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Old 22nd July 2012, 09:17 AM   #11
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Hi Tiefbassuebertr

I make my own transformers en a wel known manufactor helped me to get the best out of it.
If you measure the transformers there is nothing wrong with it large bandwidht and low los.
But still the sound difference is huge like I told before.
I only use it for the mid high ribbon not for the bass panel.
Do wat you like and tell us later what you think.

Rob
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Old 22nd July 2012, 10:24 AM   #12
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Quote:
Originally Posted by Rob Dingen View Post
Hi Tiefbassuebertr

I make my own transformers en a wel known manufactor helped me to get the best out of it.
If you measure the transformers there is nothing wrong with it large bandwidht and low los.
But still the sound difference is huge like I told before.
I only use it for the mid high ribbon not for the bass panel.
Do wat you like and tell us later what you think.

Rob
In which respect you perceive the mentioned sound difference by your listening test and which amp model you have in use therefore?

In general it is for me completly clear, that each additional device in the signal pad have an influence regarded the sound. A good known example therefore is a scaly or burnt-off relay contact for DC protect in series to the loudspeaker. Even without relay and with a capacitor in the signal pad you will get an influence to the sonic character (this is my favorite approach to avoid mechanical contacts, despite the present and mostly unwanted high pass character). Basically a directly dc coupled connection between amp out and speaker input saves lowest signal loss (at best with only very short cable connection, directly solder, i. e. without terminal and plug) - this is clear.

One user of Apogee Scintilla uses four power stereo amps in "Mono-Bridged" mode and Bi-Amp mode since a short time.
The model is "SA-Reference" from Plinius Audio - go to
http://www.pliniusaudio.nzld.com/doc...efbrochure.pdf
and
http://www.pliniusaudio.nzld.com/doc...arefmanual.pdf
Output power at 8 ohm load impedance is 1000 watts (and thus theoretically 16000 watts at 0R5 load impedance but the 10 amp fuses prevents this in real live, of course).
The output stages (8 pairs power BjT devices in parallel mode/each amp) runs with a voltage of +/- 86 volts switchable for class A (2200mA, 275mA/each pair) and class AB (320mA, 40mA/each pair).
Sound quality is exceptionell good, the user says, the best amplifiers ever heard.
But I told him, that the reliability is very low and the likelihood that occur very expensive damage is very high, particularly in such cases, when high sound pressure levels are trying to achieve.

This is the reason to start this thread. Concerning the max SPL of this Apogee planar radiators unfortunately I have no comparison to good known loudspeakers with cone transducers (thus the various mentioned SPL values offer no evidence for me and therefore are no helpful). Also there are no information about the maximal input power rating of this model (for the most cone speakers usually published).

There are only two options for good reliability in the case of further use of this amplifier model:
1) the use of four impedance matching transformers
2) power amp modify in such way, that the supply voltage is halved or quartered (+/-43 volts or +/-21,5 volts) and the idle current accordingly doubled or quadrupled. Basically easy (only reducing the resistors for reference current through the CCS), but in real life much more efforts than matching transformers. From this view I would prefer the first possibility.

If the disadvantage by sonic quality (by use of the matching transformer) is only present at low level aera below 150 Hz, it does not matter, because for this frequency range an additional subwoofer will come later (include an additional high pass filter).

Last edited by tiefbassuebertr; 22nd July 2012 at 10:48 AM.
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Old 22nd July 2012, 06:54 PM   #13
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I use an AX200 with the transformers and the amp described earlyer for direct drive.

