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 Post subject: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 2:45 am 
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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.

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 2:56 am 
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Here is the schematic.
Image

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Last edited by john8750 on Jan Tue 02, 2018 7:17 am, edited 4 times in total.

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 3:02 am 
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dupe

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Last edited by john8750 on Jan Tue 02, 2018 7:19 am, edited 1 time in total.

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 3:17 am 
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One twist will be a tone control circuit.


Attachments:
tone control.jpg
tone control.jpg [ 58.63 KiB | Viewed 1842 times ]

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 3:21 am 
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And an RIAA
Attachment:
OPA2134-Opamp-MM-MC-RIAA-Phono-Preamp-Schematic[1].png
OPA2134-Opamp-MM-MC-RIAA-Phono-Preamp-Schematic[1].png [ 53.66 KiB | Viewed 1841 times ]

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 3:56 am 
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You must really like your cousin! :lol:


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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 6:46 am 
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Mike Toon wrote:
You must really like your cousin! :lol:



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
Opamp%20Preamp%20Bipolor%20Supply2[1].jpg [ 78.53 KiB | Viewed 1819 times ]

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 8:09 am 
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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.

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 8:29 am 
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Here is my idea of the block diagram
Attachment:
Ricke amp 1 line.png
Ricke amp 1 line.png [ 12.95 KiB | Viewed 1814 times ]

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 6:10 pm 
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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
20180101_082845.jpg [ 131.61 KiB | Viewed 1787 times ]

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 6:16 pm 
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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
20180101_082732.jpg [ 173.8 KiB | Viewed 1786 times ]

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Mon 01, 2018 10:30 pm 
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It will be a tight fit, but ordered this remote control volume pot. I will take a gamble for the price.
https://www.ebay.com/itm/9V-Infrared-Re ... Ciid%253A1

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Tue 02, 2018 2:49 am 
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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
Doubler - heaters - opamp 3.jpg [ 107.13 KiB | Viewed 1748 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
Doubler - heaters - opamp 2.jpg [ 111.16 KiB | Viewed 1614 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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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Tue 02, 2018 5:03 am 
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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.

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Tue 02, 2018 5:10 am 
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Just wondering, C5,8- electrolytic?

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Tue 02, 2018 6:27 am 
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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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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Tue 02, 2018 6:28 am 
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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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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Tue 02, 2018 7:16 am 
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dupe

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Tue 02, 2018 7:24 am 
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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.

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 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Jan Tue 02, 2018 10:48 pm 
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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.

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