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Skeptico Saloon: An Objectivist Joint - Page 7

post #91 of 915

Well, the flame wars are sometimes entertaining...Yet if it continues, this place is headed towards something like a Jerry Springer flavor of Sound Science popcorn.gif

post #92 of 915

It's like the Romans and the Huns.

post #93 of 915

*delete*


Edited by Meremoth - 7/1/13 at 11:26pm
post #94 of 915
It shouldn't matter if you stack components on top of each other. If they do cause interference, they are remarkably poorly designed.

I'll let someone else answer the impedance question. That isn't my ballywick.

Solid state amps are almost always neutral. I think the main reason for tube amps is to have the nice glowing tubes. Sound quality is better with solid state.
post #95 of 915
Quote:
Originally Posted by bigshot View Post

It shouldn't matter if you stack components on top of each other. If they do cause interference, they are remarkably poorly designed.

I'll let someone else answer the impedance question. That isn't my ballywick.

Solid state amps are almost always neutral. I think the main reason for tube amps is to have the nice glowing tubes. Sound quality is better with solid state.

 

I don't think that's always necessarily true about valve amplification. Valves are better at providing voltage than solid-state, but solid-state are better at providing current. Also, from what I've heard tubes don't distort as harshly near an amplifier's maximum power output (probably do to their intentional distortion covering it up). When tubes first started production they had unintentional distortion due to their manufacturing process and the technology of the time, higher-end tubes used to be neutral like solid-state. Tubes can be neutral, but because people like the "warm, vintage tube sound" manufacturers continue to produce them to  sound this way. Sound flavor is usually intentionally done by the manufacturer. Correct me if any of this information is wrong though, I'm still learning about audio.

post #96 of 915
Quote:
Originally Posted by Meremoth View Post

*delete*

When you delete a post completely you basically corrupt the thread.  Some forums will boot you for doing this. There could be a response being written to your post at the time you delete it, which will then make no sense once it's posted.  It's just not good forum conduct.

post #97 of 915
Quote:
Originally Posted by jaddie View Post

When you delete a post completely you basically corrupt the thread.  Some forums will boot you for doing this. There could be a response being written to your post at the time you delete it, which will then make no sense once it's posted.  It's just not good forum conduct.

 

It's was a cross-post, which is against the rules.  Only reason I posted it was because the thread it was originally in was temporarily locked, but I thought it was going to be permanently locked, so I copied and pasted it here.  

 

Sorry, jaddie, but I'm not going to break the rules just because you want me to.  I'm going to go by the forum's conduct code, not yours.

 

Also, I don't appreciate being bossed around/threatened by a non-mod.  Most forums, I'm aware of, boot non-mods for attempting to moderate.  You need to take that garbage elsewhere.  

 

But if you want to see the original post, here it is:

 

http://www.head-fi.org/t/669903/headphones-needing-power/60#post_9579177


Edited by Meremoth - 7/2/13 at 1:23am
post #98 of 915

There's a couple of concepts here that could stand a bit of clarification.

Quote:
Originally Posted by ToddTheMetalGod View Post

I don't think that's always necessarily true about valve amplification. Valves are better at providing voltage than solid-state, but solid-state are better at providing current.

This idea comes from the fact that tubes mostly operate with high plate voltages and low plate currents, where transistors operate at low voltages and higher currents.  However, neither actually supplies voltage or current, it comes from the power supply.  The active devices modulate that power supply's output, and the result drives the load.  The most ideal situation would be if the output of the circuit can drive the load directly, and in the case of valve circuits operating at high voltages and low currents, a transformer is required to drive a low impedance speaker.  The transformer is itself a source of distortion, and a fairly significant one.  Transistor output circuits can drive speakers directly.

 

Quote:
Originally Posted by ToddTheMetalGod View Post

When tubes first started production they had unintentional distortion due to their manufacturing process and the technology of the time, higher-end tubes used to be neutral like solid-state. 

Neither valves nor transistors are particularly neutral by themselves, both have a smaller range of more or less linear operation, and a progressively larger range with more distortion.  Both benefit from designs that linearize the total circuit, usually through application of negative feedback, and in the case of valves, that feedback loop usually includes the output transformer. However, there are trade-offs to be made with the application of feedback.  If by "higher-end" tubes vs their earlier predecessors we mean more sophisticated tubes like beam power tetrodes or power pentodes as compared to earlier triodes, the neutrality came from the ability to operate those tubes in more sophisticated circuits and take advantage of their additional electrodes.  You can operate a pentode as a triode if you want, but nobody really wants.  

Originally Posted by ToddTheMetalGod View Post

Also, from what I've heard tubes don't distort as harshly near an amplifier's maximum power output (probably do to their intentional distortion covering it up). 

 

Well, the statement is kind of loaded.  Tube circuits be designed to slide into clipping more gently and softer, but it also has a lot to do with power supply design, and what's going on in the output transformer.  Another way to look at it is that a tube amp could provide gently distorted audio all the time, and just keep getting more distorted as levels go up, but a typical SS amp will play clean and distortion free for it's entire operating range right up until it clips, which will be kind of nasty, but you'll have clean audio up until that point.  Both methods have their points.

