Point my brain somewhere

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Madmike2

Member
2005-04-24 11:55 pm
Toronto
Would someone be so kind as to point me towards a thread that explained the differences in amplifiers and and their theoretical affects on the electrical signal. i.e FET Bi Polar Digital CHiP TUBE

I got a quick sketch the other day but i want to delve further in. Surely there was a thread that someone explained the differences and theories that developed from tube to solid state.

Michael \

and yes i did search but it became annoying to go through all of them :angel:
 
I don't think you're going to find a simple answer to that. Complicating matters by throwing in chip circuits is going to really, really muddy the waters. Then adding digital? Ugh.
To get a semi-reasonable answer, this will have to be a three hundred page thread...five hundred once you add all the people who want to throw in their opinions, then argue semantics, then get into flame wars.
They each have advantages and disadvantages. Digital amps run cool and (assuming a switching power supply) are lightweight. Chip amps are convenient to build and can be quite cheap. Bipolars, FETs, and MOSFETs require more intensive fiddle-factor, but can produce either good or poor amps depending on who is doing the fiddling. Tubes run hot and have potentially hazardous voltages, but can produce truly glorious sound.
People get religious about this stuff and it quickly goes from fact to fantasy if you're not careful.
Note that negative feedback rates, operating class, and parts choice will rear their heads before the thread passes ten pages, guaranteed.
Good luck.

Grey
 

rnrss

Member
2005-07-20 7:41 pm
na
GRollins said:

To get a semi-reasonable answer, this will have to be a three hundred page thread...five hundred once you add all the people who want to throw in their opinions, then argue semantics, then get into flame wars.

People get religious about this stuff and it quickly goes from fact to fantasy if you're not careful.

Note that negative feedback rates, operating class, and parts choice will rear their heads before the thread passes ten pages, guaranteed.
Good luck.

Grey

No kidding on the semantics and flame wars and fanatics and religious... I guess religious is ok if its good design practice...


I always try if possible back up what I say by some kind of proof when I can but in this case since I doubt most of you have a lab or at least a scope to test these things for yourselves when it comes to the comparison of amps the only real proof to be had besides peoples ears which are really subjective and often biased, is what can be mathematically proven such as damping, and the way the cone is controlled... these are measureableand easily calculated by the layman, but as far as the sound well that is all subjective and there is no proof just taste and if you have not listened to several amps most of the posts will boil down to taste and this thread will go literally no where that you would want it to go... unlike wire hearing and taste cannot be proven...

I think the only way to approach this is to keep it rather basic leaving feeback and all the other stumbling blocks out of the picture... Fet as a rule can have better transient response and cleaner than bipolar and bipolar is very close to fet but from my experience leans more toward tube sound when compared to good fet design...

The biggest difference in amps is between transistor and tube/ccs which gives sound similat to a tube (constant current sounce) is damping and coloration or lack of...

Tube and ccs amps have little or no damping and produce lets say a controlled under/overshooting of the driver and has its own unique coloring effects and as a result the driver will exhibit gain and compression nonlineararities when compared to the original source material...

Tube systems are appropiately coined soft and bright sounding and tubes are typically used by a small group of us old timers who remember them typically on horns because people often believe that is the only way to get the raspiness out of a horn and often just plain like the way a tube colors the sound... at the same time from my experience and I really do not have a good way to describe this but a tube driven horn sounds like its in resonance at all the frequencies because much of the 3rd harmonics are rounded thus more subtle... not just the bass hump area hence the bright sound and a reduction in 3rd harmonic content gives the listener the impression of cleaner more pure sounding music... Its a very interesting sound and has certain properties I really like but not as a reproducer... I like a tube amp as a producer there are certain sounds that are very difficult to produce with a transistor amp that a tube just does naturally...

A tube amp on a guitar tends to mellow out the steeliness of them just enough to cut the shrillness and it has a neet kind of almost a ringing tone with its own harmonics mixed in with the fundamental... so many musicians love em.... the only way to come close in a transistor amp would be to find a low damping amp, (preferably under df=15), or put a resistor possibly starting at 8ohm and possibly as high 20 ohm in series with the driver to lower the damping would work too... but make sure you size it correctly for the wattage or you will get a nasty smell in the house as it starts to fry LOL

Unlike transistor amps tube amps and trans amps have very low or very little damping and usually low power so your how well your speaker is controlled is mainly dependant on the box damping because it will get very little additional damping from a tube amp... Tube and ccs amps usually have a df up to 20ish typically and transistor amps can run from 500 in a faily good one to 20,000.

