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Multi-Way Conventional loudspeakers with crossovers

Altec 605a duplex crossover upgrade
Altec 605a duplex crossover upgrade
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Old 26th October 2017, 09:04 PM   #21
bentoronto is offline bentoronto  Canada
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Altec 605a duplex crossover upgrade
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Originally Posted by mrmky View Post
Would going active be that noticeable? I’ve done a bit of reading and it seems to be that the most profound gains are made with three ways. With the woofer on the 605 going from ~30-1500hz I’m wondering how much of a difference it would make.
My conceptual starting point is a mic where my head usually is and REW running frequency sweeps. Can I make the FR nice?

There is "active with amp adjustments" and there is "active with lotsa adjustments". You can make an active cover with no controls what so ever mimic your passive crossover exactly as to FR and you will also have the major advantages of dividing the tone compass power in two (or three) and trashing that piece of crude hardware between the amps and the drivers.

Once you get into adjustments (esp DSP*), you can do many wonderful adjustments to make that mic and your ears very happy. Even just exploring other crossover frequencies and slopes - not to mention choosing the power to each driver without needing an awful L-pad - will be an improvement.

Any modern ambitious speaker has like 18 elements in the crossover of each speaker to smooth the response. Are you planning to make the effort to create such a crossover? No fancy manufacturer selling whole-boxes would go to market with the simple xover from the textbook.

B.
*Wouldn't your woofers (and all BR and pseudo-horn boxes) really like to have a sub-sonic cut below 25 Hz (or 40 Hz for pseudo-horns) to keep 'em from flapping about needlessly?
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Last edited by bentoronto; 26th October 2017 at 09:13 PM.
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Old 26th October 2017, 11:24 PM   #22
kaputt is offline kaputt  Germany
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Originally Posted by WBS View Post
One last question (for now ) what cabinet do you have your 604s mounted in?
Onken cabinets.
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Old 27th October 2017, 04:37 AM   #23
WBS is offline WBS  United States
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Altec 605a duplex crossover upgrade
You're the second person I've corresponded with who chose an Onken enclosure for the 604. How low do your speakers go in those cabs?

The low frequency inductor you have is quite a bit larger than the stock or Markwart xover. What is your xover frequency?
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Old 27th October 2017, 10:03 AM   #24
kaputt is offline kaputt  Germany
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They start dropping at 45Hz. Crossover frequency is at 1500Hz.
I'll post the measurements later.
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Last edited by kaputt; 27th October 2017 at 10:04 AM. Reason: typo
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Old 27th October 2017, 10:38 AM   #25
Pano is online now Pano  United States
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Altec 605a duplex crossover upgrade
There is really no need to go active for Altec coax crossovers, and there are some good reasons not to. The passive crossover isn't the easiest you'll ever build, but there are some great designs out there now to serve as starting points. Get it right and you'll have an amazing speaker.

As for the Behringer active crossovers mentioned, I'd only use the DCX2496 and ONLY with a modified output section. Stock it has a "ground glass in mud" sound to it that your 605s will be happy to reveal.
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Old 27th October 2017, 11:03 AM   #26
dotneck335 is offline dotneck335  United States
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Originally Posted by Pano View Post
There is really no need to go active for Altec coax crossovers, and there are some good reasons not to.
Such as?
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Old 27th October 2017, 11:45 AM   #27
bentoronto is offline bentoronto  Canada
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Altec 605a duplex crossover upgrade
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Originally Posted by Pano View Post
As for the Behringer active crossovers mentioned, I'd only use the DCX2496 and ONLY with a modified output section. Stock it has a "ground glass in mud" sound to it that your 605s will be happy to reveal.
This "mud" effect you post every so often never seems to show up in my measurements (or ever in any measurements in the forum devoted to this unit). Nor it is apparent on my laser-crystal-clear electrostatic speakers or fancy headphones.

Do you have this unit or can you post measurements or are you just reporting what some people who sell mods for this unit say?

Tens of thousands of happy amateur and professional users for 15 yrs (?) can't all be insensitive to the mud.

B.
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Old 27th October 2017, 07:18 PM   #28
Pano is online now Pano  United States
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Altec 605a duplex crossover upgrade
You are many years behind the times, Ben. I've posted the measurements here on this very website. And there is a cottage industry of modifying the DCX, for good reason. The digital section is rather nice, the analog section not so much. The power supply can use a little help, but it's nothing major.

Dig a little a Ben, the weakness of the DCX analog section is a known issue and has many flavors of mods. There is a long thread or 3 about them on this forum, as well as across the web. Try some, you'll like 'em.
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Old 27th October 2017, 07:24 PM   #29
Pano is online now Pano  United States
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Altec 605a duplex crossover upgrade
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Originally Posted by dotneck335 View Post
Such as?
Good reasons NOT to go active with the 604-605.
  1. It's just a two way, why bother?
  2. It's coaxial, no vertical shift to deal with
  3. It's coaxial, the low pass will put the woofer into phase with the tweeter if you do it right
  4. You don't need two amps and another line level device
  5. Easy volume control
  6. You can play it on any amp you want, if enjoy listening to different amplifiers
  7. The sound from a single amp can be more coherent than from 2 or 3 (yeah, really)
  8. Street Cred
  9. Real men build passive crossovers. Active is for wimps
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Old 27th October 2017, 08:06 PM   #30
bentoronto is offline bentoronto  Canada
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Altec 605a duplex crossover upgrade
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Originally Posted by Pano View Post
I've posted the measurements here on this very website.
As the search engine for DIYaudio is challenging for searches of that sort, could you please provide a link or two to your measurements.

There are some posts in the electronics forum showing the usual inaudible digital blips and quantizing artefacts in the microsecond vicinity. But nothing that I can recall demonstrating audible issues. Please correct me if there are.

Thanks.
B.
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