Tuesday, December 31, 2013

Altec 2-way horn system redux



Truth be told, I was never fully satisfied with the performance of the Altec 2-way which is why I never uploaded the old article in the Arkiv.

Let's recap how the 2-way horn system evolved...



The project was conceived in mid 1998 because I needed a monitor system that was more efficient than the OB/755 so I could listen to SE amps with 2 watts output and below.

I commissioned my cabinet maker neighbor to build 614 bass reflex cabinets and loaded them with Altec 419A 12" drivers + 811 horns (early version/heavy sand cast) and 804A compression drivers gathered from hamfests and radio shows. Crossover was a textbook 1st order/6dB/octave hinged at 900 hz and the horn padded down to match the sensitivity of the low frequency driver.

Altec 614 cabinet plan

Eventually I acquired proper 12" woofers - Altec 414As, which lack the upper midrange nasties of the 419As. The 414As have great midrange quality even if they lack the bass end of their larger 416/515 brethren.

Note damping is applied only
on two sides and the back.

802D compression drivers replaced the smaller magnet 804As

Altec 802D

+ super tweets...
Altec 3000H 

Series crossover


While exploring proper monophonic playback, I discovered the N1600C crossover which came with a single 605B Duplex I acquired. When I inserted it into my Altec 2-way, it sounded significantly better than the textbook parallel 1st order/6dB per octave crossover I had been using.

N1600C clone

Using paper in oil caps and low DCR air core chokes, I cloned the N1600C and thought it was as good as it gets with my Altec components...

ca. 2006


Lessons learned over the past 15 years

  1. Choose a woofer with excellent midrange characteristics.
  2. In hindsight, the 804A/811 was a much easier combination to tame than the 802D/811. Perhaps this is due to the smaller magnet on the 804A which makes it 3dB less efficient. Note: the 806A is similar in specs to the 804A but some sources say they are built differently.
  3. Horns sound better crossed over at least one octave above its rated cut off.  I'd go as high as possible if my woofer can play well into the upper midrange.
  4. Don't be afraid to pad down the compression driver which is at least 10dB more efficient than the woofer.
  5. Try series type crossovers like the Altec N1600C above or N1500A which have lower insertion loss due to the 1st order/6dB/octave low pass filter. Note: the high pass section =  2nd order 12dB/octave 
  6. I only use paper in oil caps in my crossover. 


811>32C


Through the years that I had been attending radio shows and hamfests, I got to know people who opened rare opportunities for me to hear the Western Electric 753C, Western Electric 757A and Altec 1505 horns with Western Electric 555 field coil drivers on top of 825 cabinets loaded with 515s. Most memorable was a single Western Electric 15A horn  + WE555 field coil compression driver driven by a pocket FM radio my buddy Ding and I heard at Scott Stilwell's shop in Philadelphia. The huge horn produced mid bass and rolled off like a 755C or 755E. Thus, "shouty," honky or harsh is not something I associate with good horn speakers.

Altec 32C/802D + Altec 3000
trial ca. 2009

A pair of Altec 32C horns I got in trade back in 2009 had been languishing in my storage bin despite realizing its potential after an initial test run. Given the 32C's pedigree - a direct descendant of the metal WE32A horn found inside Western Electric 753C monitors - I had an inkling that it would be better than the 811. But a busy schedule and other life matters got in the way. ;)


Replacing the 811 horns with the 32Cs transformed the 2-way horn system. The 32C/802D blended with the 414A/614 without any crossover alteration. If the 811 gives a front row seat perspective, the 32C is more like sitting at the middle to back row wherein instruments and/or vocals have been given enough time to reverberate in the hall. Exactly the kind of sound perspective I prefer. Despite its polite and refined presentation, the 32C still retains the transient speed and dynamic ability expected from a horn.

Although there is another tweak I am experimenting with at the moment, this horn is here to stay. As Johnny Hartmann sings, "...it's wonderful..."


HAPPY NEW YEAR!












35 comments:

  1. I am a big fan of the 32 horn and have used it (both A and B versions) with Altec 414 and Jensen 15" P15LL woofers. The only compression driver I have used on the 32 is an Altec 802-8G. I think the 32 is a terrific sounding horn especially because it can blend so well with a paper cone woofer. Each of my setups has sounded very coherent, more like a full-range speaker than a 2-way.

