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Thread: Altec A7 500-8 and Altec 1224A electronic crossovers

  1. #41
    Hostboard Member Lycoming680's Avatar
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    Quote Originally Posted by Old Guy View Post
    Considering the drivers, cheapest route is likely pick up a second crossover, and one amp.

    Concentrate on amp quality. 35 watts/channel at 8 Ohms is enough.
    I hear you, old guy. I think both 416's should probably get checked in to GPA . I'll get pics of the separation that I had mentioned soon. Haven't even pulled them out this weekend, have an assigned list I have to chip away at!

    I do have my one crossover completely off it's mounting, evidently a first for it. It's cool looking at it and thinking- "Oh yeah, that's my Altec crossover for my A7's out in the garage..." Examining it helps to make more sense of it after reading some.

    Thanks again,
    -Brandon

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    Hostboard Member Lycoming680's Avatar
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    Anyone do any smoothing/matching of ports and gaskets on the driver to horn throat transition? And polishing maybe?

    Just curious,
    -Brandon

  3. #43
    Senior Hostboard Member GM's Avatar
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    Yes, back in my 20s I thoroughly tweaked to a fare-thee-well one pair of 511/802, align boring, machine matching coupling surfaces with wax paper gaskets, cutting out the vane welds to stress relieve the castings, ground down internal welds, removed now useless brace, used Liquid Rubber? to fill the vane gaps and seems like I did some other stuff, but can't remember ATM.

    Anyway, while the women could tell a big difference, which BTW they didn't like as it just made record hiss worse; me and the other guys just noticed less 'horniness' along with increased record noise, which I would later learn was mostly due to less reflections back to the throat, so never did my other pair, instead began my experiments with using various damping materials around the mouth to damp them at the source, finally winding up with 'trail pad' open cell foam used in sleeping bags at the time and continue to this day to recommend open cell foam horn mouth 'baffles', preferably mounted to wood baffles, plus some in the throat to 'taste', but few do due to being more interested in cosmetics and its raw prosound even though a perforated screen does basically the same thing when spaced at the proper 3/4" and what I used as a grill for my long gone system.
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

  4. #44
    Hostboard Member Lycoming680's Avatar
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    Quote Originally Posted by GM View Post
    Yes, back in my 20s I thoroughly tweaked to a fare-thee-well one pair of 511/802, align boring, machine matching coupling surfaces with wax paper gaskets, cutting out the vane welds to stress relieve the castings, ground down internal welds, removed now useless brace, used Liquid Rubber? to fill the vane gaps and seems like I did some other stuff, but can't remember ATM.

    Anyway, while the women could tell a big difference, which BTW they didn't like as it just made record hiss worse; me and the other guys just noticed less 'horniness' along with increased record noise, which I would later learn was mostly due to less reflections back to the throat, so never did my other pair, instead began my experiments with using various damping materials around the mouth to damp them at the source, finally winding up with 'trail pad' open cell foam used in sleeping bags at the time and continue to this day to recommend open cell foam horn mouth 'baffles', preferably mounted to wood baffles, plus some in the throat to 'taste', but few do due to being more interested in cosmetics and its raw prosound even though a perforated screen does basically the same thing when spaced at the proper 3/4" and what I used as a grill for my long gone system.
    Had the desired effect I'd always suspected, just like a 2 stroke!

    - - - Updated - - -

    Quote Originally Posted by Lycoming680 View Post
    Had the desired effect I'd always suspected, just like a 2 stroke!
    Did you ever encase everything but the driver?

    *Encasing the exterior, that is...

    - - - Updated - - -

    Quote Originally Posted by GM View Post
    Yes, back in my 20s I thoroughly tweaked to a fare-thee-well one pair of 511/802, align boring, machine matching coupling surfaces with wax paper gaskets, cutting out the vane welds to stress relieve the castings, ground down internal welds, removed now useless brace, used Liquid Rubber? to fill the vane gaps and seems like I did some other stuff, but can't remember ATM.

    Anyway, while the women could tell a big difference, which BTW they didn't like as it just made record hiss worse; me and the other guys just noticed less 'horniness' along with increased record noise, which I would later learn was mostly due to less reflections back to the throat, so never did my other pair, instead began my experiments with using various damping materials around the mouth to damp them at the source, finally winding up with 'trail pad' open cell foam used in sleeping bags at the time and continue to this day to recommend open cell foam horn mouth 'baffles', preferably mounted to wood baffles, plus some in the throat to 'taste', but few do due to being more interested in cosmetics and its raw prosound even though a perforated screen does basically the same thing when spaced at the proper 3/4" and what I used as a grill for my long gone system.
    Honestly, what were you "align boring" on speakers? Unless you're riding a Leslie speaker powered bike- I fail to see your point as to "align boring" and speakers.

  5. #45
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    Some locals had done it long before I got mine in '64 plus one even used Portland cement! Anyway, makes an audible difference to the point where I've periodically recommended mass loading them by adding removable weight for folks that don't want to/can't handle the weight.

    That said, adding weight and/or Ductseal or similar to one of the bell hollows goes along ways towards damping the horn as well as the aforementioned speaker width baffle, preferably 24" high: https://www.homedepot.com/p/Gardner-...-110/100212441

    Ideally, the horn box would be part of the bass cab, which it too needs mass loading if not heavily braced to make it rigid enough to 'ring' well above its pass-band: Audio Asylum Thread Printer

    Align boring in the sense that to get a seamless match between the tapered horn throat and the tapered throat of the driver, a primary source of poor HF response easily seen in measurements, I obviously had access to a well equipped machine shop, so the horn's mounting flange holes were opened up a bit to ensure best alignment, then locked in place and an industrial grade adjustable brake alignment hone was used to perfectly blend the two together, adding alignment pins to ensure it stayed aligned.