Quote:

Originally Posted by ToddTheMetalGod View Post

Tubes can be neutral, but because people like the "warm, vintage tube sound" manufacturers continue to produce them to  sound this way. Sound flavor is usually intentionally done by the manufacturer. Correct me if any of this information is wrong though, I'm still learning about audio.

 

This is an interesting and astute statement.  What's the point of building a tube amp that sounds like the typical SS amp?  None, you want  your amp with big glowing bottles to sound different than a SS amp.  That's part of why there are small, under-powered tube amps made today, designs that starve the output tubes for plate voltage, circuits without adequate negative feedback, and class A circuits, which everybody thinks should be great (class A is good, right?) but often operate beyond the linear part of their characteristic curve, and inefficient, and very low power.  Well, all of that will sound different from a solid state, high power, low impedance amp.  And, speaking of that little impedance thingy, it's darn hard to get a tube amp's source impedance anywhere near as low as a SS amp, mostly because plate impedances are high, and that means a transformer.  So a tube amp has a higher source impedance, and a speaker's impedance curve now translates into an inverse response curve.  Sure, that'll sound different too.  

 

But you don't need a tube amp for any of this.  You can simulate the effects of distortion, higher source Z and response variations while using a SS amp.  Been done, proven, marketed with limited success.  But ultimately, even though the SS amp that sounded like a tube amp was indistinguishable from a high-end tube amp sonically, it ultimately failed as a product because it wasn't as much fun.  It didn't heat up, have big glowing glass, and weigh a ton.  You can't separate the physical and visual impact of tubes from the experience without taking the fun out of tubes.  If you didn't know the amp had tubes, it would just sound like a strangely distorted amp.

post #99 of 915
Quote:
Originally Posted by Meremoth View Post

 

It's was a cross-post, which is against the rules.  Only reason I posted it was because the thread it was originally in was temporarily locked, but I thought it was going to be permanently locked, so I copied and pasted it here.  

 

Sorry, jaddie, but I'm not going to break the rules just because you want me to.  I'm going to go by the forum's conduct code, not yours.

 

Also, I don't appreciate being bossed around/threatened by a non-mod.  Most forums, I'm aware of, boot non-mods for attempting to moderate.  You need to take that garbage elsewhere.  

 

But if you want to see the original post, here it is:

 

http://www.head-fi.org/t/669903/headphones-needing-power/60#post_9579177

Hmmm. Ok, sorry.  I don't want anyone to break the rules.  I don't have a code either.  And I'm sorry if it seemed I was bossing or threatening.  I did have a reply to your post, but your post vanished.  

 

Taking my garbage else where.  Now.

post #100 of 915

Thanks for clearing that up, and teaching me about differences between solid-state and valve amplifiers Jaddie smily_headphones1.gif. I wasn't trying to misinform anyone, I'm still learning about this stuff myself.

post #101 of 915

Speaking of tubes, what does tube rolling do? Do different tubes introduce different amounts of distortion?

I'm assuming op-amp rolling exists too but if a circuit is optimised for X op-amp, Y op-amp may not be optimal.

post #102 of 915

Not only not be optimal, but swapping op-amps "blindly" can in fact lead to oscillations which can cause damage.

post #103 of 915

Yeah, tube rolling in simpler circuits the variance in some tubes can make changes in the sound or at least potentially can.  And I have heard of people doing the same for op-amps.  Op amps tend to be more linear when used properly so I would think usually unless switching to an op-amp that wasn't really fit for the circuit you would get no real audible difference. 

post #104 of 915
Quote:
Originally Posted by jaddie View Post

 

This is an interesting and astute statement.  What's the point of building a tube amp that sounds like the typical SS amp?  None, you want  your amp with big glowing bottles to sound different than a SS amp.  That's part of why there are small, under-powered tube amps made today, designs that starve the output tubes for plate voltage, circuits without adequate negative feedback, and class A circuits, which everybody thinks should be great (class A is good, right?) but often operate beyond the linear part of their characteristic curve, and inefficient, and very low power.  Well, all of that will sound different from a solid state, high power, low impedance amp.  And, speaking of that little impedance thingy, it's darn hard to get a tube amp's source impedance anywhere near as low as a SS amp, mostly because plate impedances are high, and that means a transformer.  So a tube amp has a higher source impedance, and a speaker's impedance curve now translates into an inverse response curve.  Sure, that'll sound different too. 

 

Correct me if I'm wrong, but most valve amps don't use NFB because it's not plausible in the design. Tying the feedback loop to the output with an OPT would introduce phase shift and all sorts of other problems. Rod Elliott wrote about this a little bit. Maybe there are a few designs out there that manage to do so, but I'm not aware of them.

 

Also, since most valves are constricted to fairly low gain, trading it in with NFB doesn't make sense. There's no need to use NFB to stabilize the circuit like you would with an op-amp (infinite gain). Saying that valve amps need "adequate negative feedback" is a bit misleading methinks.


Edited by OJNeg - 7/3/13 at 10:25pm
post #105 of 915

triodes have V feedback built in - the mu parameter

 

its difficult to build any amplifying circuit of any utility without feedback - but it may be local feedback, not global - certainly global feedback around output transformers is limited by the transformer bandwidth/phase shift

 

some marketing "no feedback" amplifiers try to deny that local or internal feedback is exactly that, negative feedback

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