So just what is Constant Voltage

[mas]

When I posted the article on the Calculated Fx of Interconnects and Cable, I mistakenly assumed a few things...I assumed that many would understand both the reference to a CV analytical model as well as what is, in practical sense, referred to as a CV distributed model. I understand that many may have not had the opportunity to have experience with the distributed model of sound distribution.

But I never cease to be amazed at the tangents that so many rather simple posts take!

May I commend Gil for asking a wonderful question that most missed - but which never seems to prevent some from running with scissors! And for those who may also have more questions, I have atttached an adapted article that - while its title may seem to remove it from the interest of many, if you bother read it all of the way through, you just might discover both the applicability and to just what the reference refers - in addition to how your home system also fits into this larger seemingly alien landscape! Of course I am sure many will not wait for the nexus and will instead run amuck decrying its applicability - after all, there is a tradition to uphold...[*-)]

And still everyone is wondering, what the heck is he referring to!?

So, may I suggest reading the attached article and the link that follows the article for more information regarding both the CV analytical circuit model as well as some practical application comments regarding what is commonly referred to as CV in the link that addresses an aspect of sound of which some may be unfamiliar. And on that note, let me make an observation that is sure to kick the proverbial hornet's nest. (As I know all of you would be very disappointed if I didn't do this at least once in each post!).[] But hey, it just may pique someone's interest and cause one or two to think outside of their comfort zone! And it just may 'offend' some who are more content to 'sit in a small universe content with knowing allot rather than looking out into the big world of audio and being impressed by how little we are really aware of and wanting to know more', premise.

Folks, speaking very generally (and not with any direct reference to this thread!)...there are allot of new technologies and developments in audio (as elsewhere), as well as additional applications in mainstream audio - and many are considered 'professional' as opposed to amateur applications (a silly demarcation IMO - but certain situations may be more commonly encountered in one than another), but they are nevertheless real and widespread. We have lots of folks with a wide variety of experience, knowledge and interests. Some are aware of them and even have substantial experience and knowlwdge, while others have no idea of what I am referring.And still others have no interest in areas other than in what they are interested. And all are fine! But, if some is not aware of a technology, some choose to dismiss it. If it is of no interest, by all means ignore it if you choose. For those who may not be aware of a particular technology, may I suggest that rather than simply objecting to any mention of these technologies and dismissing them, that some might instead respond by asking more questions rather than simply dismissing them as they might not quickly or easily fit into one's preconceived notion of what constitutes 'audio'. Just imagine the possibility that some of these aspects of the trade might lead to a greater understanding of your own particular chosen niche. Again, this is a general common sense idea aimed at topics in general. And I appreciate Gil asking just how the concept of constant voltage was being used. I suspect that many had the same question.

For some the use of a CV distributed system may seem a bit unusual as well, but the particular analytical circuit model is very applicable to a 'standard' system. The article on cable calculations simply crossed several boundaries that normally are not encountered, and thus raised a few unusual topics if one has an interest and choses to pursue them. And this might be of help to some who have less experience in circuit analysis and the more theoretical approach to circuit analysis.

But in any event, may I suggest that a more expansive view provides some real benefits and additional insight. There is allot of 'stuff' out there, as the area of audio has allot of facets and applications. And the various analytical models provide one more way to qualify and quantify various critical parameters.

OK, thank you for all waiting patiently! Now you can all run to fetch the tar and feathers! And don't forget your scissors! []

Constant Voltage and Distributed Systems.pdf

[DrWho]

let me post another reference along with a link to another online
discussion that attempts to simply address an aspect of sound that most
seem to be unaware of.

Am I missing something? [*-)]

[mas]

Mike, be nice, or I will run off about Nyquist and Heyser spirals! [][]

Yep, it is for those who have less experience with various circuit topologies and analytical circuit analysis - as well as some of the practical benefits that this particular topology affords.

[DrWho]

Btw, I noticed this at the bottom of the article:
"Adapted from the JBL Technical Note, Vol. I, No. 2."