    For folks wanting to get the rated 22 kHz at a clean/audible [to some] output, this is a mandatory tweak.
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

  6. #46
    Hostboard Member Lycoming680's Avatar
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    Quote Originally Posted by GM View Post
    Some locals had done it long before I got mine in '64 plus one even used Portland cement! Anyway, makes an audible difference to the point where I've periodically recommended mass loading them by adding removable weight for folks that don't want to/can't handle the weight.

    That said, adding weight and/or Ductseal or similar to one of the bell hollows goes along ways towards damping the horn as well as the aforementioned speaker width baffle, preferably 24" high: https://www.homedepot.com/p/Gardner-...-110/100212441

    Ideally, the horn box would be part of the bass cab, which it too needs mass loading if not heavily braced to make it rigid enough to 'ring' well above its pass-band: Audio Asylum Thread Printer

    Align boring in the sense that to get a seamless match between the tapered horn throat and the tapered throat of the driver, a primary source of poor HF response easily seen in measurements, I obviously had access to a well equipped machine shop, so the horn's mounting flange holes were opened up a bit to ensure best alignment, then locked in place and an industrial grade adjustable brake alignment hone was used to perfectly blend the two together, adding alignment pins to ensure it stayed aligned.

    For folks wanting to get the rated 22 kHz at a clean/audible [to some] output, this is a mandatory tweak.
    Very interesting. I was sitting on the couch last night messing around with my disassembled horn & driver components and thinking... Thumping around on the horn and dampening it in different locations.

    I've got a few lathes and a couple of Bridgeport mills along with the rest of a machine shops goods and have no issue TIG welding cast aluminum. Are the horns aluminum or a pot metal of sorts?

    Thanks,
    -Brandon

    - - - Updated - - -

    GM - I ask about the horn material because I've got a few broken corners and wallowed out holes on the flange and wondered if they welded like normal cast aluminum or not...?

    The boring, port matching and honing of the throats is exactly what I was thinking of, locating pins or stud sleeving to ensure alignment - yes, something along those lines. I really appreciate the input.
    Thanks again,

    -Brandon
    Last edited by Lycoming680; April 5th, 2021 at 11:56 AM. Reason: Additional info

  7. #47
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    Always advertised as cast alum., for sure non-magnetic and have had them weld repaired with no comment from the welder.

    511B sawed in half: https://www.hostboard.com/forums/hbm.../2013/01/9.jpg

    edit: Note that I omitted the thick cardboard gasket, so if only wanting to fine tune it you'll need a metal spacer substitute, otherwise it's wasted effort performance wise.
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

  8. #48
    Hostboard Member Lycoming680's Avatar
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    Quote Originally Posted by Old Guy View Post
    The Pascalite is probably the best compromise. The Radian handles more power.

    My preference is the standard aluminum for home use. But hey, the Radian was designed by an ex-Altec employee. Renkus designed the 2 inch Alnico version of the Western digital driver for Altec. Had Altec brass seen fit to mass produce it, the 70's might have turned out differently.


    11


    12

    13

    - - - Updated - - -




    Specs:
    http://greatplainsaudio.com/wp-conte...6/9444B-01.pdf

    I'm in Central Ohio. Near Columbus.
    Old guy,
    Beautiful country up there. I used to visit Wynkoop Airfield in Mt Vernon every summer for many years attending an antique biplane gathering. Love the old barns and houses in that area, just lovely.

    -Brandon

    - - - Updated - - -

    Quote Originally Posted by GM View Post
    Always advertised as cast alum., for sure non-magnetic and have had them weld repaired with no comment from the welder.

    511B sawed in half: https://www.hostboard.com/forums/hbm.../2013/01/9.jpg

    edit: Note that I omitted the thick cardboard gasket, so if only wanting to fine tune it you'll need a metal spacer substitute, otherwise it's wasted effort performance wise.
    GM,
    Wow! Did you saw it in half to get dimensions for a good drawing or just exploration?
    I've got the perfect saw for this if anyone wants their 511B halved.

    I cut these in half some time back - came out nice
    https://youtu.be/eCR1P5w2Oik

    -Brandon
    Last edited by Lycoming680; April 5th, 2021 at 01:00 PM. Reason: Misspelling

  9. #49
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    No, it was done by Brad [bfish] as part of DIYing an optimized 511E, but he 'disappeared' long ago, never [AFAIK] to return to the boards nor respond to my repeated PMs WRT to some personal stuff from when he visited me. There were some other construction photos, but couldn't find them in a quick search.

    edit: Interesting! He was an active poster for many years, but now doesn't come up in a member search! Cool table!
    Last edited by GM; April 5th, 2021 at 01:25 PM.
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

  10. #50
    Hostboard Member Lycoming680's Avatar
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    Re: Altec A7 500-8 and Altec 1224A electronic crossovers

    GM- Hopefully you can run him down... Life, eh?

    While I've got your ear, if you don't mind - I have a question about active crossovers. Are you a resource on that topic?

    Edit: and thank you.

    -Brandon

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