Time to winnow down the speakers. Cornwalls? Valencias? 605A's?

[Bauhausler]

Darker background = better.

So 12 Ohms is the lower HP trace and higher LP trace
20 Ohms is higher HP trace and lower LP trace.

I was confused.

 

[Zilch]

Zilch
I vote for the darker background. Interesting what the LF curve does above xo, 1600. Thank you for the data.
On the schematic, is the 16 woofer # Z or DCR? The DCR on my 605s is 12.
I could not figure out which lines were 800, 1100, & 3200
Don

That's just nominal impedance on the woofer. Somebody needs to measure the impedance of the woofer at 1.6 kHz for better accuracy in the sims. The Le's I used are just guesses there, as well.

The horizontal scale goes by twos, i.e., 2, 4, 6, 8, 0.

Certainly the sims have revealed a major drawback with series crossovers: Change virtually anything, anywhere, and the response of BOTH drivers will be altered.

They may be simple and economical, but they're also a major crapshoot, and VERY specific to a particular driver set. :yes:

Darker background = better.

So 12 Ohms is the lower HP trace and higher LP trace
20 Ohms is higher HP trace and lower LP trace.

I was confused.

See the probe points on the schematic. A & B, Violet and Cyan, are 12 Ohms, C & D, Yellow and Green, are the same circuit with 20 Ohms substituted. :thmbsp:

[Or, so I intended, at least.... : ]

 

[Zilch]

I thought of an easy way to check whether the inductor has shunt resistance:

Just hook it up as a single-pole lowpass, i.e., in series with a resistive load, and measure the voltage drive.

Is it a step filter (L||R) or a 6 dB/octave lowpass?

Another method: Just measure the impedance of the inductor. If it's L||R, it'll go flatline at the R value at higher frequency. We'll know what the R is, then, as well.

[These inspirations occurred to me in the "Small Room".... ]

 

[Steve O]

I tore into an Altec N1500A I had because I had the schematic for it. This is a series network similar to N1600C but intended for 604E. There were a few differences in the xover values from the schematic:
-The LP shunt C is spec'd @14uF and meas 14.8uF
-The HP series C is spec'd @ 3uF and meas 4uF
-The attenuator pot is spec'd @ 25 ohm and meas 25 ohm
-The attenuator series resistor is spec'd @ 15 ohm but is marked and meas 20 ohm
-The inductor is spec'd @1.5mH and meas 1.5mH w/0.3 ohm series resistance using LCR meter to meas

I also measured the magnitude of impedance of the inductor at various frequencies and compared this to the calculated impedance using 1.5mH and 0.3 ohms. I used a signal level of ~1VAC. The results are shown graphically below. Based on this I conclude the following about the inductor in the N1500A I measured:
1. It is 1.5mH as specified.
2. There is no parallel resistor internal to the inductor. If there had been, the measured plot would have leveled off at whatever that resistance was. No leveling is evident in the plot.

Although a sample of one doesn't constitute unequivocal truth, I consider this further evidence that Altec didn't hide parallel resistors in their xover inductors. However, this doesn't preclude the use of unique magnetic materials (unlikely IMO) or the use of magnetic materials that change over time.

It will be interesting to see how Bauhausler's measurements turn out.

 

[Steve O]

I thought of an easy way to check whether the inductor has shunt resistance:

Just hook it up as a single-pole lowpass, i.e., in series with a resistive load, and measure the voltage drive.

Is it a step filter (L||R) or a 6 dB/octave lowpass?

