AD15 Mods - Questions for the Experts

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Sooner
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AD15 Mods - Questions for the Experts

Post by Sooner » Thu Nov 15, 2018 4:56 am

Back in 1999, shortly after I bought my AD15, I went to the Orange shop on Denmark Street in London asking about a 110/220 voltage converter to use when I took the amp back to the USA. They brought Ade Emsley up from the basement to help and he explained how to rewire it for 110V so no need for a converter. Great!

He also told me about a couple of mods I could do to make it sound more "gnarly". Here are my notes from that discussion:
Image

The first mod is pretty clear. On the main board the left 2 solder tags he's talking about appear to be the C4 cap position that's empty and labeled O/C (open circuit?) on the schematic:
http://s106.photobucket.com/user/orange ... sort=3&o=1
He suggested adding a 10 mf 20V cap there. I'm wondering if it would be feasible to add a micro switch in addition to the new cap to make the mod switchable or would that potentially add noise to the circuit?

The second mod is a little more fuzzy. As I recall he was talking about replacing the 150 pf 630V silicone cap (C3 in the schematic) with a 350 pf 4000V+ cap. Does this make sense? Is going from 630V to 4000V really necessary or is that just a standard value for 350 pf caps?
http://s106.photobucket.com/user/orange ... sort=3&o=2

Any thoughts?
Sooner
AD1512 Serial No. 001

Les Paul Lover
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Re: AD15 Mods - Questions for the Experts

Post by Les Paul Lover » Thu Nov 15, 2018 3:17 pm

I read 400v+ rather than 4000?
Ant

Orange Gear: RV50 MKI, R30, AD15, AD5, PPC212
Past Orange: Orange AD30TC Combo, Tiny Terror

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Re: AD15 Mods - Questions for the Experts

Post by Sooner » Thu Nov 15, 2018 4:39 pm

Les Paul Lover wrote:
Thu Nov 15, 2018 3:17 pm
I read 400v+ rather than 4000?
Good point. I can't even read my own writing! :lol:
Sooner
AD1512 Serial No. 001

Les Paul Lover
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Re: AD15 Mods - Questions for the Experts

Post by Les Paul Lover » Fri Nov 16, 2018 4:56 pm

Sooner wrote:
Thu Nov 15, 2018 4:39 pm
Les Paul Lover wrote:
Thu Nov 15, 2018 3:17 pm
I read 400v+ rather than 4000?
Good point. I can't even read my own writing! :lol:
It happens to the best of sooner. :wink:
Ant

Orange Gear: RV50 MKI, R30, AD15, AD5, PPC212
Past Orange: Orange AD30TC Combo, Tiny Terror

Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute

Les Paul Lover
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Re: AD15 Mods - Questions for the Experts

Post by Les Paul Lover » Fri Nov 16, 2018 4:58 pm

I've also been wondering if these mods are in the 2nd channel of the AD30tc.

I love the AD15 stock though. Thick, warm, a bit dark, so responsive to playing dynamics.... Love it.
Ant

Orange Gear: RV50 MKI, R30, AD15, AD5, PPC212
Past Orange: Orange AD30TC Combo, Tiny Terror

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Re: AD15 Mods - Questions for the Experts

Post by Sooner » Fri Nov 16, 2018 8:48 pm

I don't see a cap listed as O/C on the AD30 schematics like there is on the AD15. There is however a resistor (R16) listed as O/C on the AD30. I wonder what that's about.

I like the AD15 sound as is myself too but curious what one or both of these mods would sound like. Particularly the first mod if it could be switchable that might be pretty cool.
Sooner
AD1512 Serial No. 001

Les Paul Lover
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Re: AD15 Mods - Questions for the Experts

Post by Les Paul Lover » Sat Nov 17, 2018 12:05 pm

Sooner wrote:
Fri Nov 16, 2018 8:48 pm
I don't see a cap listed as O/C on the AD30 schematics like there is on the AD15. There is however a resistor (R16) listed as O/C on the AD30. I wonder what that's about.

I like the AD15 sound as is myself too but curious what one or both of these mods would sound like. Particularly the first mod if it could be switchable that might be pretty cool.
I haven't checked the schematics for the AD30 for a long time now.

All I remember is that with a phase inverter for each channel, fitting an FX loop to the AD30tc is nigh impossible.
Ant

Orange Gear: RV50 MKI, R30, AD15, AD5, PPC212
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Re: AD15 Mods - Questions for the Experts

Post by LD50 » Wed Nov 21, 2018 3:48 pm

The best person to answer this would be Ade but I guess he does not get time to visit here now.
c4 is a cathode bypass cap. The cathode resistor of 1k5 is a very generic value for an ECC83 running a plate resistor of 100k. Adding a bypass resistor will give you a gain boost that will be quite full (if you go lower to eg .68uF or 1uF it will be brighter and maybe a bit harsh) any bigger than 25uF might be a bit bassy. Well worth a try.
Re The second mod I cannot see a 150pF cap on the main schem but on the second sheet there is a 150pF in the tone stack and doubling that cap size is probably the intention. Any cap in this part of the circuit should be 400v rated. A ceramic disc will be gnarly here, vs a silver mica and to get the right physical size to fit you might need 1kV or even 4kV to span the holes in the mini pcb on the front panel - just guessing!