How dare the Harman disease be brought to these forums. JBL = [+o(]

[]

[mas]

Yeah, I know - the entire world seems to be in the process of being 'Harmonized'! [][:S]

But if you want to see an even bigger more depressing catastrophy, go visit Electro-Voice! Even the contact link on the web site sends you to the Sullivan Group - who make T-Shirts and apparel! [:|]

But in each house (JBL and EV) there are still some great minds! Unfortunately I cannot say that they extend into the new management structures...

Its sad to watch as it seems the entire audio industry seems to be re-orienting itself to become a manufacturer of computer headsets, iPod accessories, home theaters in a box and room-correcting(sic) subs and receivers...

[DRBILL]

I'm at a loss, too. I would have assumed that many (if not most) people on this forum would have had at least a little hands-on experience with constant-voltage distribution systems at church or lodge or school or work. What is the point?

Mas, I used to have to grade papers like yours which assumed that I knew the wonderful secret.

DRBILL

[Guest " "]

The devices used to step up and step down the line signal are typically 30hz - 15khz,  with an insertion loss of +- 1db at each link, and handle 150 - 300 watts per unit.  Atlas AF140, Crown CT-170, etc.   These range in price from 50 - 75 bucks.  A wide bandwidth autoformer that can span 2hz - 2mhz, low DCR, and handle more power, falls in the 250 per unit price range.  Zero autoformer product.

The coloring of the audio signal as it passes thru such a process is sometimes desireable....comparable to voltage limiting....espeacilly on the extreme ends of the bandwidth spectrum....basiclly introducing a new roll off point, depending on the bandwidth of the transformers or autoformers used.

Pitfalls while using wide bandwidth directly coupled solid state amplifiers with  a transformer based architecture to convert to constant voltage  is the problem with low DCR transformers and the high current loads caused by very low frequency signals in a low DCR environment which basiclly produces a dead short to the amp.  To avoid this, solid state amps require either a sub-sonic filter in the area of 10hz to prevent the amp from generating DC pulses, or large value capacitors to block the DC (basiclly converting to capacitance coupled).

There is also an issue with using solid state amps to be mindful that the amp can tolerate reflective inductive loads generated in the step up transformer and being sent back into the amp.

[mas]

That's why I attached the article.

I too often assume that many are at least aware of concepts only to be proven wrong.

That is why I posted an article that might explain alittle more about an aspect of audio that may be of interest or value to some, but for which others might not have an immediate use or interest.

[Duke Spinner]

fritzie .....

most 70 volt transformers roll off at like 100 hz

to avoid saturation

[DrWho]

mmmm saturation...just like tubes []

did i say that out loud?

[Duke Spinner]

Noooooooo....

Saturation ... as in dead short......[:S]

[Guest " "]

fritzie .....

most 70 volt transformers roll off at like 100 hz

to avoid saturation

True, atlas AF-140 and the crown CT-170, as well as a few others, are rated down to 30hz. I have a few atlas AF-140's, they really sound pretty good.

Now, they might be fairing better on frequency response becuase they are autoformers that can be used for constant voltage power distribution at various voltage ranges.

I could post a data sheet if you are intrested.

Also, saturation, can cause reflective inductive loads to be sent back into amps.....vary bad thing.

[DrWho]

Does it really cause a dead short? I should be all over this crap since I've got a final tomorrow that deals only with transformers...

[Guest " "]

Dead shorts are a problem below 10hz.

Keep in mind, thay you can have a DC signal, or near DC, pulse generated by wide bandwidth direct coupled amps, and blow an amps output stage , fuses, circut protection, etc, before the transformer actually saturates.

I plugged 2 AF140's in series directly into a wall outlet, and while it buzzed like heck, it did not saturate (60hz ). It would take far less juice below 10hz, to cause a dead short due to the reduced DCR at near DC frequencies.

As we all know, the DCR of an inductor drops as you get closer to DC, resulting in high levels of current thru the transformer or autoformer.

