That circuit is fairly common. If you look at the Tubelab Simple P-P, SY's Red Light District, Morgan Jones Bevois Valley, and Broskies circuit, you will find them very similar. Why? Even though most of these appear to be independently developed, this seems to be the simplest way to make a small P-P amp with good performance.
OK,
This morning I finalized one channel and fired it up for a smoke test. All went well so I put the tubes in. I must say that I am very happy with this PP amp.
Next on the docket...
1. Clean up finished channel wiring
2. Complete second channel
3. Put bias pots on the EL84's
4. Implement a CCS for EL84 cathode bias
Pics to come in the next couple days...
This morning I finalized one channel and fired it up for a smoke test. All went well so I put the tubes in. I must say that I am very happy with this PP amp.
Next on the docket...
1. Clean up finished channel wiring
2. Complete second channel
3. Put bias pots on the EL84's
4. Implement a CCS for EL84 cathode bias
Pics to come in the next couple days...
UPDATE
Both channels are done! I still need to implement a pot for bias adjustment and maybe a CCS for the EL84 cathodes...
Not the prettiest wiring, I'm sure but for my first P2P wiring job I think it came out OK...Just got to listen for a couple mins tonight before I got yelled at by the 3 yr old...
Also, a fellow board member was nice enough to point out an error in the schematic...The shared cathode resistors for the EL84s should be 200 ohm, not 400 ohm. I bought matched tubes but I still need to take some measurements to see how they are behaving...
Both channels are done! I still need to implement a pot for bias adjustment and maybe a CCS for the EL84 cathodes...
Not the prettiest wiring, I'm sure but for my first P2P wiring job I think it came out OK...Just got to listen for a couple mins tonight before I got yelled at by the 3 yr old...
Also, a fellow board member was nice enough to point out an error in the schematic...The shared cathode resistors for the EL84s should be 200 ohm, not 400 ohm. I bought matched tubes but I still need to take some measurements to see how they are behaving...
XPWR007 120V 60Hz to 550 volt (275-0-275) @ 200mA,
6.3 volt @ 6A, 5.0 volt @ 3A
Power Transformer
RoHS Compliant
CXPP25-MS-7.6K 25Watt 7600 Z ohms to 4, 8, and 16 ohms
40% Screen Voltage
Classic Push Pull Transformer
RoHS Compliant
Maybe I missed it last time but they do show a 8K Z ohm OPT now...I swear it wasnt there when I ordered mine...
There is also a non-multiple secondary version that is a couple bucks cheaper too. I have a couple different speaker drivers in the stable so I figured I would go with the multiple option.
6.3 volt @ 6A, 5.0 volt @ 3A
Power Transformer
RoHS Compliant
CXPP25-MS-7.6K 25Watt 7600 Z ohms to 4, 8, and 16 ohms
40% Screen Voltage
Classic Push Pull Transformer
RoHS Compliant
Maybe I missed it last time but they do show a 8K Z ohm OPT now...I swear it wasnt there when I ordered mine...
There is also a non-multiple secondary version that is a couple bucks cheaper too. I have a couple different speaker drivers in the stable so I figured I would go with the multiple option.
Nice catch...That is tonight's project...add the power switch. My mouser order arrives today with the trick LED tipped NKK toggle switch
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...
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...
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.)
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.)
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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...
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...
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
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...
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...
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
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...
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
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