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 Post subject: My SE 12SL7 - 6V6G stereo
PostPosted: Jan Mon 06, 2020 2:01 am 
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Location: Haledon, NJ, usa
A revisit to a great simple project:
Just sitting here tonight enjoying listening to the fruits of my labors from last year.
Here's my single-ended 12SL7 - 6V6G stereo amplifier.
These 6v6g tubes were made about 84 years ago in 1936... still creating magnificent sound!
Note: The extra sockets on the chassis are for optional use of (12sl7 or 12ax7) and (6v6 or 12v6 or 6aq5 or 12aq5) Whatever of those tubes you can find can be used in this amp as per design.
All prints and other images are on my web site http://www.pbpix.com/amp .
Attachment:
12sl7 - 6v6g se.jpg
12sl7 - 6v6g se.jpg [ 294.45 KiB | Viewed 4580 times ]



Image

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Last edited by Pbpix on Jan Mon 06, 2020 8:03 am, edited 1 time in total.

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Jan Mon 06, 2020 6:54 am 
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Location: Haledon, NJ, usa
Here's the inside wiring of the chassis tubes underside and the power supply.
So you can see how simple and easy it is to build. Remember I have three extra parallel sockets to allow for the alternate use of miniature tubes as opposed to octals. So you can see how much less wiring there would be without including the extra sockets.

The last image, of course is the top view.

Attachment:
se 6v6gt inside.jpg
se 6v6gt inside.jpg [ 423.3 KiB | Viewed 4544 times ]


Attachment:
se 6v6gt power.jpg
se 6v6gt power.jpg [ 328.55 KiB | Viewed 4543 times ]


Attachment:
se 6v6gt top.jpg
se 6v6gt top.jpg [ 278.06 KiB | Viewed 4541 times ]

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Jan Wed 08, 2020 6:03 am 
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Location: Mesquite NV 89027 (from Coventry, UK)
It looks as good as it did last year. I am glad that you are still enjoying it.


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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Jan Wed 08, 2020 6:29 am 
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Colin Ames wrote:
It looks as good as it did last year. I am glad that you are still enjoying it.

Well.... yeah ... of course.. lol I get it.
I know... but, in a way... it's a joyful ...revisited reminder...
get it?
it's so nice that every now and then I just want to share that pleasure with you guys.. y'know?

So as I'm drinking in that moment of all that pleasure... I feel an urge to remind you guys about what it is that I'm enjoying.. Do you get it?
To share it all... ( well...you can't hear what I'm hearing)
... but at least I can get close and let you imagine it through the schematic... and the eye-candy of seeing the wiring and the final build.

" A thing of beauty, is a joy forever"

------------------- John Keats --------------
A thing of beauty is a joy for ever:
Its loveliness increases; it will never
Pass into nothingness; but still will keep
A bower quiet for us, and a sleep
Full of sweet dreams
, ......

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Jan Sun 12, 2020 6:18 am 
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Today I tried rolling tubes.
I used a 12AX7 as the driver and 6AQ5s on the output and got REALLY surprisingly nice results.
Things sounded " Brighter/crisper"'
I pulled the 12AX7 and used its low noise equivalent tube the 7025 and that is wonderful as well.

I realized that the 12AX7 or 7025 has greater gain compared to the 12SL7 I had in there so I think that everything sounded better partly due to the higher drive signal.
So I pulled out the 6AQ5s and put the 6V6G tubes back... and this combo does sound fine too.

So if anyone here decides to build this great little amp, I think you'll be impressed using a 12AX7 or 7025 driving the 6AQ5 or the 6V6g....

But if you prefer to keep it small, then the 12AX7 or 7025 driving 6AQ5s is a great choice; and probably better on the budget.

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Jan Mon 13, 2020 3:46 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2101
Location: NorthWest TN.
I have enjoyed your posts for several years. Thanks for making these!


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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Jan Mon 13, 2020 3:52 am 
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drmitch wrote:
I have enjoyed your posts for several years. Thanks for making these!

Thanks ... great fun and easy build
but most rewarding to hear

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Jan Mon 13, 2020 7:07 am 
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Location: Omak,wa,usa
hello Peter,
beautiful

Sincerely rich


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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Jan Mon 13, 2020 10:29 pm 
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radiorich wrote:
hello Peter,
beautiful

Sincerely rich

Thanks Rich... maybe you'll find this amp easier to build than the 5902 amp (the one that John sent you the parts for)...since the sockets are larger on this amp.

