Simplest flea-powered amp?

arnoldc · 11th February 2006, 03:38 AM

I have always wanted to make something really small I can bring to the office (and also use at home) and 0.5W - 1W is all I need.

I have been reserving my 12B4 for this but I was side tracked

and made a 12B4 preamp instead, which I really liked. Besides, I don't think that the 12B4 can be run without a driver.

I wanted the purest (sic) single triode amp (duh) that can be driven from a CD player.

From the tubes available with me, it seems that the 417A is capable of producing some watts with a 5W plate dissipation, so I was thinking of putting in a 5K load and drive it around 25-30mA. Bias it around 2V and I should be fine? Maybe?

Are there any triode candidates out there? Maybe I can beg friends if they have any that you may suggest

Sheldon · 11th February 2006, 03:46 AM

With ss power supply, this would be one tube:

http://www.sempermusica.com/

Search under "spud amps" for more examples of the genre.

Sheldon

arnoldc · 11th February 2006, 03:51 AM

Hi Sheldon, I like that! Can we ditch the input transformer?

Sheldon · 11th February 2006, 04:05 AM

Quote:

Originally posted by arnoldc
Hi Sheldon, I like that! Can we ditch the input transformer?

I don't see any reason you couldn't sub in a cap for the transformer, or no cap. Note that I haven't looked up that transformer to see if he's getting any gain there. But here's one with the same tube and just a pot on the input:

http://digilander.libero.it/paeng/projects_frame.htm

Edit: Actually, no pot shown, but could be one. Should be no problem as long as the source has no DC.

arnoldc · 11th February 2006, 04:26 AM

Great!

Now I'm fired up

I'm taking my amp prototyping chassis from the storage and make one, now!

Thanks Sheldon.

Sheldon · 11th February 2006, 04:35 AM

These always looked cool to me, and I might build on some day. Curious to see what you think.

Sheldon

Shoog · 11th February 2006, 08:30 AM

How about an ECL82/PCL82 amp - cheap and plentiful and a one tube amp.
Even better try an ECL86, slightly better tube but slightly more popular.

Shoog

Jack Crow · 11th February 2006, 09:26 AM

Hi all,
I cheated and took the easy way out.

Got the amp kit from Antique Electronic Supply and it works. Each morning I get into the lab and turn it on. It runs a full 12 hour day, every day.

It gets coments and always brings a smile to visiting brass who come here.

I don't have the 'ears' any more to know good from great, but it keeps me happy and it was a snap to build.

Good luck on this project, perhpas I will order parts for one of these as well.

Later dude
Jack Crow
tdy
Camp Arifjan, Kuwait

jane · 11th February 2006, 02:53 PM

Quote:

Originally posted by arnoldc
Hi Sheldon, I like that! Can we ditch the input transformer?

You probably can. The output tube (6S45P-E) needs 2V peak for full drive, quite close to line level.

arnoldc · 11th February 2006, 04:05 PM

Done!

The picture shows the amp in testing in the kitchen (yeah, I assembled it in the kitchen as my workbench has another unfinished project on it) with Kenwood car speakers.

This amp sounds great with the cheap Hammonds on it

I like the tone so much! So this is how a real single triode amp sounds like

It's so pure, I'm listening to Hayley Westenra's Pure album.
It's now driving my DIY Altec speakers.

I like it, I like it!

11th February 2006, 03:38 AM	#1
arnoldc diyAudio Member Join Date: Apr 2003 Location: Makati	Simplest flea-powered amp? I have always wanted to make something really small I can bring to the office (and also use at home) and 0.5W - 1W is all I need. I have been reserving my 12B4 for this but I was side tracked and made a 12B4 preamp instead, which I really liked. Besides, I don't think that the 12B4 can be run without a driver. I wanted the purest (sic) single triode amp (duh) that can be driven from a CD player. From the tubes available with me, it seems that the 417A is capable of producing some watts with a 5W plate dissipation, so I was thinking of putting in a 5K load and drive it around 25-30mA. Bias it around 2V and I should be fine? Maybe? Are there any triode candidates out there? Maybe I can beg friends if they have any that you may suggest

11th February 2006, 09:26 AM	#8
Jack Crow diyAudio Member Join Date: Nov 2005 Location: Herndon Virginia	Tube amp kit Hi all, I cheated and took the easy way out. Got the amp kit from Antique Electronic Supply and it works. Each morning I get into the lab and turn it on. It runs a full 12 hour day, every day. It gets coments and always brings a smile to visiting brass who come here. I don't have the 'ears' any more to know good from great, but it keeps me happy and it was a snap to build. Good luck on this project, perhpas I will order parts for one of these as well. Later dude Jack Crow tdy Camp Arifjan, Kuwait

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11th February 2006, 03:46 AM	#2
Sheldon diyAudio Member Join Date: Dec 2003 Location: San Diego	With ss power supply, this would be one tube: http://www.sempermusica.com/ Search under "spud amps" for more examples of the genre. Sheldon

11th February 2006, 03:51 AM	#3
arnoldc diyAudio Member Join Date: Apr 2003 Location: Makati	Hi Sheldon, I like that! Can we ditch the input transformer?

11th February 2006, 04:26 AM	#5
arnoldc diyAudio Member Join Date: Apr 2003 Location: Makati	Great! Now I'm fired up I'm taking my amp prototyping chassis from the storage and make one, now! Thanks Sheldon.

11th February 2006, 04:35 AM	#6
Sheldon diyAudio Member Join Date: Dec 2003 Location: San Diego	These always looked cool to me, and I might build on some day. Curious to see what you think. Sheldon

11th February 2006, 08:30 AM	#7
Shoog diyAudio Member Join Date: Aug 2002 Location: Eire	How about an ECL82/PCL82 amp - cheap and plentiful and a one tube amp. Even better try an ECL86, slightly better tube but slightly more popular. Shoog

11th February 2006, 04:05 PM	#10
arnoldc diyAudio Member Join Date: Apr 2003 Location: Makati	Done! The picture shows the amp in testing in the kitchen (yeah, I assembled it in the kitchen as my workbench has another unfinished project on it) with Kenwood car speakers. This amp sounds great with the cheap Hammonds on it I like the tone so much! So this is how a real single triode amp sounds like It's so pure, I'm listening to Hayley Westenra's Pure album. It's now driving my DIY Altec speakers. I like it, I like it!

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