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 Post subject: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sat 06, 2018 10:56 pm 
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About 6-7 years ago I wanted to start to learn about TUBE amps for Mp3-players, so I found a nice beginner's circuit using 5902 mico-mini tubes using an op275 op-amp.
I loved learning from that and teaching myself w/lots of help to slowly modify it using a CCS for cathode bias etc.
(5902 PP)
http://www.pbpix.com/amp/5902%20PP%2020 ... change.png
That little amp worked so well that I made a 6V6/6aq5 version which I also learned a great deal from.
(6V6 PP)
http://www.pbpix.com/amp/6v6%20pp%20amp ... e%20hw.png

Both these PP amps are working beautifully in my living room and I LOVE them both. Hard to believe anything might ever sound any better.

Recently I've been reading about some of the differences in audio quality derived from SE amps so I started browsing and found the "lacewood SE" amp Ver-1 and Ver-2.
Image
Image

Lacewood (VER 1)
http://www.cascadetubes.com/the-6v6-lacewood-amp/

Lacewood (VER 2)
http://www.cascadetubes.com/the-6v6-lacewood-amp-v2-0/
http://diyaudioprojects.com/Technical/6 ... imization/

So I decided that I want to try building that "Lacewood" Ver2 amp and if I build it as properly as the author describes I should have another true HiFI amp to try to see how it sounds compared to my 6v6PP types.

So I probably already have most of the parts but I had to order the new SE output transformers.

I see that the author took great pains and costs to build a hefty clean, no ripple power supply.

I built and designed the power supply for both my PP amps and I believe that I will be able to just incorporate the same 292v B+ supply I used in my 6V6 PP amp. I know it well and it only has 20mv pp ripple at +292V, and can handle 100ma. So I think that part of the build will be a "cinch" and will greatly reduce the build time and cost and chassis space.

Last month prior to ordering the OTs I was experimenting on my bench using 6SH7 to drive a 6V6 in SE. and feel it was sensitive enough to use the Mp3 input from my SanDisk Clip Jam Mp3 player. ( https://www.sandisk.com/home/mp3-players/clip-jam )

The Lacewood amp is using 6SN7 triodes on the input and he claimed they are ok for "Line level" inputs.
My Mp3 player puts out much less ... so "Flipperhome" suggested I try using the 6SL7 instead because it has much greater gain.

So I think I'll try that if he can help me set up the bias on the 6SL7.

I will try to compare the 6SL7 to the 6SH7 pentode.
I think I may also try using the op-275 opamp as well as the opa604 opamp.

So Flip... if you are reading this... can you suggest the component values for proper bias on the 6SL7 please?

i think I will begin with either +292 or +300v B+

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Last edited by Pbpix on Jan Sat 06, 2018 11:38 pm, edited 3 times in total.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sat 06, 2018 11:09 pm 
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Location: Minneapolis, MN USA
I built a 3 tube headphone from scratch a few years and have wanted to do a tube based speaker amp next. I like the open top chassis layout in your links. It is always impressive looking to have the tubes and iron on display. They make some sweet sound too.

DIY tube electonics is so much fun and I think tube audio even more.

Keep us posted. Some of us have to live vicariously!


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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sat 06, 2018 11:19 pm 
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Here's the scope results the Author got showing harmonics:

Attachment:
lacewood scope.jpg
lacewood scope.jpg [ 139.72 KiB | Viewed 1954 times ]

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sat 06, 2018 11:25 pm 
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Dale Saukerson wrote:
I built a 3 tube headphone from scratch a few years and have wanted to do a tube based speaker amp next. I like the open top chassis layout in your links. It is always impressive looking to have the tubes and iron on display. They make some sweet sound too.

DIY tube electonics is so much fun and I think tube audio even more.

Keep us posted. Some of us have to live vicariously!

Thanks dale... will do.

Here's some shots of the two earlier PP amps:
Image

Image

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sat 06, 2018 11:41 pm 
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I am always amazed looking at your work Peter. I would be interested in the Lacewood, but after other projects.
Don't know what I will do with it. But would be fun to build.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sat 06, 2018 11:51 pm 
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john8750 wrote:
I am always amazed looking at your work Peter. I would be interested in the Lacewood, but after other projects.
Don't know what I will do with it. But would be fun to build.

