Modding an amp for more gain.

[somedude]

As a bit of background, I have an Orange AD140 that I really like the tone of but I'm finding it a little lacking in the gain department. It's not that I'm a gain-head by any means, but I like to have a certain level of saturation/sustain available it's falling short. I've tried various stomp boxes and I don't like how they all change the tone, particularly they way they emphasize the pick attack and make the strings sound stiff.

Anyway, long story short I'm now considering adding another gain stage and I'd like to know what all is involved in this kind of mod? The AD140 has two channels, each of which has it's own separate preamp (each channel has it's own V1 and PI). I would only want to mod one channel.

[rockon1]

Hit the front end with a clean boost. My cheapo Seymour Duncan pickup booster doesnt color the sound and realyy pushes an amp into OD. Bob

[epluribus]

Before you add a gain stage, have you looked into changing the existing ones a bit? Personally, I've had terrific luck by tweaking plate voltages, bias (natch), and plate load resistors. Bypass caps are another great tool for gain structuring. I've done several variants of all these things to all the gain stages in my little bench-top guinea-pig amp, and the impact on gain structure, saturation, feel, and dynamics is huge. Not to mention S/N, detail and tone... ;)

--Ray

[jjasilli]

Ditto to all the above. It's not clear if you want more gain, or just earlier break-up. If you want to avoid pedals, then epluribus has a solution.

[donnyjaguar]

I agree with Rockon. I have a DOD tube screamer that when you turn the overdrive all the way down becomes basically a high-gain preamplifier. The level can then be used to supply the appropriate drive to the amplifier.

That said, you can often modify the voltage amplifiers for more gain but the tone is likely to change and I don't think that's your goal.

DJ

[epluribus]

I agree with Rockon. I have a DOD tube screamer that when you turn the overdrive all the way down becomes basically a high-gain preamplifier. The level can then be used to supply the appropriate drive to the amplifier.

That said, you can often modify the voltage amplifiers for more gain but the tone is likely to change and I don't think that's your goal.

DJ

Hey DJ, I agree with both you and Rockon, a clean boost is just too easy a way to go if you want to spank the front end. Much easier than rewiring in any event, not to mention far more flexible, gain and EQ-wise. Jm2c, I use a comp to do that, a Humphrey Audio modded Boss CS-3. The really cool part of doing this is that you can kind of preview what an added gain stage will do for you if end up deciding to put the amp under the knife.

Oh yeah, one mo' thang...the tube screamer trick--isn't that what SRV actually used his for? That seems to be the prevailing conventional wisdom on the web, and we all know what a wonderfully reliable source web CW is. ;)

Ditto to all the above. It's not clear if you want more gain, or just earlier break-up. If you want to avoid pedals, then epluribus has a solution.

Ha! I got one right! I'm postin' this on the fridge! :BEER

--Ray

[stratotone]

Can change plate resistors on the preamp, add cathode bypass caps on preamp stages that lack them, or change values of cathode resistors. That'll add more gain.

Pete

[HipKitty]

Before you add a gain stage, have you looked into changing the existing ones a bit? Personally, I've had terrific luck by tweaking plate voltages, bias (natch), and plate load resistors. Bypass caps are another great tool for gain structuring. I've done several variants of all these things to all the gain stages in my little bench-top guinea-pig amp, and the impact on gain structure, saturation, feel, and dynamics is huge. Not to mention S/N, detail and tone... ;)

--Ray

+1 to this experimentation. You'd truly be surprised at how much gain/distortion you can get out of just 1 1/2 out of a pair of 12ax7a's let me check into the schematic and see what can be done....

[HipKitty]

Maybe this can be of some help:

http://users.telenet.be/orangefg/orange_mods.htm

[somedude]

Maybe this can be of some help:

http://users.telenet.be/orangefg/orange_mods.htm


I found these on that site;

http://users.telenet.be/orangefg/OFG_SCHEM/AD140TCmainboard.pdf
http://users.telenet.be/orangefg/OFG_SCHEM/AD140TCmainboard2.pdf
http://users.telenet.be/orangefg/OFG_SCHEM/AD140TCfrontpanel.pdf

But I'm afraid I'm not experienced with amps to actually understand what does what.

[stvnscott]

You can increase the overdrive in the amp without adding actual gain (or at least not much), which can lead to noise or instability. Start by replacing the preamp cathode resistors with 820R. This will make each gain stage clip more easily.

[WaltC]

If you've not looked inside a new AD140C Orange lately, it's not a place you'd want to send an unsuspecting amateur. PC-board mounted tube sockets, surface mounted pc-board 1/4w resistors, coupling caps and jumper wires connecting differing parts of the pc-board. Very little correspondence between the schematic and the physical layout of the circuit board. No published layout diagrams, and (finally <G>) the above listed schematics are the Trace Elliot developed ones, not necessarily the same (is several instances I know they're not the same, the AD30HC and combo models) as the shipped Orange Amp schematics. I don't have my Orange schematics here at home (I'm an auth. Orange service "center" <G>), but adding a quality clean boost or relatively transparent OD pedal (Any of the Xotics, AC, RC or BB, G2D Cream Tone, etc.) is IMHO a much preferable method of getting where the OP wants to go, easier and cheaper (even at $250 a pedal <G>).

My 2¢...