Easy to prevent with a subsonic filter, or blocking capacitor.

[WMcD]

Hey. mas said something nice about me. . . I think.

I was talking about amplifiers as "voltage sources" which is somewhat of a theoretical point of view.

I will not get into the line transformer issue except to note that transformers can have good bass characteristics as in our power amps. A.C. power distribution transformers pass 50 or 60 Hz of course. Our power distribution scheme is based on that.

= = = =

The 70 volt line transformer for audio distribution scheme is based on the same principle as high voltage power distribution.

This arises from the fact that transmission losses are "IR" loses, as in V = I x R. The V is the voltage drop caused by the resistance in the wire.

When we are using speaker wire, we can increase the wire size down to 10 gauge, or whatever. And we see in the tables that low resistance (impedance) speakers need bigger wire to reduce loses.

But let's look at the the problem of moving a.c. across the plains or music up the ski slope or to the back of the church. Particularly in the a.c. across the plains, we want to limit the wire size. Thick wire is expensive and difficult to run from pole to pole.

We look at the I*R = Vdrop and realize we can reduce Vdrop by reducing I (current intensity) overall. The current I through the loop (including the wire) is reduced if we reduce the load resistance. That can be done by the use of a step down transformer at the load end. If you look at the Atlas mid driver spec for 70 volt version, the resistance for the taps are up to 1 kOhm. The same applies in a.c. power distribution.

So, now we have less current in the loop (particularly the long piece of wire). But also less power delivered. What we have to do is increase the voltage at the driving end. That can be done with a step up transformer.

Again, the overall scheme is to keep power transfer high but current low. It is the same in the 70 volt system or our power distribution of a.c.

The JBL article points out that this is to make voltage constant. It says it wants to keep voltage constant at the receiving end by reducing I*R losses in the transmission line, which would cause it to sag otherwise.

= = =

The 70 volt system with taps on the receiving end transformer in "watts" is somewhat like what we do with household lightbulbs. We're not given the internal resistance of the lightbulbs or the amps they draw at 120 volts a.c. That could be calculated. Like the 70 volt line transformers on the distribution system up the ski slope, light bulbs are in parallel on a given circuit at home.

None the less we know that ten 50 watt bulbs draw 500 watts. Or two 250 watt bulbs draw the same. For good or bad, our circuit breakers are not rated in watts, but amps. It would be fair (in view of a known voltage) to rate them for 1000 watts or 2000 watts. The taps on the 70 volt line transformers should add up to the amplifier power in the same way.

- - - -

mas, I believe, is trying to make a bigger point. (I should let him speak for himself. Smile.)

It is that when we are first learning, we tend to apply Ohm's law to the narrow technology under immediate study. But it applies everywhere across a broad range of power transfer situations. Per the above, we have 8 ohm speaker issues and zip cord (or super wire); 70 volt line audio distribution systems; and general a.c. distribution systems.

It is somewhat unfortunate that "circuit theory" in schools give few practical applications. Specific practical technologies skimp on theory. And thus there is a bit of hole in the middle where they all should merge.

Best,

Gil

[DrWho]

Oh come on Gil, all this cool theory I'm learning is certainly practical...if I wanted to go to grad school [6]

[Guest " "]

Ok, it helps to know this is about theroy, and not the application, pros and cons, lessons learned, and implementation proceedural issues.

I got, from the inital post, that their was a perception of limited or very narrow experience in this area amoung members of the forum, perceived by the thread originator.

So I responded with specifics, things one would know only by being there and have done it, rather than googling the internet for technical documents to first read, then post.

I think the experience level of folks on this forum is being severely under estimated.

