[Harp-L] Re: Harp-L Digest, Vol 33, Issue 29



I am self-taught, so take my observations accordingly.....

Fender typically uses 2 W series resistors in the power supply. Other manufacturers often use 1/2 W resistors, particularly at the preamp tube level. You should be able to get some idea of this on your amp by inspection of the resistor. I use a standard size Alpha 200K pot mounted in a Lee Oskar harmonica box when I fuss with the series resistance. I don't know the rating of the pot. It has not failed.

Nothing personal, but......THIS WORK IS CONDUCTED WITHIN A FEW CENTIMETERS OF A SPOT WITH 450V DC DURING OPERATION. THIS VOLTAGE MAY BE PRESENT EVEN WITH THE AMP UNPLUGGED BECAUSE THE POWER SUPPLY CAPACITORS ARE CHARGED DURING AMP OPERATION. THE CHANGE MIGHT BE MAINTAINED FOR SOME TIME AFTER THE AMP IS TURNED OFF. IF YOU DO NOT KNOW HOW TO DISCHARGE THE HIGH VOLTAGE AND DETERMINE IF THE VOLTAGE HAS BEEN SUFFICIENTLY DISCHARGED, YOU SHOULD NOT BE UNDERTAKING THIS.



On May 16, 2006, at 9:01 PM, harp-l-request@xxxxxxxxxx wrote:

From: G <gigs@xxxxxxxxxxxxxxx>
Subject: Re: [Harp-L] Low plate voltage on the preamp tubes?
To: harp-l@xxxxxxxxxx
Message-ID: <3.0.3.32.20060517125348.01b2df04@xxxxxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset=us-ascii

Date: Mon, 15 May 2006 22:23:28 -0500
From: Dina Janzen <dlj@xxxxxx>
Subject: Re: [Harp-L] Low plate voltage on the preamp tubes?
To: harp-l@xxxxxxxxxx

I agree that reducing the plate voltage of Fender....

Jim R

Hi Jim,
Basic question: What kind of wattage do the resistors or POT have to be
for this sort of thing?
-- G.







This archive was generated by a fusion of Pipermail 0.09 (Mailman edition) and MHonArc 2.6.8.