AA networks...

[Deang]

The other problem with L-pads. 

 

 

[Deang]

The chart isn't showing power loss, it's showing the effect that an L-pad has on the source impedance (damping factor). Most tube amplifiers don't have much of that to begin with - especially SET amplifiers. With good solid state amplifiers, you're losing a good deal of what the designers intended. 

 

Roy doesn't like the phase shift that an autoformer causes, but it's not a show stopper on low order filters like it is with something employing steeper slopes.

 

If you'll look carefully at the new designs - I don't think you'll see any L-pads (there is no shunt element).

 

I don't know what to think about your assertion of a resistor being the least offensive electronic part. A resistor changes power into heat, and power lost means less efficiency. 

 

Yeah, cancer isn't a lot of fun. I'm in my fourth year of remission - so far so good. I have some nagging back issues that are causing me quite a bit of misery - I need surgery. Thanks for the good thoughts - much appreciated!

[Deang]

It's all good, no worries - I know I'm a pain in the butt, but nevertheless, I'm known by The Lord, so your prayers mean very much to me. Thanks William. 

[erik2A3]

Dean, 

 

We all choose our own sets of design compromises - and you're correct that an L-pad does not permit the same power transfer function as that of an autoformer.  I'm aware of that.  However, were I to base all my choices on plots and graphs, I would probably toss the majority of my equipment out the window (or at least sell it to get something in return).   The Lowther drivers I use in our rear loaded horns measure terribly, particulaly their impedance characteristics, which are all over the place.  It's the same speaker that Art Dudley of Stereophile used to have; he and I got into Lowthers at about the same time.  Yet, they are very, very special, despite their flaws - a single, extremely efficient driver, nearly full-range, and one of the reasons I like them so much: they don't need a crossover.  All manner of filters have been made for them to tidy up their response, and I've done most of them, only to find they just sucked the life out of the music.

 

So, with the Lpad type A:  If I like what I hear, that will win every time.  I don't need a graph to confirm what I should or should not be hearing.  It's really as simple as that.  The other part of this equation is that the tweeter filter was on it's own, and so probably got some immunity from the ESR effects associated with the usual input cap into the autoformer - which is also in series with the tweeter cqpacitor in the A network.  Using Bob's tweeter, I also crossed to the tweeter as low as 3.8khz, but used a second order filter for a sharper cutoff at that lower frequency.  Quite good sounding, too.  That was a completely different animal from the type A though -- but a network for which I wound and tested all the chokes it needed myself.

 

I am sorry to hear of your back pain.  I've had multiple surgeries and fusion after a crash on my mountain bike reaulted in bilateral fractures at L4/L5.   Back pain can be so very exhausting....I'm sorry and I hope you are able to get some relief from it.

[Schu]

4 hours ago, erik2A3 said:

Dean, 

 I don't need a graph to confirm what I should or should not be hearing.  It's really as simple as that. 

Isnt that what some of us have been saying thruout this thread? 

[mikebse2a3]

32 minutes ago, Schu said:

Isnt that what some of us have been saying thruout this thread? 

 

 What.... to Fumble around till you hopefully get lucky..... that's not for me I want all the help I can get 

[mikebse2a3]

The graphs if used correctly are to enlighten and broaden our understanding of what we are hearing and not just confirm what we are hearing but sometimes more importantly what we are not hearing. 

 

miketn 

[Schu]

16 minutes ago, mikebse2a3 said:

 

 What.... to Fumble around till you hopefully get lucky..... that's not for me I want all the help I can get 

Fumble around... jesus, I must be an idiot that is not capable of making an informed decision without crutches or suffer from "good fortune"... hyperbole

 

Engineers build race cars and rocketships, yet they rarely if ever have the ability to pilot them to their fullest extent... fact.

[mikebse2a3]

38 minutes ago, Schu said:

 

38 minutes ago, Schu said:

Fumble around... jesus, I must be an idiot that is not capable of making an informed decision without crutches or suffer from "good fortune"... hyperbole

 

Engineers build race cars and rocketships, yet they rarely if ever have the ability to pilot them to their fullest extent... fact.

Schu I simply disagree with the putting down the importance of technical understanding when used properly that Eric and you are implying and I would never call you an idiot I just disagree.

 

miketn

[erik2A3]

Mike,

 

I have some history under my belt with this, and was building speakers and their attendant crossovers exactly twelve years befor I even ventured to this forum in 2002.

