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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. The 811 (as well as the 32B) sound better crossed over at a higher frequency than its rated cut off. In my implementation it's an octave above (~1600hz). Based on Western Electric documents I have read, the horn sections in the WE753C and WE757A were crossed over in a similar fashion.
  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.
  6. I only use paper in oil caps in my crossover. 


811>32B


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 32B/802D + Altec 3000
trial ca. 2009

A pair of Altec 32B 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 32B'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 projects got in the way until I pulled them out to try before the end of 2013.


Replacing the 811 horns with the 32Bs transformed the 2-way horn system. The 32B/802D blended with the 414A/614 without any crossover alteration. If the 811 gives a front row seat perspective, the 32B 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 32B 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!

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.

    ReplyDelete
    Replies
    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.

      Delete
  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.

    ReplyDelete
  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

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

      Delete
  4. Thank you sir. Great setup you have there.

    ReplyDelete
  5. 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!

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

      Delete
  6. how can I upgrade my xovers I my heathkit as 101 ?

    ReplyDelete
    Replies
    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

      Delete
  7. 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.

    ReplyDelete
    Replies
    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

      Delete
  8. 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

    ReplyDelete
    Replies
    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.

      Delete
  9. 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

    ReplyDelete
  10. 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!

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

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

    ReplyDelete
    Replies
    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.

      Delete

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