Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Colas LeGrippa on December 10, 2020, 09:54:15 pm

Title: Midget mono amp for.my tv
Post by: Colas LeGrippa on December 10, 2020, 09:54:15 pm: Hola amigos,

I need a small mono amplifier for.my tv. With one RCA input, one volume and one headphone out. My tv is not connected to any cable and the sound is coming with the picture through an inside rabbit ears antenna. The tv is modern though with an optical sound output to which is connected an adapter with a RCA plug.
Up to now I was using an old cassette deck with earphone out to listen to the tv. I am 50 percent deaf and that s the way I can listenn to t.v. I dont want to buy nothing cheapo (china)or transistorized but build me one. It will last for years and I ll be able to do the service when it comes defective.

Thanks for help
Title: Re: Midget mono amp for.my tv
Post by: Colas LeGrippa on December 10, 2020, 11:09:39 pm: I only need a proven good schematic, no more !

(But if there's a christmas gift that comes with it, I' ll take it :laugh: ).
Title: Re: Midget mono amp for.my tv
Post by: sluckey on December 10, 2020, 11:16:22 pm: Maybe use that small amp you just built. Easy to put a headphone jack on it.
Title: Re: Midget mono amp for.my tv
Post by: Colas LeGrippa on December 11, 2020, 10:29:22 am: Too much distortion..
Any circuit diagram for the headphone ?
Title: Re: Midget mono amp for.my tv
Post by: SILVERGUN on December 11, 2020, 11:42:11 am: Colas, I searched for "headphone" and look what came up. :icon_biggrin:
HEADPHONE tube amp (el34world.com) (https://el34world.com/Forum/index.php?topic=13029.msg121513#msg121513)
Title: Re: Midget mono amp for.my tv
Post by: Colas LeGrippa on December 11, 2020, 02:05:26 pm: very interesting indeed :laugh:
Title: Re: Midget mono amp for.my tv
Post by: PRR on December 11, 2020, 10:00:43 pm: .
Title: Re: Midget mono amp for.my tv
Post by: AmberB on December 11, 2020, 10:06:50 pm: It would be pretty easy to build a stereo version of this little amp...just double the VA capacity on the power transformers and get 2 output transformers.
Title: Re: Midget mono amp for.my tv
Post by: Colas LeGrippa on December 12, 2020, 03:17:20 pm: PRR, gee an intelligent answer.

You're my man.
Title: Re: Midget mono amp for.my tv
Post by: blackcorvo on December 14, 2020, 02:33:57 am: Quote from: AmberB on December 11, 2020, 10:06:50 pm
It would be pretty easy to build a stereo version of this little amp...just double the VA capacity on the power transformers and get 2 output transformers.

No need to double the VA on the isolation transfomer, 10VA is plenty for a pair of 6AU6's (they can take 3w of plate dissipation max, and this desing is at about half of that).

But for the filament one, you could use either 6v @ 1.2A or a 12v @ 0.6A, since you could wire the tube filaments in series. You could even use the mid-point between each filament to make a "center tap" for reducing hum.

Just to give you an idea, I redrew PRR's schematic on DIYLC, with the alternative 12v transformer filament supply.
Title: Re: Midget mono amp for.my tv
Post by: Colas LeGrippa on December 14, 2020, 09:57:05 am: Very neat drawing
Title: Re: Midget mono amp for.my tv
Post by: blackcorvo on December 16, 2020, 12:16:06 am: I'm now tempted to try it, but using 5636 submini tubes, just to hear how loud it can get...

[UPDATE]
I tried it and it works! But it's probably better suited as a headphone amp (loud enough to run some 600-ohms headphones, I bet).