 

Of course measurement can be an extremely effective tool.  To assume otherwise is a misinterpretation of what I wrote.  Someone above made what I would describe as a completely accurate statement about the simplicity of the majority of Heritage networks -- particularly the type A.  There is just nothing that remarkable about it.  The majority who have worked with these networks or some of their own variations of them, do so with a general understanding of the characteristics of the drivers in question.  We are also able to go through the simple calculations for the values of capacitance and inductance for reactance at specific frequencies in relation to the nominal impedance of the of the drivers with which they are associated.  How complicated is it to make a first order, 6kHz high pass filter for a tweeter!?  If one is doing the basic math for appropriate reactance at specific frequencies for specific impedances, and particulalrly for a simplistic, very low order design, one is already in the ball park.  I also mentioned that I wound (and very carefully MEASURED the inductance) of chokes I wound myself -- which is not a big deal.  There are an enormous number of audio DIYers around the world who do the same and much more.

 

So you bet! With something as basic as a first order crossover, used with drivers whose response behaviors have been generally pretty well established here over the past 15 years or so, I am entirely comfortable with refining the final sound, as do many designer does, by ear.  Even the second order tweeter network at 3.kHz was just not a big deal.  One thing I didn't care for about the A was that its filter is derived from the band-pass portion of the network rather than being independently terminated.  That's one of the first changes I made to it, and preferred the sound to the original.

 

Also, I think it was mentioned above somewhere that an autorformer should not be used into an L-pad.  If that is really true and accurate, than one should pass (cough) on McIntosh amplifiers, which use an autoformer on the output.  Nowhere did I put down the importance of measurement -- I use it myself.  What I did say is that I have a thorough understanding of the behavior of drivers I have used for nearly 20 years, their wild impedance swings in particular.  I also know of the measured (and decidedly more visibly -- ON PAPER -- linear response) of correction filters that were designed using measurment tools.  And I know how much life they sucked out of what was (for me) formerly an incredibly life-like, immediate, clear, and engaging presentation.  So, since the sound of reproduced music is as highly personal and subjective a thing that it is, shouldn't I do what sounds best to me, and allow others to do as they see fit without criticising their personal choices? 

 

It's getting late, time to go!

[PrestonTom]

9 hours ago, mikebse2a3 said:

The graphs if used correctly are to enlighten and broaden our understanding of what we are hearing and not just confirm what we are hearing but sometimes more importantly what we are not hearing. 

 

miketn 

Mike, the funny thing is that when we look at engineering projects such as designing an elevator or making a braking system, or synthesizing antibiotics, we insist that those involved have a working knowledge of engineering, science, measurement, etc (graphs and everything else). We would be horrified if we found that these products were created by hit-or-miss methods and devoid of any conceptual foundation other than "it seems to me ......"

 

When it comes to audio reproduction, some retreat into this other world and do not consider the fundamental design as an engineering project and cannot be bothered by "graphs" and other "stuff". Presumably, one can ramble along and eventually stumble into a good system. That just seems like a lengthy and haphazard process with no guarantee of progress.

 

When I go to the airport and board the plane, I am glad it was approached as an engineering project. I won't bother with inserting the smiley faces ....

[Marvel]

2 hours ago, wdecho said:

A 2 db reduction of the mids over what the stock crossovers are set at is much more preferred by me in my room.

 

I had the mids pulled down about 3 db in my fairly well damped room. Much better balance for me in my room. That also made an apparent boost in the bass.

 

1 hour ago, PrestonTom said:

We would be horrified if we found that these products were created by hit-or-miss methods and devoid of any conceptual foundation other than "it seems to me ......"

 

This reminds me of the story, oft repeated about Albert Einstein speaking of imagination.

 

Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.

 

He used the knowledge he had, but also used his imagination.

 

Bruce

[NOSValves]

1 hour ago, Marvel said:

 

This reminds me of the story, oft repeated about Albert Einstein speaking of imagination.

 

Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.

 

He used the knowledge he had, but also used his imagination.

 

Bruce

 

[PrestonTom]

2 hours ago, Marvel said:

 

I had the mids pulled down about 3 db in my fairly well damped room. Much better balance for me in my room. That also made an apparent boost in the bass.

 

 

This reminds me of the story, oft repeated about Albert Einstein speaking of imagination.

 

Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.

 

He used the knowledge he had, but also used his imagination.

 

Bruce

I hear stories like that and they are nice stories.

