slew rate of analog tape?

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[Moon Unit]

I do know that the incredibly fast slew rates of most vacuum tubes contribute to what we all know and love about tube gear versus solid-state. That's what kind of got me thinking/wondering.

Huh ? ?

[SkullChris]

zuh?

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[A-Barr]

Very interesting, I always thought the slower slew rate was supposed to sound "warmer" yet people say (though I think it baloney) that tubes sound "warmer" yet they apparently have higher slew rates?

I would really expect tape to have a slower slew rate than an A/D converter, it is a moving tape head and there will always be a lag in any moving part between when you signal it to function and when the inertia catches up and actually moves it.

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[A-Barr]

You make good points.

To me warm always meant "rich in harmonics," so the bridge pickup on a strat sounds warm to me and the neck pickup sounds cool.

If I recall correctly, tubes generally distort by first adding second harmonic distortion, then third, and so on, so at a normal volume, the tube may sound clean but may actually be distorting in that it is adding 2nd and third order harmonics, which add a certain singing tone and a fullness, respectively. When a sharp transient occurs, tubes add more higher order, less musically-related harmonics, in a very similar way to how our ears react to loud, sharp transients. Solid state devices hum along with very little distortion, until they reach a certain threshold and a large amount of odd and higher order harmonics are dumped on the signal at once.

The slew rate thing had never occurred to me however, I am pretty sure big meaty tube-era transformers with a lot of inductance would have pretty low slew rates too. EDIT: Maybe this is why the transformerless 12AY7 pre works so well on acoustic guitars?

And don't forget that push-pull guitar amps cancel even-order harmonic distortion from the power amp!

I agree, we were robbed by the bean-counters to an extent, but if you ever build any tube gear, you'll quickly discover that the real big cost is in those transformers!

Don't know where I am going with any of this, just adding more food for thought to the discussion, hopefully.

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[A-Barr]

I'm totally ignorant regarding the manner in which various design principles of transformers would affect their slew rates.

You and me both! But inductance is a measurement of how reluctant a transformer is to change its magnetic field, so just like with a tape head, there is a little bit of force that must be overcome before the signal gets passed through the device, which seems to me like a slew-rate limiter. I would expect, could be wrong, that the higher impedance transformers in tube gear would have higher inductances as well. That's all I got.

I am pretty sure the AY7 uses a bifet opamp to unbalance and balance the signal, but can't they make super-high slew rate opamps these days? I think solid state gets a little bit of a bad rep because, just as with tubes, there are varying degrees of quality and consumers often get stuck with some really crummy opamps and transistors in their gear, just look at the whole Black Lion Audio phenomenon...

[A-Barr]

A Barr... this all has piqued my curiosity and I'm doing some research about slew rates and how they relate to transformers.

it seems that stepping voltage up or down can actually reduce or increase the perceived slew rate of a circuit, depending on application. If I can make sense of any of this stuff, I'll report back...

Please! That's crazy!

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[A-Barr]

Yeah jeez, I know that "Sorry I asked" feeling pretty well. That thread quickly jumps over my head, but that's the way I've learned all the (small amount) of electronics theory I know- read until your head spins, give up, sleep on it for a week or a month, come back and take the next step forward with that little bit of understanding you've gained.

So tube preamp input transformers step the voltage up quite a bit, relative to ss inputs, increasing slew rate, but then tube output transformers step down quite a bit, as opposed to the even or upwards transition in SS OT's, so where does that leave you? It seems like, from that article, that any amount of applied gain will increase the volts:time ratio and increase slew rate?

"fuck all of this, I'm just going to go play some music."

Here here!! Thanks for the info though, much to think about!