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john8750
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Post subject: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 2:45 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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Yes, another 6V6 amp project. But with some added features. The power amp section will be 6V6-PP-CC-UL. The driver-inverter will be an OP275. This amp was greatly modified by Peter, and Flip.
_________________ John Smith, over and out. If I did something right, I made a mistake.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 2:56 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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Here is the schematic. 
_________________ John Smith, over and out. If I did something right, I made a mistake.
Last edited by john8750 on Jan Tue 02, 2018 7:17 am, edited 4 times in total.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 3:02 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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dupe
_________________ John Smith, over and out. If I did something right, I made a mistake.
Last edited by john8750 on Jan Tue 02, 2018 7:19 am, edited 1 time in total.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 3:17 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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One twist will be a tone control circuit.
Attachments: |

tone control.jpg [ 58.63 KiB | Viewed 3444 times ]
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_________________ John Smith, over and out. If I did something right, I made a mistake.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 3:21 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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And an RIAA Attachment:
OPA2134-Opamp-MM-MC-RIAA-Phono-Preamp-Schematic[1].png [ 53.66 KiB | Viewed 3443 times ]
_________________ John Smith, over and out. If I did something right, I made a mistake.
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Mike Toon
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 3:56 am |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 8315 Location: Beautiful Downtown Burbank CA
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You must really like your cousin! 
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 6:46 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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Mike Toon wrote: You must really like your cousin!  Hi Mike. He is a real nice guy. We live close and have always been good friends. And I have most all the parts left over from other projects. My 300b is completed, just need better speakers. This is the second 6V6 I have built. The first one is the same. It is a very good performer. Gonna modify a wooded chassis for this one, so should build fast. Here is another section I will add just for the MP3 low level boost. Thanks to Flip. Attachment:
Opamp%20Preamp%20Bipolor%20Supply2[1].jpg [ 78.53 KiB | Viewed 3421 times ]
_________________ John Smith, over and out. If I did something right, I made a mistake.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 8:09 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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The grid leaks need to be inserted. I believe it should be 470K. Will check with Peter. And, I believe it should connect before the stopper.
_________________ John Smith, over and out. If I did something right, I made a mistake.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 8:29 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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Here is my idea of the block diagram Attachment:
Ricke amp 1 line.png [ 12.95 KiB | Viewed 3416 times ]
_________________ John Smith, over and out. If I did something right, I made a mistake.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 6:10 pm |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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Here is the wood chassis I will use. Just need a few changes. A different power transformer will be needed. And 3 sets or input jacks will be installed in the rear. I would like to add a remote volume control, but don't know if there is enough room. Attachment:
20180101_082845.jpg [ 131.61 KiB | Viewed 3389 times ]
_________________ John Smith, over and out. If I did something right, I made a mistake.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 6:16 pm |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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I built a test circuit of the tone control circuit. Works very well. You can see the actual PCB it will be built on at the top of photo. The TDA1524A has perfect authority of the preamp functions. So far, so good. Attachment:
20180101_082732.jpg [ 173.8 KiB | Viewed 3388 times ]
_________________ John Smith, over and out. If I did something right, I made a mistake.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Mon 01, 2018 10:30 pm |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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Flipperhome
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Tue 02, 2018 2:49 am |
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Joined: Nov Sat 26, 2011 4:09 am Posts: 9585 Location: Texas. USA
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Here's the power supply with more 'practical' values for the caps, namely C2, C3 and C4. It has slightly lower ripple too. Attachment:
Doubler - heaters - opamp 3.jpg [ 107.13 KiB | Viewed 3350 times ]
A more efficient PS would be to use a transformer full wave doubler rather than a cap doubler (which is half wave) for B+. Attachment:
Doubler - heaters - opamp 2.jpg [ 111.16 KiB | Viewed 3216 times ]
The objection that some have is that the heater supply gets it's return to the transformer through the bottom 470 uF cap (the reason it's non symmetrical with the upper 220 uF) but, as far as I can tell, that's purely 'visual' and has no detrimental effects on performance. Edit: Corrected C5/C8 caps. Edit 2: C5/8 were correct after all.
Last edited by Flipperhome on Jan Wed 03, 2018 10:21 pm, edited 2 times in total.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Tue 02, 2018 5:03 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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Thanks Flip. You caught me just in time, was laying out the power supply. R1,2 10watt? C1-4 400volt? C6,7 50volt? T1 400ma ok? That's what I have already installed.
_________________ John Smith, over and out. If I did something right, I made a mistake.
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Tue 02, 2018 5:10 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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Just wondering, C5,8- electrolytic?
_________________ John Smith, over and out. If I did something right, I made a mistake.
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Flipperhome
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Tue 02, 2018 6:27 am |
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Joined: Nov Sat 26, 2011 4:09 am Posts: 9585 Location: Texas. USA
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john8750 wrote: Thanks Flip. You caught me just in time, was laying out the power supply. R1,2 10watt? C1-4 400volt? C6,7 50volt? T1 400ma ok? That's what I have already installed. No, 400 mA isn't enough. It really depends on which version you choose and the idle current of the 6V6s but a Triad N-77U is about minimum. R1,2 should be 5 Watt, or more. C1-4 again depend on which circuit you pick. For the cap multiplier circuit C1 can be 200 V but the rest should be 400 V. For the transformer multiplier C1 and C2 can be 200 V with C4 and C4 400 V. 50 V is fine for C6 and C7.
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Flipperhome
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Tue 02, 2018 6:28 am |
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Joined: Nov Sat 26, 2011 4:09 am Posts: 9585 Location: Texas. USA
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john8750 wrote: Just wondering, C5,8- electrolytic? Rats. I made a boo-boo on one of the schematics. C5 and C8 should be non-polar. I'll go back and edit that.
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Pbpix
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Tue 02, 2018 7:16 am |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 23950 Location: Haledon, NJ, usa
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dupe
_________________ To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind. -Emerson
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john8750
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Tue 02, 2018 7:24 am |
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Joined: Dec Mon 29, 2014 9:39 pm Posts: 5159 Location: Los Angeles
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Thanks Flip. Just wanted to be sure. My mistake about the PT. I was forgettin the filaments. And thanks peter for the accurate 6V6 schematic. I replaced the one I had with the update.
_________________ John Smith, over and out. If I did something right, I made a mistake.
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Pbpix
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Post subject: Re: 6V6 amp project- with a twist Posted: Jan Tue 02, 2018 10:48 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 23950 Location: Haledon, NJ, usa
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Flipperhome wrote: Here's the power supply with more 'practical' values for the caps, namely C2, C3 and C4. It has slightly lower ripple too. Attachment: Doubler - heaters - opamp 3.jpg A more efficient PS would be to use a transformer full wave doubler rather than a cap doubler (which is half wave) for B+. Attachment: Doubler - heaters - opamp 2.jpg The objection that some have is that the heater supply gets it's return to the transformer through the bottom 470 uF cap (the reason it's non symmetrical with the upper 220 uF) but, as far as I can tell, that's purely 'visual' and has no detrimental effects on performance. Edit: Corrected C5/C8 caps. Flip: Remember when I tried to implement the full-wave version... there were problems? Something to do with C2... or such. Remember it didn't work... so I had to abandon it? Do you remember what it was? I'm foggy about the exact details.
_________________ To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind. -Emerson
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