Another method: Just measure the impedance of the inductor. If it's L||R, it'll go flatline at the R value at higher frequency. We'll know what the R is, then, as well.
[These inspirations occurred to me in the "Small Room".... ]

Been there: Done that See above (in chronological mode)

Interesting where we become inspired. Got mine while out with the dog last night in her "Really Big"room

 

[dlp4341]

ZILCH
Here are Zs for a 605A reconed by GPA as 16 Ohms , Original spec.
Hz Ohms
150 = 16.6
200 = 15.0
250 = 14.8
300 = 15.5
400 = 17.2
500 = 19.0
800 = 22.8
1100= 25.5
1300= 30.0
1600= 32.5
2000= 38.0
2500= 40.5
3200= 46.0

Do any of you have 605's reconed to 8 Ohm woofers ?
Don

 

[Bauhausler]

Update time

I got sidetracked from this project. I had to diagnose and repair a big Yamaha PA amp, repair and repaint a Mac 2100, clean house (a lot!) have house guests over, fix more misc busted stuff and start building a pair of Dyna MK III clones that are promised for Saturday. So I've been busy.
But I did fool around with the 605As a bit. I went back to the original component values matching my N1600C crossovers. I'm using a 1uf choke and no resistive bypass on it. I like this better. It seemed to being a little more life back into the mids, but I didn't listen long enough to verify that for certain.
Since I had the AR3 subs and line level crossover hooked up, I tried out a number of speakers that do well in here with some bass reinforcement: Dyna A25's, Fried H satellites, B&W 610 II's, supermodified Spica TC60s, the stock JBL L77s and finally the Altec Boleros.
Man, I really like these Boleros with some bass support under them. I'm crossing over at around 100 hz, determined by ear and subject to fiddling. I think if I was to use the Boleros semipermanently with a bandwidth limited signal, I would look into taking out the PR and changing the cabinet loading to optimize the performance down to 100 hz. I think the midbass tone could be improved and some looseness taken out at the expense of extension by sealing the cabinet and adding some damping. These speakers will never produce adequate bottom octave in this room anyway. They also work perfectly perched on top of the AR3 'subs' cabinets. So why not do a reversible mod to optimize them for that purpose? The mids are already outstanding.
Anyway, I took the 605As out because I wanted to hear other speakers in the system for comparison. The 605As just weren't knocking my socks off. Changing to other speakers didn't reveal any glaring deficiencies in the 605As, so probably they have potential for development. At this point I'll be fooling with several options for implementing the Boleros and the 605As with the aforementioned subs.

 

[Tom Brennan]

Altec used the model 406 woofer in a sealed box slightly smaller than the Bolero, the model was called the Madera, I never heard one.

 

[Zilch]

Anyway, I took the 605As out because I wanted to hear other speakers in the system for comparison. The 605As just weren't knocking my socks off. Changing to other speakers didn't reveal any glaring deficiencies in the 605As, so probably they have potential for development. At this point I'll be fooling with several options for implementing the Boleros and the 605As with the aforementioned subs.

The recording industry wasn't much impressed, either, thus concluding Altec's preeminent role in the recording studio:

http://www.audioheritage.org/html/history/jbl-pro/1960s.htm

In the larger perspective, the 605A "blunder" may be seen as a major contributing factor in Altec's ultimate demise....

 

[Bauhausler]

The recording industry wasn't much impressed, either, thus concluding Altec's preeminent role in the recording studio:

http://www.audioheritage.org/html/history/jbl-pro/1960s.htm

In the larger perspective, the 605A "blunder" may be seen as a major contributing factor in Altec's ultimate demise....

Yeah, I came across that and wasn't too encouraged. I'd like to hear these in really big back horn cabinets, but I do not want to design, pay for, build, house and move cabinets of that sort. If these 605As struck me as The One Speaker To Make Me Happy I'd go to a lot of trouble to do a proper implementation of them. I'm really not certain about any conclusions from this series of comparisons. I need to go back to a baseline and recalibrate my ears for a while.
Then something else happened.
Today I changed the speakers in the system AGAIN. A package came from Greece with some custom BBC LS3/5A crossovers. I quickly assembled some LS3/5A cabs, B110 woofers & T27 tweeters and installed those in the system with the line level crossover and the AR3 subs. That's quite a change from 605As and even from Boleros in components, intent, sensitivity, etc. It sounded lousy, but the crossovers have never been run and the drivers not run in over 10 years. it's getting better. These may end up in the shop, where space is at a premium.
ANYWAY, I'm deferring judgment on the 605As for now pending comparison to a known standard.

