Column II Internal arrangement

ran across the data sheet for the column II and thought i'd post it. last paragraph has some very interesting information and follows my original line of speculation. interesting, that the column II was considered an advancement over the more exotic WTLC, with its walsh tweeter. also note, even infinity can mis-spell bass!

Great find! Thanks for posting it.

Looks like the mystery of the tar has been solved. The Column II listed for much more than the WTLC, so that doesn't surprise me that it was a higher end model. But agree that most find the WTLC tweeter as highly sought after moreso than the hand modified and tuned piezo's.

My testing showed that the FR was lower (slightly) and the T-S params reflected the additional mass. And the bottom legs were indeed intended to act like a port to lower FR even further. So that all makes sense. But the W1038R's still have the same FR curve as the originals (Slightly better) when connected together. However, I did not test the Infinity woofers individual FR while disconnected. That might have shown the mechanical roll-off the extra mass had induced. Interesting info. I am leaning even more to that single inductor for both woofers being the problem. If Infinity planned for the bottom woofer to have its own mechanical roll-off, they wouldn't have needed an inductor on it right?

I wonder if I disconnected the bottom woofer if the FR crater would go away? Hmmm. And... 750 Hz crossover is nowhere near what that inductor would give them.
 
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Just thinking out loud here, but wanting to gather the facts as I understand them.

The crossover of the woofers is supposed to be 750Hz.

The diagrams that I have seen posted and the way the Column II's were sent out do not match.

Using a 2.7mH inductor that Infinity supplied would result in 750 Hz IF the load was 13 Ohms. However, the load would actually be closer to 16 Ohms if they were mounted in series, which they are not. To achieve a 750Hz crossover with the drivers in parallel (4 Ohm) would take a .85mH inductor.

Testing shows that there is a large dip in FR at the 150Hz region which would be close to the crossover point if using the 2.7mH inductor in parallel. If the bottom woofer were wired bypassing the inductor, that dip would probably go away. But it would make no sense to have the front woofer crossing over at ~470 Hz (2.7mH @8Ohm) while allowing the bottom to crossover at its natural roll off. The mid range pot allows adjustment of the crossover between 700Hz and 800 Hz. So again, that would agree with the 750Hz crossover and further dispute the front woofer crossing at 500Hz.

There are actually two dips in the FR of the Column II. One bottoms at about 240Hz and the other at about 350Hz. These two dips could be due to the difference between the front and bottom woofers reacting to the inductor since they are sharing it and do not have the same characteristics.

4.2 mH (from the the factory printout) would provide a 750 Hz crossover if a 20 Ohm load were present and if they were mounted in series. Neither of these are true so I assume the 4.2mH in the drawing should just be ignored as a typo of sorts.

The 2.7mH that was sent out and the 4.2mH per the design sheet will not give a 750Hz crossover no matter how you wire the drivers. Neither of those values seem to be correct.

My W1038R's have a natural roll off at 1500Hz. Let's just assume the Infinity models had a similar roll off, and the bottom woofer rolls off earlier due to the added tar mass at ~750 Hz. That would seem like a fairly good assumption since the brochure stated that the bottom woofer did not need circuitry to make it roll off and the crossover is at 750 Hz.

I think we can deduct a 750 Hz crossover is correct, the bottom woofer has a natural roll off at 750 Hz or less, the diagram does not match the way they were sent out and the way they were sent does not provide a 750 Hz crossover. The inductor value in both the drawing and in what was sent out will not give the 750 Hz crossover point no matter how they are wired. So, the issue is that it has to be rethought without regard to what has been printed and what was sent out since both of these we know are not correct.

I think there are only two variables that remain to be considered.

Should they have been in series or parallel?
Should only one of the woofers had an inductor on it and what value?

