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Old 18th March 2013, 11:18 AM   #1
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Default Apogee Full Range Crossovers

Hi

I'm considering purchasing a pair of the orginal Apogee Full Range's. In my mind they're like the ultimate speaker so, really should get em However the passive crossover boxes with transformers are missing.

There seem to be plenty knowledgable apogee owners on this forum so I'm hoping someone can verify what I've found so far:

- The bass ribbons originally had a step-up transformer but are just 1.7 ohms so I could drive them direct?
- The midrange is below 0.1 ohms so obviously needs a step-up transformer (assuming I dont want to burn 95% of amp power in series resistors)
- Crossovers were just 1st order, for high pass on midrange and tweeters there were series capacitors in the passive crossover boxes but what about Low pass? I dont see any series coils employed on old pictures, I think I see some caps in the original active crossover boxes though, parallel caps then before the amps (not quite sure how that would work)?

My current line of thought is:
-Get step up transformers for the midrange ribbons
-Get 6 channels of amplification (thinking hypex class-D modules for now, already have 2 of those)
-Series caps for high pass for mid/high amps, low pass series coils or? Parallel caps + resistors?

The dutch ribbon replacement installer has some step up transformers (3 ohm primary) but says those make the mids play 15 dB's louder then the rest, sounds a bit odd, not sure how that works?? He also has transformers for the tweeters but I dont see why I would want to use them in that position, should be ~2 ohms so no problem for direct drive?
Hope someone can shed some light on this.


Some pictures of the corssovers I found on the allmighty internet:

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Old 18th March 2013, 04:24 PM   #2
tyu is offline tyu  United States
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http://www.apogeespeakers.com/.............i gess you saw this...crossover is in the manul
you can down lode.......bewair of the Apogee panel Buzz!...theses are the oldest... i think?... I have Had the Stages an the Duetta Sig....
Good luck
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Old 18th March 2013, 04:41 PM   #3
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Quote:
Originally Posted by tyu View Post
http://www.apogeespeakers.com/.............i gess you saw this...crossover is in the manul
you can down lode.......bewair of the Apogee panel Buzz!...theses are the oldest... i think?... I have Had the Stages an the Duetta Sig....
Good luck
Hmm thanks, this version has a last page with schematics of the active crossover So that has series caps for mf/hf highpass and parallel caps for lf lowpass. 1 step further..

So only things I need to figure out if there's a midrange lowpass in the passive box and what kind of transformer I need for the midrange.

Oh and I've read both 3.5K as 9K for the hf highpass?
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Old 18th March 2013, 05:38 PM   #4
tyu is offline tyu  United States
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Apogee Acoustics • Index page

Go here ... If you havet.... i think your calling a coil, a tranfourmer...anywho...these guys well help you with this.....good luck
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Old 19th March 2013, 10:33 AM   #5
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Quote:
Originally Posted by tyu View Post
Apogee Acoustics • Index page

Go here ... If you havet.... i think your calling a coil, a tranfourmer...anywho...these guys well help you with this.....good luck
Those are actually transformers, however I think 1 should be enough, the midrange has a below 0.1 ohm impedance, supposedly LF and HF are just below 2 ohms
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Old 20th March 2013, 06:24 PM   #6
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Hi You might want to contact Paul Spetz, he make's the anti cables, I think what your looking for would be an autoformer to raise your impedance, he make's them for soundlabs and maggies as well. Al
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Old 20th March 2013, 07:04 PM   #7
a.wayne is offline a.wayne  United States
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You can use a wire wound series resistor , IMO better than using an autoformer, of course you will have to match driver gain after adding , shoot for .5 ohm , best to parallel resistors for increased power handling ....

Regards,
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Old 20th March 2013, 10:53 PM   #8
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Hi edbk,

We have a pair of Apogee Full Range Speakers in our living room. They came with the 4-ohm network box.


Over the Full Range production lifetime Apogee made a few minor changes to the construction of the Bass Panel, midrange ribbon, and tweeter ribbon which affected their resistance, efficiency, and resonance.
MY SPEAKERS:
Bass Panel = 1.86 ohms
Midrange Ribbon = 0.14 ohms
Tweeter Ribbon = 0.88 ohms

Original passive front-end crossover box is 6db at 320Hz between the bass panel and mid-tweet ribbons.
=================

You will want to measure your speakers before you build a custom crossover, or decide to clone a production circuit. Bi-Amping (bass + mid-tweet) using an active circuit crossover is a good starting option. The low efficiency 1.9 ohm bass panel can easily consume 300-1000 watts.

The midrange ribbon step-up transformer that you build or purchase will be the cornerstone specification for the rest of the passive or active crossover design. The turns ratio will set the impedance step-up. The inductance of the production midrange step-up transformer input is actually part of the low-pass crossover slope. The inductance of any transformer you purchase will need to be measured and factored into the total crossover design. This step-up transformer will set the midrange ribbon efficiency and effective amplifier input inpedance load. The ribbon impedance is almost pure resistance, and this simplifies the design of a passive crossover between the MID-TWEET ribbons.

Apogee also offered a 1-ohm network box for JUST the midrange+tweeter ribbons. This box included a 0.14-to-1 ohm step-up transformer for the midrange ribbon, plus R+C crossover network for the tweeter ribbon. There is potential for sonic improvements with this 1-ohm network box vs. the 4-ohm network box, but only if the amplifier can deliver HUGE amperes into 1-ohm like the BIG Krells.

Naturally, constructing a custom Bipolar amplifier that can drive 0.2 or 0.5 ohm resistive ribbon loads directly is another option, and not very difficult. From my listening experiments, adding a small series resistance to increase the 0.14 ohm midrange ribbon up to 0.2-0.5 ohms improved the sonics.
=================

My Speakers...
Each 3-way Full Range is bi-amped with one Krell KSA250 located just behind the speaker. A Krell KRX-1 electronic crossover with 18db/octave at 200Hz is used for for bass-MT outputs to each amp. One KSA250 channel direct drives the 2 ohm bass panel, and the second channel drives Apogee's M-T interface box which is ~4 ohms. This interface box contains a large toroidal step up transformer for the 0.14 ohm M-ribbon, plus resistors to step up the tweeter ribbon resistance to ~4 ohms, plus a 6db/octave passive L + C Xover at 10Khz. This is a very robust setup for the Full Range.

I have built DIY amps which direct drive the 0.1 ohm midrange ribbon and 2 ohm tweeter ribbons. Direct drive always produces greater dynamics and detail, but it is also easier to damage a ribbon by human error.
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Old 21st March 2013, 11:13 AM   #9
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Thanks! Just what I was looking for! I'll borrow an higher grade measuring device then my own to get some accurate readings. However when I replace the ribbons someday (will probably happen) it may change again ofcourse..

I'm now thinking of going 3 way active using hypex modules. The DLCP digital 6 channel preamp/crossover, 4 x nc400 (570 watt/2ohms) for mid/high and 2 x ucd2000 (2000 watt/2ohms), can aquire those with some equipment trades so I can atleast get everything running.

So I wont need to reconstruct the passive crossover anymore but will still need the step-up transformer.

However it seems somebody in my country has 4 of once custom made sowther transformers for the full range for both mid/high. What are the odds

Now they're rated for 300 watts with 50% (so 150 watts) continuous load, it may do, I dont know, if loaded with over 150 watts continously theyll overheat.

Almost there, cant wait to have these babies playing, they were my childhood dream system.
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Old 21st March 2013, 12:41 PM   #10
tyu is offline tyu  United States
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Good Luck....let us know how thay sound....
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