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Re: AD15 Mods - Questions for the Experts

Post by Sooner » Wed Nov 21, 2018 7:35 pm

LD50 wrote:
Wed Nov 21, 2018 3:48 pm
The best person to answer this would be Ade but I guess he does not get time to visit here now.
c4 is a cathode bypass cap. The cathode resistor of 1k5 is a very generic value for an ECC83 running a plate resistor of 100k. Adding a bypass resistor will give you a gain boost that will be quite full (if you go lower to eg .68uF or 1uF it will be brighter and maybe a bit harsh) any bigger than 25uF might be a bit bassy. Well worth a try.
Re The second mod I cannot see a 150pF cap on the main schem but on the second sheet there is a 150pF in the tone stack and doubling that cap size is probably the intention. Any cap in this part of the circuit should be 400v rated. A ceramic disc will be gnarly here, vs a silver mica and to get the right physical size to fit you might need 1kV or even 4kV to span the holes in the mini pcb on the front panel - just guessing!
Thanks for the input. Those were Ade's suggestions so I assume he would agree with them if he were to visit here. My main question though is whether or not it would be feasible to add a switch to the C4 cap to make the mod switchable, or if the additional wiring would add a bunch of noise.
Sooner
AD1512 Serial No. 001

LD50
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Re: AD15 Mods - Questions for the Experts

Post by LD50 » Thu Nov 22, 2018 10:29 am

Very easy.
Neatest non invasive way would be a push pull pot.
You interrupt the end of the cap that goes to ground. So solder one end of cap to pcb that goes to the tube and raise the other. Solder one wire to this and your switch. Solder the other wire to the empty hole on the pcb and to the other half of your switch. If that is fiddly the ground wire can just go to a nearby convenient ground lug. You may need to secure the cap to the board with a dab of glue or silicone. The other way is to use a toggle micro-switch but that does mean drilling a hole in the chassis. As before there are only a few volts on the cathode so no worries about ratings. If you use a polarised electrolytic make sure that you get the +ve going to the tube direction.

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Re: AD15 Mods - Questions for the Experts

Post by Sooner » Fri Nov 23, 2018 1:34 am

LD50 wrote:
Thu Nov 22, 2018 10:29 am
Very easy.
Neatest non invasive way would be a push pull pot.
Cool idea. May have to give that a try.
Sooner
AD1512 Serial No. 001

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Re: AD15 Mods - Questions for the Experts

Post by bclaire » Fri Nov 23, 2018 4:44 pm

All of this is all well and good, but if I had serial number 001, I wouldn't touch anything. Just saying. :mrgreen:

Les Paul Lover
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Re: AD15 Mods - Questions for the Experts

Post by Les Paul Lover » Sat Nov 24, 2018 2:28 pm

bclaire wrote:
Fri Nov 23, 2018 4:44 pm
All of this is all well and good, but if I had serial number 001, I wouldn't touch anything. Just saying. :mrgreen:
I lost that from sight.....

I would defo buy another one to play around with.
Ant

Orange Gear: RV50 MKI, R30, AD15, AD5, PPC212
Past Orange: Orange AD30TC Combo, Tiny Terror

Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute

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Re: AD15 Mods - Questions for the Experts

Post by Sooner » Sun Nov 25, 2018 12:35 am

Les Paul Lover wrote:
Sat Nov 24, 2018 2:28 pm
bclaire wrote:
Fri Nov 23, 2018 4:44 pm
All of this is all well and good, but if I had serial number 001, I wouldn't touch anything. Just saying. :mrgreen:
I lost that from sight.....

I would defo buy another one to play around with.
Well with a push/pull pot it would be reversible... and it's not like the inside is still original anyway. New heater wires and master pot that are now hard wired.
Sooner
AD1512 Serial No. 001

Les Paul Lover
Duke of Orange
Posts: 6518
Joined: Tue Aug 18, 2009 9:08 am
Location: Derby, England

Re: AD15 Mods - Questions for the Experts

Post by Les Paul Lover » Sun Nov 25, 2018 8:36 am

Sooner wrote:
Sun Nov 25, 2018 12:35 am
Les Paul Lover wrote:
Sat Nov 24, 2018 2:28 pm
bclaire wrote:
Fri Nov 23, 2018 4:44 pm
All of this is all well and good, but if I had serial number 001, I wouldn't touch anything. Just saying. :mrgreen:
I lost that from sight.....

I would defo buy another one to play around with.
Well with a push/pull pot it would be reversible... and it's not like the inside is still original anyway. New heater wires and master pot that are now hard wired.

That's a shame... but unfortunately, the heater wire is a necessary improvement!!!!!
Ant

Orange Gear: RV50 MKI, R30, AD15, AD5, PPC212
Past Orange: Orange AD30TC Combo, Tiny Terror

Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute

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