 

[Zilch]

The Valencias seem to have dropped off the screen there. Those, I know something about.

In which regard, I'd advocate acquiring a pair of BMS 4552nds in the group buy, of course.... :yes:

 

[Bauhausler]

The Valencias seem to have dropped off the screen there. Those, I know something about.

In which regard, I'd advocate acquiring a pair of BMS 4552nds in the group buy, of course.... :yes:

The Vals got moved to an inconvenient place temporarily. I'll be bringing them out for a comparo against the 605As. Not quite fair as I'll be using subs on the 605As, but I'm looking for the midrange tone more than anything else in this comparison.

The BMS drivers look interesting. Three bills isn't impossible, but this week I bought another Accuphase (busted) preamp and another (busted) Heath tube amp. I suppose I could swing that if it was a sure thing upgrade and not just an experiment. Please point me to any previous descriptive work on the BMS drivers.

 

[Zilch]

Please point me to any previous descriptive work on the BMS drivers.

Valencia HF is the same driver as in your 605As, with the same problems: Forward midrange and nobody home above 10 kHz.

I'm going to point your first to three posts by member Steve O who is working with BMS independently:

http://audiokarma.org/forums/showthread.php?p=1343513#post1343513

http://audiokarma.org/forums/showthread.php?p=1464079#post1464079

http://audiokarma.org/forums/showthread.php?p=1467251#post1467251

Here's the AK thread describing a collaborative upgrade development project with BMS in Valencia:

http://audiokarma.org/forums/showthread.php?t=106759

That'll link you to the monster main "Babies" thread over on LHF, aptly described by an AK member as "Group therapy," but also 5-Star rated over there:

http://audioheritage.org/vbulletin/showthread.php?t=14690

Bottom line: Member Jackgiff and several others swapped BMS into Valencias and added compensation to flatten the mids. Adding tweeters was found to work, but a less optimal solution than simply using a driver that has the requisite high frequency extension to begin with.

There's a good answer for their wimpy bass, as well: JBL 2235H woofers or Altec 416B/C (perhaps,) if you're willing to take an efficiency hit. 416A/Z efficiency is artificial, anyway, from what we've been able to determine thus far, and actually responsible for Valencia's perceived deficiency in low frequency response.

[Not fatal.... : ]

 

[Bauhausler]

Modded Valencias

I'm sure it's been noted elsewhere that what you're describing as an improved Valencia is basically the box and the 811 with everything else changed. If I was going to go that route, I would be unlikely to keep the box either. Something taller and narrower would work far better for me. Also, mine are 'A's with the slot ports. I'd probably want the later developed tube ports. Regarding the 811, I've used 511s in other systems and somewhat prefer them. So modding the Valencias to the extent described still retains one significant compromise (cabinet) and one lesser one (811) while dispersing most of the parts of a nice original pair of vintage speakers.
The analogy to Abe Lincoln's ax applies here.
I think I should be able to get closer to what I want with stock drivers and cabinet. I'm willing to change crossovers of course.
When I have time I'm going to put the Vals back in the system and do up a better crossover for them. Right now these LS3/5A clones with the AR3 subs sound pretty good.

 

[bowtie427ss]

I'm willing to change crossovers of course.

Just my .02 here, but that's probably the least costly and least invasive change that will reveal the most improvement.

I don't want, or intend to discredit any of the other mods/changes that have been highly researched and proven at this juncture.

In a nutshell the point of diminishing returns varies for all of us according to budget and what we're willing to throw at a project.

Valencia HF is the same driver as in your 605As,

I respectfully disagree Zilch, 605 has a alnico slug just over 8 oz., while the 806 slug is 13 oz.. Maybe "in system" it isn't really relevant because the LF mag is also smaller on the 605 rendering the sensitivity ratio between the HF and LF nearly the same...................... maybe?

