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Driving ESL transformer more efficient on SS-amp
Driving ESL transformer more efficient on SS-amp
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Old 4th November 2017, 09:14 PM   #21
bolserst is offline bolserst  United States
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Quote:
Originally Posted by Joshcpct View Post
..But funny, I have neither one of them. I drove to Zurich 2015 to 2nd hand dealer. I got only 2 normal connectors, and a power in. No external resistor at all.
Ha! That is funny…you have Type C
Does your step-up transformer look the same? Can you post a pic?

Quote:
I conclude lowering the resistor value will do the same as those versions, lift the highs few dB. But also the poor 10 watt resistor has to stand a lot. Gets hot, changes value, bä. I bought a bunch of 44 MOX with 47R each. Would give me 2.1 Ohm and 220 watts, wrapped in a cooler, with 0.45% eff tolerance. Not yet installed though. Nice idea?
That should work just fine. You could also try the RC circuit you asked about in post#2. With the values shown below the response should be very similar, but the impedance at frequencies < 100Hz may be a little easier for the amplifier.

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Originally Posted by Joshcpct View Post
well considering that the official manual from the company sais it can run more than 100dB.... I think ive been usually faaaar away from that. Still the fostex amp with 150 watts easily clipped.
Maybe not as far away as you think. Based on your measurement in post#9, 2.83Vrms @ 1m = about 80dB.
So 35Vrms(ie 150W/8ohm) would be about 102dB.
Reducing the resistance from 6.8ohm to 2.2ohm will mainly flatten out the HF response, but you will also gain a few dB in the midrange and bass.

Hopefully you can get together with Calvin to have the step-up transformers and bias supply checked out to set you mind at ease.
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Old 7th November 2017, 08:19 PM   #22
Joshcpct is offline Joshcpct  Germany
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Thank you!
Guess that second circuit will drop from 4 to 2 Ohms to the higher freq. ??

Made some photos for you. Discovered the voltage poti.

Click the image to open in full size.

Click the image to open in full size.
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Old 11th November 2017, 03:46 AM   #23
bolserst is offline bolserst  United States
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Quote:
Originally Posted by Joshcpct View Post
Guess that second circuit will drop from 4 to 2 Ohms to the higher freq. ??
You are correct; the impedance will drop down close to 2 ohm at 20kHz. Based on impedance measurement you show in post#1, it would likely be about 2.5 ohm. I am still curious about how that impedance measurement was made, and what voltage level was used. You will find that the impedance of the transformer at the lower frequency (20Hz – 200Hz) will increase with signal level by as much as a factor of 5 or more, because the permeability of the core increases with flux density…a very nice thing for amplifiers. This increase continues until signal level is such that the core is saturated and then the impedance will drop quickly with any additional increase in signal level. If the impedance measurement was made with a small voltage level < 1Vrms, the low frequency impedance may be giving a pessimistic view of what the amplifier load would be at normal listening levels. If possible, try measuring the impedance without the 6 ohm resistor in series(or at most a 2 ohm) and at voltage levels of 1Vrms and something a bit higher like 5Vrms. This will tell us a bit more about what the low frequency capability of the transformer is.

Thanks for the photos. Very interesting to see another variation on the Capaciti interface design. Looking at the first photo it struck me how similar the transformer is to the one used by Audio Exklusiv. I recall asking Calvin once if there was a connection between the two companies but he was not aware of one.
HIFISTATEMENT | netmagazine - Audio Exklusiv P 6.1
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Last edited by bolserst; 11th November 2017 at 03:49 AM.
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Old 11th November 2017, 04:38 AM   #24
Joshcpct is offline Joshcpct  Germany
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THANk u!!! That explains a lot. I measured with 0.1 volts.
Heres 0.1 and 1 and 3.5 volt. Cant go higher. Does that look good? Still all with the resistor, just had the file in my pocket, sitting in the airport...
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Old 11th November 2017, 01:15 PM   #25
Joshcpct is offline Joshcpct  Germany
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Ah yes the audio exclusive. Heard in Munich.
Very very similar to Capaciti. Sound wise and optically, even the bars and the silicon fixings.
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Old 11th November 2017, 04:00 PM   #26
bolserst is offline bolserst  United States
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Originally Posted by Joshcpct View Post
...That explains a lot. I measured with 0.1 volts.
Heres 0.1 and 1 and 3.5 volt. Cant go higher. Does that look good?
Yes that looks very good
This confirms the primary inductance of the transformer is > 200mH not 5-7mH as was indicated by the first measurement. You can see now why using a 2.2 ohm resistor will mainly affect the impedance at higher frequency. At low frequencies the impedance is dominated by the transformer primary inductance, so adding or subtracting a few ohms of series resistance makes little difference. Based on this, the second circuit shown in post#21 is not really needed.
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Old 11th November 2017, 08:17 PM   #27
Joshcpct is offline Joshcpct  Germany
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Id only need it for higher DCR to be able to run bridged mode, to have more amp power or.
Though u guys say, it wont need 1000 watts, it would at least give my amp 10dB Headroom and run way easier, considering the phase shift might be also a little difficulty for the amp, just my thinking.
In general lowering impedance would flatten the high frequencies and the strong rolloff, then maybe only increased voltage would bring the last 5dB overall and all as good as possible?

Of course, given the assumption nothing is broken which should be checked before.
Does the impedance tell you so far anything bout the health of the transformer???
Regarding voltage I’ll buy resistors for divider soon and check.
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Old 14th November 2017, 03:53 AM   #28
bolserst is offline bolserst  United States
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Originally Posted by Joshcpct View Post
...Does the impedance tell you so far anything bout the health of the transformer???
To me, the impedance curve looks like a healthy ESL.
The next thing to do is to measure impedance of both speakers at the same voltage level and compare. Also measure frequency response of both speakers with mic in same relative position and same voltage level. If both of these measurements match well between the two speakers, it is highly likely that your ESLs are healthy. It is unusual for two speakers to be damaged in exactly the same way.
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Old 24th November 2017, 02:48 PM   #29
Joshcpct is offline Joshcpct  Germany
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Hi bolsert

I was thinking again... actually wanted to use a sub below, crossing the capacity active anyway. So what about skipping the parallel resistor in second proposal completely?
Id have a serial capacitor and resistor only. Thinking about 100uF and 2 Ohms.
That should give infinite high DCR that makes the bridged amps very happy for their DC offset. And dropping still to 2 Ohms in the highs.

But... seeing how the impedance in lower frequency increases with the voltage so extremely...
Wouldn’t that react with the caps, changing the response depending on the voltage level.
Respectively create a lot of IM Distortion ???

Cheers
Josh
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Old 24th November 2017, 06:59 PM   #30
bolserst is offline bolserst  United States
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If you are crossing active, why are you needing a 100uF in series with the 2 ohm?
The output required from the amps at low frequencies and DC should be minimal if active crossover is used.

You are correct that the varying impedance would react with the capacitor resulting in frequency response variations with volume level and other distortion types. The usual way to handle this is with a shunt resistor upstream of the capacitor to swamp the variations. Here is a link to the Acoustat Spectra 11 high pass filter network.
Martin Logan CLS Power Supply
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