fact very few can. Of those almost all of them are high power transmitter tubes. EG 4CX10000 by Varian.

How much current do you need? That matters a lot as well in sizing the tubes.

?-)

Reply to
josephkk

"josephkk"

Well, not all tubes can handle 5 kV; in fact very few can.

** See 6DQ6 data.

formatting link

6kV peak plate voltage.

Common horizontal valve in monochrome TV sets.

Many others can handle the same or more plate voltage ie the PL509.

... Phil

Reply to
Phil Allison

Someone on a private forum mentioned a PL509. It is about like a 6KG6 from what I recall. I am not sure about the absolute voltage, but overall a 6MJ6 is better in currnt and I think equivalent in voltage. Close at least. I u sed them as replacements/upgrades in color TVs for the 6JE6 and a few other s.

Unfortunately I do not know the equivalents for these in your world. I am s ure most if not all exist, but maybe with a differnet filament or someting, but really, not even that. If you got a 110 volt mains or a 220 volt, 6.3 is still 6.3.

There are a couple of American tubes that beat the PL509, but not all that many.

But hen really, to get really serious about this, there are trasnsmitter tu bes. I mean stud mounted triodes that do not give up. I mean on a heat sink like never seen before. Yup.

But then comes the problem with this, what to do with the RF ? Put it in a shield ? Faraday cage ? Wire mesh ? Electrice fence ? What ?

Enough

Reply to
jurb6006

Very much later, the OP revealed that it apparently had to do with direct driving some electrostatic speakers.

First of all, 5 kV in an electrostat sounds a bit lot, especially in humid or dusty environment. IIRC, the QUAD ESL took the diaphragm bias voltage from the anode voltage of the driving QUAD II amplifier, thus about 400 Vdc.

Typically electrostats are driven with antiphase voltage on the stator plates, usually with a center tapped audio transformer to increase the voltage.

To drive these stators without a transformer, two power stages fed with opposite phase would be needed. The simplest would be using two single ended stages taking the output signals from the anode and get the anode voltage through a choke. Much of the even order distortion is canceled out by the other stage in antiphase on the other stator.

If totem pole output is used with one tube sitting on top of the other, then totally four tubes are needed for antiphase output. In addition the tubes would need a floating filament voltage.

The current needed depends on the large capacitance of the electrostatic speaker when fed at 20 kHz.

Reply to
upsidedown

..

** No way.

The original Quad ESL is self contained with a PSU having outputs of 6.2kV and 1.5kV.

6.2kV is for the bass panels and 1.5kV for the mid/treble unit.

** Or a pair of transformers as in the ESL63.

Using valves to do the same job is barking mad.

.... Phil

Reply to
Phil Allison

The money some people spend on things like this is barking mad.

Reply to
jurb6006

** That is just opinion - smartarse.

My comment was technically accurate, cos using valve instead of a transformer has no advantages - only massive disadvantages.

.... Phil

Reply to
Phil Allison

Using a tube/valve, I have to agree. But still some nut will pat for it. I have smartened up a bit since I stareted thinking about all this, and IF a tube design were to ever happen, it would be class AB. They want to pay for the tube sound we got it. whaddya say to nine grand ?

Some will pay, but you could starve waiting to sell one. I think being more practical would be a good move. Let's price it towards that sixtieth to ei tghtieth percentile in income. Or stupidity.

Actually, if I achieve a sound never before achieveed, something so good th ey kiss my ass on public square and give me a half an hour to draw a crowd, it means nothing if nobody buys it.

Thing is now that I know there are 4 kV MOSFETs out there. I really did not know. What, I just started thinking of this shit recently. Now the limitat ions of devices and such are bcoming clear to me, and might explain why thi s is not already being done. I think the transformer is cheaper and that is why they do it. As such, the REAL nuts over this shit will pay out the ass to get out of that paradigm.

As such, I want my amp to be able to drive the ESLs directly, without ant t ransformer at all.

NOBODY can say that this does not make the sound more pure. Whether the dif fernce is hearable is their problem, once I got the money.

Whatever. I know what you mean.

Later.

Reply to
jurb6006

Know what ?

If someone wanted to make fuly ES, Ls right now, ke the old Quads or whateveer, we could do it better. Direct coupled. This was such the rage in the 1970s, and for good reason I say.

And driving a huge "membrane" ?

Maybe my mechanical aspirations should move toward the low end, by electrostatic.

You know, putting an insulating material on those electrodes doesn't raeall affect the electrostatic pul.... Much.

I will have to give this some thought. Alot of (more) thought. I do believe I have a backer and I do not want to waste his money.

But then actually this is a back burner thing. there is another project that comes first which is unrelated.

Reply to
jurb6006

I haven't understood the idea behind a full range ESL.

At low frequencies, you really need a _lot_ of air for a decent audio level at 20-40 Hz at say 100 dB. This means a large surface area (not much a problem for an ESL) but also a long membrane "travel", which means high voltages and problems at higher frequencies. In addition, in any dipole style speaker, the front and back wave will cancel at low frequencies due to "acoustic short circuit".

At high frequencies, a large plane radiator will act as multiple point sources, creating a narrow beam in one direction, thus, there is just one "sweet spot" in the listening room. Later Quad models tried to address this complex concentric structures.

IMHO, a better approach would be to use the ESLs only for mid-range, say 300-3000 Hz and use something more appropriate for the lows and highs. For a mid-range only ESL, the amplifier design and/or transformer design would also be easier.

Reply to
upsidedown

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