My guess, and I emphasize that this is a guess at this point, is that they should be mounted in a parallel as they were shipped and as the drawing indicates. I base this on the testing I have done previously showing both parallel and series response. Parallel is more in line with the SPL of the tweeter and mid pot adjustment ranges. BUT, only the front woofer should have had an inductor on it. And the inductor value should have been 1.7mH instead of 2.7mH.

On mine, the impedance is actually slightly less. I could simply replace the 2.7mH with a .65mH inductor to get the 750 Hz crossover since the drivers are identical. I have some 1mH inductors in my parts bin. So what I will do is replace the 2.7 with a 1 just to see what it does before buying the .65's. It should crossover at about 450Hz and remove the crater.

If this works, on the Column II with original drivers the inductor should be replaced with a 1.7mH and relocated so that it only supplies the front woofer. In other words, the woofers should branch off before the inductor is placed and not after, as they are.

We'll see what happens...
 
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I wonder if I disconnected the bottom woofer if the FR crater would go away? Hmmm.


i was curious about that myself, and wondered if you'd tried isolating the fronts and the bottoms to see what their individual FR graphs looked like.

Just thinking out loud here, but wanting to gather the facts as I understand them.

i think your reasoning seems logical. your logic also seems reasonable. lets hope that doesn't mean they cancel each other out! :)

putting on my technical illustrator hat, i see something on the schematic that is of interest to me. the date on the drawing is 1978. now, i don't know the years the column II was produced, but i was told my pair was originally bought in 1976. robert says he's had his since '77. the '78 schematic is a revision. we know this revision was to document a wire color change, but don't if this revision was the only revision. it would be nice to find an original (pre-revision) schematic for comparison.

reading the tech sheet got me thinking. if the column II was an outgrowth of the WTLC, why not look at what the WTLC was doing. i found the following document on the WTLC which has almost word-for-word the same description of the woofer system.

http://www.davidsaudio.com/Infinity_WTLC.pdf

marketing hyperbole aside, i know the WTLC used 8" woofers, and had other differences, but if the circuit in the column II was an outgrowth of the same concept the WTLC was using, there might be clues in the schematic of the WTLC that may shed light on what the column II was doing. maybe its comparing apples and oranges, but here it is.

http://elektrotanya.com/infinity_wtlc_200w_speaker_system_sm.pdf/download.html

of course this dates from as late as '81, and may have gone through revisions as well. apparently the column II and WTLC were produced concurrently. i didn't know that.
 
http://www.davidsaudio.com/Infinity_WTLC.pdf

marketing hyperbole aside, i know the WTLC used 8" woofers, and had other differences, but if the circuit in the column II was an outgrowth of the same concept the WTLC was using, there might be clues in the schematic of the WTLC that may shed light on what the column II was doing. maybe its comparing apples and oranges, but here it is.

http://elektrotanya.com/infinity_wtlc_200w_speaker_system_sm.pdf/download.html

I think it is worth looking at, like you say, it may have some clues to the puzzle. I did notice that the woofer VC inductance on the CII's was right around 2.7mH for both. Mighty odd they used 2.7mH inductors as well. Or is it odd? Hmmm. :confused:

For now, I'm still going to go with what I mentioned and try that. I need to take it a step at a time. I'll post some graphs as soon as I can. I got a new i7 laptop (YAY:thmbsp:) but now I have to recalibrate all my measuring stuff and get it installed on the new one so there will be a delay in my testing (BOO:thumbsdn:). Maybe this weekend.

Essentially I will run a test as is. A test with one driver removed and finally a test with the inductor replaced and both drivers re-installed. That should tell us a lot.

I wish I knew someone with a set of these in original condition that I could run tests on. You live anywhere near Kansas?
 
Some interesting observations of the WTLC links.

The diagram shows the woofers have no filtering on them at all. They are wired direct. The booklet states the bottom woofer has its own low pass filter. :wtf: Do they mean the natural mechanical roll off? I didn't see anything in there when I had the cone off. What about the front woofer?