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Fri 06, 2020 3:19 am 
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Location: Los Angeles
Hi peter.
Just getting ready to build A control amp for this one. It will sit in my bedroom for MP3 only.
Will make new thread soon. And will call you soon.

OMG, those big oil caps give me goose bumps.

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Fri 06, 2020 10:26 pm 
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Location: Southern Ontario
Thanks Peter, I'm going to build it.

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If you can't figure it out, cool the iron and start your day over.


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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Fri 06, 2020 10:35 pm 
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lwhite46 wrote:
Thanks Peter, I'm going to build it.



Hi Lee
I am going to build that amp and add a control section.
Will let know when I start the new thread.
I built the amp before and love it.

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Sat 07, 2020 3:18 am 
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john8750 wrote:
lwhite46 wrote:
Thanks Peter, I'm going to build it.



Hi Lee
I am going to build that amp and add a control section.
Will let know when I start the new thread.
I built the amp before and love it.

I've used it with both the (octal) 12SL7 as well as with the 9-pin 12AX7.
I'm sure you'll find, as I have, that since 12AX7 has more gain... you'll like the performance better.

( btw: the 7025 tube is excellent too because it is exactly a 12ax7 but built to be quieter)
https://frank.pocnet.net/sheets/168/7/7025.pdf

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Sat 07, 2020 5:57 pm 
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Location: Omak,wa,usa
Hello Peter,
Well this amp is a very simple design and I like that it only has a THD of 2.5%

Sincerely Rich


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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Sat 07, 2020 9:29 pm 
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radiorich wrote:
Hello Peter,
Well this amp is a very simple design and I like that it only has a THD of 2.5%

Sincerely Rich

Hi Rich:
Build it... it's a VERY rewarding experience.
It's so simple that you will get a great sense of satisfaction from the great listening experience
and in knowing you built it all yourself!

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To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Sat 07, 2020 9:47 pm 
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BTW guys... for the 50k bleeder resistor (R4) in the power supply, I used three 150k 2watt resistors in parallel.

298v / 50,000 = 6ma
6ma x 298v = 1.8 watts ( triple for safety) = approx 5 or 6 watt resistor

Using these big 820uf caps
https://www.ebay.com/sch/i.html?_from=R ... =0&_sop=15
will cause a heavy initial surge on power-up; typically enough to keep blowing your 1amp fuse. So by adding a CL-90 inrush limiter you'll avoid that problem. ( you could have less in-rush current if you drop the filter caps down to 470uf but the ripple will be higher.)
https://www.digikey.com/product-detail/ ... ers%20(ICL)

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Sat 07, 2020 10:41 pm 
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Peter,
I have several 12AT7 tubes on hand. They have less gain, similar to the 12SL7. What are your thoughts on using a 12AT7?

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If you can't figure it out, cool the iron and start your day over.


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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Sun 08, 2020 1:00 am 
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lwhite46 wrote:
Peter,
I have several 12AT7 tubes on hand. They have less gain, similar to the 12SL7. What are your thoughts on using a 12AT7?

Hard to say for me because I haven't used it.
But it has lower gain than the 12sL7.

I think this list for gain is accurate?
12AT7= 60
12SL7 = 70
12AX7 = 100

I think as far as feeding the input with Mp3 levels ( I use a Sansa Clip+) that the best results are from using the 12AX7.

Someone w/more 12AT7 experience can perhaps shed more light on your question.

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Mon 09, 2020 8:49 am 
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john8750 wrote:
Hi peter.
Just getting ready to build A control amp for this one. It will sit in my bedroom for MP3 only.
Will make new thread soon. And will call you soon.

OMG, those big oil caps give me goose bumps.

I was thinking... what will the "control amp" control?
Tone & vol and maybe Riaa?

I love it w/o anything in front.... just feed it Mp3

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 Post subject: Re: My SE 12SL7 - 6V6G stereo
PostPosted: Mar Wed 11, 2020 3:43 am 
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Joined: Apr Thu 14, 2016 8:25 pm
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Location: pensacola fl
Hi Peter
It may not be the 12AT7 that is as much as it is that you have to crank up the mp3 player to drive it to get the same level. This could mean the mp3 player is operating closer to its useful level end.


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