Altec 753C


After many years of raving about the Altec 32 horn, the only stone left unturned was using it as it was originally designed, that is, with the compression driver oriented to radiate upwards.


Last year, I received a message from John Piro, whose beautifully crafted preamp project was previously featured in this blog. He sent me pictures of his interpretation of the legendary Western Electric WE753C using Altec 414-16B woofers and Altec 32A horns. I was very impressed and asked if he could build a pair for me. We finally met at the Kutztown Radio Show last September. He and his wife had dinner here at home when he delivered my beautiful cabinets!

Altec 414A + 32C + 802D + 20275 

As an homage to the WE753C, which was a major inspiration for this project, I henceforth christen this speaker system as the Altec 753C.

Altec 2-way XO redux

I've settled on running the 414A woofers in full range mode (ala J-Rob) and replaced all the crossover resistors with non-inductive 12W Mills. This took away the last vestiges of grain in the upper frequencies.

RTA Graphs


Altec 2-way
Altec 614 + 414A + 32C + 802 with GPA34258

The above RTA was taken from this blog entry

VS

Altec 753C
Altec 753A + 414A + 32C + 802D with 20275

I could've lived happily with my Altec 614 or repurposed 861 (aka Madrid) cabs + the inverted 32 horn situated on top. However, with proper horn orientation, the sound was taken to another level of refinement. Now the blend between the 414A and horn is practically seamless and I bask in the airiness of the top end, which I attribute to significantly improved high frequency dispersion, precisely as envisioned by Western Electric engineers.


In spite of the stellar midrange performance of the Open Baffle mounted Altec 755As, I started the Altec 2-way project in the late 90s to address the following issues:

1. More efficiency
2. Extend the frequency extremes
3. Less congestion in dynamic peaks with complex musical passages

After 20-some odd years, those goals have been realized. The Altec 753C is pretty much end game!


Thanks to my buddy Joe Roberts, who explained the intricacies of proper 32 horn orientation. The idea was carefully stored in my mind. I just had to wait for the right opportunity to implement it. And of course, a big thanks to my friend John Piro (aka RCA NUT), craftsman extraordinaire!









Comments

  1. Beautiful! I've been slowly collecting parts for this project and always wanted to build them with the horn in the cabinet ala WE753. Are you willing to share the cabinet details and dimensions? Are they the same as the 753's?

    ReplyDelete
    Replies
    1. Thank you!

      I don't have the exact dimensions that's why it's not in the article. My friend John Piro built the cabinets based on his "study" of the WE753A cabinet.

      JE

      Delete
  2. Those are absolutely beautiful! Expert craftsmanship executing a lovely aesthetic, congrats!

    ReplyDelete
  3. Hi,

    That is a beautiful build. I would like to request if you will be able to please share the cabinet dimensions and the crossover. i have 414-16b and 802 16 ohms as well and 32c horns that i can use to clone these.

    thaanks

    ReplyDelete
    Replies
    1. The crossover schematic is linked in the article. With regards to the dimensions, please refer to my reply to MB.

      Thanks!

      JE

      Delete
  4. Interesting that the post date of April 1 coincided with this unusual horn orientation. Now I'm not saying that that is a beautiful speaker cuz it really is. Just wondering if Ol' JE is slipping one by us.....Regardless, nice work!

    ReplyDelete
    Replies
    1. Hey thanks man!

      I can be a serious person...but not in this instance ;) The serious work on this cabinet was done by my buddy JP!

      Delete
  5. Very beautiful cabinets enjoy them...

    ReplyDelete
  6. Wow. Great cabinets. I have the same setup you had earlier with Altec 614 with Altec 32B with 802D drivers.. We Could follow the step of yours on this to achieve efficiency / extend the frequency extremes / Less congestion in dynamic peaks with complex musical passages if your friend John Piro could issue the built plan... Waiting for that.
    regards

    ReplyDelete
    Replies
    1. Go and register at www.hifihaven.com John Piro uploaded pictures showing how he built the cabinets.

      Delete
  7. This is the speaker that I have been dreaming for years, so thank you so much for showing how you did it! Could I have to honor to get a little guidance from you to build this? I am not technical so I don't think I can fix used drivers. I would like to buy the 802 and 414 from Great Plains Audio for this build. Should I get the 8 oms or 16 oms version if I follow your build? Thank you!