The concept does seem similar to the CII, but I don't think this is going to help. It does reassure that the bottom woofer mass was increased to 3X of the front. I wonder what mass they are measuring? The woofer tester only showed about 4.5 grams difference. It makes me wonder about the W1038R on the bottom. If I should add mass to it or if it needs a separate flter. Well, one issue at a time. I won't know anything till I can get my test gear back up. As long as I can get a relatively flat FR... I'll be happy.

The W1038R's already have a good bit more mass than the CII's. Since the mid goes much lower than on the WTLC, the front woofer doesn't have to go up to 2Khz. The 40Oz magnet and 2" voice coil on the W1038R's makes them more efficient, even with the greater mass. When I measured the FR they went as low as the CII's did. So I think they will be OK to use the same driver on both the front and bottom.

I really wish I had measured the individual FR of the CII's drivers. What I am thinking (hoping) is that the W1038R's are able to accomplish in a single driver (as far as frequency range) what it took Infinity 35 years ago to accomplish using two.
 
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sorry but i'm a long way from kansas. i'm in california, near san diego.

don't mean to be nit-picky, but the phrase infinity used was not that the bottom woofer "has" its own low pass filter, they said it "is" its own low pass filter. the implication was the mass addition had something to do with it, not that there was a separate filter physically added. so i think the natural mechanical roll off was what they meant. i obviously didn't dissect the voice coils on mine, but didn't see any difference between the fronts and bottoms when i had the dust caps off.

in terms of how they measured mass addition, i think they generalized a bit when they say 3X. since they added mass by painting tar on the cone with a brush, it would be hard to get the exact same application on each woofer. i also tend to think they are likely using the word mass interchangeably with weight. i know the two are not the same, but i''m guessing if the paper cone weighed, let's say, 1 gram by itself, they just told the "tar baby" to paint on 2 grams of tar.

well, my IIs are back together and i got to hear them for the first time yesterday. all drivers seem to be functioning which is a relief. i'm listening in the garage, so i'm not getting the best they have to offer. i did replace the 12.5 caps as long as i had them open, so i assume a burn-in period is in order. honestly, so far i'm not really impressed, but holding off judgment until i get them in the house. still need to address cosmetic issues, so for now they'll be doing garage duty. source material in my garage is limited to what i send by wifi from my mac, and room acoustics are hideous. i still have high hopes for them. want to get a turntable hooked up as source and really wring them out with some vinyl. for now, they work and i'm happy about that. no doubt if this FR issue gets resolved, i'll be opening them up again. maybe its because we've been talking about it so much, but i swear i could "hear" that crater…

hey, i've been meaning to ask, what are you guys driving your IIs with amp wise? how many watts? my reference series are rated 35-250 watts but are not happy unless they get 100 watts or more. are the IIs that way too, or are they happy with what ever you feed them? i'm giving mine 67 watts from one of my pioneer SA-1000s right now.
 
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sorry but i'm a long way from kansas. i'm in california, near san diego.

don't mean to be nit-picky, but the phrase infinity used was not that the bottom woofer "has" its own low pass filter, they said it "is" its own low pass filter. the implication was the mass addition had something to do with it, not that there was a separate filter physically added. so i think the natural mechanical roll off was what they meant. i obviously didn't dissect the voice coils on mine, but didn't see any difference between the fronts and bottoms when i had the dust caps off.

in terms of how they measured mass addition, i think they generalized a bit when they say 3X. since they added mass by painting tar on the cone with a brush, it would be hard to get the exact same application on each woofer. i also tend to think they are likely using the word mass interchangeably with weight. i know the two are not the same, but i''m guessing if the paper cone weighed, let's say, 1 gram by itself, they just told the "tar baby" to paint on 2 grams of tar.

