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If "Tube Sound" Is a Myth, Why Tubes?

Robin L

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I recorded on a 24 track Studer at 30ips once. Didn't like it. 15 sounded better.
I've heard a lot of tape recordings from 30 ips sources from the 1940's/1950's. I owned several collections of Wilhelm Furtwängler performances from tapes of Live performances, many recorded for radio re-broadcast. Pretty good for the era, though the bulk of audio flaws in the recordings is due to the vagaries of recording concerts "Live" at the time.
 

mhardy6647

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Every time I think I want a 30 IPS machine, I realize I'd have nothing to play on it... ;)
You really only want 15 ips. The bass is better. B)

I'd love to have a Studer -- but I'll never be able to justify the investment.
I've mentioned this here before, but I do know a guy...

1608426750897.png
 

Robin L

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Funny how this thread detoured into analog tape. That might be the point. A lot of what people think of as "tube sound" is saturated analog tape. The "classic" old recordings that were recorded via tubes to analog tape were compressed or artfully gain-ridden to maintain a certain general saturation of sound when the signal hit the tape.
 
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Blumlein 88

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I tried tell my wife that our Studer is an investment.

She didn't buy it.

I wonder about things like this. There was never a big price increase on 78 rpm recordings and the gear it is played upon the way there in some sense is for LP. But it seems many things follow a trend. People want what was top of the line and out of their reach when they were growing up. There is a 20 to 30 year lag where those people reach adulthood, get the kids out of the house, and have some spare money, and all the things they wanted go up in price and collector value. That seems to last for maybe 20 years and then it fades away as those people finally die off or get so elderly such pursuits just aren't in the cards anymore. After which the gear has a very limited market.

So when will the Studer bubble burst? Time it wrong and you don't have a good investment. Now something like the Studer has going for it that the very finest few examples of old tech never really get cheap or unwanted. Just some of the good, but not greatest gear goes thru this cycle.
 
OP
watchnerd

watchnerd

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People want what was top of the line and out of their reach when they were growing up. There is a 20 to 30 year lag where those people reach adulthood, get the kids out of the house, and have some spare money, and all the things they wanted go up in price and collector value.

I think I'm exhibiting this phenomenon myself right now.

Here is what I wrote about my interest in the retro-looking Dynaudio Heritage Special:

"So if the Heritage Special makes me feel good when I see it, makes me feel nostalgic for speakers I wanted but couldn't afford when I was younger, and it sounds more-or-less-as-good as the Contour, I'll probably buy it because then I'll know it will bring me joy over the years just to see it every day."

It's not actually vintage, but it's vintage looking and evokes the same recollections.
 

MakeMineVinyl

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I recorded on a 24 track Studer at 30ips once. Didn't like it. 15 sounded better.
The only reason I could see for a preference for the lower speed is that the faster analog tape runs, the worse the low end response extension (but the better the high frequency extension). So if you were recording music which depends on a lot of very low bass, 30ips could be a liability.
 

dfuller

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The only reason I could see for a preference for the lower speed is that the faster analog tape runs, the worse the low end response extension (but the better the high frequency extension). So if you were recording music which depends on a lot of very low bass, 30ips could be a liability.
15ips has a low end bump, which was nice for the music I was working on (a loud rock power trio).
 

MakeMineVinyl

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15ips has a low end bump, which was nice for the music I was working on (a loud rock power trio).
All tape speeds have 'head bumps'. Just where and to what degree depends on the tape speed, and the geometry of the face of the heads. At low frequencies, the whole head face starts to act like the 'gap'.
 

Frank Dernie

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Overload in tape at higher than normal operating levels is due to tape saturation - this is separate and distinct from tube distortion. The VU meters on tape machines don't reflect the pre emphasis either in the bass or high frequencies, so it is up to the engineer to 'know' how to set levels to accommodate this. Also, VU meters were average responding devices and would be rather blind to transient peaks. If there was for instance a flute solo and during it a big bass drum hit, the flute could take on a very audible 'fluttery' quality from saturation.

Tape playback preamplifiers have, due to the reproduce EQ, up to 40dB or so of feedback from that source alone. RIAA phono EQ is similar. These EQ curves don't have to be implemented in feedback, but in tape machines that is the way it was mostly accomplished. Due to the nature of the EQ curves, the low frequencies have the least feedback, and the high frequencies the most.

IM distortion is usually not spec'd for tape machines, probably because it would look pretty ugly. Tape, by its nature suppresses even order harmonic distortion so what remains is almost totally odd order distortion (in a 'perfect' machine this would be totally the case). The typical harmonic distortion of tape at normal operating levels is about 0.6%.

Since the distortion products are mostly low-order, the ear doesn't hear the distortion as such, at least at levels below saturation. On direct comparison, tape verses digital is totally obvious but that doesn't keep tape or vinyl from sounding very, very good.

This is a graph I made awhile back which compares the 1kHz harmonic distortion at normal operating levels between tape and vinyl. The tape machine was vacuum tube.

https://drive.google.com/file/d/1FoPWw0pe_5L6rZk8qBSa0rLDQtDv8fOz/view?usp=sharing
Excellent and very interesting. Thanks.
 

