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Old 14th May 2013, 01:52 PM   #181
Magz is offline Magz  United States
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The OPT cores are Metglas AMCC1000. Attached are the specs for this series from Elna Magnetics:

http://www.elnamagnetics.com/wp-cont.../powerlite.pdf
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Old 14th May 2013, 02:56 PM   #182
Magz is offline Magz  United States
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BTW, OPTs have both 4 ohm and 8 ohm taps. I'll be using the 4 ohm with my hot-rodded Infinity RSIIb speakers.
Attached Images
File Type: jpg 833 OPT coil and core.jpg (166.4 KB, 661 views)
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Old 14th May 2013, 03:31 PM   #183
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Hello Matthias,

Did you plot the frequency response of the Hammond 1642SE transformer? Does it have any ringing problem?

Quote:
Originally Posted by Mister Ed View Post
Hi,

This is an very intresting thread, because I was starting my own "Midlife Crisis 833C Amp" nearly at the same time (On March 18 I was ordering two of this "Monster-Tubes" to playing around with this ).

So I try to discribe this project in my bad english...

The starting Point was the german "silvercore-project". But in my opinion is 15W out of this Monsters like sex with no touching . For this I don't need to build a new amp, I could use some of my older projects...

The frist step were a lot of simulations with LTSpice...and some tests with the B+
The Picture shows the current and at the voltage near 1kV...
833c Test | 833ctest | hifi-forum.de Bildergalerie

And yes, the Spice-model of the 833A is far away from real 833C!

I was calculating the amp for about 50W sine...makes a B+ of about 1kV and a bias current of 200mA.

The reason were, I want to use normal available parts for all... And 1kV is much more handy like 2.3kV ...Over all it was expensive enough to be an "Midlife Crisis Amp" also.
The first two stages are build from one 12AT7 followed by an SRPP (2 x 6CV7/EL34) in triode mode driving the 833 with up to 100V peak to peak
trough an electolytic capacitor of 47uF (briged by 100nF MKP).
I use a lot of Hammond transformers, including the OTP 1642SE.
Kupfer und Eisen...1642SE | eisen1642se, kupfer | hifi-forum.de Bildergalerie

Ok, the 8ohm outputs of this transformers are useless, but because I have 8ohm speakers only I can use the 16ohm output so I have a Raa of 10kohm and this seems to fit perfectly for the 833C...

Here some photos of one the ready monoblocks...while testing...
833C Endtest | 833c, endtest | hifi-forum.de Bildergalerie
SAM 0226 | sam0226 | hifi-forum.de Bildergalerie
833c | 833c | hifi-forum.de Bildergalerie

And some scope photos...
833C 20Hz | 20hz, 833c | hifi-forum.de Bildergalerie
833C 100Hz | 100hz, 833c | hifi-forum.de Bildergalerie
833c 1KHz | 1khz, 833c | hifi-forum.de Bildergalerie
833C 10 kHz | 10, 833c, khz | hifi-forum.de Bildergalerie
SAM 0234 | sam0234 | hifi-forum.de Bildergalerie
power...About 60V peak to peak are 50W sine...
833C 50W Audio | 50w, 833c, audio | hifi-forum.de Bildergalerie
And some photos at live action...
833C Amp | 833c | hifi-forum.de Bildergalerie
833C | 833c | hifi-forum.de Bildergalerie
833C Amp | 833c | hifi-forum.de Bildergalerie

Matthias.
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Old 14th May 2013, 05:21 PM   #184
JLH is offline JLH  United States
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Quote:
Originally Posted by Magz View Post
BTW, OPTs have both 4 ohm and 8 ohm taps. I'll be using the 4 ohm with my hot-rodded Infinity RSIIb speakers.
Beautiful transformers. I know they were not inexpensive , but would think they will be well worth it. Those are probably the nicest OPTs I've seen used in a 833 amp.
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Old 14th May 2013, 05:22 PM   #185
hpeter is offline hpeter  Europe
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Quote:
Originally Posted by Magz View Post
BTW, OPTs have both 4 ohm and 8 ohm taps. I'll be using the 4 ohm with my hot-rodded Infinity RSIIb speakers.
i bet its bit HEAVY
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Old 14th May 2013, 05:24 PM   #186
nhuwar is offline nhuwar  United States
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Quote:
Originally Posted by Magz View Post
BTW, OPTs have both 4 ohm and 8 ohm taps. I'll be using the 4 ohm with my hot-rodded Infinity RSIIb speakers.
Is that ruler metric or imperial? If its inches then those thinks are huge.

Nick
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Old 14th May 2013, 06:37 PM   #187
CV6045 is offline CV6045  United Kingdom
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Please please tell me where you got that Massive Output Transformer from ???


Quote:
Originally Posted by Magz View Post
BTW, OPTs have both 4 ohm and 8 ohm taps. I'll be using the 4 ohm with my hot-rodded Infinity RSIIb speakers.
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Old 14th May 2013, 07:13 PM   #188
Funker is offline Funker  Germany
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Quote:
Originally Posted by Magz View Post
I received an update from Monolith on the progress of my OPTs. The amorphous cores have been received and the bobbins have been wound. Performance is a little better than specification:

L=68H (spec>60 H)
-3dB FR = 7Hz - 66kHz (spec 8Hz - >60kHz)
32 Hz saturation frequency at 1400 Vrms input (spec <35 Hz)

Attached is a picture of the core from one OPT with the bobbin in place. Note the teflon dielectric. An metric ruler and an ECC83 are in the picture for size reference.

They are still waiting on the laser-cut enclosures; once those arrive the OPTs will be assembled and on the way to me!
Hi,
wow! What a huge piece of iron & copper.

Respect!!


73
Wolfgang
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Old 14th May 2013, 10:19 PM   #189
Magz is offline Magz  United States
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Quote:
Originally Posted by nhuwar View Post
Is that ruler metric or imperial? If its inches then those thinks are huge.

Nick
Metric.
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Old 14th May 2013, 10:20 PM   #190
Magz is offline Magz  United States
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Quote:
Originally Posted by CV6045 View Post
Please please tell me where you got that Massive Output Transformer from ???
Monolith Magnetics, located in Belgium. BTW, I don't have them yet, that's an in-construction photo from them.

www.monolithmagnetics.com

.

Last edited by Magz; 14th May 2013 at 10:30 PM. Reason: Added link
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