well, my IIs are back together and i got to hear them for the first time yesterday. all drivers seem to be functioning which is a relief. i'm listening in the garage, so i'm not getting the best they have to offer. i did replace the 12.5 caps as long as i had them open, so i assume a burn-in period is in order. honestly, so far i'm not really impressed, but holding off judgment until i get them in the house. still need to address cosmetic issues, so for now they'll be doing garage duty. source material in my garage is limited to what i send by wifi from my mac, and room acoustics are hideous. i still have high hopes for them. want to get a turntable hooked up as source and really wring them out with some vinyl. for now, they work and i'm happy about that. no doubt if this FR issue gets resolved, i'll be opening them up again. maybe its because we've been talking about it so much, but i swear i could "hear" that crater…

hey, i've been meaning to ask, what are you guys driving your IIs with amp wise? how many watts? my reference series are rated 35-250 watts but are not happy unless they get 100 watts or more. are the IIs that way too, or are they happy with what ever you feed them? i'm giving mine 67 watts from one of my pioneer SA-1000s right now.

I don't mind the nit picky stuff. I want the truth and have no problem admitting to my errors. Vanity doesn't get in my way. I went back and looked. Sure enough, just like you said, which makes sense.

As a side note... Actually... mass IS the same as weight. I think what you may have been referring to is the density/volume of mass being variable. Since the engineers there had a physics background, like me, I'm sure they were saying the cone weighed 3X more.

I'm using a Yamaha RX-a2000. 7-channel 910W total (130W x 7 RMS). It somehow can dynamically give more power to other channels as they need it (As long as you don't exceed the 910W), up to 165W/Channel @ 8Ohms. Since my La Scalas and the Klipsch RC-64 center require very little power, I would guess the CII surrounds benefit from the full 165W/channel.

I can travel a good bit for my work. The travel is sporadic though. Haven't left home for over a year now. I spent about two months in LaJolla back when the fires were going on. If I ever get a chance to go back, maybe I can look you up and bring my test gear.

Sentenced to garage duty ehh? Well, hopefully we can get the crater out, you can spruce them up and they will get their rightful place in the living room. Was there a reason you didn't replace the 3.5mF cap? I also removed the fuse on mine. Whether that helps is questionable. I have convinced myself that they sound better w/o it, but its very easy for one's mind to play tricks when wanting something to be true. In other words, I can't say there was a remarkable benefit anyone could hear, but I think there was improvement. Make sure you have a good air tight seal on all the drivers too. When you push up on the bottom woofer, the front woofer should extend and stay that way until you release it.

I'll see if I can find a song that has a LOT of music in the range where the craters are at. It would be good for a before and after listening test.
 
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I'll see if I can find a song that has a LOT of music in the range where the craters are at. It would be good for a before and after listening test.

Quoting myself feels a bit awkward, but...

Don McLean seems to have a lot of music concentrated around 240 Hz. It might be his guitar hitting the range. B string?. That's a bit low for a voice. Either way, both "Vincent" and "American Pie" have a good bit of sound at a high SPL at the 240Hz region (Don't tell me you don't have "American Pie"). There isn't a LOT above 350Hz in either of these songs.

Sarah McLachlan's "Angel" is another one that has a lot in both the 240 and 350 Hz regions. Piano maybe?

Surprisingly, it took a while to find some songs that had a significant amount of sound at a decent SPL in those regions. But all these had enough where the craters should be noticeable.

Maybe you could listen to the CII's and the Reference's and see if you can tell a difference in the FR when listening to these songs. I haven't listened to them myself yet, but will get to it this weekend when I unhook them as my rears for testing.
 