Tube amps tend to like sine waves when driving a speaker and from tests I have done as you approach the rails they tend to compress the peaks of a sinewave...

When hooked up and measured at the driver as a result of the high source impedance tube amps, square waves tend to be rounded off on the edges as a result of back emf and that is what goes on electrically to tame the 3rd harmonics down in a tube system... meanwhile the low z transistor impedance will force the driver to put out a squarewave much more readliy giving a horn a very raspy sound if not properly adjusted with auxilliary sound processing equipment....

I would not recommend a tube amp for any type of reflex or enclosed box design and its best to stick with transistor in those... Tube amps are commonly used in low power horn systems in a home environment...

A little background on damping... Damping is the ability for an amp to push a driver in/out/stop in exact proportion as determined by the dynamics of the program material... then stop the cone and/or reverse it... ie: transistor amps will force a driver to play a squarewave and a tube will tend to round everything and tend to have a square wave with rounded edges that is why the shrillness of the guitar is cut back a bit giving that nice smooth sound, and a transistor amp playing the same note would require 3rd harmonic frequency cut back considerably to play the same chord to reduce the shrillness...

Driver damping factor is calculated/measured at the driver terminals is a quality measurement that help buyers better understand how well any particular system can follow the input signal... and also how much driver compression/overshoot/undershoot to expect with any given amp/wire/crossover/speaker combination and the amount can be caculated using the theile/small model...

Many tube horn experts will adjust the series resistance using this method of calculation to get a sort of extended bass response from single driver horns...

So basically anything with low damping will sound like a tube amp and anything with high damping will sound like a transistor amp... bipolar will drive a speaker more accurately than a tube, (but not necessarily sound better in "all" cases), and good fet designs will drive a speaker as a rule better then a good biploar design.... and there are always exceptions to every rule.... There are more differences but thats another chapter... and I wanted to sort of stick somewhat to the basics...

So there is the results of several tests I have done on various toys...
 

rnrss

Member
2005-07-20 7:41 pm
na
jh6you said:

That simple . . . ? ? ?
Intersting . . .
[/i]
Regards
jH

yeh pretty much that simple.... I promised to keep it basic... the only place that I can see for this to go from here is to start splitting hairs to the n'th degree, (I can go there too if you wish), but sure hang variable resistor in series with a horn speaker normally driven with tubes, adjust it to tune up your lower region and you will get very similar results because low impedance is used for a voltage source and hi impedance for a current source and matched impedance is used for the most efficent maximum power transfer between 2 devices, (which is not the same as max damping)... in this case an amp and speaker... basic electrical circuits... if you have a scope, a good microphone this can all be very easily demonstrated... If you enjoy experimenting as much as I do try it :)
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
> explaine the differences in amplifiers and and their theoretical affects on the electrical signal. i.e FET Bi Polar Digital CHiP TUBE

They are all the same. Gm proportional to current, plus parasitics.

BJTs are nearly "perfect", which makes them horrible linear amplifiers. The art of transistors is all about adding "parasitic" resistances to linearize them with feedback.

Tubes have large parasitic resistances, so large that the raw Gm is hidden under near-linear parasitics. You can design an acceptable audio amp with tubes without any explicit feedback (tubes have large internal feedback).

FETs sit in the middle. Chips are just BJTs or FETs but so very cheap that you can use 40 transistors to do what can be done in 6 transistors.

What is probably just as important is the EAR. We don't understand aural perception well, and much of what has been learned is widely ignored.
 

rnrss

Member
2005-07-20 7:41 pm
na
jh6you said:

You must be an audio scientist . . .


I don't know the figure . . .
But, my amp has rather high output impedance . . .

When I listen to jazz music from 4ohm impedance speakers . . .
mmm . . . the excited bass play . . .
I hear at the bottom, say 40Hz-50Hz, the sound of standing wave . . .

How should I fix this . . . ?