    One of the secrets to using the 32 successfully, in my opinion, is using the equalization circuit that Altec developed specifically for the 32/802-8G. Altec's 9849 studio monitor used a 414 woofer with 32B/802-8G, and the crossover developed for the 9849 includes a gentle high-frequency boost that makes the top end fully extended to my ears. It also includes a zobel network to smooth out the lower end of the 802 and tame any tendency to honk. To my ears the 802-8G in the 32 horn has no horn colorations at all.

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    1. Thanks for sharing your thoughts and experience! I studied the 9849 crossover as well as the 1201-8A from the Model 19. Both incorporate an EQ network that was derived from Altec 30923 attenuator which I am using on the high pass section of my crossover (see next post). To my ears the the Zobel network (309040) and its attendant loss of a few dB in efficiency in the 414A was not worth the sonic gain in the context of my system. The crossover/EQ I am using now is also tailored for my 16 ohm drivers.

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  2. I know what you mean about the zobel. Each time I have tried a zobel on a woofer, I have noted that there is an adverse effect on dynamics which was too high a price for whatever benefits it allowed in terms of frequency response smoothness. The zobel I use now is only in the 802 circuit and I haven't noticed any adverse effects from it, perhaps because it is after the attenuator.

    When I switched from the 414 to the Jensen P15LL, I was not able to use the 9849 crossover (Altec 32343) since the Jensen is 16 ohms and my 414 woofers were 8 ohms. I basically scrapped everything but the equalization circuit for the 802 and designed the rest of the crossover from scratch. I ended up with a 2d order Butterworth for both low-pass and high-pass. After trying different value parts (up to 50% greater or 50% less) for each of the crossover elements, I am satisfied that my textbook values are the ones that sound best. I then spent a long time trying different types of caps, chokes and resistors before settling on my present setup. Unfortunately every component has an effect on sound quality and I don't know any shorter way to find out which ones sound best except to try them out.

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  3. How did you mount the Altec 32. I have a similar speaker and I cannot figure out how to do it. Any help will be great thank you

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    1. I mounted it on a 3/4" plywood stand, please see second to the last picture above. Hope that helps!

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  4. Amazing, how one's priorities change when your health degrades. I have a pair of Altec 14's, two pairs of 9842A's and one 9844A and I still haven't gotten around to listening to them!
    They all have the "bent horn", which was why I bought them.
    I had a single WE753C with the metal bent horn and I thought it was one of the most amazing speakers I'd ever heard!
    I have a single horn from a 753C that was run over by a bulldozer so I'm looking for another.
    I'm also looking for a single old style silver-grey empty 612 cabinet for my 604B's.

    I'm looking forward to comparing the 604B/612's to the 9842's.

    Your post got me all excited about this again. Thanks!

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    1. I hope you enjoy them as much as I do. Happy Listening!

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  5. how can I upgrade my xovers I my heathkit as 101 ?

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    1. I had to do a quick Google search to find more info on the Heath AS101. It turned out to be a Heath version of the Altec Valencia with 416/806A/811. Also, I need more info as to why you want your XO upgraded. If the caps are just out of spec, you can try replacing them with fresh caps from Parts Express or a similar supplier.

      Assuming that your present XO is within spec and you are not happy with the sound, you may try my XO - http://jelabs.blogspot.com/2014/01/altec-2-way-xo-update.html - I cannot guarantee that it would be an improvement since I tweaked this XO using 414/802D/32B components.

      Happy Listening!

      JE

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  6. Is this the way to go with your Simple 45 amp and pre- amp - I have built both and looking for a pair of speakers that I can enjoy the broad range of music that I listen to. More classic rock than Jazz - is this the way to go? Or is there a cheaper route? These AL parts add up?
    Thanks - love your blog.

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    1. Hi Comer,

      To my ears this speaker system sounds good with the JEL preamp + Simple 45 amp. Hard to say whether the more laid back presentation of the 32B horn would suit your musical taste vs. the more upfront 811.

      I wish I had more time and resources to experiment with more affordable drivers.

      Thanks for the kind words and happy listening!

      JE

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  7. Interesting. Well the 811's are 25% the cost of the 32b so that's a start. The 414's come in a variety of styles. Is it important to stick with he 414a?
    Again - thank you for your time.
    Comer

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    1. I don't have much experience with later versions of the 414. But as I mentioned above, I chose this particular 12" Altec driver because of its excellent midrange performance. Fortunately for me, I had the luxury of listening to the drivers before purchasing.