[mas]

For some additional info on transformers for those who are not so familiar, may I suggest

http://www.jensen-transformers.com/an/Audio%20Transformers%20Chapter.pdf

http://www.jensen-transformers.com/an/an002.pdf

(Also of value, but for related topics...

http://www.jensen-transformers.com/an/generic%20seminar.pdf

http://www.jensen-transformers.com/an/ts_guide.pdf

http://www.jensen-transformers.com/an/an003.pdf

http://www.jensen-transformers.com/an/an004.pdf

http://www.jensen-transformers.com/an/an005.pdf

And before anyone take the previously stated limitsfor transformers as gospel, there are differences in the quality of transformers (within the laws of physics!). And Bill Whitlock at Jensen is a good resource to draw on for questions and inquiries about this!

Thanks Gil...I was trying...although I fear that those who do not know me may not realize that I have a dry, or as friends have called it - an "Oh brother" sense of humor and a delight for irony intended with a big grin (even if said deadpan)! If I am upset with something, believe me, I will let you know! Otherwise assume that there is an implied grin. And I do have a self-referential side where I am well aware of the hole in which I often find myself - just as in this particular post - as you will soon see! I may get frustrated, but it is generally with my inability to ask a question or to phrase an answer and to communicate as clearly as I would like.

Heads Up! Beyond this point you may want to skip the rest if you are here based upon interest in the discussion of contant voltage systems.

Also, and in response partially to speakerfritz and also to step back and to try to address a larger issue of just how to address a very diverse group, I do not doubt that some here have perhaps extensive experience and/or knowledge. (They are often the very reason that I may post a seemingly obtuse question of response). But they is not my focus here! Just because one, several or a hand full of folks are experienced does not mean that it is valid to assume that all are! Nor does it mean that one must be only addressing those who 'know it all'! Therefore I have taken the liberty to post some information that may help some who may not be as familiar with some of the analytical and practical circuit concepts. Maybe not...I don't know.Heck, I encounter bemused looks as well as downright dismissal when I start to refer to some of the issues that occupy center stage for my own interests. I only have to mention Nyquist and Heyser spirals, let alone their implications, )let alone the practical aspects of applied Heyser concepts - let alone theory!), to send the masses running for the doors - and yet I can't really even discuss the subject as there is just too much prerequisite information that must be presented to make them intelligible in the context needed for the majority of the folks. And while I would LOVE to discuss the meaning, application and implications ad nauseum, I fear that all I would accomplish is to impress some that my technobabble was insightful but utterly unintelligible (even if expressed well!), while others simply think I am crazy - or both. Just as I quickly discovered with my attempts to get past the fact that Small Acoustic Spaces do not feature a substantial reverberent field (except perhaps at high frequencies that are relatively meaningless and very easily controlled) - hence requiring me to take a few steps back and to try to assemble some additional material to address aspects that I assumed we could move past rather quickly! It's one thing to talk to a few who already are familiar, its another to try to address the wider audience and to try to build a larger baseline audience. And with the recurring debates over set, interconnects, line noise, Monster, Bose, ss vs tube, etc. which I personally find trivial, more seem to find it a fertile ground for seemingly endless debate. Heck, we even have debates over the relative merits of disco and rap! Need I say more? [^o)]

This is not a homogeneous crowd! This forum is composed of folks form all backgrounds and experience levels! If people want me to assume a prerequisite knowledge base in graduate physics and acoustics, I can do so... but I suspect that that discussion would be better entered into at a table over some beer and pizza [pi], as I doubt there would be much of a crowd! So my dilemma is in trying to find an adequate baseline sufficient to provide for a more inclusive and meaningful discussion. And I suspect that some if not most here have not designed, installed or been involved with troubleshooting a constant voltage distributed system! Nor do most understand the nomenclature, let alone the theory behind such a system, nor its conceptual relationship to a simple living room stereo or HT configuration!

What I was more concerned about are those who do not have the pre-requisite knowledge or experience, or even those whom are quite well versed but who are just not as intimate with some of the more esoteric aspects of the developing field. And like it or not, there are many aspects of acoustics that many here do not know - or are not aware of! Heck, I have been dealing with some of the esoteric aspects for some time now with some very amazing teachers, and you don't have time to listen to all of my questions! But please do not interpret this as an attempt by me to sound like I know it all! I know a bit, but I am WELL aware of FAR too many things that I don't know! Unfortunately, many aren't! [] So where does one start if one wants to discuss some of these issues. I know that if I start where I am comfortable with many issues, I suspect that it is going to be of little value here. And maybe that is, or should be, a sign.