Regards
jH

Well hmm... no not a sceintist, but does it count that I did assemble my first horn at 8 years old... I had this brain storm that since car horns were so loud that if I put a car horn on a speaker I would have a really kool transistor radio.... So the next time my dad went to the junk yard to sell some scrap iron I scrounged up a car horn took it home and assembled my first horn speaker.... How did it sound? Like S**t LOL It sat on the table for years while I looked at my failure wondering why it did not work lol

Its a little difficult without knowing what you have but there is a couple simple things you can do to figure out what yo uneed to do...

First either rent one from a disco rental and make sure they show you the specs or call up one of your buddies with a low impedance amp, (with a damping factor of over 200 is best for this test, and no less than 100), then tell him if he brings his amp over for the afternoon you will buy the beer!

Then when he shows up, set the amp on the floor between the 2 speakers and run 2 very short peices, (like 1 or 2 foot) of awg14 wire from his amp to your speakers and play the same music that made it yelp or sound boomy...

In a properly designed system, yelping or excessive boominess occurs when the amp looses control of the motion of the driver and the driver begins to severely overshoot the signal being applied to it causing what is commonly called a yelp... and the only way to reduce it is to turn the volume down...

Yelping is a common problem in horns especially when you turn them up a bit and also boominess in the 40 - 100 area depending on your speaker and box tuning... Yelping can occur at virtually any frequency but usually shows up between 40 and 3000ish hz....

If it is a pretty good designed speaker that has the resonance hump properly nulled out that should solve it... and if it is a poorly designed speaker then it will still be there but I would expect that it would be considerably less boomy with the yelping substantially reduced...

I would guess that putting a low z amp on it would really clean it up but just be sure when taking the volume up to do the test that you do not blow your speakers because its very easy to listen to crystal clear bass and turn them up to loud...

Now that may get rid of the yelping but you may still hear that it is louder at 40-50 but your standing wave should be gone, and it is possible that it may still be to loud in that area even though the yelping is gone and in that case you will need to pick up an equalizer and put a dip there to tame it down...

But dont feel bad if that happens as I have never heard a speaker system yet that did not need one... but at least the yelping will be gone...

So for the cost of a 12pak of beer you should be able to get down to the bottom of this...

Good luck, let us know what you find out...
 

I see . . .

Beer is mine as I also have the amp of DF greater than 250 . . .

I took my way . . . very basic and simple way . . .
(mmm . . . as inspired by Nelson) . . .
I put single pole high pass filter at about 30 Hz . . .
At the input of pre . . .
The boomy gone . . .

Probably it happened in the region near to 30Hz . . .
Acc. to "the frequencies of Music" table (bar graphs) . . .
The bottom frequency of the bass is ended at about 35Hz . . .
Yes, it was at the rock bottom . . . (lower than 40-50Hz) . . .


My J-Low horn is still under construction . . .
I will see what will happen there . . .
Hopefully in 10 days . . .


Regards
jH
 
Ya i dont want this to be anything like the Wire thread :mad: LOL i just got a taste of information from a very intelligent man who sometimes forgets he is speaking to mere mortal folks. I was really interested but he had to go and so i thought that i would see what comments would be scrounged up here in DIY land.

Also since i got it here now. I am playing with 700 $ amplifiers in stores. and have three in mind, if y'all dont know anything about them its cool. I am going to try and convince them to take 1000 dollars and let me take it home for a couple days and audition them one at a time.
Wahts the Scoop on these guys

Yamaha Mid Level Natural sound amplifier, would be about 500 US $

Denon same as above

And an Onkyo Integrated for 799$

All are Japanese, i am thinking i proabably need to broaden my search as countries follow trends.

Comments ?


( Everytime i find a good deal in a used shop, its gone before i get back there, hence the buy new strategy change )
 
Althou there are gross generalizations you can make with respect to the components in an amplifier, in the end it comes down to execution & designs.

There are high damping, very low distortion tube amps (Kron Hite -- i know a guy in NZ who loves his, and another in AB that says they are BAD), tube amps that smoke SS amps in the bottom end, SS amps that approach the creamiest of SE tube amps... and within it all the speakers the amp is used with cannot be considered outside of the equation.

dave
 
analog_sa said:


I also can't think of anything better. Maybe PD can also undo some of the brainwash caused by the physics professor.


Nah he didnt brain wash me. I qualified his comments by saying that he ISNT an audiophile BUT he is a genius in his field who used to have a smoking single daughter :D SHe is no longer single and no longer smoking after 3 kids but we all still get along. He was just telling me more about electrical constants and detrimental affects of circuits on electrical signals. He didnt pick a side he just said they all have their own points but none of them are pure gain devices that dont have a personality.