      Check out the High Efficiency section of Audio Asylum or Lansing Heritage Forum + others you can Google for more ideas.

      JE

      PS: You may also consider the Altec Duple 605A or B. I've been enjoying a "B" in my mono system for the past 10 years. Cheaper than the various iterations of the 604.

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  8. Will do - also going to look at a pair of A-7's with 416 - 16's in them this weekend. Might be a fit.
    Best
    Comer

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  9. Ahh now, 32B's! I have been enjoying my JE Labs preamp/amps with 612C/4168B/JMLC's using several XO along the way (currently mini DSP using 4th order). I have a friend offering me a pair of these (32B horns) I will check it out if he still have them. I already have the 414A on stock just in case. I do not have a lot of time nowadays to construct a cabinet, butI know someone who can build me a pair in the future. Happy Holidays my friend! Tremendous blog as always!

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    1. Wishing you and your family a great holiday too! Hope to see you one of these days, it's been a while.

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  10. Hi there, what other good 12" drivers would you recommend for the 614 enclosure?

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    1. So far I haven't found any 12" woofer that has the mid-range magic of the Altec 414. But that's not to say there are no alternatives. I've been checking the specs of modern 12" drivers from Eminence, Beyma and B&C and some models look promising on paper but they cost almost as much as the Altec 414. The GPA 414 is definitely worth checking out. Those are made from original Altec parts. Best to call Bill H. if you are interested in those.

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  11. Hi Joseph--have you tried the 806A? With what results? Also any insight on the difference, if any between your 414s and 414z? Thanks!

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    1. What I said above regarding the 804A applies to the 806A. Both drivers have the sought after Altec sound. Since the magnet is smaller, they're 3 dB less efficient with a little less top end extension. Since 802s have gone up considerably in price, the 804A/806/807 motors are well worth considering!

      I also have a few entries regarding the Altec 605B duplex which is a 416 + 806A. The search function on top of this page will turn them up.

      JE

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  12. Good afternoon, dear Mr. Esmilla!
    I would like advice from a knowledgeable person like you.
    I recently finished a mono project on an Altec 601C to listen to 50s and shellac records. This is a duplex loudspeaker consisting of a 414 woofer and a 3000 series tweeter. I used a clone of the original N3000E crossover with a cutoff frequency of 3000 Hz. To my great regret, with all the richness and naturalness of the sound, the sound is somewhat annoying due to the screaming upper middle. What do you think, what could be the matter and how to fix it?
    Thank you,,
    Boris.

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    1. Simplest is to get a 0.22uf paper in oil capacitor and put it in series with the + terminal of the 3000 tweeter. If you crave for a bit more sheen, use a 1-1.5 uf paper in oil cap + an 8 or 16 ohm L-pad. Either way, the 414 woofer should be running in wide range mode (no roll off) + no plastic caps to the 3000.

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  13. I didn’t quite understand, do we connect the capacitor in addition to the crossover, or should the crossover be excluded?

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  14. Replies
    1. You would've found better tips on how to use a 3000 tweeter here - https://jelabs.blogspot.com/2022/04/altec-756b-32c-802-23744.html

      Somewhere in the middle of that entry, you'll read about how I augmented the top end of an Altec 756B with a 3000. The 756B came out of an Altec Melodist 700A - 756B + 3000A + N3000B. The N3000B made the 756B + 3000 sound bright also.

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  15. What you can say about 802-8T?

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    1. I never had a chance to listen to that particular model.

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  16. JE
    Do you happen to have a version of your crossover for an Altec 811B horn, 802D 16 Ohm compression driver, and 803B 16 Ohm woofer?
    Is there a way to contact you directly?

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    1. As hinted above, after several years of trying to make them work, I finally gave up on the 811 horns. I have no experience with the 803B woofers. I had 416As early on, they are excellent woofers but as I mentioned above, the 414As had better midrange while still good down to 40Hz.

      Given the Altec components you listed, I don't think I'm the right person to guide you on your project.