Frank Dernie

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Makes sense. The one piece of tube gear I really liked was the Stax energizer/Amp, SRM T-1:

Stax SRM-T1 Review (kenrockwell.com)

It was a hybrid amp, also OTL. My sense when I hooked up my Marantz 8b via an energizer into my Stax Signature Pros, was I was hearing the transformer in the Marantz amp. Things were much more open and clear via the SRM T-1.
I have one of those and some Lambda pros, haven't used them for ages maybe I should give them a whirl.
 

Robin L

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I have one of those and some Lambda pros, haven't used them for ages maybe I should give them a whirl.
There's a certain roundness/softness up in the top octaves. Oddly, the Drop 6XX powered by the Topping L30 has a very similar effect.
 

Frank Dernie

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15ips has a low end bump, which was nice for the music I was working on (a loud rock power trio).
The bump depends on the head profile arc, as tape speed goes up so does the frequency of the bump(s).
I don't see any reason for >15ips personally.
Edit: @MakeMineVinyl got their first
 

Rzezniq

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After http://education.lenardaudio.com/en/14_valve_amps_7.html

The entire article on valve amps is worth reading:


Valve amp
A valve amp does not require negative feedback to enable it to function. The primary purpose of Negative feedback is to quieten the amp and provide some damping to the speaker. Only a small amount of Negative feedback can be applied, before a valve amp is caused to oscillate.
A valve amp with no negative feedback (Tetrode configuration only) will attempt to provide a constant current at the secondary of the output tranny. As the Impedance of the speaker increases so does the Voltage from the output tranny. An 8Ω speaker at Resonance FS is approx 20 to 30R. The output Voltage from the valve amp will rise in an attempt to maintain constant current to the speaker.
Tetrode circuit configuration, represents the Screens being connected to a separate filtered B+ supply (not Ultra-linear). Regardless if the output valves are Tetrodes, Beam power Tetrodes or Pentodes.
If the speaker Impedance at resonance increases x 4 to 32R, then the output Voltage will rise x 4, and power is also increased x 4. Between 200Hz and 600Hz the speaker Impedance will be 8R and the amplifier gain will be normal. At 10kHz the Impedance of the speaker is 32R therefore gain and power will increase x 4. Also any electrical signal from the speaker as back EMF is not fed back. The speaker is not damped and is allowed to resonate freely. The the output Impedance of a valve amp (Tetrode configuration) without negative feedback, is Infinite, Damping factor is zero.
a14_vs_speaker-cdp.gif

Power is directly proportional to speaker Impedance.
Applying negative feedback to a valve amp reduces the output Impedance and applies damping to the speaker. Some early valve HiFi amps had a 3 position switch on the rear of the amp to allow the negative feedback to be changed to adjust the correct damping for the speaker. Regardless of how much Negative feedback is applied it is not possible for a valve amp to achieve a Zero output Impedance (100% damping factor) similar to a solid-state amp.
Comparison
If an imaginary speaker had no internal Reactance and behaved as perfect 8R resistor across the frequency spectrum, there would be little auditory difference between a valve and solid-state amp. All cone speakers are highly Reactive and the Impedance varies over the frequency spectrum (approx 400%). Therefore, because Valve and solid-state amps operate in opposite ways to how power is delivered into a changing Impedance, the resultant audible difference is very noticeable. With most cone speakers, solid-state amps appear to sound flat and lifeless, the bass and high frequencies appear dead, as if a blanket is put over the speaker.
a14_vs_vdcd-comparison.gif

  • Valve amp power is directly proportional to speaker Impedance
    therefore power increases as the speaker Impedance rises.

  • Solid-state power is inversely proportional to speaker Impedance
    therefore power decreases as the speaker Impedance rises.
When listening to a valve amp, the bass and hi-frequencies appear to spring to life with clarity and detail, or may appear to sound exaggerated. If given the opportunity for comparison, every human with ears will hear the difference and choose a Valve amp as the preferred listening option. Every musician (guitar and bass player) instantly recognises the brighter response of Valve amps. Musical instrument amps (Fender, Marshall etc) stayed with Valve technology for this reason.
But, some 2 - 3 way audiophile passive speaker boxes are deliberately designed to have a flat response with a Solid-state amp only. The mid range speaker maybe 8Ω. The tweeter maybe 4Ω, therefore x 2 more power is delivered to the tweeter. When driven by a Valve amp, the 4Ω tweeter will have 1/2 the power in comparison to the 8Ω mid range speaker. The high frequencies will sound subdued. Speaker systems that are deliberately designed to have a lower Impedance at high frequencies to obtain a flatter acoustic response when drive by a solid-state amp, will not give a flat response when driven by a valve amp.
 

Julf

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"If given the opportunity for comparison, every human with ears will hear the difference and choose a Valve amp as the preferred listening option."

Uh uh...
 

Rzezniq

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"If given the opportunity for comparison, every human with ears will hear the difference and choose a Valve amp as the preferred listening option."

Uh uh...
Well assuming drastic changes in speaker impedance telling the 2 apart shouldn't be a problem.
 

Julf

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Well assuming drastic changes in speaker impedance telling the 2 apart shouldn't be a problem.

"Hear a difference", sure, but "preferred"? "Every human"?
 

dfuller

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That article starts off with nonsense.

A valve amp does not require negative feedback to enable it to function.
Neither does a solid state amp. NFB is just error correction.
Only a small amount of Negative feedback can be applied, before a valve amp is caused to oscillate.
It's more that the gain of tubes is quite limited compared to transistors so there just isn't that much gain available to use as feedback by comparison.
 
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