Unconventional modification AFD100

[marshallmellowed]

There are no 'steps' on the EPA knob. Big Dooley just said it's doable, and I'll take his word on it. If there were steps, wouldn't the knob click? Mine doesn't.

There are "steps", but the control does not have detents for each step. Just listen as you play a chord and gradually turn up the EPA, you will hear the volume increase in steps (or increments). It's a function of the EPA circuit, not the knob itself.

 

[CaptainZero]

I'll try that. Still should work fine, just like the knob does though. Wouldn't you think?

 

[marshallmellowed]

I'll try that. Still should work fine, just like the knob does though. Wouldn't you think?

Yes, it could be made to work just like turning the EPA control, but not worth the effort to get there IMO. But hey, that's just my opinion.

 

[CaptainZero]

Yes, it could be made to work just like turning the EPA control, but not worth the effort to get there IMO. But hey, that's just my opinion.

I wouldn't do it either, but hey, some people like to mod stuff.

 

[The Ozzk]

There are no 'steps' on the EPA knob. Big Dooley just said it's doable, and I'll take his word on it. If there were steps, wouldn't the knob click? Mine doesn't.

Actually one of the improvements this amp could use is having a "stepped" knob, you know, one that you can physically feel going from one step to the next.
that was one of the things I didn't like when I had mine. Sometimes during transport the knob would move a little and it would be "in between steps"... not a good place to be.

 

[big dooley]

Actually one of the improvements this amp could use is having a "stepped" knob, you know, one that you can physically feel going from one step to the next.
that was one of the things I didn't like when I had mine. Sometimes during transport the knob would move a little and it would be "in between steps"... not a good place to be.

i agree with that...

and yes the EPA has steps, but it's regulation doesn't... it's just a dual gang potmeter like you'll find in any amp using them
me peronally wouldn't be happy with a footcontroller, that would take the powercontrol's purpose... one little itch on your toe and suddenly you're blasting trough the roof...
i'd be more happy with a switchable notch up... like in case of the YJM; that half powerswitch should've been made footswitchable

the pot used for the powercontrol is a 100K/100K lineair taper pot according to the schematic... that would mean, that each step resembles 5K...
if you place a pair of 5K or 10K in series with the pot and make that switchable, you can have some sort of boost... however, while the pot is lineair, it's effect to the EPA isn't... a 10K resistor, would make the amp twice as loud with the resistor kicked in (or out!) with the powercontrol at minimum (0.1 watt), while it is much less effective on higher powermodes

the only way i see it working is placing another powercontrol 100K/100K pot in parallel with the existing one and make it switchable between the first one or the other one... which would work similar to the twin mastervolumes on the JVM-series for example... but even then... i don't know how the EPA would react to the moment of switching itself

 

[gianluca93]

Varying the EPA does modify the tone, anytime you change the volume you are going to modify the tone, that's just a fact. All frequencies do not stay linear with volume (Fletcher Munsen). Plus, as someone already stated, the EPA control works in steps, so even if you did add a foot control the results would not be desirable. In addition, varying the EPA probably modifies the tone more than a volume pedal would, as you are not only changing the volume, but also changing the voltages on the output tubes when varying the EPA. Sorry, but I see no advantage to a modification of this type.

So Marshall is basically lying when they say that one could keep his badass tone at bedroom level varying the EPA

https://www.youtube.com/watch?v=9smsqmkWK0k

minute 3.11

 

[big dooley]

no it means, that the human ear is the worst instrument you can have to "measure" sound, as it is too susceptible for so much variables out there

 

[marshallmellowed]

So Marshall is basically lying when they say that one could keep his badass tone at bedroom level varying the EPA

https://www.youtube.com/watch?v=9smsqmkWK0k

minute 3.11

No, he says the EPA will allow you to get power amp distortion at bedroom levels, not that it will sound the same at .1w as it would with the EPA off (EPA set for full volume). In another post here on the forum, Santiago explains that this is not possible.

 

[gianluca93]

My original idea was something like that :

A/B/Y pedal (A+B Mode) 2 AFD100/YJM100 (having an uncle who owns a club has it's pros ) or 2 other amp equipped with external attenuators as Left and Right "speakers" and then mess with the EPA to sort of "move" the sound from left to right and vice versa "progressively" while playing... that's why I needed 2 potentiometer pedals and asked if the mod was doable (and it seems doable according to big dooley) got the idea from the middle section of whole lotta love , maybe I should re-think something tho

 

[The Ozzk]

My original idea was something like that :

A/B/Y pedal (A+B Mode) 2 AFD100/YJM100 (having an uncle who owns a club has it's pros ) or 2 other amp with external attenuator as Left and Right "speakers" and then mess with the EPA to sort of "move" the sound from left to right and vice versa "progressively", that's why I needed 2 potentiometer pedals , got the idea from the middle section of whole lotta love , maybe I should re-think something..

You remind me of somebody who loved Leslie speakers and Hammond organs.

 

[gianluca93]

You remind me of somebody who loved Leslie speakers and Hammond organs.

that's an insult or a compliment in your book???

 

[The Ozzk]

that's an insult or a compliment in your book???

Neither, just an observation.

 

[gianluca93]

I guess the smartest/cheapest thing to do is to borrow 2 attenuators and then have 2 friends messing up with the EPA and see how it sounds...

 

[mickeydg5]

Does the EPA track well in realtime?

 

[gianluca93]

Does the EPA track well in realtime?

What do you mean??

 

[big dooley]

i think he's asking if the effect of turning the control is instant and doesn't have latency
well... it's just like turning a mastervolume, but it goes in steps

 

[gianluca93]

i think he's asking if the effect of turning the control is instant and doesn't have latency
well... it's just like turning a mastervolume, but it goes in steps

Really close steps tho...I do think it would sound sort of natural..

 

[big dooley]

it depends...
from 0.1 watt to 1 watt the steps are quite big,
from 1 watt to 12 watt the steps are noticable
and from 12 watt upto full tilt you can barely hear them

 

[gianluca93]

it depends...
from 0.1 watt to 1 watt the steps are quite big,
from 1 watt to 12 watt the steps are noticable
and from 12 watt upto full tilt you can barely hear them

Thanks for your support and always accurate info&advises