 

However, I don't think that  developing an electro-acoustic device for home audio is really in the same league as developing big theories in theoretical physics.

 

Is developing a crossover really hindered by measurement and a basic knowledge of circuits? Let's just throw away all the instrumentation and hope we get lucky and eventually find the magic .

[Chief bonehead]

all i can do is offer some guidance and some practical ways of why some things work or what you might encounter...do what you want with it....i dont care but dont try to tell me to forget all i have learn because of some magic you have discovered....and by the way...imagination can lead to more knowledge or just some more imagination...like passing out the bonehead button.

[Marvel]

2 hours ago, PrestonTom said:

Is developing a crossover really hindered by measurement and a basic knowledge of circuits? Let's just throw away all the instrumentation and hope we get lucky and eventually find the magic .

 

I certainly don't think we should throw away all the instrumentation or knowledge. Einstein certainly wasn't saying to leave the science, but mixing the science with imagination is what has gotten us so far in technology.

 

 

[Max2]

So are we going to see a response chart with a modern LS II ?  I wonder why Klipsch no longer posts those in the advertisements like they did years ago?   Everyone is talking of the improvements on paper and I would like to see it.

 

 

 

Edit:

 

Maybe I intruding "here" asking about the changes of the 4 and 5 series, like where the frequency cutoff is? It would be informative to know what the mid is no longer getting and has been diverted to the 55D tweeter. 

[erik2A3]

Wdecho - It seems others have referred to you by name as 'William.'  

 

I have enjoyed your concise descriptions of experiments done with this, particulalrly since you made comparisons to the AL network.  The PIO capacitors you described (and I refer to Jensens in this case) did in fact seem to pull down HF response a bit.  I have to qualify this by saying that was the case when used for very low voltage crossover use -- which is completely different from interstage coupling capacitor applications in amplifiers.  In fact, I have seen cases where people are using not only the most expensive film caps available, but also those with the highest available voltage ratings; which for crossoever use in loudspeakers is simply not necessary.   It is a fact that even a 50 volt cap is good for the vast majority of amplifiers with which a speaker is intended to be used, particulalry in the case of very high efficiency horns.  On the other hand, the GE motor runs I used to use were much more to my liking in that respect.

 

 

[Chris A]

Perhaps a second expansion of Schu's thread of observations is in order based on some of the recurring comments found in this thread: 

 

1) I've found that after careful EQing of each loudspeaker for flat on-axis response and phase...that any differences in the sound of the passive crossovers simply disappears. 

 

Another way of saying this--If you hear any differences in crossover components, chances are that you're only listening to changes in the frequency response of the loudspeaker at your listening position.  This includes phase and group delay differences--in that they also introduce frequency response differences in the polar response of the loudspeaker in each frequency band.  I've found that changes in harmonic distortion of the loudspeaker aren't notable among differences in passive crossover performance, but changes in relative phase behavior within the crossover frequency bands will lead to changes in perceived signature of the loudspeaker's sound that will be very apparent, and will very conspicuously show up in the frequency response plots using upsweeps. Once the crossover phase issues are corrected, timbre of the loudspeaker will become very neutral/natural sounding.

 

2) I see no SPL and phase vs. frequency plots of the differences introduced by the changes in the passive crossovers posted here by any of the folks professing "good" or "bad" changes in crossover performance via changes in components (capacitors, etc.).  This is quite easy to measure and to calculate the differences using something like REW and a calibration microphone, and REW's easy-to-use capability to do differences in captured frequency upsweep measurements.

 

There seems to be a notion that other things are happening, i.e., "magic", that occurs when changes in passive components are made.  I've found that it's fairly simple: look at the differences in the on-axis and off-axis frequency response plots.  I can relate how I know this--but I'll save that discussion for now.

 

3) I see no discussion here or plots of the disruptions in the passive crossover bands (due to time misalignments) that are quite easy to see in any frequency upsweep or the timbre defects of any passively crossed horn-loaded loudspeaker that is discussed on this forum, with the exception of actively crossed/balanced modifications (Khorns, JubScalas, JuBelles, Cornwalls, actively crossed Jubilee that was done by Roy in the Klipsch anechoic chamber in Hope, and those that have physically moved their tweeters and midranges to be time-aligned with the bass bins while listening on-axis.

 

I've found that correction of these crossover phase/SPL disruptions dramatically improves the timbre and overall sound of any loudspeaker, making them much more neutral sounding and pleasing to listen to. 

 

Chris

[NOSValves]

good grief...