I don't trust Altec posted response or sensitivity specs to a very high degree(thank you for multiple reality checks), but i figure they should have gotten magnet weights fairly accurate.

But, my initial thought is that the reduced sensitivity of the 605 HF section plays heavily on being able to use as much compensation with it.

Am i wrong here?

 

[Zilch]

The analogy to Abe Lincoln's ax applies here.

Yup, and finally, you also get rid of the 811B horn, as well. Not sure, but I don't think you'll get 511 in that cabinet.

If you want to keep them stock, biamp analog active and engage CD compensation. There's not enough headroom between 806A and 416Z to do much better compensation passively than is already in the N800F crossover, though others are working on that. With your skills, you might take up the challenge, as well. Look to Don Patten's 605A approach, perhaps. :thmbsp:

You're still left with significant deficiency at the low end, which seems to be a priority for you and your room. Keeping the stock driver, active assist may be an option, though I've never tried it....

 

[Zilch]

Am i wrong here?

What I know from working with them is that 806A is, indeed, less sensitive than the larger-magnet 802 et al., and you need that extra 3 dB of headroom AND the Tangerine phase plug AND a woofer that doesn't have the rising response* of 416A/Z to achieve Model 19 performance, which is itself rolled off in the VHF. That's why we scrapped all that and went to the BMS HF driver once I determined that 811B would (somewhat, with beaming) support HF extension.

Another collaboration with 806As on 811B is underway on LHF right now using the dual 12" 414 woofer LF common to several Altec designs:

http://audioheritage.org/vbulletin/showthread.php?t=18913

806A on 811B is 101 dB (see below.) Best I can tell, 414 is 97 dB, and a pair of them, 100 dB.

From the measurements, that combination is therefore in deeper doodoo in this respect than Valencia, even, but, as usual, I have a plan.... :

*No one has as yet verified actual 416Z performance in Vals with groundplane, in-box, or vent-adjusted nearfield measurements.

Edit: Model 19 response as measured by CBS Labs 30 years ago, and the HF as by me last year, last two images:

 

[Bauhausler]

Yup, and finally, you also get rid of the 811B horn, as well. Not sure, but I don't think you'll get 511 in that cabinet.

If you want to keep them stock, biamp analog active and engage CD compensation. There's not enough headroom between 806A and 416Z to do much better compensation passively than is already in the N800F crossover, though others are working on that. With your skills, you might take up the challenge, as well. Look to Don Patten's 605A approach, perhaps. :thmbsp:

You're still left with significant deficiency at the low end, which seems to be a priority for you and your room. Keeping the stock driver, active assist may be an option, though I've never tried it....

I ran through a number of speaker combinations in quick succession in the last few days. Instead of doing useful work, but that's another story. The ones that I really wanted to leave hooked up are the Boleros, the lowliest of the group. I dunno what it is, but I LOVE the mids from these. With the AR subs, I get solid 25 hz output and they stack neatly on top at a good height. I'd hate to find that what I really like is a $100 pair of 890As with a minor upgrade & a pair of subs I scrounged from spare cabs & drivers. So far, these crank me up in ways that the 605A's just didn't, even with our xovr experimentation.
I have yet to set the Vals up again for a listen. I should really rehab the caps in the stock crossovers at absolute minimum before giving them a *serious* listen, but I understand they're potted and working on them is messy/destructive.
To make things worse, I've been offered a pair of Acoustats at a reasonable price & I'll probably go for those to experiment with. Cant resist the weird stuff.

 

[Bauhausler]

An update to the winnowing down

I'm posting here to update on some of teh experimentation and decisions thatwere made.

With copious generous help I ginned up a respectable set of crossovers for teh 605As and listened to them for a while. They just didn't turn me on. That's teh only way I can put it. I tried a lot of options and convinced myself the 605As weren't going to be it. They've gone to a new owner, although I retained the cabinets.

