Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Oddvar on June 19, 2018, 12:04:36 pm

Title: Advise on wiring Marshall 18w TMB (Richies Schematic)
Post by: Oddvar on June 19, 2018, 12:04:36 pm

Hi.  I have enclosed a pic of this build.  I was wondering if anyone could tip me on the best way to wire the OT an PT cables.  They are coming into the chassis approx in the middle under the board, where should I put them for less noise? 

Title: Re: Advise on wiring Marshall 18w TMB (Richies Schematic)
Post by: shooter on June 19, 2018, 01:18:04 pm

distance and angle are the key points.  coupling between wires is usually minimum when they cross at 90 degrees, distance is a squared kinda math, so 1 more inch away cancels more than 1.  You are also working in 3d, so anything "off plane" helps.
Ease n access helps when tweaking for minimum

Title: Re: Advise on wiring Marshall 18w TMB (Richies Schematic)
Post by: sluckey on June 19, 2018, 01:34:50 pm

I would move the OT closer to the PT. Center it on the chassis (front to back) and positioned such that it is half way between the two EL84s.

Title: Re: Advise on wiring Marshall 18w TMB (Richies Schematic)
Post by: Oddvar on June 19, 2018, 04:40:45 pm

Good tis there, I think I'll do that.

Title: Re: Advise on wiring Marshall 18w TMB (Richies Schematic)
Post by: bnwitt on June 23, 2018, 08:02:23 am

Here is a PDF of a Paul Ruby 18 watt chassis showing transformer postions