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How do I understand the "flow" of electricity in amp design?

24.34.142.46
Posted on October 24, 2009 at 17:21:15
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 Hi, my name is Damon and I am new to the board. Been lurking for some time now. I make my living as a musician, teacher and piano tuner. My goal is to build a SET 2A3 amp. I am a complete beginner and have no experience with amp design.
I'm trying to figure out in la-min terms the flow of electricity from the wall through the amp and into the speakers. Also the function/job of each component and how that component effects the signal and the sound.
Am I making any sense?

If you want to check out some of my music go to

Damon, welcome to the audio asylum..., posted on October 27, 2009 at 16:44:44
slownlo
Audiophile

Posts: 1067
Joined: October 11, 2003
 there is a TON of information online that can help you get started, but nefore you do anything else, make sure you read up on best practices for electrical safety! The voltages inside a tube amp CAN KILL YOU, so make sure that you study up on safety before you do anything else... I have been shocked more times than I care to mention, so I learned the hard way...no need for you to...

Most folks here will agree with me when I say that the most important part of a tube amp is the power supply. It all starts there, so in your quest for tube knowledge pay special to that...

The 2A3 is a nice place to start! Its one of my fav tubes...what kind of speakers do you have?

Be patient, and above all HAVE FUN!
RE: How do I understand the "flow" of electricity in amp design?, posted on October 27, 2009 at 04:33:37
Vatron
Audiophile

Posts: 410
Joined: March 11, 2001
 Hi Damon,

Welcome to the world of DIY audio, it can be fun.

Go slow, and experiement on the way, learning the basics as you go.

Here is a link to a wealth of audio and electronic basics.

Poke around and you will find many things that will help guide you through your journey.

Have fun!

NW

RE: How do I understand the "flow" of electricity in amp design?, posted on October 26, 2009 at 10:26:23
Matts_
Audiophile

Posts: 1975
Joined: February 4, 2005
 something to be aware of is the terms "positive" and "negative" were defined in electronics long ago, before people understood electron flow, and they made a convention that "electricity" flows from positive to negative. That's still largely followed, even though in precise physics terms we now know that electrons flow from "negative" to "positive". When reading be alert to what convention they're using.

Very quick and dirty: A voice or instrument makes sound "waves" that are analogous to AC. These are turned into very small AC signals in mics and pickups. These small signals are fed into circuits that have DC power supplies standing at the ready, and the little AC signal is to control the "flow" (like the handle on a faucet) of DC- thus getting the larger DC signal to "mimic" in respects the original AC signal, but with more current. The DC part of this is blocked in the output, so a more AC powerful signal, much like the original if the amp is linear, is sent to the speakers, that move in and out based on the AC signal, and reproduce a copy of the original sound in the air.

fwiw, the schematic you posted doesn't show the DC power supply circuit, so it would be hard to understand by itself.


Tubes were originally called "valves" because of the way they controlled flow in a circuit with the AC on the grid acting as a "faucet". All this is way oversimplified to help you get a start.

RE: How do I understand the "flow" of electricity in amp design?, posted on October 26, 2009 at 11:25:39
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 "fwiw, the schematic you posted doesn't show the DC power supply circuit, so it would be hard to understand by itself."

Sorry, I will try to find one with the DC power supply. Or do you have any suggestions for me?


"Very quick and dirty: A voice or instrument makes sound "waves" that are analogous to AC. These are turned into very small AC signals in mics and pickups. These small signals are fed into circuits that have DC power supplies standing at the ready, and the little AC signal is to control the "flow" (like the handle on a faucet) of DC- thus getting the larger DC signal to "mimic" in respects the original AC signal, but with more current. The DC part of this is blocked in the output, so a more AC powerful signal, much like the original if the amp is linear, is sent to the speakers, that move in and out based on the AC signal, and reproduce a copy of the original sound in the air."

I think I'm starting to get my head around what you are saying. Thank you.

RE: How do I understand the "flow" of electricity in amp design?, posted on October 26, 2009 at 18:28:56
Matts_
Audiophile

Posts: 1975
Joined: February 4, 2005
 don't worry about finding power supply for me- I know what they do! Just that with all this talk about higher voltage DC you may want to see where it comes from and how it affects the picture.

don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 25, 2009 at 21:56:51
elblanco
Audiophile

Posts: 826
Joined: August 20, 2004
 kjh

RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 26, 2009 at 06:54:50
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 Why?

RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 26, 2009 at 16:05:01
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 Because the reasons they provide to explain things are either wrong, nonsense, fantasy or some combination of those three.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 26, 2009 at 18:05:49
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 WOW!!! I'm just trying to get a simple understanding of how an amp works. You sound like a prick, please don't respond to any of my posts.

RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 27, 2009 at 06:16:59
Ray Moth
Audiophile

Posts: 1962
Location: Jakarta, Indonesia
Joined: November 10, 2003
Contributor
  Since: May 20, 2009
 You asked why and Doug answered your question. No need to respond with vulgar insults. You sound like a brat to me.

Don't bother to ask me not to repond to any of your posts because I have no intention of doing so.

RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 27, 2009 at 06:56:10
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 Wow! this is incredible. I guess I am burning bridges before they get built. I have to chuckle to my self a bit because I thought i would be entering an arena of free thought and ideas. This is an open forum isn't it? Am I entering a den vipers? Being told not to listen to another group of forum members is crazy. Are they black listed? Are they criminals? Scary stuff. I am hear to learn and have some fun. Please keep the cancer away!

"You asked why and Doug answered your question. No need to respond with vulgar insults. You sound like a brat to me."

You are right and what I said showed poor judgment. I have apologized and hope I am forgiven by PakProtector and the rest of the board. I will not be led astray again by your insult. Two wrongs do not make a right.

RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 27, 2009 at 20:24:41
danlaudionut
Audiophile

Posts: 3564
Location: Upstate NY
Joined: June 6, 2002
 drlowmu is on a temporary ban right now.
Their designs are - lets say different.
Their theology is sketchy at best.
But they are persistant and dogmatic.
Well mostly Jeff or drlowmu.
So they do have a following but
they have enraged quite a few also.
One thing is for sure their design is
not for the beginner as it needs to
be tweaked to get it to run properly.
You just touched a sore subject.
I hope everybody gives you time to
get acclamated to this place.
BTW Welcome 8^D

DanL
RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 27, 2009 at 03:14:57
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 Please go and listen to Jeff and Dennis, you obviously deserve it.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 27, 2009 at 06:33:29
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 Pakprotector I am sorry for calling you a prick. This was childish and inappropriate. I should have seen your ignorance for what it is. Instead I was led into the path of the evil one. I will give you some advice that comes from our father. Live by the sword and die by the sword. This is meant for me just as much as it is meant for you. Again I am sorry.

RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 27, 2009 at 06:46:26
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 -----I should have seen your ignorance for what it is.

And just what is that?

Let alone the 'ignorance' remark...how is it you're able to simultaneously ask questions as a beginner, and correctly reach conclusions about my analysis of claims/explanations made by Jeff and Dennis?
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 27, 2009 at 07:17:30
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 The ignorance I refer to is NOT allowing free speech. Why are you shutting the door on some one who has not spoken? I like to hear all sides before I make a decision. I thought that's what "higher" education is all about. Or has that been hijacked hear just like in America?

RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 27, 2009 at 07:25:33
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 ----Why are you shutting the door on some one who has not spoken?

If you're speaking of a lack of responses from Jeff and Dennis, that may be true on this particular thread. Their writings are legion on this board, and for the most part all the same flavour. I have read enough to make an open-minded judgement comfortably. That does not mean they might change their stripes/spots, and If they do I am quite comfortable revising my opinion of their ideas and methods.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: don't listen to drlowmu or tubestrangler and you'll be fine--NT--, posted on October 27, 2009 at 07:48:19
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 Thank you for sharing what's in your mind and the condition of your heart. But please allow me to judge what is the appropriate path for my goals.

RE: How do I understand the "flow" versus schematic, posted on October 25, 2009 at 10:32:36
FenderLover
Audiophile

Posts: 3308
Joined: July 31, 2007
Contributor
  Since: May 17, 2009
 In general, the way most schemtaics are drawn, electrons move from (-) to (+). So, flow from power supply (power transformer) is from chassis, which is ground reference, through the cathode of tubes up toward the anode (+). This is the DC portion of most units.

The signal is the AC portion. By convention, the signal moves from input side, through each gain stage. Then, into the power section and the output transformer. Usually, reads from left to right, on the schematic.