The Klipsch Cornwalls have gone to a new owner, as expected. To many people this is the best speaker ever made. They're too forward for me and I don't miss them.

The Valencias. I listened to them at length and I think they have the most potential of any of the vintage speakers. To get them where I'd want them I'd end up spending a lot of dough to alter them permanently. Since they're a nice original pair of 'A's I decided to sell them as is and if I want a horn 2-way for myself I can always develop something to suit.

A while back I sold a mint pair of JBL 030 Barons to a friend who had been using K-horns. He loves the barons but wanted to hear them next to the Valencias before the vals went away. We did a side by side comparo. He liked the forwardness of the Barons. I liked the better bass and cleaner mids of the Vals. He kept the Barons & the Vals are on the block.

At the end of teh comparison he asked about the Bolero "A"'s that I had stacked at the side. I set them up to play and he immediately said "How much do you want for these? They sound better than the other two!" Not for sale. I left the Boleros set up for 10 days or so after that and enjoyed every note they played.

In the meantime I bought the guts of a pair of Altec Maderas, the same woofer as the Bolero and a small Heppner tweeter. I plan to make a pair of medium sized horn based 2-ways with the woofers and a pair of nice cabs I have here. The EconoWave project horn looks like a really good match for the Altec 406 woofer from the Madera. The cabinet issue becomes more difficult with a 10" woofer and a 12" wide horn, but it's manageable. I dunno when that will get done.

For something completely different I've also acquired this pair of Acoustat 1+1's I've been fooling with. They're supposedly 'fullrange' but I've been rolling them off at 70 hz and using a pair of subs. I really like the clarity, transparency and low midrange distortion. I don't know if I can get used to the limited dynamic 'snap' compared to high efficiency speakers. Or the fact that they're 8' tall or the wall-sized image they throw, but I'm enjoying using them for now.

Hey, you know what I should try? The Altec 406 woofers run up to about 2500 hz and crossed over to the Acoustat panels from there up. Severe mismatch of sensitivity and impedance, so it would have to be biamped, but it's worth a try. That could work reeeeally good! Eight foot tall hybrids with vintage woofers and electrostatics. It's so stupid it's irresistable.

 

[Bauhausler]

Speaker winnowing down update

Well, I've made some decisions and changes.
The Altec 605As are gone.
The Valencias are gone.
The Cornwalls are gone.

I've acquired a second set of Altec 406-8Y woofers* plus the metal horn tweeters and crossovers from a pair of Maderas. Those might go in some cabinets if I don't change my mind before the weather actually gets and stays nice enough to go outdoors & do the messy cabinet work.

I acquired the Acoustat 1+1s, used them for a bit & parked them. I have parts on order for a power amp that will source a LOT of current, as they seem to require.

The big news: I have a pair of JBL L-112s of my own. I overhauled a pair for a friend a few months ago and was amazed by the sound. Just really surprised and pleased by the overall performance. I'm not generally a fan of this series of JBLs, but the L-112s sounded damn near flawless to me in terms of tonality, dispersion, balance and dynamics.
I bought the first pair that was offered to me, gladly paying the asking price. They needed foam, which is done now. They haven't been run in a while, so they're still being loosened up, especially the woofers which were down in level due to disuse and initial refoam stiffness.
Man, I REALLY like these. AK member LVB was over & we ran through a few CDs and a few cocktails. It's difficult to find anything to fault in these speakers, and I can find something to criticize in almost anything.

I'll probably still do something with the Altec 406-8Y woofers in nice cabinets, using the EconoWave tweeter setup if it doesn't cost too much. That's a fairly unchallenging project and worth the effort.

Bottom line, if you** took away all of my other speakers and left the L-112s it would be a long while before I went looking around for a substitute. And that's speaking as a guy who changes his speakers around 2 - 3 times a week.

* as used in teh Bolero and Madera

** and a large moving crew