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Old 24th June 2002, 10:02 PM   #11
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As the circuit is conceptually similar to the Threshold M1,
and I have not seen another instance of common-base
MC amplification, I am curious. What do you have for the
date on this?
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Old 24th June 2002, 11:06 PM   #12
lohk is offline lohk  Europe
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The orginal articles appered in L'Audiophile #16 June 1980 and #17 October 1980.
Btw. the possibly first One-Transistor-Amp called "Nemesis" (10W ClassA MOSFET with an output transformer) appeared in #34 and #35, winter and spring 1985.

Klaus
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Old 25th June 2002, 04:47 AM   #13
jam is offline jam  United States
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Default Common Base Head Amplifiers

Nelson,

Marshall Leach designed a common base headamp and published in Audio Magazine years ago.

http://users.ece.gatech.edu/~mleach/headamp/

PS Audio also used a common base headamp in their preamp, this also going back a few years. (In their case they converted the first transistor of the differential in the phono stage to a common base amp).

Jam
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Old 25th June 2002, 04:52 AM   #14
jam is offline jam  United States
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Oops! Wrong image.
Here is the correct one.

Jam
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Old 25th June 2002, 12:56 PM   #15
syl is offline syl  Sweden
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The original question was alternate transistors for the Hiraga MC.

I did quite a lot of transtor swapping in the early 90s. It turned out that the C1775, A872, C2389 and B737 all gave too much "bite" to the music. Initially a sense of dynamics is perceived, but after some hours of listening it was not deemed neutral. These transistors put too much focus on the high frequency range.

The BCs I tried sounded just plain bad, distorting badly compared to the japanese transistors.

I stumbled across the A1038 from Rohm. That made a big difference. A beautiful midrange without the excess high frequency fuzz of the others. Far better than the Hiraga original. Highly recommended.

Eqvivalents are A1579(smd) and A1514(smd).

Regards

Syl
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Old 25th June 2002, 03:04 PM   #16
tvi is offline tvi  Australia
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<a href="http://www.hilberink.nl/amps/amps.htm">www.hilberink.nl/amps/amps.htm</a> show the schematic I posted earlier
and and has this:

<font color=#800040><i>Below a evaluation of the original design of Hiraga of 1988. This design has all the advantages of a modern well riped design but lacks some limitations of the basic Hiraga design. As far as I know this design was never published in this form, a very similar design was published in Elektor. </i></font>
<a href="http://www.hilberink.nl/amps/amps7.htm"><img src="http://www.hilberink.nl/amps/hiraga4.jpg" ></a>
<font size="-2">pic a link</font>


James
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Old 15th February 2013, 08:02 AM   #17
noyan is offline noyan  Turkey
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Default My Hiraga MC preamplifier

Hi,
Firstly i built a very successful MM preamp. I modified the Audionote M7-M10 schematics. Now, it use 4*6072+2*6N30P-DR. Sounding incredible natural, sweet and detailed. Then i decided to built a Hiraga MC pre with 8 pins IC sockets on main board. I prepared (soldered) 2SA1038 and BC560 transistor pairs on seperate 8 pins sockets. Now, i can easily insert any of them in the sockets located on the board and compare the sound. Before this off course i am making adjustments with trimpots to ensure ''0'' Volt at the enter of the preamp. I can say that; this preamp and DENON 103R is sounding excellent with both transistors. But, my favorite is 2SA1038 -Thanks syl- I used 500.000uf capaciy for each channel. Electrolytic caps are 6800uf Elna Cerafine, cables are teflon coated silver. I will install a power switch and a socket for charging the batteries.
Noyan

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Last edited by noyan; 15th February 2013 at 08:25 AM.
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