Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => AmpTools/Tech Tips => Topic started by: kagliostro on February 20, 2015, 02:16:04 pm

Title: How to reduce Hum on a Blues Junior - An interesting read with uncommon solution
Post by: kagliostro on February 20, 2015, 02:16:04 pm

Here you can read the experience of a guy who was trying to solve a problem of Hum in a Blues Junior

the solution found is not common, but simple to implement

http://billmaudio.com/wp/?page_id=882 (http://home.comcast.net/~machrone/bjr/bjrhum.htm)


(http://billmaudio.com/wp/wp-content/uploads/2011/03/final_bend.jpg)

K

Title: Re: How to reduce Hum on a Blues Junior - An interesting read with uncommon solution
Post by: kagliostro on February 20, 2015, 05:12:05 pm

If you read the content of the link

you can read:

Quote

I tested many, many configurations and materials.

and also that strangely an aluminium cylinder, used as shield, gived best results with respect to a mild steel can

However the author ended that the best solution is that shown on the photo (you can read the details on the link)

K

Title: Re: How to reduce Hum on a Blues Junior - An interesting read with uncommon solution
Post by: vicentebd on February 25, 2015, 07:21:58 pm

nice see the positive result, with  angled piece of metal

Title: Re: How to reduce Hum on a Blues Junior - An interesting read with uncommon solution
Post by: jjasilli on March 04, 2015, 11:33:09 am

Everything old is new again!


See attached photo of a circa 1962 Stromberg Carlson PA amp with vertical shield between a power tube and a socket for an optional relay (which would generate a magnetic field).

Title: Re: How to reduce Hum on a Blues Junior - An interesting read with uncommon solution
Post by: kagliostro on March 04, 2015, 05:17:55 pm

I was thinking more to a heat shield to protect the relays from the heat of the power tube

but may be it is as you say JJasilli

Franco

Title: Re: How to reduce Hum on a Blues Junior - An interesting read with uncommon solution
Post by: jjasilli on March 10, 2015, 10:23:37 am

I never thought of that!  I just assumed it was as electromagnetic shield.   :dontknow:

Title: Re: How to reduce Hum on a Blues Junior - An interesting read with uncommon solution
Post by: trobbins on April 05, 2015, 09:47:30 pm

Definetly heat shield IMHO.