[epluribus]

If you've not looked inside a new AD140C Orange lately, it's not a place you'd want to send an unsuspecting amateur. PC-board mounted tube sockets, surface mounted pc-board 1/4w resistors, coupling caps and jumper wires connecting differing parts of the pc-board. Very little correspondence between the schematic and the physical layout of the circuit board. No published layout diagrams, and (finally <G>) the above listed schematics are the Trace Elliot developed ones, not necessarily the same (is several instances I know they're not the same, the AD30HC and combo models) as the shipped Orange Amp schematics. I don't have my Orange schematics here at home (I'm an auth. Orange service "center" <G>), but adding a quality clean boost or relatively transparent OD pedal (Any of the Xotics, AC, RC or BB, G2D Cream Tone, etc.) is IMHO a much preferable method of getting where the OP wants to go, easier and cheaper (even at $250 a pedal <G>).

My 2¢...

Ruh-Roh, bummer...the Amp Chassis Page seems to no longer be with us. They had a terrific collection of chassis photos, would have been interesting to see this one. 'Preciate the heads up, Walt.

--Ray

[somedude]

Ruh-Roh, bummer...the Amp Chassis Page seems to no longer be with us. They had a terrific collection of chassis photos, would have been interesting to see this one. 'Preciate the heads up, Walt.

--Ray

Sorry about the quality, it's what I could find on the internet. I'll try to borrow a camara tomorrow.

http://users.telenet.be/orangefg/OFG_AD140TC/AD140TCPCB.jpg

http://users.telenet.be/orangefg/OFG_AD140TC/AD140TCInside.jpg

[somedude]

but adding a quality clean boost or relatively transparent OD pedal (Any of the Xotics, AC, RC or BB, G2D Cream Tone, etc.) is IMHO a much preferable method of getting where the OP wants to go, easier and cheaper (even at $250 a pedal <G>).

My 2¢...


Cheaper if I find the right pedal on the first or second time around the block. I've been through well over $1000 worth of OD pedals already trying to find what I'm after, and I just spent another $160 last night trying yet again (OCD+shipping).

Fortunately I don't take a full loss when I resell them, but it does add up over time.

[rockon1]

Cheaper if I find the right pedal on the first or second time around the block. I've been through well over $1000 worth of OD pedals already trying to find what I'm after, and I just spent another $160 last night trying yet again (OCD+shipping).

Fortunately I don't take a full loss when I resell them, but it does add up over time.

Have you tried a simple clean boost? An inexpensive EQ pedal run flat might tell you if its what your after. You can get something higher quality if its what your after. Dont much like any OD pedals for goosing an amp but I like clean boosts -no coloring of the sound. Bob

[somedude]

Have you tried a simple clean boost? An inexpensive EQ pedal run flat might tell you if its what your after. You can get something higher quality if its what your after. Dont much like any OD pedals for goosing an amp but I like clean boosts -no coloring of the sound. Bob

I've used a few low gain ODs (Barber LTD) but not a pure clean boost. Given how fast clean boosts seem to rise in price based on public opinion I'm trying to track down a MicroAmp locally to test before I take any steps in that direction.

The thing is that I don't actually want more gain per se.... the gain 'sound' of the amp is already right where I want it. What I want is more compression/saturation whilst retaining that same sound (well, retaining as much is as reasonable possible).

[epluribus]

Boy, you ain't kiddin' Walt, that's a rather daunting prospect there. If I was newer at tinkering and wanted to try tackling a circuit like that, I'd have to find an old PCB out of something and practice my soldering technique on that first. But tell ya what, if I couldn't handle swapping out a few resistors, I'm not real sure I'd want to go tryin' to add an entire gain stage to this pup either. :)

--Ray

Sorry about the quality, it's what I could find on the internet. I'll try to borrow a camara tomorrow.

http://users.telenet.be/orangefg/OFG_AD140TC/AD140TCPCB.jpg

http://users.telenet.be/orangefg/OFG_AD140TC/AD140TCInside.jpg

[epluribus]

I've used a few low gain ODs (Barber LTD) but not a pure clean boost. Given how fast clean boosts seem to rise in price based on public opinion I'm trying to track down a MicroAmp locally to test before I take any steps in that direction.

The thing is that I don't actually want more gain per se.... the gain 'sound' of the amp is already right where I want it. What I want is more compression/saturation whilst retaining that same sound (well, retaining as much is as reasonable possible).

Wasn't aware you'd already tried the pedal thing...hm...

Y'know you might take the amp with you to a guitar shop and ask if you can try out some pedals right there in the store. From your description, I'm suspecting even more that a comp with some good clean gain is going to be a good place to start looking. It'll let you check out the idea of another gain stage in front, and may just suit your compression desires outright. But in any event, an afternoon doing some good demos won't cost you any more money, and it'll tell you a ton about what the amp is trying to do.

--Ray

[rockon1]

I've used a few low gain ODs (Barber LTD) but not a pure clean boost. Given how fast clean boosts seem to rise in price based on public opinion I'm trying to track down a MicroAmp locally to test before I take any steps in that direction.

The thing is that I don't actually want more gain per se.... the gain 'sound' of the amp is already right where I want it. What I want is more compression/saturation whilst retaining that same sound (well, retaining as much is as reasonable possible).


How about an actual compressor pedal? Bob

[somedude]

I have a Retro-Sonic Compressor. It's a copy of the old MXR DynaComp. It worked pretty good at doing what I wanted with PAFs, but with higher output hums it gives a squashed 'compressor' feel/sound to the tone.