So, most amps, have two major sections. The AC section: signal input/ gain stages/ output sections. AND the DC or power supply section which supplies power to each gain section. Push-pull amps have another major section = the phase inverter. This section sits just prior to the output section.

By convention, most power supply sections usually sit below the signal/gain stage sections on the schematic (at least should be separated from the signal section). Also, running from left (AC cord) into the power transformer to right (rectifier/power filter sections) and then into each area needing DC power.

So, obvious thing you see is that the power transformer should NOT see AC signal. And that DC power is from the power supply. This portion supplies the energy needed for each gain stage section to amplify the signal. It also supplies power to the final power section to drive the output tubes & output transformer.

RE: How do I understand the "flow" versus schematic, posted on October 25, 2009 at 17:37:31
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009



This is what I am looking. Thank you so much. Let me sink me teeth into this and get back to you. I did not know most schematics read from left to right. I didn't know the power flowed through DC and the signal flowed through the AC.
I am trying to figure out this Loftin white circuit. What all the symbols mean and what they do.

RE: How do I understand the "flow" versus schematic, posted on October 27, 2009 at 08:14:33
FenderLover
Audiophile

Posts: 3308
Joined: July 31, 2007
Contributor
  Since: May 17, 2009
 Yeah this is the very basic overview. I'd call it the "nuts" description---too basic even for "nuts-&-bolts." I feel it's kinda important to know that most amps have two distinct portions. AC-signal path, where the signal is boosted and made ready for the output transformer and speakers.

And the DC power supply, which runs from your home's AC outlet, through the unit's power transformer (often at several hundred volts above the 120VAC on the primary). Get's rectified to DC and is then used by each section to help boost the original signal. This portion supplies the needed energy for each gain stage and output stage to amplify the signal.

RE: How do I understand the "flow" versus schematic, posted on October 27, 2009 at 15:32:55
Matts_
Audiophile

Posts: 1975
Joined: February 4, 2005
 the AC signal is never actually "boosted" - it's used to "control" the "flow" of higher voltage of the power supply which results in the output. In most topologies, the AC input to each stage "dead ends" in the grid, and the variations in the plate voltage caused by the variations from the input to the grid make the "AC" input to the grid of the next stage.

RE: How do I understand the "flow" versus schematic, posted on October 27, 2009 at 08:30:13
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 Thank you thank you. I actually understand what you are saying. I have printed and will review your words for study. I am in the process understanding how to read schematics. The symbols of components, direction of currant AC or DC. and the effect each component has on the current.

one other minor note, posted on October 27, 2009 at 09:26:27
FenderLover
Audiophile

Posts: 3308
Joined: July 31, 2007
Contributor
  Since: May 17, 2009
 Thanks! Should note, some amps have other basic sections, specific to the amp and topology of the amp. Some have a volume/tone (or effects) section. Also, amps have various ways of setting their power tube's idle bias. It's kinda like the control which set the car's idle. From a few added parts to a whole dedicated section maybe used to set & control the amp's power tube idle bias.

Good luck with breaking down a schemo...
RE: How do I understand the "flow" of electricity in amp design?, posted on October 25, 2009 at 09:41:13
JimL
Audiophile

Posts: 3347
Location: New Mexico
Joined: November 24, 2002
 Two good primers on basic electrical theory, components, tubes, etc. are by Bruce Rozenblit: Audio Reality and Tube Audio Design, which are available from the AudioXpress web site. After reading them you'll have a reasonably good basic knowledge of electronices, although probably not enough to design anything. He doesn't get into some of the more esoteric arguments you'll find here and on Tube DIY Asylum about components, etc., and in fact is rather dismissive of some of the subjective foofaraw that gets the juices flowing around here :-), but you have to learn to walk before you can learn to run.

RE: How do I understand the "flow" of electricity in amp design?, posted on October 25, 2009 at 17:38:33
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 thanks you I will check it out.

The Scots Guide to Electronics, posted on October 25, 2009 at 05:36:27
Metralla
Audiophile

Posts: 6413
Location: San Jose, California
Joined: January 30, 2001
 This course is designed to help you learn about components, circuits, and the use of electronics. You can explore the contents in whatever order you wish.The emphasis is on providing information starting at the 'absolute beginners' level, but we hope eventually to provide material of use to anyone interested in electronics and its applications

This site provides a lot of guidance.