.. thanks John... not bad for a 75-year old one-handed gimpy guy trying to learn .... right? lol

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 07, 2018 12:44 am 
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Here's a suggestion

Attachment:
12SL7 Preamp.jpg
12SL7 Preamp.jpg [ 70.18 KiB | Viewed 1944 times ]


The sideways 470k is the grid leak of the following stage. The reason for the 100k pot instead of 250k is the miller capacitance. It's higher the more gain the tube has and since this has a gain of 50 it needs to be lower to keep the upper end frequency response decent.


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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 07, 2018 2:09 am 
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Pbpix wrote:
john8750 wrote:
I am always amazed looking at your work Peter. I would be interested in the Lacewood, but after other projects.
Don't know what I will do with it. But would be fun to build.

.. thanks John... not bad for a 75-year old one-handed gimpy guy trying to learn .... right? lol



How about a 66 year old, who has a learning problem, and probably cant do any better than you, with both hands :?:

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 07, 2018 2:13 am 
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john8750 wrote:
Pbpix wrote:
john8750 wrote:
I am always amazed looking at your work Peter. I would be interested in the Lacewood, but after other projects.
Don't know what I will do with it. But would be fun to build.

.. thanks John... not bad for a 75-year old one-handed gimpy guy trying to learn .... right? lol



How about a 66 year old, who has a learning problem, and probably cant do any better than you, with both hands :?:

And a hillbilly to boot.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 07, 2018 3:53 am 
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Flipperhome wrote:
Here's a suggestion

Image

The sideways 470k is the grid leak of the following stage. The reason for the 100k pot instead of 250k is the miller capacitance. It's higher the more gain the tube has and since this has a gain of 50 it needs to be lower to keep the upper end frequency response decent.

Thanks ... I'll try to get the circuit together on the bench over the next cpl days.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 07, 2018 8:28 pm 
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Peter- have you a power transformer in mind?
Where can any transformers be bought with faster delivery than Edcor?

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If I did something right, I made a mistake.


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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 07, 2018 9:33 pm 
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john8750 wrote:
Peter- have you a power transformer in mind?
Where can any transformers be bought with faster delivery than Edcor?
He indicated he's planning to build another 'death trap' power supply directly off the AC line.


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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 07, 2018 11:09 pm 
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Flipperhome wrote:
john8750 wrote:
Peter- have you a power transformer in mind?
Where can any transformers be bought with faster delivery than Edcor?
He indicated he's planning to build another 'death trap' power supply directly off the AC line.

Flip:
Where did I say that? Huh huh??
There you go again making wild unfounded inferences where none was implied or stated.

(And... it's MY life anyway.... isn't it? )

So... you see... you are soooooooooooo wrong. Again.
lol

I specifically ONLY said that I intend to build the same kind of doubler supply ....but that's all I said.
... And you can clearly see that just as before, an isolation transformer is STILL not missing from this schematic is it?

So what's with you Flip?
...Why do you seem to always like to jump on things like that and always try to make inflammatory snide remarks? Do you just like to be a smart-alec guy who insults people ?

Try to remember Flip .... this is a supposed to be a friendly helpful forum. So please try to lighten up a little and stop making snide comments ... it's not nice, ... I'm sure your kindergarten teacher would be disappointed in you for this persistent habit..
OK?. :mrgreen:
Attachment:
lacewood power.jpg
lacewood power.jpg [ 32.85 KiB | Viewed 1862 times ]

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Last edited by Pbpix on Jan Sun 07, 2018 11:22 pm, edited 1 time in total.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 07, 2018 11:18 pm 
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john8750 wrote:
Peter- have you a power transformer in mind?
Where can any transformers be bought with faster delivery than Edcor?

No John:
I haven't gotten that far yet. I am not sure how I'll even power the filaments yet either or if I'll be sticking with a tube front end or an opamp.
So... too early to decide.

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Sun 07, 2018 11:27 pm 
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Pbpix wrote:
Flipperhome wrote:
He indicated he's planning to build another 'death trap' power supply directly off the AC line.

