Anyone ever made the EL84 P-P circuit referenced on the Tubecad Journal site? - Page 2 - diyAudio
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Old 1st September 2010, 01:19 PM   #11
cjkpkg is offline cjkpkg  United States
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Quote:
Originally Posted by TheGimp View Post
Nice job.

Why no power switch?
Nice catch...That is tonight's project...add the power switch. My mouser order arrives today with the trick LED tipped NKK toggle switch
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Old 2nd September 2010, 04:50 AM   #12
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cjkpkg,

Thanks for the transformer part numbers. I'll file this away for a future project.

I like your build. Canting the circuit board to save space is clever.

Ron
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Old 4th September 2010, 01:06 AM   #13
cjkpkg is offline cjkpkg  United States
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OK...finally got done with all of the wiring...I installed 1.2 ohm resistors off the EL84 cathodes to easily figure the current - although I guess 1 ohm would have been even easier...LOL

I then hooked up the 20 ohm pot on each channel. Lastly I removed the 200 ohm resistor and added the 80mA CCS with an LM317 using a 15 ohm resistor...each cathode is running at 42mA within a half a mA by my math...

How does it sound? All I can say is BASS BASS and more BASS...Even in stock form the PP amp had a little more bass than the SimpleSE but sounded a little more thin I guess...

With the pots balancing the act and the CCS I must say that at "reasonable" listening volumes the PP amp really shines.

Not that the SimpleSE in its current configuration is a slacker by any means...it is still my favorite overall...

Click the image to open in full size.
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Old 4th September 2010, 06:37 AM   #14
Ian444 is offline Ian444  Australia
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Nice job, very compact. Bet you're real proud of it I would be too.

What I find interesting about this circuit, which is different to other split load/cathodyne circuits, is the two 1M resistors setting the DC bias for the cathodyne. So its not really DC-coupled, but the bias can be set for the cathodyne without compromising the operating conditions of the gain stage. (The schematic is on post #7.)

Last edited by Ian444; 4th September 2010 at 06:40 AM.
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Old 4th September 2010, 08:30 PM   #15
cjkpkg is offline cjkpkg  United States
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Yes...thank you and I am proud of it since is sounds soo good...

The circuit I found mostly was based on the oddwatt referenced circuit that has been around since the 50's...the CCDA posed on the tubecad journal seemed a little different and since I love my Aikido so much I figured I would give it a shot...

Next up might be an octal Aikido P2P with a MOSFET back end...
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Old 4th September 2010, 11:58 PM   #16
athos56 is offline athos56  United States
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Quote:
Originally Posted by cjkpkg View Post
Yes...thank you and I am proud of it since is sounds soo good...

The circuit I found mostly was based on the oddwatt referenced circuit that has been around since the 50's...the CCDA posed on the tubecad journal seemed a little different and since I love my Aikido so much I figured I would give it a shot...

Next up might be an octal Aikido P2P with a MOSFET back end...
Been there, it is sweet. I used the BUZ901 and 905s, the mosfet supply was the hardest part to get quiet, find a nice regulator. Farnell carries the Mosfets, which are a bit pricey.

Athos
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Old 5th September 2010, 05:28 PM   #17
cjkpkg is offline cjkpkg  United States
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Yes I have acquired the BUZ MOSFETS already...I am really now saving up for a 3U or 4U chassis with heatsink - I have a couple other hifi2000 cases so I have my heart set on one of these...

I have a Pass F5 in a 5U - I thought would be overkill but I have it biased kinda high and it gets really hot!

A 3U will be plenty of space but a 4U might be in order...

I am really dying to try out an octal aikido...
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Old 5th September 2010, 05:34 PM   #18
athos56 is offline athos56  United States
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Quote:
Originally Posted by cjkpkg View Post
Yes I have acquired the BUZ MOSFETS already...I am really now saving up for a 3U or 4U chassis with heatsink - I have a couple other hifi2000 cases so I have my heart set on one of these...

I have a Pass F5 in a 5U - I thought would be overkill but I have it biased kinda high and it gets really hot!

A 3U will be plenty of space but a 4U might be in order...

I am really dying to try out an octal aikido...
Hmm... We should talk, I want to make a F5.

Athos
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Old 10th November 2010, 12:50 AM   #19
cjkpkg is offline cjkpkg  United States
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put some finishing touches on the el84PP over the past couple days...bought a small piece of oak at HD and finished up a couple side pieces. I needed to raise up the chassis a little due to the heatsink for the heater regulator and was browsing mouser hammond chassis for another project and saw their walnut sided units...and the rest is DIY...
Click the image to open in full size.
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Old 20th December 2010, 10:10 PM   #20
jeffe is offline jeffe  Canada
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Hi,

Was looking to start gathering parts for this amp. Would just like to check a couple of details...
-the cathode resistor for the EL84's should be 200 ohms ?
-a good value for the power supply (B+) capacitor? no value is given...

I think I might go with the Dynaco clone opt's from TriodeElectronics. This would be my first tube amp scratch build. I've built s.s. amps and done a ST-70 rebuild.

Thanks,
Jeff
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