Tube (valve) amp really works!

You need to quote more than that.

The first part of that paragraph is missing.

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Lucifer Morningstar
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Is this it ?

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If that is it, I see no reason for it. you got OP AMPs on the end of triode s, if the OP AMPs can deliver the nuances of the sound from triodes they sh ould be able to do it by themselves.

Of course it is a pentode, but wired as a triode. And the way it is showing it is a directly heated cathode which means one channel has bias and the o ther does not.

What you are probably hearing is an anomoly due to the input coupling cap c harging to make for some badly needed negative bias. I have seen other amps like this and when I see them I think Madman Muntz. If what I found there is actually the print for it, I would never buy it.

These no bias people can sit there and say all day that "The audio biases i t", sure does, now when it comes down to half the conduction where you shou ld have biased it in the first place it shifts DC level on the output. I co uld design better than that at fifteen years old. If I am looking at the ri ght thing of course.

The thing here is cheap. Sure, use a DC filament supply, but if a directly heated cathode you don't put them in series. You need that positive voltage , and in STEREO, remember there are two identical channels, you need the sa me bias on each channel. Not for one to be biased by the power supply and t he other to be self biased like the horizontal output in an old TV set.

Not not be mean, but if the link I put up is of that thing, it is not high fidelity, it is not worth shit by any metric. If you like it then that is b ecause you like a certain type of distortion, because that has it Man. No b ias ?

Probably designed by a millenial.

That is my opinion. It affects nothing else.

I believe they got you fooled because of that grid current biasing system. It probably makes the soundstage sound a bit different because of the delay in output of one of the channels. The other channel has bias.

I have seen shit like this before.

Reply to
jurb6006

I know what the placebo effect is; I was making two separate statements.

We have any number of ways and the means to measure any deviation from the original signal. "Fidelity" in this case is: "the reproduction of sound with little distortion, giving a result very similar to the original."

I have nothing against the idea of coloring sound to make it more pleasing (subjectively) to the listener, but it is very subjective and there will always be someone that will disagree with me.

Ultimately, when you've gotten the sound source as good as it gets, you have to start looking to the listening room, because more money can't improve the fidelity of the equipment by a noticeable margin. The law of diminishing returns takes over, and it is healthy to start questioning your own sanity IMO. (I've been there - I've pair of Crown linear kilowatt range amps for the bass, and home-brew 100 watt Mosfet amps for the mid and treble) Sounds damn good too, but then reality steps in and I do most of my listening while kayaking with earbuds....

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default

Re Audio and "burn in". I was looking at teflon caps some time in the past. I couldn't find any except on Audio sites. Caps were something north of $50 each! And for the best sound the caps needed to be "burned in" by sending white noise through them for several weeks.

George H

Reply to
George Herold

Token tubes driving opamps is laughable. The resistor values on the output amp are optimized to make noise.

The datasheet of that PT2308 chip is silly too. A few bullets and no specifications!

The board layout, the red thing, is really ugly.

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John Larkin

People burn in RCA cables too. The signal direction matters.

And power cords. Soaking them in liquid nitrogen has stunning acoustic effects.

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John Larkin

No, that isn't it. I don't understand why you can't get the other link to work because it works fine for me. Would you like me to email you the pdf? I would appreciate you critiquing the circuit. I know very little about tube circuits. Eric

Reply to
etpm

Not to minimize the rest of the rant, but these little 1.2V filament tubes are almost universally designed so that if one end of the cathode is grounded and the other is positive, the 0.6V (average) voltage on the cathode makes for a pretty good biasing. 'cuz -- toobs.

I think you're probably correct for the rest of it -- sometimes you build a toob amp because you think it'll do something for you, and sometimes you just build one so you can say "I got toobs!".

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Tim Wescott 
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Tim Wescott

Whacking someone upside the head with the cable when it's still below

100K would have even more stunning effects, I bet.
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Tim Wescott

I got it now. I had to switch browsers, I won't "upgrade" FF because I want 23, not the new version. Not sure I even want to go that new actually. Eve ry new version takes away features, some of which I like. Same way with Ado be reader, downloaded DC at work, what a nightmare. Hand cursor switches to select after a few seconds and I could not find a way to turn that off. Wh at kind of brainiacs figure this shit out anyway ? So I had to use (egad) I E8.

Looks like the print I had was the old version. I seem to have been correct ed about the bias, as long as one end of the filament is connected to a pos itive supply. Also, as they said, the operating points of the tubes are now the same.

I say this : Whatever you're hearing is probably even order distortion, whi ch some people like thus the "SET" crowd. (single ended triode) Not sure bu t I think Audio Asylum has a group just for that, but I take to mean the ou tput to the speakers.

What I think makes the tube sound is the interaction between the high imped ance plate(s) of the output(s), the transformer and the speaker. Even in gu itar amps I see no reason to use tubes in the input stage(s). In the old da ys, some musicians used to take a small tube amp, literally put it in a box with a microphone when they got up on stage.

When tubes are used as outputs into an inductive load they got something th at no solid state device has - it is a diode first. That means any inductiv e kickback from the speaker is allowed to just happen, whereas in a solid s tate amp it would be clamped. People have told me this is nothing, but then why do they have to take steps to keep protection relays in high power amp s from welding themselves on when they go into DC protection ?

You can do it with solid state but you have to be using an output transform er, then you put a diode in series with the anode, collector or drain of th e output devices.

