Strange wreck experience, worth a listen though.

JamesHealey · Post by **JamesHealey** » Sun Sep 27, 2009 7:11 am

I was round at a friends house tweaking a wreck based amp I made for him, we started out by just having a good visual inspection of the amp and upon looking through the amp I spotted a 1/2w resistor and decided to upgrade this resistor with a 1w of the same value.

Well it threw the amp out completely it sounded so much more trebly and dynamic and vintage.. I was gob smacked, he really didnt like this so we put the original resistor back and didn't sound as good as it did before... so we spent some time tweaking lead dress and made a few leads a tad longer and increased the grid stoppers on the power tubes to shave off some of that high end.

wow how tempremental this amp was totally suprised me, but by the end of the day we had a far superior amp than we started with in the morning.

Structo · Post by **Structo** » Sun Sep 27, 2009 6:02 pm

Where was this resistor and what do you attribute the change in tone to?

Also, what composition were the two resistors in question?

gearhead · Post by **gearhead** » Sun Sep 27, 2009 7:42 pm

It also depends on the variance. A 100k could be, nominally, 105k or 95k.

I ended up with a set of the CDE 40 uF that are 10% on the low side. Am trying to leave space for another electrolytic if needed, lol.

JamesHealey · Post by **JamesHealey** » Mon Sep 28, 2009 9:16 pm

it was the 150k grid leak on the 2n2 cap, they were both carbon film resistors.

67plexi · Post by **67plexi** » Wed Oct 07, 2009 6:17 pm

James, Did you use a heat sink when soldering the resistor ?
I will buy a 100 resistors at a time and measure the value
90% will be out of spec. so you get 10 good resistors
this will change voltage readings.
Do you have a cap. tester ? at 10% +or_ value on Mallory PVC.
Tube tester is a must and a fluke VOM. next a scope frequency generator.

JamesHealey · Post by **JamesHealey** » Thu Oct 08, 2009 7:37 pm

I used the same resistor again, I didnt use a heatsink when soldering.

I have a good Digital Multimeter, Scope and Signal Generator, Dummy Load etc.. pretty well geared up I can't understand this phenominon at all but hey thats half the interest of something as unstable as a wreck.

PaisleyTube · Post by **PaisleyTube** » Sat Oct 10, 2009 9:22 am

I did experience some > 40k readings on some 22k CC resistors over here, new......

Always measure Rs...

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