OR-80 Overdrive vs OR-120 tone and volume differences?

[Delicieuxz]

I have an OR-80 Overdrive with the master volume, and a friend has an OR-120 without a master volume.

My friend says he needs to have the gain turned around 3/4 of the way up before he starts getting breakup from the amp. But on my OR-80 OD I get breakup almost as soon as the gain is turned up, and I have to run the gain dialed just about all the way down to keep the amp clean.

Why do our amps function so differently on the gain dial? Also, do the OD and non OD versions of the Orange OR 80 / 120 sound different from each other at all?

I'm wanting to get more clean headroom out of my amp. Will I have to sell it and get a non-OD version to have comparable headroom to my friend's non-OD OR-120?

Here's a photo of how far I can turn the gain dial up before it starts breaking up.

[bclaire]

Put your master all the way up and see how it is....

[Delicieuxz]

Hi bclaire, thanks for the reply.

As shown in the photo of my amp settings I posted, my master volume is all the way up.

I have JJ EL34 and Beijing Shuguang 12ax7 tubes in the amp right now.

I did a storm of reading about differences between the 70's Orange amps yesterday and I currently have the impression that the earlier non-OD versions might have more clean fidelity than the '74 and later ones. I also read that a small amount of re-wiring can make the OD version just like the earlier non-OD ones.

http://www.orangefieldguide.com/overdrive_page.htm

The overdrive heads are indeed graphics with the dual master added. The unfortunate side effect of the 1 meg dual pot is that even cranked all the way up it messes with the overall volume and tonal response a little bit. I change that master to Ken Fischer's dual master that simply replaces the 220K bias resistors, and IMO it not only sounds better, but
you get the fully cranked sound and it really improves the fidelity of the clean sound.

One more important point in reference to the orange circuits is that they changed the circuit in '74, and rewired the phase inverter. I suggest to anyone that has a '74 graphic or later, including the overdrive, to switch to the old circuit. It only takes about a half hour to rewire it, and incidently Mike Soldano use to offer this mod when he was in L.A. and obsessed with Oranges. (he actually still offers it). It really makes the amp more punchy and responsive. The post '72 amps IMO can sound kind of mushy, not as dynamic as the earlier ones. Orange continued to make some more little circuit changes around '76 and IMO those amps are the worst they ever made.

I don't know if those are the only differences between the early '70s and the mid and late '70s Orange amps. I have downloaded the schematics for the '72 and the '74 revisions though, so if I have work done on my '78 OD I'll have it reviewed.

What I guess are the things that can be done to make my amp have the early '70s response and fidelity is to disconnect the PPIMV and replace any different values with the '72 version values.

That huge clean headroom is very important to me and is what I want the amp for. So, I wonder if my only options here are to rewire my OR-80 OD, which is currently all stock (and I would find it unfortunate if I had to change that and possibly impact its collector's and historical value - as it is one of the most pristine condition classic Orange amp I've seen), or to sell it and buy a pre OD one.

If you have any other thoughts and ideas, please share them with me.

[megalithic]

Have both amps been biased recently? If so, were the plate dissipation percentages similar?

[Delicieuxz]

My friend's OR120 was rebiased recently after he had 2 of its tubes pulled to bring the wattage and volume down a bit.

My OR80 OD was reportedly serviced shortly before I bought it, with new tubes installed. I suspect it's biased properly because the sound is pretty good and clear, while still within its clean headroom range. I momentarily tried some other tubes I have in it, and they sounded really muddy, and that gave me an impression that they were running too hot in the amp and that it's biased properly for the JJs that came in it.

By the way, my friend lives on the other side of the country as me, and so I haven't compared the volumes of our clean sounds next to each other. But I can actually bear to play my OR80 OD with it at its maximum clean volume while standing next to the amp, without needing any hearing protection. I cannot do that with my JCM 2203.

[megalithic]

My OR80 OD was reportedly serviced shortly before I bought it, with new tubes installed.... But I can actually bear to play my OR80 OD with it at its maximum clean volume while standing next to the amp, without needing any hearing protection. I cannot do that with my JCM 2203.

If you're using the same cab as the JCM, I expect the word "serviced" to have been used really loosely by the former owner.

[LD50]

The circuits of post 73 OR120s and the 80 overdrives are not that different, the MV in the circuit is not the purest type and will always give a little grit and distortion.
Personally I would also advise your friend not to pull output tubes on a healthy OR120 (the volume drop is minimal, the cab options are decreased as you have to us the 8 ohm selector for a 16ohm cab to ensure you do not have an impedance mismatch and the two tubes left will get more hammer as you have two less tubes which means less of a voltage drop, but up to him!)
Speakers are important (greenbacks or T75s are less efficient than lets say G12Hs or at the extreme JBL120s so bear that in mind too.
If you want clean fidelity consider 5751 or Phillips JAN 12AX7s as they are of cleaner type.

