I've just build this steroe amplifier

pilovis · 09:51 PM

http://i44.servimg.com/u/f44/17/14/70/27/stereo10.jpg

http://i44.servimg.com/u/f44/17/14/70/27/stereo11.jpg

http://i44.servimg.com/u/f44/17/14/70/27/insult11.gif

Components:

R1 = 220 kohm 1/2W
R2 = 1,2 kohm 1/2W
R3 = 100 kohm 1/2W
R4 = 470 kohm 1/2W
R5 = 47 kohm 1/2W
R6 = 330 ohm 1/2W
R7 = 330 ohm 1W
R8 = 22 kohm 1/2W
R9 = 220 ohm 2W
C1 = 0.1 mF poly 400V
C2 = 47 mF el. 350V
C3 = 100 mF el. 25V
C4 = 100 mF e. 350V
C5 = 100 mF el. 350V
C6 = 47 mF el. 350V

2 PCL86
4 diodes 1N4007
T1 = T2 = 220/15 30VA
TU = 5 kohm / 8 ohm
F1 = fuse 1A

Cassiel · 11:32 PM

Oh man I don't want to see an amp without chassis again. Today I've got a taste of 400 volts potential. It was really BAD so bad that it still hurts (psychologically). I have promised to myself this is the last time.

Sorry but that amp looks too dangerous. Put it in a dress, conceal the idea from others because it looks too hot as it is.

VMUNIX · 7th January 2012, 11:52 AM

How much current do you get from that transformer setup? wouldn't be cheaper and easier to use a single 230v - 230v transformer?
Do you have a PCL85 at hand to try? I have a few of those but are from TV sets and not intended for audio, though I've read it is possible to use as a 6BM5/ECL82 replacement with different heater and slightly different triode specs

pilovis · 7th January 2012, 12:22 PM

the first transformer reduces the supply voltage from 220 to 15 Vac for getting the 15 Vac necessary for PCL86 filaments.
The second transformer brings the same 15 Vac from the first transformer and increase the voltage to 220 Vac.

pilovis · 7th January 2012, 12:24 PM

Quote:

Originally Posted by Cassiel

Oh man I don't want to see an amp without chassis again. Today I've got a taste of 400 volts potential. It was really BAD so bad that it still hurts (psychologically). I have promised to myself this is the last time.

Sorry but that amp looks too dangerous. Put it in a dress, conceal the idea from others because it looks too hot as it is.

You're absolutely right, but this is just a lab prototype.

costis_n · 7th January 2012, 12:39 PM

I have 2 observations.
Your fuse looks too big. The fuse should be able to JUST not blow to give protection. Try 250ma or less.
The switch should be on the same side of the transformer with the fuse.
PCL86's are cool!

pilovis · 01:15 PM

Quote:

Originally Posted by Cassiel

Oh man I don't want to see an amp without chassis again. Today I've got a taste of 400 volts potential. It was really BAD so bad that it still hurts (psychologically). I have promised to myself this is the last time.

Sorry but that amp looks too dangerous. Put it in a dress, conceal the idea from others because it looks too hot as it is.

Try my 24Vcc tube amp!

Note for audiophiles: for TU use 750 ohm / 8 ohm audio transformer
Warning: ECC82 filament (pins 4-5)= 12V

Cassiel · 7th January 2012, 04:08 PM

Pilovis- that PCL86 amp was my first tube amp. Oh the memories ....too much water has passed under the bridge. I still think a good NOS ECL86/PCL86 sounds better than modern EL84's. The pentode connection lasted like two days. I wired it in triode, disconnected the feedback loop and never looked back.

M Gregg · 7th January 2012, 06:42 PM

Quote:

Originally Posted by Cassiel

Oh man I don't want to see an amp without chassis again. Today I've got a taste of 400 volts potential. It was really BAD so bad that it still hurts (psychologically). I have promised to myself this is the last time.

Sorry but that amp looks too dangerous. Put it in a dress, conceal the idea from others because it looks too hot as it is.

B+ voltage is bad enough....The main thing is you are still with us...high capacitance with high B+ is realy BAD news....the other thing is you managed to let go....the effect that makes you not be able to let go (DC) can be fatal.

Were you in contact with the chassis or just through you to Gnd... your shoes reducing the current?

Regards
M. Gregg

Richard Ellis · 7th January 2012, 07:07 PM

Nice job!!!! Yes it is kinda dangerous as is, but one can tweak & finish er up. Please put some bleeder resistors across C5 & C6, 220K would work fine.BUT FIRST HOOK UP YOUR METER & LEAVE IT HOOKED UP TO BLEED IT OFF BEFORE YOU SOLDER IN ANYTHING. Organize your groundings, case her up in something pretty.....so you can put it on display prominently, without fear of zapping someone poking around.

__________________________________________________ _____Rick.......

6th January 2012, 11:28 PM	#2
Cassiel diyAudio Member Join Date: Sep 2004 Location: Madrid	Oh man I don't want to see an amp without chassis again. Today I've got a taste of 400 volts potential. It was really BAD so bad that it still hurts (psychologically). I have promised to myself this is the last time. Sorry but that amp looks too dangerous. Put it in a dress, conceal the idea from others because it looks too hot as it is. __________________ Hello Last edited by Cassiel; 6th January 2012 at 11:32 PM.

7th January 2012, 04:08 PM	#8
Cassiel diyAudio Member Join Date: Sep 2004 Location: Madrid	Pilovis- that PCL86 amp was my first tube amp. Oh the memories ....too much water has passed under the bridge. I still think a good NOS ECL86/PCL86 sounds better than modern EL84's. The pentode connection lasted like two days. I wired it in triode, disconnected the feedback loop and never looked back. __________________ Hello

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7th January 2012, 11:52 AM	#3
VMUNIX diyAudio Member Join Date: Sep 2009	How much current do you get from that transformer setup? wouldn't be cheaper and easier to use a single 230v - 230v transformer? Do you have a PCL85 at hand to try? I have a few of those but are from TV sets and not intended for audio, though I've read it is possible to use as a 6BM5/ECL82 replacement with different heater and slightly different triode specs

7th January 2012, 12:22 PM	#4
pilovis diyAudio Member Join Date: Jan 2012 Location: Nizza Monferrato - Italy	the first transformer reduces the supply voltage from 220 to 15 Vac for getting the 15 Vac necessary for PCL86 filaments. The second transformer brings the same 15 Vac from the first transformer and increase the voltage to 220 Vac.

7th January 2012, 12:39 PM	#6
costis_n diyAudio Member Join Date: Aug 2008	I have 2 observations. Your fuse looks too big. The fuse should be able to JUST not blow to give protection. Try 250ma or less. The switch should be on the same side of the transformer with the fuse. PCL86's are cool!

7th January 2012, 07:07 PM	#10
Richard Ellis diyAudio Member Join Date: Sep 2006 Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.	Nice job!!!! Yes it is kinda dangerous as is, but one can tweak & finish er up. Please put some bleeder resistors across C5 & C6, 220K would work fine.BUT FIRST HOOK UP YOUR METER & LEAVE IT HOOKED UP TO BLEED IT OFF BEFORE YOU SOLDER IN ANYTHING. Organize your groundings, case her up in something pretty.....so you can put it on display prominently, without fear of zapping someone poking around. __________________________________________________ _____Rick.......