Regards,
Geoff
My advice., posted on October 24, 2009 at 23:32:36
twystd
Audiophile

Posts: 1663
Location: Austin,Texas
Joined: December 9, 2000
 If you wait to understand what you are doing before you build, you may be at it for a very very long time. My advice would be for you to research a very good kit, learn to solder, build the kit while learning to read schematics, read a few books at the same time, and seek clarification on the various forums. Then try and do a few mods if you think it has room for improvement (almost all kits do, since they are made to a price point). Remember to do them one at a time, and listen for the changes, making sure to allow enough time for break in. I think most of us who weren't EEs, or had formal training learned that way.

One of the most important things is to make sure that you have sensitive enough speakers for a 2A3 amp. It won't do you a lot of good to build a whiz-bang 2A3 amp, and try and use the typical "Sterophile approved" 83-89Db efficient speakers. Although many people here will say that a 2A3 amp will work well with speakers 93Db (or in some cases even lower) efficient and above, I disagree.

The reason I say that is that I'm a musician too, and I'm used to hearing live level dynamics. 93Db efficient speakers can certainly play loud enough, but there isn't enough headroom for a 2A3 amp to deliver the dynamics and transients I like. I find that I prefer 99Db and above efficiency for a 2A3 amp. You may consider a 300B amp, IMO you can use 96Db speakers with those, and still get pretty impressive dynamics and transients. Also there are many more speaker choices available in the 96Db and up range.

Although you'll rarely if ever hear actual live level dynamics in your, or anybody else's, listening room, I think musicians tend to be a little more demanding of that than others. As a matter of fact, after 10 years (I'm a slow learner) I'm finally able to design my own simple designs. Right now, I'm in the process of building self designed 30 watt integrated amps, to drive my 96Db speakers. I've always loved these speakers, but the amps were always the weak link, 30 watts ought to solve that.

twystd

RE: My advice., posted on October 25, 2009 at 17:52:34
dwade277
Audiophile

Posts: 19
Joined: January 14, 2009
 Thank you for your help. I am going to build MLTL box's for an Altec 604 speakers. I'm guessing they should be 98% or higher efficient.

"My advice would be for you to research a very good kit, learn to solder"

Well, I know how to solder and I know how to read. That should get me started.

I'm just trying to build a great simple system that does not screw up the source. For as little as possible. I figure find a good CD player use a good digital converter with a volume control into a 2A3 SET amp connect that to some Altec 604's and I will live happily ever after.

RE: My advice., posted on October 25, 2009 at 22:52:42
twystd
Audiophile

Posts: 1663
Location: Austin,Texas
Joined: December 9, 2000
 I assume you meant 98Db efficient speakers, in that case, you should be fine with a 2A3 amp, IMO a 300B amp would be even better. If you get a good CD player, a DAC may not be necessary. If you do get a DAC with a volume control, make sure it is a resistor based or transformer based attenuator, and not a digital volume control. Digital volume controls attenuate by throwing away information, not a good thing for an audiophool quality system.

For the front end, I'd recommend either a very good CD player, that has a good DAC built in, feeding an active preamp, with either a TVC (transformer volume control), or a nice stepped attenuator. If you already have a CD player that has a very good transport, but maybe not the best DAC section, then buy a separate DAC, and feed it to the active preamp with the recommended attenuation.

I'm not a big fan of passive preamps (just attenuators), as it takes a very unusual amp to give good slam and dynamics with complicated music, like orchestral, big band, or lets say my favorite, high energy rock'n blues jazz fusion. Not saying it can't be done, but with most amps, only girl and guitar music is satisfying with passive type preamps. However, nothing wrong with girls with guitars, I've been known to enjoy them!;-)

I'm sort of extreme, but the direction I'm going is computer audio server> USB DAC> 30-45 watt integrated amp, with an active preamp section> 96Db speakers. This route isn't cheap, as I'll have about $5,800 into building the whole system. Not saying this is the way only way to go, but very direct, high rez, and near live level peaks. So far, I've built the DAC, and am working on the computer audio server now (I have the stuff), have to get about another $500.00 in parts to breadboard the amps. The speakers are a done deal.

