Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: BobbyS on January 13, 2023, 12:29:43 pm

Title: Princeton 6G2 too dark
Post by: BobbyS on January 13, 2023, 12:29:43 pm

Hello,


Has been awhile since i was here last. I looked at my last post and saw it was 2013 I believe. Well, sometimes life just gets in the way. OK, I built up a Princeton 6G2 amp head, and probably my hearing has changed  :director: lol, but it sounds too dark. I would like to brighten it up some.


I built it to Fender schematic specs, no mods except the diode for the vibe. I run it into an Eminence Alessandro 12" speaker.


Any suggestions would be appreciated.

Title: Re: Princeton 6G2 too dark
Post by: SILVERGUN on January 13, 2023, 12:40:05 pm

No reason I can see why it would be perceived as dark.
Try lifting the .oo5 cap attached to the tone pot. Better, worse, same, hate it?
Double check those cap values while you are there.

Title: Re: Princeton 6G2 too dark
Post by: sluckey on January 13, 2023, 12:54:55 pm

Let me start by saying... my hearing is much darker than it was in 2013!    :icon_biggrin:

Try this...

1. Change the 25µF cathode bypass cap on V1 to 1µF or 4.7µF.
2. Change the two .1µF PI coupling caps to .047µF or even .022µF.

That's all I got.

Title: Re: Princeton 6G2 too dark
Post by: SILVERGUN on January 13, 2023, 01:02:38 pm

Also, your output tubes can lose a little high end as they wear out.

Title: Re: Princeton 6G2 too dark
Post by: bmccowan on January 13, 2023, 05:20:11 pm

I would agree with checking it over carefully before changing components. I built one to spec - except weber 12" speaker & adjustable bias. Plenty bright to my old ears.

Title: Re: Princeton 6G2 too dark
Post by: BobbyS on January 13, 2023, 10:20:29 pm

Yeah, I installed adjustable bias when I built the amp and sure am glad.

Title: Re: Princeton 6G2 too dark
Post by: BobbyS on January 13, 2023, 10:21:46 pm

Thanks everyone! I am going to give these options a try!

Title: Re: Princeton 6G2 too dark
Post by: BobbyS on February 05, 2023, 01:24:39 am

Thanks everyone! I changed out the coupling caps and the cathode bypass cap and it really helped. My amp has an Eminence George Alessandro speaker in it that sounded good but the amp was just too dark. The mods perked it up a bit, not a huge amount but pretty much what I wanted.

Title: Re: Princeton 6G2 too dark
Post by: tubeswell on February 05, 2023, 02:45:44 am

remember that the type of guitar pups (and the guitar tone pot(s)) also affect the ‘brightness’

Title: Re: Princeton 6G2 too dark
Post by: HotBluePlates on February 06, 2023, 07:06:59 am

Quote from: BobbyS on February 05, 2023, 01:24:39 am

... My amp has an Eminence George Alessandro speaker in it that sounded good but the amp was just too dark. ...

The speaker may be darker/smoother than your preference.

The Oxford speakers in the original Brownface amps were quite bright & edgy.  It certainly in in the 1962 Deluxe I have, and was brighter than a vintage Jensen ceramic or a vintage Celestion alnico speaker.