[Delicieuxz]

Thanks for the insightful information, everybody.

I spotted this video of another OR-80 OD, in which it sounds like it's pretty darn clean with the gain knob at 50% - which is quite different than what I get from my OR-80 OD:

https://youtu.be/Ct0_6t8mYzM

I use Lace Sensors which are higher gain, though, but I don't know if they can account for that much of a difference in clean headroom. I also notice that when turning the master volume down on the amp, the amp will distort sooner on the gain dial. Yet the place I've shown the gain knob to be in an earlier photo where I start to get distortion is with the master volume turned up to its maximum.

Ultimately, I really like the Orange sound and the sound of this amp, but I want to have the '72 Orange circuit. So, I have a couple of questions about that:

1. Is it feasible for me to have my OR-80 OD modded to be exactly like the official '72 schematic?

2. Would it be cheaper and more practical for me to mod my OR-80 OD to be like the '72, or to sell mine and get an actual '72?

[LD50]

Please post some internal pictures (Hi res if possible) of your amp.
Pay attention to the board and the controls (ie pots and FAC switch).
It may have been messed with and we can point you in right direction of getting the original tone you seek.

[Delicieuxz]

I might open it up to take additional photos, but for now here are a couple of internal photos I took a while ago. No work has been done on the amp since I got it over 2 years ago.

[Delicieuxz]

Here are some pictures the person who owned it before me took:

[Delicieuxz]

I've found that if I lower my guitar's pickups and stay off of the bridge pickup, I can get very clean sound from the amp with the settings at about what they're shown in this video:

https://youtu.be/Ct0_6t8mYzM

So, the guitar pickups and setup are playing a big role here.


What do people think of the comparison here between a vintage OR-80 (with PPIMV modded in) and a vintage OR-80 OD?

https://youtu.be/aB2QAscsjCk?t=183

The OR-80 sounds brighter than the OD, perhaps with more sizzle and cut. But I wonder if that's just a difference of pot values or something that's can be compensated for with the amp settings.

Edit: I notice that in the comparison video the non-OD OR-80 has its presence set to maximum, while the OD OR-80 has it set to 50%. So that's why the non-OD one sounds much brighter.

[LD50]

Looking at your amp it looks pretty clean, the wiring has been nudged around a little, can't tell why.

The PI output couplers on these are normally 0.068uF, there are two pairs two for the cathode side and two for the anode side from the PI either side of the MV dual 1M pot. On yours the caps closest to the valves (downstream from the pot) have been replaced with 0.047uF (aka 47nF) ones. Presumably to trim some bass off in the power stage?

Yours also has the second 220k resistor to ground just before V2a which is presumably to dump a little gain (voltage divider. I've only seen the 220k before the V1a grid on later Oranges. There is a 470k to ground used by Matamp on their mid 70s GT100.

You could get a bit more gain/headroom by lifting one of these resistors or even subbing for a 470k or even 1M resistor.

[megalithic]

I might open it up to take additional photos, but for now here are a couple of internal photos I took a while ago. No work has been done on the amp since I got it over 2 years ago.

Can't say I'm an expert in electrolytic capacitor brands, but they don't look that new and they should probably be replaced after 25 years.

Someone else may have a better idea, seems like that company is still in business, but I couldn't find that they still make electrolytic caps.

The amp will still work if those caps are faulty, but it won't be as loud and may cause some other components to fail.

Nice amp, by the way.

[LD50]

Can't say I'm an expert in electrolytic capacitor brands, but they don't look that new and they should probably be replaced after 25 years.

Someone else may have a better idea, seems like that company is still in business, but I couldn't find that they still make electrolytic caps.

The amp will still work if those caps are faulty, but it won't be as loud and may cause some other components to fail.

There is an element of truth in the above, although personally, I am against the didactic replacement of working filter capacitors in a fully functioning vintage amp. Having changed the voice of some old amps with a recap (and not always for the better) I will replace when caps are failing (ghosting, ripple hum, physically leaking electrolyte) without hesitation.
In this case if the amp is not as loud and clean as you wish or it has become a little noisy with mains hum coming through then a cap change may help. For this you need x2 100uF 500v radial cans for the mains caps on the chassis,
x2 32uF (or 33uF 500v) axial caps for the screens, x2 16uF 500v axial caps for the preamp. Sometimes 16uF is hard to find so I would go up to 22uF rather down to 15uF.
I think the TAD versions are best.