Rob
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Old 24th July 2012, 12:14 PM   #14
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Sorry, a pic of my transformers will not help you, since they are moulded/hermetically sealed in a plastic box, size apx 10cm x10cm x 10cm, rated with 250 Watt, for the tweeter they transform 3 into 1 ohm, for the Mid 3 into 0,2ohms ( good for 35 amperes), you just can see the wires.
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Old 24th July 2012, 12:20 PM   #15
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Quote:
Originally Posted by Groove-T View Post
Sorry, a pic of my transformers will not help you, since they are moulded/hermetically sealed in a plastic box, size apx 10cm x10cm x 10cm, rated with 250 Watt, for the tweeter they transform 3 into 1 ohm, for the Mid 3 into 0,2ohms ( good for 35 amperes), you just can see the wires.
It seems to be very small for such a current. Are there a very special core in use?
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Old 24th July 2012, 04:31 PM   #16
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They have amourphous cores, i am not sure if C-Core but believe so, and are made for a limited frequency range in the lower area, below that the impedance will drop down.
The wire are HF-Litzwire.
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Old 25th July 2012, 02:49 PM   #17
el`Ol is offline el`Ol  Germany
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The ultimate solution would be the GTE Trinity amp, which can do 1 Ohm. But more a theoretical option, when looking at the price.
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Old 25th July 2012, 04:07 PM   #18
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Quote:
Originally Posted by el`Ol View Post
The ultimate solution would be the GTE Trinity amp, which can do 1 Ohm. But more a theoretical option, when looking at the price.
mean you the amplifier from follow URLs ?
TRINITY Electronic Design GmbH
GTE - Trinity Mono-Endstufen
http://www.trinity-ed.de/pdf/MKII100.pdf
http://img.photobucket.com/albums/v5...9/hiend040.jpg
http://marcs-hifi-blog.audiodoo.de/w...-trinity-3.jpg
http://www.trinityamps.com/ForumGall...uide_3.921.pdf
Unfortunately there are no price lists mentioned and in the tests there are also no price informtions.
Nevertheless - a good advice at all. A large amount of output transistors in parallel mode is also from my view a very good solution.
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Old 26th July 2012, 12:01 PM   #19
el`Ol is offline el`Ol  Germany
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HigherFi-Ultimate - The Worlds Best and Most Expensive Audio Amp and Amplifiers
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Old 26th July 2012, 03:01 PM   #20
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by LineSource View Post
I owned Apogee Scintillas for several years. I bi-amped each speaker with a Krell KMA100 monoblock to direct drive the M-T ribbons using the 1-ohm ribbon load connection, and one side of a Krell KSA250 to direct drive the 1 ohm bass panel. The sound was wonderful. The Scintillas were my first dipole speaker and convinced me that dipole radiation helped compensate for some of the limitations of the stereo recording process and room effects.

The Scintilla's M-T ribbon design is worth study. There is just one magnet cavity with a corrugated Al midrange ribbon in the center of the gap, and narrow T-ribbons along the left and right sides, both in-front and behind the midrange foil. This approximates cardiod radiation. (See below diagram)

T.....T
MMMM
T.....T


The 110db SPL in the owner's manual is a near field measurement.

In the near field a linesource response slopes downward at a 3 dB per doubling of distance (10 dB per decade) rate, while the far field the response declines at a 6 dB per doubling of distance (20 dB per decade) rate.

I sold the Apogee Scintillas and purchased the original Full Range Apogee speakers, which we still have in our living room.
Line , could you explain the midrange setup a bit more , what's the advantage of the t-ribbons , this would appear to me to be more harmful than good ...advantages ...?

Agree with those who feel transformers to be the worst , I have found resistor to be the best with .8 being the optimum for sonics , lower for drive....

Quote:
Originally Posted by Groove-T View Post
The low impedance version is declared to be 1 ohm, lowest value with x-over is 0,88 Ohm in bass, without x-over 0,72 ohms, measured with Ohmmeter, in use its a little bit higher.

The 4 ohm version is apx 3,8Ohm.

You will need a huge transformer for doing 1200 watts or more into 1 Ohm on the secondary side. Amorphous core is mandatory....
Not really they will not require more than 500 watts at 1 ohm , if you measure the current and voltage being used u will see this ...

Quote:
Originally Posted by Rob Dingen View Post
Hi Tiefbassuebertr


I build a lot of ribbons and use resitors transformers and amps to direct drive the ribbons.
As for best to worst sounding order 1 amp 2 resistor 3 transformer.
I find the difference to direct drive the ribbon with an amplifier and a transformeer huge.
Build an amplifier like the F5 turbo but with 2sk170/2sj74 IRF610/IRF9610 and the Sanken 2SOC3264/2SA1295 each 4 pieces and they deliver about 50A to 0,1 Ohm and sound good.

Rob
Output impedance with 4 pr might have issues with direct drive ....
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