Point my brain somewhere - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 4th August 2005, 07:20 PM   #1
diyAudio Member
 
Madmike2's Avatar
 
Join Date: Apr 2005
Location: Toronto
Default Point my brain somewhere

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
__________________
Persistence is better then intelligence. Unless persistence kills you.
  Reply With Quote
Old 4th August 2005, 09:13 PM   #2
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
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
  Reply With Quote
Old 5th August 2005, 01:06 AM   #3
diyAudio Member
 
Madmike2's Avatar
 
Join Date: Apr 2005
Location: Toronto
gulp never mind then. I saw what happened just talking about wire.
__________________
Persistence is better then intelligence. Unless persistence kills you.
  Reply With Quote
Old 5th August 2005, 05:31 AM   #4
rnrss is offline rnrss  United States
diyAudio Member
 
Join Date: Jul 2005
Location: na
Send a message via AIM to rnrss Send a message via MSN to rnrss Send a message via Yahoo to rnrss
Quote:
Originally posted by GRollins

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...
  Reply With Quote
Old 5th August 2005, 06:03 AM   #5
Account Disabled
 
Join Date: Aug 2002
Location: Near to the Pacific Ocean
Quote:
Originally posted by rnrss

So basically anything with low damping will sound like a tube amp...

That simple . . . ? ? ?
Intersting . . .


Regards
jH
  Reply With Quote
Old 5th August 2005, 06:46 AM   #6
rnrss is offline rnrss  United States
diyAudio Member
 
Join Date: Jul 2005
Location: na
Send a message via AIM to rnrss Send a message via MSN to rnrss Send a message via Yahoo to rnrss
Quote:
Originally posted by jh6you

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
  Reply With Quote
Old 5th August 2005, 06:47 AM   #7
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: USA
> 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.
  Reply With Quote
Old 5th August 2005, 06:50 AM   #8
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Quote:
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...

This promises to develop into another erudite and informative thread. We expect more revelations please!
  Reply With Quote
Old 5th August 2005, 07:11 AM   #9
rnrss is offline rnrss  United States
diyAudio Member
 
Join Date: Jul 2005
Location: na
Send a message via AIM to rnrss Send a message via MSN to rnrss Send a message via Yahoo to rnrss
Quote:
Originally posted by analog_sa

This promises to develop into another erudite and informative thread. We expect more revelations please!
Dont you think I stuck my neck out far enough? They will hunt me down!!!! lol
  Reply With Quote
Old 5th August 2005, 08:00 AM   #10
Account Disabled
 
Join Date: Aug 2002
Location: Near to the Pacific Ocean

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
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Wire Wrap connections for point to point mashaffer Tubes / Valves 10 7th July 2007 01:11 PM
Benifits of point to point wiring for digital circuit? MGH Digital Source 15 14th September 2006 10:17 PM
Anyone use magnet wire for point to point wiring projects? Hybrid fourdoor Parts 10 2nd February 2004 08:11 AM
Audio Note's Kit One done in point-to-point wiring Wram Tubes / Valves 18 29th April 2003 10:59 PM
Point to point crossover soldering Ilianh Multi-Way 9 24th December 2002 04:14 AM


New To Site? Need Help?

All times are GMT. The time now is 05:31 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2