Things that helped being able to successfully get rid of it were: proper orientation of coupling caps (paramount) and... use of selected components (resistors and caps) throughout the preamp.
Proper orientation of the coupling caps, is that the outer wrap thing or how close the middle and bass caps are go each other?
Select components, this always a controversial topic, some people swear they can hear the difference between different resistor brands while others say they don't hear it.
Gil has built quite a few amps using different brands of caps. I wonder what are the caps that work and how did how he/you determine that?
Was there a scientific approach?
EDIT: I later realised I've asked this question before.
Mark
You're an old timer here surprised you were asking about cap orientation.
For those that don't know? Cap orientation in these Dumble style amps (ODS's) is a common practice. Most of the big boys orient their caps to some extent. Some even have certain directions for certain spots. Resistors are the same way (basically) and although most of the resistors Dumble used are unobtainable many of the "Custom" ODS builders (Bludo,Two Rock, Welagan,and many others) have built amps using NOS resistors and pots for a certain sound they are chasing. This is common knowledge amongst the commercial amp building community.
Don't make me pull out my pictures..
Tony
" The psychics on my bench is the same as Dumble'"
Hi Tony, agreed this is an old topic, though not really topic that has been settled.
I have asked about capacitor orientation in the past, looking for that test that proves it works or doesn't work.
R.G.Keen definitely doesn't believe that cap orientation makes any difference whatsoever, while other people swear by it. It is good to have a standard practice while building amps, however if the step is pointless, why do it?
I can't say that when I have measured the outside wrap of a cap and wired it up to the lowest resistance to earth that the amp sounded better or was quieter. The same goes with resistors, I can't say I've heard of a test that demonstrates the sound of resistors.
I was interested in Gil's comments about using different cap types and what he achieved. Years ago I removed the two coupling caps from my Champ clone and switched between several different brands of caps. I measured all of them so not to hear a difference in value. What surprised me is that they all sounded the same. Prior to this I thought 715's sounded good between the P.I. and the output valves etc, but these results made me think twice.
I was also curious about the proximity of components to one another this could effect the timbre of an amp.
I dare say one day I will have to build a sacrificial amp with more stages where I use a Ditto to ensure a standard signal and put different caps and resistors in it while the valves, transformers, pots and speakers are the same.
Mark wrote: ↑Wed Jul 29, 2020 4:15 am
Hi Tony, agreed this is an old topic, though not really topic that has been settled.
I have asked about capacitor orientation in the past, looking for that test that proves it works or doesn't work.
R.G.Keen definitely doesn't believe that cap orientation makes any difference whatsoever, while other people swear by it. It is good to have a standard practice while building amps, however if the step is pointless, why do it?
I can't say that when I have measured the outside wrap of a cap and wired it up to the lowest resistance to earth that the amp sounded better or was quieter. The same goes with resistors, I can't say I've heard of a test that demonstrates the sound of resistors.
I was interested in Gil's comments about using different cap types and what he achieved. Years ago I removed the two coupling caps from my Champ clone and switched between several different brands of caps. I measured all of them so not to hear a difference in value. What surprised me is that they all sounded the same. Prior to this I thought 715's sounded good between the P.I. and the output valves etc, but these results made me think twice.
I was also curious about the proximity of components to one another this could effect the timbre of an amp.
I dare say one day I will have to build a sacrificial amp with more stages where I use a Ditto to ensure a standard signal and put different caps and resistors in it while the valves, transformers, pots and speakers are the same.
Mark
The only thing I'll say about that is a "Champ" is no Overdrive Special try it in an ODS style then let me know
As far as proximity of components go? It depends on the amp? however for the most part and in the case with the ODS In my experience yes proximity does matter especially an amp utilizing cascading gain stages (high gain).
Good Luck!
Tony
" The psychics on my bench is the same as Dumble'"
