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Old 30th December 2012, 07:24 PM   #1611
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Location: Recife - Brasil Northeast
Default I am glad too you like it so much

for sure i am.... for sure.

regards,

Carlos
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Old 30th December 2012, 07:50 PM   #1612
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Default MJE15XXX transistors are popular..and they are the ones i have in my home

All them a kind gift from dear friend Evette (the Canadien).

I do think they are not that good...they can tollerate high voltages and because of that i have used them..also because people "believe" they are special...i do not think so...i have used then because i had to use them..no choice...they were the ones i have..they were the ones people approve...there are political solutions too..not only technicall solutions..if i want people to build my amplifiers i have to detect their beliefs and target their beliefs of special capacitor and provide room for them.

Try others folks....MJE340/350 is no good to...but you can try... i have tried..they oscilate very easily...maybe base to emitter capacitance or high gain..i do not know.

In my other amplifier i have suggested builders to remove 2N5551 and 2N5401, to use BC546 and BC556 instead and to remove MJE15XXX and replace them by BD139/140 and asked them to keep voltage at 42 volts maximum.

My home edition, as you know..is a smaller board..i have cutted it's sides and have used these transistors for comparison and for sure they sounded much better...why?... i am not sure, but i do think they are just perfect to this range of voltage and this range of current i am using.

BD139/140 seems to me to be very good units..they are here with us since sixties..and even now a days brazilians use these transistors in high end equipment because the resultant quality.

I am sorry...these transistors cannot operate with your high voltage.... they will burn because over voltage..despite i have used them into 55 volts for a couple of years without problems...that amplifier using BD139/140 is already operating in a friend's home....and he use to push the amplifier hard..he is 20 years old and loves to play loud music.

I have some MPS transistors , also some 2SC1815 and i gonna test them to replace BC546 and BC556... the problem is their voltage limit...so..only to low voltage power amplifiers.

regards,

Carlos
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File Type: jpg 003.jpg (409.2 KB, 236 views)

Last edited by destroyer X; 30th December 2012 at 08:07 PM.
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Old 30th December 2012, 08:56 PM   #1613
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Too bad there aren't any high-voltage BD139/140. Someone has any suggestion for replacing the MJE15030/MJE15031 at the VAS and driver position? I would like to give it a try. Of course a TO-220 package with BCE pinout is an absolute requirement.

Martin.
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Old 30th December 2012, 09:44 PM   #1614
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by BMW850 View Post
I have soldered the 100R resistors and the bias set to 54mv.
Wow what a heat after an hour, that should be me thinking about my Musical Fidelity P270 years ago.
I have the bias back to 24mv and what a great sound now.
You have the volume knob no longer in the hand, you always want to turn the music harder.
Thank you Steve and Martin for the measuring info.

Regards,
Rudy
How does yours differ from stock , 100ohm gate stoppers and 24 mv bias ...?
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Old 30th December 2012, 11:58 PM   #1615
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Default 2SC4793 and 2SA1837 may fit

I have used them...sadly they finished and i could not find them anymore.

They are high speed...can operate at 230 volts and the internal capacitance is low.

It is made of plastic material (have plasticity, you can make it in the shape you want) that is an electrical insulator....due to that, the power dissipation is not that big..but current is fine and you will not need insulators for it.

Sound is good...i have used and they are fine.

regards,

Carlos
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Last edited by destroyer X; 31st December 2012 at 12:01 AM.
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Old 31st December 2012, 12:31 AM   #1616
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2SA968 & 2sc2238 seems good candidates as well... They gives good results in simulator

http://www.dzsc.com/uploadfile/compa...1112757699.pdf

*SRC=2SC2238B;QSC2238B;BJTs NPN;Power;
*SYM=POWBJTN
.SUBCKT QSC2238B 1 2 3
* TERMINALS: C B E
* 200 Volt 1.5 Amp SiNPN Power Transistor 12-03-1991
Q1 1 2 3 QPWR .67
Q2 1 4 3 QPWR .33
RBS 2 4 9.5
.MODEL QPWR NPN (IS=4.26P NF=1 BF=240 VAF=254 IKF=.9 ISE=467P NE=2.1
+ BR=4 NR=1 VAR=20 IKR=1.2 RE=46.15M RB=40 RBM=4 IRB=55.556U RC=966M
+ CJE=50.7P VJE=.6 MJE=.3 CJC=32.9P VJC=.22 MJC=.2 TF=1.6N TR=61.2N
+ XTB=1.5 PTF=120 XTF=1 ITF=9.6)
.ENDS

*SRC=2SA968B;QSA968B;BJTs PNP;Power;
*SYM=POWBJTP
.SUBCKT QSA968B 1 2 3
* TERMINALS: C B E
* 200 Volt 1.5 Amp SiPNP Power Transistor 12-03-1991
Q1 1 2 3 QPWR .67
Q2 1 4 3 QPWR .33
RBS 2 4 9.5
.MODEL QPWR PNP (IS=4.31P NF=1 BF=162 VAF=254 IKF=.8 ISE=469P NE=2
+ BR=4 NR=1 VAR=20 IKR=1.2 RE=46.15M RB=40 RBM=4 IRB=55.556U RC=966M
+ CJE=111P VJE=.6 MJE=.3 CJC=72.5P VJC=.22 MJC=.2 TF=1.6N TR=61.2N)
+ XTB=1.5 PTF=120 XTF=1 ITF=9.6)
.ENDS
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Old 31st December 2012, 12:43 AM   #1617
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2SA1930 & 2SC5171 could be good too... I don't find any SPICE model though...
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Old 31st December 2012, 02:14 AM   #1618
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I know I should stay away from that... but how could we determine if these are fake??

http://www.ebay.ca/itm/1pair-OR-2PCS...ht_1943wt_1163

Mart.

Last edited by canonnica; 31st December 2012 at 02:27 AM.
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Old 31st December 2012, 02:43 AM   #1619
evette is offline evette  Canada
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Mr. Carlos you can try 2sk216 2sj75 these work great. Evette
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Old 31st December 2012, 02:45 AM   #1620
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Evette, these are Mosfets (?!?)

2SB861 & 2SD1138 maybe?
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