Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on January 09, 2011, 03:52:34 am

Title: How not to build an amplifier
Post by: kagliostro on January 09, 2011, 03:52:34 am
I've find this project

http://www.rficdesign.com/vacuum-tube

May be it is a very imaginative and frugal one

and passionate about cars can look at that with some interest

But I think it is very dangerous ! or I'm wrong ?

the "Output Transformer" has galvanic continuity between primary and secondary windings and that can't be a good thing ...............

Kagliostro
Title: Re: How not to build an amplifier
Post by: stingray_65 on January 09, 2011, 10:44:31 am
LOL I have built this amp 2 yrs ago.

It works, it is dangerous!

Later on I found a 250-0-250 pt and 2 identical SE trannies from AA5 radios and built a stereo amp for my mp3 player.

with a proper power supply and output trannies this is is actually a decent amp, (not guitar) I'm driving a pair of Goodwill sourced Aiawa's and gets just above conversation levels.

My Daughter (10 yrs old at the time) landed and soldered all the wires, she also helped me restore the cab and do the finish work on the poplar and aluminum chassis.


Ray
Title: Re: How not to build an amplifier
Post by: kagliostro on January 09, 2011, 11:10:04 am
Quote
My Daughter (10 yrs old at the time) landed and soldered all the wires, she also helped me restore the cab and do the finish work on the poplar and aluminum chassis.

That certainly is a great satisfaction for a father !  :grin:

Kagliostro

Title: Re: How not to build an amplifier
Post by: PRR on January 09, 2011, 09:27:11 pm
It says:

Quote
...the ignition coil does not provide electrical isolation between the 170 volts DC of the “plate” power supply and the speaker, thus elevating the speaker connections to tha voltage with respect to ground. Since obviously placing wires on your head with high voltage to ground would be very hazardous, please do not use headphones!

WARNING: do not touch any wires or terminals while the amplifier circuit is energized!

Yes, it is dangerous and reckless.

Also not a very good audio transformer.

Unless you (like me) have pieces of a 1970s Plymouth laying around your yard, it will be as easy/cheap and much safer to get a real audio transformer.
Title: Re: How not to build an amplifier
Post by: DummyLoad on January 09, 2011, 09:28:18 pm
i wonder which brand sounds better. GM, Ford or Mopar?  

 :smiley:
Title: Re: How not to build an amplifier
Post by: kagliostro on January 10, 2011, 04:47:01 am
May be I've one Fiat Panda old model ignition coil laying around

But neither Ferrari nor Maserati

I don't think those I've will give good sounds, that car is a poor model  :grin:

Kagliostro
Title: Re: How not to build an amplifier
Post by: supro66 on January 10, 2011, 07:40:38 am
May be I've one Fiat Panda old model ignition coil laying around

But neither Ferrari nor Maserati

I don't think those I've will give good sounds, that car is a poor model  :grin:

Kagliostro

I have one my Grandfather gave me 1914   :grin:

(http://i282.photobucket.com/albums/kk243/supro66/AUTO%20TRUCKS/Modelteecoil2.jpg)
Title: Re: How not to build an amplifier
Post by: Willabe on January 10, 2011, 10:46:11 pm
Man I wish I had one of those!

What a look, the grain of the oak, the shape, I'd love to have that in my house on display!


      Brad      :smiley:
Title: Re: How not to build an amplifier
Post by: kagliostro on January 11, 2011, 08:14:50 am
Quote
I'd love to have that in my house on display!

I'd love to have it in an automobile of adequate level in order to use it  :angel

:grin: :grin: :grin:

Kagliostro