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Old 18th December 2010, 12:17 AM   #11
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by a.wayne View Post
wouldn't bridging be worst due to the impedance ...? cant imagine an F5 powering Apps..

and Current for the Apps ...
No problem with the Apogees, the F5 can work with a very low impedance speakers (1 Ohm) (If you choosen the adequate transformer) and have 10A peak per channel. Less impedance (More drive) = less heat

But one F5 isn't enough.

With two F5's in bridge, I believe that you can get almost 100W or more per channel, more than enough for a Stage or a Caliper.
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Old 18th December 2010, 12:49 AM   #12
AVWERK is offline AVWERK  United States
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7 midbass drivers..#!!.. Now we're seerious aren't we!.All you have to do now is roll off the panels at maybe 5K or maybe stretch it a bit higher and stick a DIY ribbon tweeter of the same height Ala Magnepan or similiar construction and you can rip...
The ML panels are clearly uncontrolled at the top end (serious slow decay waterfall plots at the top mean lost control of that diaphram althought it doesn't sound too bad considering the damage, but test instruments are to dumb to lie and that should be enough since others do better
Time align everything and you can wash up and go home!

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David
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Old 18th December 2010, 08:05 PM   #13
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Thanks, David.....and I wouldn't even try all this "mixing and matching" without a Driverack "bring it all together". Fun little thing, that Driverack.....!
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Old 18th December 2010, 11:55 PM   #14
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by ramallo View Post
No problem with the Apogees, the F5 can work with a very low impedance speakers (1 Ohm) (If you choosen the adequate transformer) and have 10A peak per channel. Less impedance (More drive) = less heat

But one F5 isn't enough.

With two F5's in bridge, I believe that you can get almost 100W or more per channel, more than enough for a Stage or a Caliper.
I would love to hear bridged F5 on calipers even if they only last 5mins..
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Old 19th December 2010, 07:29 AM   #15
Calvin is offline Calvin  Germany
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Hi,

the ML-Panels are quite efficient. Driving them with audio trannies with transformation factors between 1:60 and 1:80, a HV-Bias of 1.5-1.8kV and X-over freqs of >300Hz everything above app. 20W(8Ohms) is sufficient for full stroke.
The typical problem with hybrid panels is not due to too low specced power of the amp, but its ability to drive a complex load stable. Also, the low impedance towards the upper bandwidth limit ususally represents no problem to a decent amp. Again, its the amps ability to drive severe capacitive loads.
This asks for capable power supplies and oversized current and heat paths to deal with the complex currents which may exceed the real currents alot.
The problem increases the better the audio trannys quality is. The original ML trannies were therefore deliberately chosen to be of very poor quality, which made the driving amp´s life a lot easier. Since this resulted in poor bandwidth, considerable amounts of equing were necessary. What saved the day was the inherent high efficiency of the panel, which after equing (that costed ~10-15dB!) was on par with the partnering bass.
Driving such a panel with a first class transformer much less equing is necessary and SPLs of >>90dB@4m are possible, which proves that rather low wattage amps may be fully sufficient.

jauu
Calvin
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Old 21st December 2010, 07:17 PM   #16
AVWERK is offline AVWERK  United States
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Calvin, how much of the decay trails are coming from the transformer vs. the panels?
I get their reasons on compromise but the top end load is still tough. My 50 watt Krell clone is not as happy as my 100 and 150 Krell copys are, but the 50 drives my Quad esls fine all around. You can just feel the juice necessary to make the SL3's sing properly.

So has anyone actually done what you suggested and brought both panels and new trannys together and shown the end results are superior? If so, I'd would be interested in modifying

regards
David
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Old 22nd December 2010, 07:37 AM   #17
Calvin is offline Calvin  Germany
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Hi,

every ESL panel exhibits a multitude of resonances. The most pronounced beeing the free air resonance fs which is due to the mechanical stretching of the diaphragm. As frequencies increase there´s first a range of resonance freedom until the wavelengths reach the dimensions of the segments. Then standing wave effects occur, which could be controlled by introducing damping. The use of hard materials as spacers/dampers makes things worse. ML gave up on soft spacer material in the 90´s and introduced ´clearspars´. A tightly stretched membrane, hold taut in a stiff frame made of hard materials...... no wonder the panels show many standing waves artefacts. The big Q is...does it influence sound? and if so ... does it influence in such quantities that it matters? Or is it rather just a measurement problem? I tend to the latter. Highs usually sound very well, integrated and natural with ESLs. If listeners complain about the highs of a panel its usually because of amplitude matters but not because of the sheer quality of reproduction.
I assume that the majority -if not all- those decay trails are due to the panel construction. Using a different tranny will not change the panel´s behaviour with regard to decay considerably. The main difference in using a different transformer lies in the amplitude- and distortion-behaviour.
Using a superior transformer design, you may gain a more linear amplitude response with lower equalization needs together with higher SPL and lower distortion figures. As a possible downside it may be more diffult for the amp to drive the panel properly, because of the larger phase shift and if You want to tweak an existing system You have to rematch the new higher efficiency of the panel to the bass.

see: Polarising Voltage on older Sequel II
Ping Calvin

jauu
Calvin
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