So of course they also have guitar amps with solid state inputs sections an d a tube output section. some are quite powerful with three pairs of 6L6. T hen you don't use that amp for practice if you want the sound, and a power soak is not the same because it decouples the speaker. And full power is ou t of the question usually because you get too much feedback. Some also from the neighbors or even police.

One things you also may be hearing is a real sort of damping factor to the headphones. Most amps and receivers do not have dedicated headphone amps, t hey just take the speaker output through a resistor. That means the frequen cy response will vary with the impedance curve of the drivers in the phones . This doodad drives directly, being a voltage source. You might hear an im provement because of that but IMO that has nothing to do with the tubes. An ything you hear out of those tubes is going to even order distortion.

And I see nothing that would make it anything other than flat frequency res ponse, those tubes are small so their response is most likely good up into the RF. The coupling caps are huge (in value) for the impedances involved, but not the output caps. Most headphones are greater than eight ohms, but a 1,000 uF to feed eight ohms is not enough. You lose quite a bit of low end . That's why some of the early AC coupled SESAPP solid state amps had that cap within the global feedback loop. Of course phase comp was required or t he thing might oscillate. I had that happen once when I was trying to upgra de one. If it is in the feedback loop then frequency response could be smoo th but power bandwidth drops off at the low end.

Best headphone sound I even heard was Sony MDR-CD5. The frequency response ruler flat from 2-22,000 Hz. NOT 20 to 22,000, TWO. You could feel the air rush in or out when the stylus landed on the record groove. They were 45 oh ms, so running off a receiver or amp that just had the sound resistored dow n from the speaker outputs they were much louder. They would probably not b e louder on your doodad.

I calculated by the sensitivity and the maximum power rating that they were capable of 126 dB. I jumped the resistors. But they were not the loudest p hones I had, those were the Sansui SS-10. They required a modification to t he foam surrounds to get them to sound good which involved cutting some of the inner part away and get it so your ear gets right up to them. I did tha t after I heard my buddy' Koss that had them cut that way. What a differenc e ! And loud ? Let me put it this way, with the resistors jumped, on a Ster eotech 1200 (McIntosh red headed bastard child receiver) I could use them a s speakers. I mean, they were louder than some table radios.

What I would really like is a very low power tube amp that uses an output t ransformer. There are several problems with such a design. First of all the calculations, and then getting a transformer company to wind it. You are n ot going to want to pay $100 for a transformer that can only do one watt or so. But this, with an appropriate dummy load, I mean really built to emula te a real speaker, Fender or whatever, and EQ after to reproduce that old g uitar amp speaker sound, I think there may be a market for that. However th ey come pretty close it seems using a DSP so it might be another futile ide a.

Bottom line, I think the improvement you hear is due to damping factor. Any one who doesn't think damping factor matters is welcome to take eight ohm r esistors in series with their speakers and turn it twice as loud.

Reply to
jurb6006

People burn in RCA cables too. The signal direction matters."

Now that is audiophoolery.

ects. "

Do you mean the nitrogen boiling or the cable insulation breaking into litt le pieces ?

they got tubes they say are dipped in liquid N as well. Phil (it may have b een over in SED) pointed out the difficulties with doing that, mainly havin g to do with differing thermal expansion coefficients. So obviously if true it must be done before the elements of the tube go into the bottle. Even t hen, if you want to throw money away, put a bigger getter in it so it lasts longer. I had some 6550s had three getters in them. I sold them to a guy i n Chicago ad he was worried about the looks of one of them. I sent him pict ures of the other getters and he sent the money.

Reply to
jurb6006

Now John, you've claimed to have a tin ear, so you can't really appreciate the warm and fuzzy sound of a tube amp.

Eric, I'm no audio guy, but I hear tubes clip more gently than opamps. A lot depends on what type of music you are listening to. As far as burn in it could be that your ear/ brain adapts to the source.

George H.

Reply to
George Herold

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Another psycho-acoustic illusion:

Halo effect

One study in 2011 asked professional violinists to compare violins made by Stradivari and Guarneri with high-quality new instruments while playing blindfolded in a room with relatively dry acoustics. Contrary to all expectations, the researchers found that the most-preferred violin in the test set was a new one and the least-preferred had been made by Stradivari. They also found that most players seemed unable to tell whether their most-preferred instrument was new or old.

The same thing happens in wine tastings: people prefer expensive wines only when the know which are expensive.

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John Larkin         Highland Technology, Inc 

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John Larkin

Right, I remember hearing some violinist playing different violins on the radio... They liked the newer ones too. (I couldn't really hear much difference....)

George H.

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George Herold

I wonder how much of that sound you could get with a small tube and a choke for a plate load, with the audio from the plate applied to a clean solid-state amp.

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Tim Wescott 
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Tim Wescott

I am surprised they don't do that. You should see the complexity of some of these amps.

If it is just a choke it would be single ended but then how many of those little amps were single ended.

Where is Les Paul when you have these questions ?

Reply to
jurb6006

:)

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Tim Wescott 
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Tim Wescott

Les Paul who ?>:-} ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Jim Thompson

Read some audiophile reviews!

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John Larkin

Speaking of not coloring sound, I built another headphone amp, (the Objective 2) that I like very much. It's open source and a kit can be purchased from JDS Labs. The amp, as near as I can tell, only amplifies the input sound. It does not add any other noise that I can hear. It runs off either two 9 volt batteries or a wall wart. I REALLY like it. Eric

Reply to
etpm

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