Flip:
Where did I say that? Huh huh??...
"I believe that I will be able to just incorporate the same 292v B+ supply I used in my 6V6 PP amp."

That was a direct off the AC line power supply and a reasonable 'guess' (I said "indicated") you were planning on the same thing again.


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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Mon 08, 2018 1:04 am 
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Flipperhome wrote:
Pbpix wrote:
Flipperhome wrote:
He indicated he's planning to build another 'death trap' power supply directly off the AC line.

Flip:
Where did I say that? Huh huh??...
"I believe that I will be able to just incorporate the same 292v B+ supply I used in my 6V6 PP amp."

That was a direct off the AC line power supply and a reasonable 'guess' (I said "indicated") you were planning on the same thing again.

Yeah.. Flip... I know I said I'd be using the "same 292v B+ supply" ...
but that supply shown here and on DIY shows an isolation transformer... right?
So ... whether I incorporate that transformer or not was NOT stated.

... but you just seem to enjoy using the nasty "death-trap" adjective without really knowing anything.
I may or may not choose to use the transformer on the final product in my own home... but that's my personal decision... isn't it?

Here's the as PUBLISHED 6V6 supply I've been posting both here and on DIY. So where is the "death-trap" part that you so loosely and inaccurately refer to?:
Image

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Mon 08, 2018 1:26 am 
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Pbpix wrote:
Flipperhome wrote:
"I believe that I will be able to just incorporate the same 292v B+ supply I used in my 6V6 PP amp."

That was a direct off the AC line power supply and a reasonable 'guess' (I said "indicated") you were planning on the same thing again.

Yeah.. Flip... I know I said I'd be using the "same 292v B+ supply" ...
but that supply shown here and on DIY shows an isolation transformer... right?...
You could have simply said you have since changed it to use an isolation transformer but, no, you have to turn this into a pissing contest.

Btw, you changed the "published" schematic when DIYaudio took the original down because it was unsafe which, as you well know, was what I referred to as a "death trap." You know it because we went round and round about it being one yet you claimed it was 'safe'.


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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Mon 08, 2018 1:29 am 
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Flipperhome wrote:
Pbpix wrote:
Flipperhome wrote:
"I believe that I will be able to just incorporate the same 292v B+ supply I used in my 6V6 PP amp."

That was a direct off the AC line power supply and a reasonable 'guess' (I said "indicated") you were planning on the same thing again.

Yeah.. Flip... I know I said I'd be using the "same 292v B+ supply" ...
but that supply shown here and on DIY shows an isolation transformer... right?...
You could have simply said you have since changed it to use an isolation transformer but, no, you have to turn this into a pissing contest.

Btw, you changed the "published" schematic when DIYaudio took the original down because it was unsafe which, as you well know, was what I referred to as a "death trap." You know it because we went round and round about it being one yet you claimed it was 'safe'.

Yes.. and you knew that the transformer was added back then... so why would you still want to call it "death-trap" when you were fully aware the transformer was added last year??
Huh Huh?

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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Mon 08, 2018 1:34 am 
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Pbpix wrote:
Flipperhome wrote:
You could have simply said you have since changed it to use an isolation transformer but, no, you have to turn this into a pissing contest.

Btw, you changed the "published" schematic when DIYaudio took the original down because it was unsafe which, as you well know, was what I referred to as a "death trap." You know it because we went round and round about it being one yet you claimed it was 'safe'.

Yes.. and you knew that the transformer was added back then... so why would you still want to call it "death-trap" when you were fully aware the transformer was added last year??
Huh Huh?
Because the only thing I knew was you belatedly tacked an ISO onto the existing schematic 'for show' to get it past DIYaudio. That was the only thing I was "fully aware" of.


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 Post subject: Re: 6V6 SE HiFi amp (new project)
PostPosted: Jan Mon 08, 2018 1:39 am 
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Flipperhome wrote:
Because the only thing I knew was you belatedly tacked an ISO onto the existing schematic 'for show' to get it past DIYaudio. That was the only thing I was "fully aware" of.

YEP... and you admited you KNEW the transformer was added ... so what was there to still criticize???

NOTHING.

so ... just apologize.

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