And often as a result of ignorance - and I always mean this as 'un-awareness', the ignore-ance - of various attributes, ideas too often tend to be dismissed or considered erroneous rather than to have some ask or think about the more expansive questions the seemingly obtuse information implies. People in general, both informed and uninformed - for different reasons - too often tend to do this. And this area in particular is one where this can be a problem. ...Especially as there is not only many facets of this field that one may not have direct knowledge or experience. And with regards to acoustics (as opposed to much of the electronics), there is SO much ongoing research and development (unlike most of the other relatively 'dead' sciences where 'most' behavior is rather well understood), we are constantly adding information as well as encountering many wrinkles and formulating more questions that have yet to be resolved. One needn't go much further than the websites selling solutions and many of the books that are dated and in many ways incorrect that many consider gospel (and I will leave poor Everest alone - even as his text occupies my shelf!). But at least some make well intentioned attempts to point towards the light!

Unfortunately, an additional result is that we are also encountering more pseudo-science as well! And sometimes I do become frustrated with the amount of crap that passes for fact. (After all, we all know that audio sounds best at night when we don't have to deal with the additional 'noise' of solar and cosmic radiation! - credit here to Audio Advisor, the National Inquirer of all things audio! [:|] I just thank goodness that I have my light insulated and my water insulated cables elevated on the cable stands to protect the integrity of the audio signal! But I think I may have to replace the aluminum foil in my hat! But I wonder if maybe silver foil would be more effective! I mean, if it works for audio frequencies....)

As I ramble here (as I am simply typing stream of conscious without an outline or proofing the copy) I realize that I am trying to talk to several groups simultaneously - while on the one hand, trying not to talk above, alienate or denigrate those who may not be familiar with some technology, and at the same time perhaps attempting to address those more familiar with some technology that assumes a baseline prerequisite knowledge. And the result is a probably a confusing mess for all. Maybe I simply can't successfully do both. Maybe I shouldn't try, and simply be content to speak to one group in deference to the other. I don't know... Maybe I, and perhaps all, should preface our posts with some sort of rating that indicates the level and type of prerequisite knowledge assumed, if any. Then we can exclude the more ignorant and only speak to peers who have the necessary prerequisite knowledge or experience. To do less is to suffer one group or the other - or more likely both - being upset that they are not being properly respected. Sounds a bit elitist, but hey... Or maybe the alternative is for the readers to simply stand back and do a bit of thinking themselves...and realize that there are tradeoffs, and that there has to be some assumed level of knowledge, and that they are a part of this as well. And that no one here is the sole arbitor of what level of knowledge is assumed - you either meet it or you have work to do - and it is not the author's job to meet each individual's level.

Heck, I don't know. All I know is that when I try to talk about some more esoteric tehnology, many 'cry'; and if I try to lower the baseline to be more inclusive and to try to bring more up to speed, others 'cry'. And then when I try to address the issue of everyone crying, I 'cry'. ...Big crocodile tears![] But its really pretty simple...If you already know all about the topic, move on and find something else more to your liking. You would think those so intelligent could figure that out.

I suspect that this is why I suggested initially that the article could stand on its own...Especially as they come from an environment that has a very high baseline of common understanding. But that is to Pat's benefit and in large part to his credit.

Life, as they say, is a b!tch![]

Sorry for so many words. But you are always free to skip my ramblings...

[Guest " "]

"Heck, I don't know. All I know is that when I try to talk about some more esoteric tehnology, many 'cry'; and if I try to lower the baseline to be more inclusive and to try to bring more up to speed, others 'cry'. And then when I try to address the issue of everyone crying, I 'cry'"

Best bet is 

If you have a question ask it.

If you have an opinion, state it.

