PLC84 amp

lquintas · 8th October 2009, 05:48 PM

Successfully finished my JE LABS 2A3DX amp, it was so fun that I needed to go on with another project. I decided to build an amp for my pc. Just then I received a surprising present from a colleague whose father was a TV repairer: a bunch of TV tubes: PCC189, PCF80, PCF86, PCL84, PY88 and others. After a search in Internet I decided to build an amp with two PCL84 using the schematic for ECL84 tubes:

http://www.diyaudio.com/forums/attac...4&d=1152603590

It is a double tube with a triode and a pentode inside, so tjhe whole amp can be made with a single tube.
The only difference between the PCL84 and the ECL84 is the filament voltage (15 V instead of 6,3)
I used Hammond 125ESE OPTs and common components (except the ALPS volume pot, the SOLEN coupling capacitors and MILLS cathode resistors)
I have finished the amp and I am surprised how good sounding it is (I’m not an expert and I hear mainly classic music). No hum, good bass, detailed mids and highs. I am very pleased with it. Here is a pic.

derwhalfisch · 9th October 2009, 01:59 AM

Lovely looking amp there :P

And that they sound nice is great news for me, I have around 40 ECL84's (or 6DX8's). Don't know how many go, or how well, but out of 40 some have got to be okay, right? :P

lquintas · 9th October 2009, 03:42 PM

Thanks derwhalfisch. I only have 8 PCL84, Miniwatt, Tungsram and Mullard. I used 2 Mullard and both work perfectly. Not tried with the rest.

MellowTone · 20th October 2009, 02:00 PM

Quote:

Originally Posted by derwhalfisch

Lovely looking amp there :P

And that they sound nice is great news for me, I have around 40 ECL84's (or 6DX8's). Don't know how many go, or how well, but out of 40 some have got to be okay, right? :P

I recently got a box of one hundred NOS, used and unknown 6DX8 tubes from eBay on the cheap.... just trying to figure out which design to work off...

Tubes4e4 · 20th October 2009, 02:18 PM

Anode curves for triode-strapped ECL84 / 6DQ8 / 6DX8 / 6Phi4Pi or series heaters variant PCL84 / 15DQ8 here: http://www.tubes.mynetcologne.de/roe..._as_triode.pdf

Regards,

Tom Schlangen

revintage · 20th October 2009, 08:02 PM

Why not parallell some ECL84´s and skip the triodes. This one with 4 tubes will give you 4-5W at 1%THD. And this without GNFB!

sco1t · 2nd April 2010, 05:16 PM

Hiya

How do you pick what type of speaker transformer to use??? Sorry about my spelling if its wrong.
I am useing a 14 ohm speaker on a small 5 watt RS universal "what is say" specer transformer but it's only seems to be giving the speaker about 500mW of power at full volume from the valve

I used this plan too: http://www.diyaudio.com/forums/attac...4&d=1152603590

Gorgomat · 2nd April 2010, 06:50 PM

Hello,

the pentode is connected as a triode, I wouldn´t expect more than 1W of power. If you need more power, you should consider building a PSE amplifier with at least 2 ecl84 valves per channel or chose a stronger valve.

George

sco1t · 2nd April 2010, 07:58 PM

Thanks Gorgomat for your help.
I'll try the PSE amplifier because I have 4 pcl84's

20th October 2009, 02:18 PM	#5
Tubes4e4 diyAudio Member Join Date: Jul 2005 Location: Leverkusen	Anode curves for triode-strapped ECL84 / 6DQ8 / 6DX8 / 6Phi4Pi or series heaters variant PCL84 / 15DQ8 here: http://www.tubes.mynetcologne.de/roe..._as_triode.pdf Regards, Tom Schlangen __________________ If in doubt, just measure.

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9th October 2009, 01:59 AM	#2
derwhalfisch diyAudio Member Join Date: Aug 2008	Lovely looking amp there :P And that they sound nice is great news for me, I have around 40 ECL84's (or 6DX8's). Don't know how many go, or how well, but out of 40 some have got to be okay, right? :P

9th October 2009, 03:42 PM	#3
lquintas diyAudio Member Join Date: Sep 2006	Thanks derwhalfisch. I only have 8 PCL84, Miniwatt, Tungsram and Mullard. I used 2 Mullard and both work perfectly. Not tried with the rest.

2nd April 2010, 05:16 PM	#7
sco1t diyAudio Member Join Date: Mar 2010 Location: Northeat England	Hiya How do you pick what type of speaker transformer to use??? Sorry about my spelling if its wrong. I am useing a 14 ohm speaker on a small 5 watt RS universal "what is say" specer transformer but it's only seems to be giving the speaker about 500mW of power at full volume from the valve I used this plan too: http://www.diyaudio.com/forums/attac...4&d=1152603590

2nd April 2010, 06:50 PM	#8
Gorgomat diyAudio Member Join Date: Aug 2009	Hello, the pentode is connected as a triode, I wouldn´t expect more than 1W of power. If you need more power, you should consider building a PSE amplifier with at least 2 ecl84 valves per channel or chose a stronger valve. George

2nd April 2010, 07:58 PM	#9
sco1t diyAudio Member Join Date: Mar 2010 Location: Northeat England	Thanks Gorgomat for your help. I'll try the PSE amplifier because I have 4 pcl84's

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