As for Peter Daniel. Yes i think i will see him if he will let me. No point bringing this cheesy amp with me. I would rather bring beer and a pen to take notes :D
 

rnrss

Member
2005-07-20 7:41 pm
na
jh6you said:

You must be an audio scientist . . .
I don't know the figure . . .
But, my amp has rather high output impedance . . .
When I listen to jazz music from 4ohm impedance speakers . . .
mmm . . . the excited bass play . . .
I hear at the bottom, say 40Hz-50Hz, the sound of standing wave . . .
How should I fix this . . . ?
Regards
jH

jh6you said:

I see . . .

Beer is mine as I also have the amp of DF greater than 250 . . .

I took my way . . . very basic and simple way . . .
(mmm . . . as inspired by Nelson) . . .
I put single pole high pass filter at about 30 Hz . . .
At the input of pre . . .
The boomy gone . . .

Probably it happened in the region near to 30Hz . . .
Acc. to "the frequencies of Music" table (bar graphs) . . .
The bottom frequency of the bass is ended at about 35Hz . . .
Yes, it was at the rock bottom . . . (lower than 40-50Hz) . . .


My J-Low horn is still under construction . . .
I will see what will happen there . . .
Hopefully in 10 days . . .


Regards
jH




So what exactly is your point here?

That pulling out your soldering iron, designing and soldering up a circuit for the front end of a preamp is easier than simply hooking up the Vs amp you had all along?

I am sure soldering up an input filter is last thing that Mike and other non engineering type people out here plan on doing as it is not that simple to them...

I suppose you feel it is easier for them to get a degree in engineering so they can get rid of the boominess that most likely never would have occured in the first place had you used a Vs amp to begin with....

In fact most non engineers would not even consider soldering up a prefilter much less know how to do it in the first place...

Secondly you did not tell me what the problem "really" was now did you?

You gave me a ficticious problem to solve and expect me to come up with the correct answer for the problem really was...

I solved the problem you gave me man, I cannot read your mind and correct your question...

The bottom line here is that we both told you to use equalization, I as a last resort him as a first resort... and of course this other guys solution was the only solution that could possibly work in your mind.... get a clue... his solution just chopped off the bottom 3/4 octave and if that makes you happy all the better... so much for the quality of your system...

I should have guessed....
How entirely rude....
You baited me my friend...
Now I think I dont like you...
You already had your problem solved before you even asked me that question... Trying to set a trap for me to see if I would give you the same answer as this pass guy did... when you gave me an incorrectly stated problem...

There are a lot of people who are totally clueless, (including many acoustical engineers), in how to properly set up and eq a Vs system... and worse there are those would not put to much effort into it hoping it fails....

Well I have news for you... there is nothing anyone can do with a trans or tube amp on "any" coil style speaker that I cannot do better with a Vs amp and low damping and my associated equipment... and I am willing to prove it...

Any volume level, 45 - 135db... rock solid, smooth as silk, floor shaking 22 cycles, incredible dynamics, transparent and pristine imaging... Crystal clear and my house physically heaves when they blow up the arizona in the movie pearl harbor... If you are ready you compete with that using a high z amp then you know less than you think...

I dont solve problems the same way this other guy does and I certainly dont chop off a very hearable part of the spectrum....

My designs are very natural sounding and extremely linear go very low and also go very loud with no spikes or dropouts, zero yelping at any freq as loud as it can go till you blow it at around 140db... Since you feel the need to present me with a challenge bring it on buddy... anywhere in the us... I will bring my equipment and you bring yours... any size audience... winner take all... so make sure you bring all your best gear... and make it worth my while...

You play what you want and I will play the same thing any level... and when its loud like a real band:

hint: they wont even hear yours...

There is nothing that you can do with a trans amp or tube amp in a "reproducer" system that I cannot do better with a Vs amp and my associated equipment... and if you are running this thing without an eq its a joke to begin with...

I have yet to see a high z amp in a "good" theater, live band or concert... So bring it on man, when you lose your equipment then you will be rnrss inspired...

Save it I know what j-horns sound like... not even close, not impressed, nothing new...

Yeh regards
 
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