If you come across an intresting specific lesson learned, or insight, on an issue as a result of a current project, or are reminded of one as a result of someone else's current project, please share those specific's.

If someone ask an intresting question, and you come across some addtional point of intrest, post it.

However, I'm not clear on the purpose of doing internet searches, reading some material, then posting a thread, followed by judgement values of folks based on their non response or lack of intrests.  Especially if there is no related project or specific question  in such post.  

You  will be surprised what folks on this forum have done, and know how to do.  It's not up to them to prove themselves, rather, a challenge to determine, and recognize the contribution of others.

[mas]

However, I'm not clear on the purpose of doing internet searches, reading some material, then posting a thread, followed by judgement values of folks based on their non response or lack of intrests. Especially if there is no related project or specific question in such post.

What? Some internet search? That is not where nor how I get my material!

And as far as cable issues, they seem to be a neverending ad nauseum/as absurdum subject. And I only wish that they were not one of the most frequent subjects.

If you want me to simply post and make statements...how is this... I posted an article. An issue was raised regarding the more general nature of a constant voltage system, so I posted additional info for some who may not be as erudite as yourself. I don't care what you have done nor what you think nor what you think you have done. Nor do I think there is any value in using a transformer or any other device to mitigate or augment an interconnect (except in a distributed environment - and then not for the purpose of changing the sonic character if the signal). Especially as the position of many is that as long as the LRC values of he interconnect are relatively small relative to the speaker, it is not a critical issue. So why would we debate that larger values may have an effect? Duh! And if you already know all about what I have posted, may I suggest you ignore the post as it must be very boring and I would hate to distract you from playing with your transformers. It wasn't intended for you! But in each thread you keep reappearing with your challenges that you can make a system sound different by massaging values artificially. Now maybe that is exciting to you. To me it is a moot point. I avoid the issue entirely by trying to avoid additional impedance! But it seems that in almost every post regarding cables I keep reading of it as if it is news. And yet you continue to post this same topic in an attempt to ellicit responses.

And my response was NOT in reference to any "non response or lack of intrests"! But I did express a bit of bemused surprise at the tack some of the responses took. Especially as someone attempted to turn cable calculations and CV circuit models into a seminar on transformers. Wow, but that seems to happen again and again, doesn't it!? Hmmm...

If you want to discuss the issue, start a thread and discuss it...but then you did and it was very lively as I recall as you had a rousing debate with yourself.

So please, by all means humor yourself as you play with your cable and transformers.

Maybe I should bait every thread with a statement maintaining that I can effect the gain of a system by injecting large resistive values in the signal chain. You want to debate the L & C values, I will claim the R values! That should ellicit a rousing debate![^o)][*-)]

But as you recall, you responded earlier thinking that I had some interest 'debating' the issue and that was the basis of your attempt at 'baiting'. And I told you then that I did not and that that was not the reason for the post. It was simply to present a rather well reasoned approach for others who had questions about the perennial cable obsession. But, as per the usual pattern, you continued...evidently upset that some wouldn't pursue your issue.

I simply posted some additional info on transformers as Doc mentioned he had a class/test on them and as there has been allot of talk at various times on balanced and unbalanced interfaces, hum and grounding as well as ground loops (just recently by some!), so I posted those resources as well. If only transformers were as effective a tool for noise in this forum! Then I would become a big fan of trandformers![]

If the topics don't interest you, please don't waste your valuable time reading them. And if you choose to post and express your disinterest or dislike, then I will simply post my opinion and that is that I don't care what you do or don't think; nor that you have discovered the wonder called the transformer. []

So we can agree to disagree. I won't worry about your fetish with cables and transformers and you can ignore my total disinterest in them except as very basic 'tools'.

But if you have anything of value to offer with regards to acoustics or Gabor's analytic and Heyser's expansion of it, I will be quite surprised. (And if I do post regarding these issues, it is nice to know that I won't have to qualify anything for you, as I am sure that you already know everything! [] )

There. Now I feel a bit better.[]