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sorry, when i said mass and weight were not the same i was going back to my days working with NASA scientists at the ames research center. they would insist mass and weight were not the same, and would always point out that mass is the amount of matter in an object, and weight was the amount of pull gravity exerted on it. on earth they are generally considered to be the same, but those NASA guys were not on earth a lot of the time. your mass would be the same in space, but your weight could be very different. we're on earth and gravity is pretty much a constant, so i go along with your statement. we couldn't even hear the speakers if we were in space…

i didn't replace the 3.5 cap because i'd read in some of the other column II threads that were specifically about replacing caps that it wasn't necessary to replace the 3.5. several posts seemed to indicate this, so i just went with the flow.

i'd also read about bypassing or eliminating the fuse, and it did make sense to me in a way. i've never blown a fuse in a speaker, and the idea that i had these nice fat 12 awg speaker wires, and the fuse choked them down to a filament the size of a hair had some merit. but looking at the gauge and quality of the wire that went from the individual driver terminals to the voice coils convinced me that even a complete internal rewire was not going to eliminate a "weak link" in the chain.

part of the decision process was probably just being lazy, but also the idea that i should listen to them in a basically stock configuration before i started monkeying with things. i could always open them up again if i decided it was necessary. plus, i'm financially challenged, so i'm a cheapskate.

along those lines, the idea of paying $320 to recone, or even $280 to replace, the woofers in a pair of speakers that, in perfect working order, have a market value of less than $200 seems odd to me. i paid $100 for my IIs, and i'm into them for another $60 with what i've done to them (refoaming the woofers, replacing the caps, refinishing the wood, etc). a couple months ago, i bought a pair of fully functional, cosmetically beautiful, reference fives for $140, including delivery. thats 2 pairs of working infinities i'm into for less than $320. no shortage of orphaned speakers out there at a good price point.

i know your speakers are a different situation, being basically custom made, one of a kind units. just the time you have into them makes them priceless. and they are absolutely beautiful. i'm just thinking out loud as a most-bang-for-the-buck kind of guy.
 
greg

next time you run into an origional set of column2s for 100 bucks, let me know. i would not mind picking up origional parts for that and shipping.

i know what you mean limited resorces i am on social security, 674 amonth does not go far. but home and car are paid for. so watch my bills and i eek by.
 
sorry, when i said mass and weight were not the same i was going back to my days working with NASA scientists at the ames research center. they would insist mass and weight were not the same, and would always point out that mass is the amount of matter in an object, and weight was the amount of pull gravity exerted on it. on earth they are generally considered to be the same, but those NASA guys were not on earth a lot of the time. your mass would be the same in space, but your weight could be very different. we're on earth and gravity is pretty much a constant, so i go along with your statement. we couldn't even hear the speakers if we were in space…

i know your speakers are a different situation, being basically custom made, one of a kind units. just the time you have into them makes them priceless. and they are absolutely beautiful. i'm just thinking out loud as a most-bang-for-the-buck kind of guy.

Thanks for the compliments. Yes, the cabinets are the ONLY reason I replaced the woofers. Plus its a fun DIY hobby that I find interesting and am fortunate enough to be able splurge a bit on. Its also why I am not reluctant to improve or replace the factory parts. I think send2r has some sentimental reasons for being willing to invest some money in them.

In a previous life, 25 years or so ago, I was a Nuclear Engineer. A bit rustier now and with quite a few brain cells destroyed at this point I always enjoy talking physics just to get that reassurance it wasn't all a dream.

Well, yes, the NASA guys don't always live here on planet earth with the rest of us. But they are correct. Mass and Weight are not the same thing. Weight is a unit of measure describing mass. It is not mass. Mass is indeed a body having atoms in it. Mass and Weight are proportional to each other within earths gravitational pull.

I often find myself saying it is the "same" thing when talking to someone when I am discussing the weight of mass. Here on earth (or within earths gravitational forces) mass is conveniently = weight... mathematically. This was selected as a nice easy to work with constant for Newtons 2nd Law based on the gravitational forces exerted on a body.

You can think of it like this. Say you weigh 200lbs. You are exerting 200 Lbs-Force on the ground (due to gravity). You also have 200 lbs of mass. In fact... if you think about the units mass is measured in you will notice they are indeed units of weight. (grams oz's etc.) Mass is also measured using units of volume and density. For example one lb-mass of lead is much denser than one lb-mass of cotton, though they have the same mass, the lead will occupy much less volume. There are many ways to describe the physical characteristics of a mass. But when it comes to weighing mass, here on earth, they are equal.

