Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: billcreller on November 18, 2016, 09:36:54 am

Title: Too Trebly Supro
Post by: billcreller on November 18, 2016, 09:36:54 am

Back around 2007 I built a single-end type Supro.  Schematic Heaven calls it "Late'50s 1X 6V6 Amp"  It works good, but  it has a too treble tone for my taste.  I had added a cathode cap to the cathode resistor on the 6V6, and added one the 2nd half of the 12AX7, (2nd stage pre-amp ?)  Coupling caps are .047 in place of the spec .01 caps.  Very simple circuit, but not as simple as I am !
Any ideas about getting less treble from this ?   
I'll see if I can show the schematic....

well, that didn't work ! :cussing:

Title: Re: Too Trebly Supro
Post by: sluckey on November 18, 2016, 09:50:07 am

A different speaker could be all you need.

Title: Re: Too Trebly Supro
Post by: PRR on November 18, 2016, 03:41:49 pm

> cathode cap ....the 2nd half of the 12AX7

10-20uFd? Or 0.68uFd?

0.68 gives the Marshall Scream. Not what you want.

Fender leaned to 10+uFd which gives full bass (equal to treble).

Title: Re: Too Trebly Supro
Post by: billcreller on November 18, 2016, 10:11:22 pm

That cathode cap is a 20 mf.   I'll try smaller values.  The speaker is a 10 inch Weber. Chassis has 
a speaker jack, so I can try some others..

Thanks !

Title: Re: Too Trebly Supro
Post by: Willabe on November 18, 2016, 10:39:40 pm

Smaller cap value will have less bass. 

Title: Re: Too Trebly Supro
Post by: PRR on November 19, 2016, 08:36:29 pm

> Smaller cap value will have less bass. 

Which can have the effect of "more treble".