    ReplyDelete
    Replies
    1. I have no experience with 8 ohm drivers because I used what I already had the 16 ohm drivers. The XO has values for both impedances so there shouldn't be any problems.

      The crossover is very simple and shows values for both 8 and 16 ohm drivers, so that shouldn't be a problem if you get the recent manufacture alnico units from GPA. If you go for 16 ohm drivers, make sure your (tube) amps have 16 ohm taps.

      Also, please keep in mind that the speakers were voiced using my DIY preamp and SE amps.

      JE

      Delete
  8. Hi--long time follower and have built a number of your projects. Do you know if John will build a set of cabinets like these? They are truly beautiful. Any leads on someone who will make the cabinets (for a fee of course) would be appreciated

    ReplyDelete
    Replies
    1. Send John P. a message in Hi-Fi Haven forum. His handle is "RCA NUT", it's hyperlinked in the last sentence of the blog entry.

      JE

      Delete
  9. Hi JE:

    Thank you so much for the guidance. I will go for 16ohms so that I stay closer to how you did it. I have a question on the Altec Lansing speaker model A8: They look like they use the ALtec 32 horn, but I am not sure. Is that correct? I am trying to buy a pair so I can strip the horns out for my build.

    Thank you!

    Li

    ReplyDelete
    Replies
    1. AFAIK, the A8s used the 32 horn. Happy hunting!

      JE

      Delete
    2. Hi JE:

      I bought the A8 and they arrive later today and I will get GPA 16 ohms 802 and 414. So I am planning ahead - I really need to learn how to build that crossover from you because I have no technical knowledge so just want to copy what you did if that is OK. I will get the parts first: From the picture above, I can see you have 3x12W mills resistor, and a 4mf 1000 vdc capacitor, but I can't recognize the rest. Is it possible for you to provide a list of all the parts that I need to get? Let me know what I can do because I am on the train. Thank you!

      Delete
    3. If you click the "Altec 2-way XO redux" you will find all the crossover information.

      Here's the XO schematic with all the parts: https://4.bp.blogspot.com/-l2jS8p-O5Cg/WKyAd5dcm7I/AAAAAAAAEx8/CrqYe3vWGCIdH8HE9qUjsAa6Nr4e2BPnACPcBGAYYCw/s1600/XO.jpg

      JE

      Delete
    4. Hi JE, Thanks for the input over the past week or so. Have you ever heard the 414 in the Petite Onken? I'm wondering if I should go with the 753C (which, of course, is designed for WE version of Jensen A15PM) or the petite onken. I have 414s, 806s, your XO etc. I vastly prefer the looks of 753C cabinet--do you get a nice response into the orchestral foundation, i.e., are the low strings robust enough in that cabinet?

      Delete
    5. Yes, I've heard the Petite Onken loaded with Altec 414s . These were the speakers Herb Reichert wrote about in Sound Practices . He "parked" it at the home of our mutual friend, Ding, in Staten Island after he vacated the firehouse. Incidentally, if you google "Jensen cabinet plans" you'll see the origin of the Onken .

      The original WE753A/C was a sealed cabinet using a KS specified 15" woofer OEM'd for WE by Jensen. However, if you look closely at 753C clone cabinets built by John Piro, it has a rectangular vent. The internal volume of this cabinet is very similar to the Altec 614, which I used for many years.

      I chose the 614 over the Petite Onken because they were easier to build, more compact and less tweaky. Herb was stuffing books and other materials in the vents of his Petite Onken to get proper tuning, whereas the 614 was basically plug and play. To my ears, the "Petite Onken" didn't offer significantly more bass extension even if it was significantly bigger than the 614.

      This set up has enough low end response for my purpose. But what sounds good to me may not be good enough for others.

      JE

      Delete
    6. Thanks JE--this is super helpful. I did notice the vent in John Piro's 753C style boxes and wondered if this was because the original was just some sort of leaky box, or that it was sealed and you tuned it for the 414--now I have my answer

      Delete

Post a Comment

Total Pageviews