Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Tone Junkie on February 19, 2011, 11:40:46 am

Title: Trim boost pot wiring on the bluezmeister
Post by: Tone Junkie on February 19, 2011, 11:40:46 am

Ok Im looking at this and Im in the middle of wiring it up but its confusing . On the layout it looks like the input and wiper are going to ground and the normal ground is going to the trim boost relay. Im just confused and wanted to double check before I wired it. another cup of coffee might help too  :laugh:
Thanks Bill

Title: Re: Trim boost pot wiring on the bluezmeister
Post by: Geezer on February 19, 2011, 11:51:39 am

The schem is a little clearer.... http://www.el34world.com/Forum/index.php?action=dlattach;topic=9498.0;attach=21898

To see it clearer in your mind, disregard the 0.68u cap for now (it's only there as an "anti-pop" cap).

The basic idea is this.....when the trim boost is "off", the ground lug of the 100k trim pot is connected directly to ground (no boost).
When the trim boost is "on", the ground lug of the 100k trim pot is routed to the 25k trim boost pot, enabling you to pre-set a higher gain entering the OD section by "elevating" the ground lug of the 100k trim pot.

Hope that helps....Geezer

Title: Re: Trim boost pot wiring on the bluezmeister
Post by: Tone Junkie on February 19, 2011, 04:58:36 pm

So i guess my question is, Im still confuzed input and wiper to ground or wiper and  usually the lug going to ground set to ground if that makes sence. Thanks Bill

Title: Re: Trim boost pot wiring on the bluezmeister
Post by: Geezer on February 20, 2011, 05:36:59 am

Quote from: Tone Junkie on February 19, 2011, 04:58:36 pm

So i guess my question is, Im still confuzed input and wiper to ground or wiper and  usually the lug going to ground set to ground if that makes sence. Thanks Bill

No...can you re-phrase the question?

G

Title: Re: Trim boost pot wiring on the bluezmeister
Post by: Tone Junkie on February 20, 2011, 11:47:45 am

Sorry what im asking which side is going to ground one side and the wiper are tied together so is the normal input side going to ground or the normal ground side. Sorry for being confusing.
Thanks Bill

Title: Re: Trim boost pot wiring on the bluezmeister
Post by: Geezer on February 20, 2011, 12:20:58 pm

To be honest, I can't remember right now, but there is a way to test it beforehand.
You want the resistance to INCREASE as you turn the pot CLOCKWISE (like you are turning the pot "up")....the increased resistance to ground will give more gain @ the OD entrance.

G

Title: Re: Trim boost pot wiring on the bluezmeister
Post by: Tone Junkie on February 20, 2011, 03:36:24 pm

Thanks Geezer now that i can wrap my puny little brain around.  :laugh:
Bill
PS. I have to get away from auctions and other tube buying.
But there,s just so many
(I GOTTA HAVE MORE)<G>