Where I'm at now: decent CD player> home brew parafeed preamp, with a custom Goldpoint attenuator> 7 watt single ended 300B amp> 96Db speakers. It cost me about $3,500 to build that. I'd think that by the time you're done, it'll probably take you at least $2,500 to put together a decent system (CD player/DAC, preamp, amp, and speakers).

twystd

A basic primer..., posted on October 24, 2009 at 18:48:12
Audiodyssey
Dealer

Posts: 512
Joined: November 7, 2004
 Here's one link to a helpful site.
"I KNOW you can hear it, but are you REALLY listening?"
Great site..., posted on October 25, 2009 at 09:07:49
Dingojazz
Audiophile

Posts: 587
Location: Sonoran Desert
Joined: January 3, 2005
 This is a great source for complete electronics novices...

Cheers,

K.

RE: A basic primer..., posted on October 24, 2009 at 19:03:23
Audiodyssey
Dealer

Posts: 512
Joined: November 7, 2004
 Ahh, like the Blues, do ya?
Well ya can't be that bad then. I've got the bug real bad lately, been buying up all kinds of new music. Johnny Lee Hooker is my flavor of the week, but I got John Mayall on now, and just finished with Albert Collins...
AND I CAN'T BELIEVE I GREW UP WITH THE ALLMAN BROS. ON THE RADIO, & NEVER PAID ANY ATTENTION TO THEM!!!

...If you try to become an engineer before you build, it'll be a long time before you do. Learn to read schematics and learn something of components, transformers, and tubes, and you can start building designs that are readily available on the web. If you want to design circuits, well that's another thing. I've built a few pieces, and I still don't know which way my electrons are flowing, and I never quite grasped what the Jensen Capacitors are doing besides costing me a lot of money :)
"I KNOW you can hear it, but are you REALLY listening?"
RE: How do I understand the "flow" of electricity in amp design?, posted on October 24, 2009 at 18:43:29
Paul Joppa
Industry Professional

Posts: 5028
Location: Seattle, WA
Joined: April 23, 2001
Contributor
  Since: July 1, 1999
 Wow - nothing like a challenge!

You're going to need to know Ohm's Law and understand the idea of electrical power, as opposed to force (voltage) or motion (current). There should be plenty of material on the web or at the library if you are not yet familiar with these.

Then you can break down an amplifier into two parts - the power supply and the amplifier itself. The power supply delivers the various voltages and currents needed for proper operation of tubes. One of those is a steady source of current at a fixed voltage (fairly high, several hundred volts, which is enough to shock or even kill you - there are safety precautions you'll need to learn before actually building something). That current is modulated in time to the musical vibrations by the tube or tubes, then the musical variations are separated from the steady current and routed to the speaker.

Is that a good start? Too simple? Too puzzling?

Thanks, Paul ! I knew Paul would start this off..., posted on October 24, 2009 at 19:02:04
Interstage Tranny
Audiophile

Posts: 1403
Location: Eastern
Joined: October 4, 2006
 It takes time, reading and rereading books and manuals, over and over. You cannot trust Wikipedia or google searches as a reference. It takes time. After months, even years, ideas and concepts take shape in the mind. Much theory needs to be remembered and simply trusted, first. Understanding comes later, much later. There is NO free ride or quick guide. It will certainly pay off to learn what your mind yearns...

One concept that we techies and engineers remember early and always use to describe electronics is "AC Rides DC." That is, the AC signal, like music, voice and noise is riding on top, or with, the proper DC voltages needed to power the electronic devices. So, while a tube or transistor needs proper DC voltages to work, music(AC) is playing thru the same device elements that are DC powered.

I highly recommend library visits, finding text from the 1920s or 1930s, pre-WWII for certain. My reason is simple. The authors talk to us like we are laymen or novices, not engineers. The simple text can easily be found in early Radio magazines. Pre-1934 was my fave, pre-1930 best...

RE: Thanks, Paul ! I knew Paul would start this off..., posted on October 24, 2009 at 20:59:05
Dmannnnn
Audiophile

Posts: 140
Location: Las Vegas
Joined: November 23, 2008
 Is the DC that the AC 'rides on' the bias?

RE: Thanks, Paul ! I knew Paul would start this off..., posted on October 24, 2009 at 22:14:38
twystd
Audiophile

Posts: 1663
Location: Austin,Texas
Joined: December 9, 2000
 Well, that's one instance where the incoming AC signal runs on top of the DC bias on the grid of a tube. On the same tube you will have very high DC plate voltage, with the amplified AC signal running on top of that. There are many instances of an AC signal running on top of DC voltage throughout an amp.

twystd

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