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  17. Thank you,
    The 803B has the same specs as the 416A 16 Ohm woofer. Apparently, they started out the “803A”, then made some modifications to the paper cone and how it was attached to the surround. Possibly some other modifications, and renamed it the “803B”. The problem with this designation, is that it began to overlap with their horn nomenclature (e.g. “803 horn”, 811, etc.) so…they renamed it again as the “416A”…and then continued the “416-“ classification in their latter iterations.

    I had heard on YouTube someone who had implemented your “JE Labs Altec Crossover”, and was impressed with the sound…even over a computer it was compelling, very open, and natural -just like music. I thought this guy must have some good ears, and has figured some things out. Discovering that you had gone down this road, I had hoped you might be able to provide a analogous crossover schematic for the above listed A7 components. I understand they may not be ideal to your current preference, but even so…I thought your experienced solution might possibly be better than the given standard Altec 800Hz 2nd order crossover I’ using now? Who knows?

    I have not tried a 1200Hz, or even 1600Hz crossover point, but supposedly the 803B/416A is more than comfortable at that frequency. Noting your lessons learned over 15 years section of the blog, “Horns sound better crossed over at least one octave above its rated cut off. I'd go as high as possible if my woofer can play well into the upper midrange.”…leads me to think, hmmm, maybe the woofer taken to 1200Hz or 1600Hz…bring the 802D in at 1600Hz (which would be about an octave higher than the 811B horn’s cutoff frequency of 800Hz)…and maybe this is moving in the right direction??

    Regarding the 811 horn, if it isn’t ideal over the long haul, maybe I could change it out for something that is a better fit right latter on (when means allow). This is a journey after all…

    Thank you for your blog, time, and help. It is appreciated by many of us enthusiasts trying to find our way.

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    1. No guarantees, but I suggest trying the XO schematic dated 1/14 in this link -https://jelabs.blogspot.com/2018/01/altec-2-way-xo-redux.html

      The low pass is a series connected 6dB/octave slope hinged around 1200Hz which, IME, doesn't choke the woofer too much (good for maintaining efficiency and micro dynamics). The high pass is a sharper 12dB/octave ~ 1600 Hz which is one octave above the 811 rated cut off frequency. Hopefully, the constricted throat distortion I (and a few others) associate with this horn won't bother your ears.

      You can adjust the upper midrange/lower treble EQ by varying the value of the cap I preset @ 1uf.

      After you've tried your best to tune the system and your still bothered by a glaring upper midrange, replace the 811 horn with either a metal or plastic Altec 32, an Emilar EH500 or EH800, more info - https://jelabs.blogspot.com/2018/02/altec-32a-32b-emilar-eh1210-eh800-eh500.html

      Happy listening!

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  18. Very helpful! Greatly appreciated. Thank you.

    Currently, the 802D/811 are tamped down by use of L-pad, to bring HF horn closer to woofer level (Movie theaters needed upper horn lift to punch through cinema screen…I don’t ; )

    If the HF is 12db/octave slope, that should protect the compression driver well. Do you find in practice that the 6db/ octave slope for the LF limits it any way? In other words, do you feel you can play it at realistic sound levels, or only quiet levels?

    I noticed you favor paper in oil caps; do you recommend a source, brand, or place to get them?

    Thanks again

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    1. I get my PIO from radio shows, hamfests or eBay. I'm not very particular about brand.

      IME, the 414A is one of those rare drivers that can play the entire vocal range cleanly. That's the reason I chose it because it rolls off very smoothly around 3500 Hz without break up modes. I used an Altec 605B (416A + 806A + N1600 XO) for my mono system years ago -https://jelabs.blogspot.com/2015/06/altec-605b-duplex.html - I could not listen to the woofer section without the 6dB/octave filter in the N1600 XO because of break up modes in the 1500 Hz region. I tried other XOs with more complicated slopes (musical dynamics are impaired since I use SET amps) with the 605B but always went back to the N1600 I built with PIO caps + an air core choke. And yes, the 12dB slope for the compression driver offers excellent protection.

      Like I said before I can't really guide you on your project since I currently don't use any of your Altec components except for the 802. So you have to do a lot of listening and reading. That's how I learned during the pre-internet days since I'm a classically trained violinist, not an audio engineer. Besides musical tastes vary that's why other people love the 811 horns while I couldn't live with them.

      Here's another blog entry that might help you - https://jelabs.blogspot.com/2020/07/reality-check-musical-instrument.html

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