In outer space, beyond Earth's gravitational pull, mass has no weight as we have defined it. The NASA folks call it weightlessness. Obviously the mass is still there, but since wight (as we know it) is defined by Earth's gravity it is N/A. Einstein came along and ruined it all with his relativity theories and E=MC^2. Its best not to get into those lest I be reminded we are actually talking about speakers here.
 
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greg

next time you run into an origional set of column2s for 100 bucks, let me know. i would not mind picking up origional parts for that and shipping.

i know what you mean limited resorces i am on social security, 674 amonth does not go far. but home and car are paid for. so watch my bills and i eek by.

I wish I could have sent you drivers in better shape. But if they were in better shape I would never have sought replacements. Ultimately, I'm glad I replaced them but I would hate for you to invest $280 in new drivers and be dissatisfied. Sound really is a personal preference and nobody can tell you what sounds better to YOU.

I have my audio test gear back up and calibrated. I'll do some testing tomorrow.
 
Initial testing has shown some interesting data.

Removing the inductor altogether (As in the WTLC) seems to give the flattest curve +- 3dB. The mid, even at its lowest setting, still needs to be reduced by about 6dB and the tweeter by about 12dB. I'll work on those after I can close on the woofers.

Will post some charts in a bit.
 
brian

looks like your on to something.

jolly good show

Yeah, but not exactly what I had anticipated. The crossover point didn't seem to change, just the SPL.

Klipsch used these transformers on many of their networks. They essentially match the VC inductance and just attenuate the level. It is looking like that is what Infinity may have been using it for. 6dB drop to compensate for the 6dB increase by having the woofers in parallel? The Voice coil inductance is 2.7mH just like the transformers they used.

I still have a few more things to check. But it doesn't look like there was any need to attenuate the woofers, the mid and tweeters are much more sensitive. There also appears to be something strange going on at 100 Hz.
 
So... here is a plot of the individual drivers and the overall FR with all connected (Yellow), all pots set to minimum and the woofer inductor removed. Doesn't look too bad, as far as the woofers (Cyan line).




Well, I just ran some more tests on the woofers by themselves with the 1.0mH and 2.67 mH inductors in place. Also ran another overall FR curve with the 1.0mH. It appears that running them w/o an inductor is going to be as flat as they can get. I think I need to look at the mid and tweeters next to see if I can bring them more in line.

The Column II's original drivers will be close to this. I don't know what the natural roll-off of the original front woofer is. Without having the original drivers anymore, at this point, I would recommend only those that have W1038R's do the crossover upgrades that I find improve the FR, unless you just want to experiment with the sound. My guess is they will benefit about the same, but I don't have the ability to test and prove it. One big difference between the woofers that can affect their being drop in replacements using the same crossover is the originals are 8 Ohm and the W1038R's are 6 Ohm. But the magnitude of improvement by just removing the inductor more than makes up for a few tenths of a mH off in crossover point due to differences in impedance.
 
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I may have stumbled onto something.

I added two 1.0mH inductors in parallel to give .5 mH and placed inline with the woofers. This was the best curve yet.

The FR spread of the various inductors to 5Khz is as follows:

2.7mH = 15dB
No Inductor = 13dB
1.0mH =16dB
.5mH = 11dB
.73mH = 13dB (2.66 in parallel w/ 1.0)

So.... it appears that a .5 mH provides the flattest curve all the way to 5Khz. +- 5.5dB, where the tweeter joins in on the fun.

Still working on them. I added a rough attenuation circuit and was able to get down to +- 5dB. Will have to see what more tweaking on the mid can do.

The tweeters are another story. I'm considering replacing them with some domes that aren't quite as sensitive and have better dispersion. So, send2r, you may be in luck down the road.
 
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