Differences Between ORS, GRO & OR Models

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mflemmer2
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Differences Between ORS, GRO & OR Models

Post by mflemmer2 » Mon Oct 02, 2017 3:12 am

I've recently developed an obsession with the early era of Orange amps, and am trying to become more educated. I have a fairly good understanding of the OR series and later, but am more interested in the earliest models. Besides wattage and "pics only vs text", what are the basic differences between the ORS, GRO & OR models? I believe that the F.A.C. is after the preamp circuitry in the OR's, and before it in the GRO's. Also, that their tone is similar, with the GRO being slightly cleaner and less fuzzy when overdriven. Finally, the ORS didn't have an F.A.C., I think. Besides that, I can't find any other distinctions between these three. Does anyone have some clear info? Thanks in advance.

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Re: Differences Between ORS, GRO & OR Models

Post by Gladmarr » Mon Oct 02, 2017 10:16 pm

You can review the schematics at the Orange Amps Field Guide (link below). There are differences in the EQ, the phase inverter, the order of sub-circuits, the addition and subtraction of different components. They're all great amps to be into. They've held my attention for almost 20 years at this point.

fiveightandten
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Re: Differences Between ORS, GRO & OR Models

Post by fiveightandten » Mon Oct 02, 2017 11:26 pm

Here's some circuit info I put together, though it's really centered around the OR amps.

viewtopic.php?f=2&t=55823

Back in the day of the Plexi Palace forums, a member with no posts messaged me saying that he had an old Orange head in great shape he wanted to sell. He was an older gentleman and said he bought the amp new, but that it had been sitting in a closet for many years and he wanted it to go to someone who would appreciate it. He didn't have a camera to show me pictures. He didn't have PayPal, or anything other than a phone number. I'm in CT and he lived in CA. After a phone call, I felt confident enough to take a chance. I sent a postal money order out to his address in CA.

3 days later, I had a box at my doorstep. He didn't even wait for the money to come. He sent the amp out and it was exactly as described. That was in 2004 or so. So, mine is GRO100 #559. It's a plexi panel amp, large pics only.

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When I got it, I contacted Orange via email attempting to get info about the amp. Cliff Copper himself replied (some 10 months after I sent the email :mrgreen:) and told me that it was produced in 1971.

In March 2011, I was contacted by someone else through the forums. He said he had heard about my GRO100 and wanted some information and pics on it for a feature in his magazine. I sent him some details and photos (including the one above), and a month later, the amp was featured in the April 2011 issue of Vintage Guitar.

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Mine doesn't match either of the GRO schematics on the OAFG (#463 and #842). The tone stack cap values are different (with those 2 also being unique to one another).

The GRO's have smaller coupling caps (.047). They let less low end through. The presence knob on mine barely does anything. It's more effective when the amp is loud, but it's still nowhere near as responsive as the presence on an OR amp. The sound is warmer, less fuzzy, and more clear. It's a great sounding amp.

Mine has a 115V primary on the PT. The plate voltage is about 515V, and my heaters are about 6.8 VAC. It's running hotter than it should.

The output transformer was unfortunately long gone when I got the amp. It had a Dangall out of an old Marshall in it when I bought it. I replaced that with the only drop in replacement that was available at the time...the AD140 OT. I bought that from Orange and it's been in the amp ever since.

It had the standby switch in it when I got it as well. I've been meaning to clean that up a bit, and replace the rest of the filter caps that are original. It normally has a bolt in shield over the FAC knob and inputs, that's removed so you can see what's going on. Original signal caps are WIMA. B+ rail electrolytics were Dubliner (I replaced most with Sprague atoms, they were SHOT when I got the amp). The big cans are 150 mfd, not 100 as you see in the OR amps. Well, I know this is a book, but you said you wanted to talk shop, so here it is!

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'71 GRO100 || '96 OR-80 || AD30 || '64 AC-50 || AC-30TBX || Hiwatt DR504 || HI-TONE HT30
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mflemmer2
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Re: Differences Between ORS, GRO & OR Models

Post by mflemmer2 » Tue Oct 03, 2017 4:02 am

fiveightandten, thanks for the info. While I have a decent understanding of electronics, I can only get so much from merely looking at a schematic when it comes to how it affects the sound. However, if someone explains that a certain capacitor or resistor is a different rating, and that affects the sound in a certain way, it makes sense. So, I think you basically confirmed what I had heard regarding the GRO vs the OR---less low end, less fuzzy, more clear. I'm not sure how that would translate to it being warmer, unless it's how the mids are voiced. Perhaps warm and dark aren't the same thing in this case, because the OR series can certainly sound dark, dense and thick. Of course, with the F.A.C. on the right setting, they can also have a Vox-like brightness and chime with lower gain settings. Perhaps the GRO is a bit less aggressive overall, in both the lows and highs? Does it have an F.A.C. at a different place in the circuit?

Also, if anyone can contrast the ORS variety with these two, I would appreciate it. Keep the info coming!

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Re: Differences Between ORS, GRO & OR Models

Post by fiveightandten » Tue Oct 03, 2017 12:21 pm

mflemmer2 wrote:
Tue Oct 03, 2017 4:02 am
fiveightandten, thanks for the info. While I have a decent understanding of electronics, I can only get so much from merely looking at a schematic when it comes to how it affects the sound. However, if someone explains that a certain capacitor or resistor is a different rating, and that affects the sound in a certain way, it makes sense. So, I think you basically confirmed what I had heard regarding the GRO vs the OR---less low end, less fuzzy, more clear. I'm not sure how that would translate to it being warmer, unless it's how the mids are voiced. Perhaps warm and dark aren't the same thing in this case, because the OR series can certainly sound dark, dense and thick. Of course, with the F.A.C. on the right setting, they can also have a Vox-like brightness and chime with lower gain settings. Perhaps the GRO is a bit less aggressive overall, in both the lows and highs? Does it have an F.A.C. at a different place in the circuit?

Also, if anyone can contrast the ORS variety with these two, I would appreciate it. Keep the info coming!
The GRO has the same circuit elements that the OR amps have, they're just in a different order, and slightly altered.

TONE STACK:
The GRO tone circuit is the same Baxandall type as the OR amps, but it's much later in the pre-amp. The earlier gain stages distort the signal, then the tone circuit filters it. In the OR amps, the tone circuit is in the first pre-amp stage, so it applies filtering very early, then that filtered signal gets distorted by the other gain stages. The frequency response of the GRO tone stack is different from the OR amps, as some of the cap values are different. Then again, the OR amps differ from each other as well.

www.duncanamps.com has a software program called the Tone Stack Calculator. You can download it and plug different component values into the "James" circuit if you want to see how the GRO and OR tone stack frequency response differs.

FAC:
The GRO FAC knob is the very first thing after the inputs in my amp, and in #463. In #842, there's a pre-amp stage before the FAC knob. So they clearly differed a bit, even from each other. The FAC knob on the OR amps seems to affect the gain structure more than my GRO. In the OR, the FAC affects the gain quite a bit, and makes the amp sound more aggressive and more fuzzy as you click it left. It also has a more abrupt transition into breakup, which is very apparent if you roll the guitar volume back for cleans. The GRO FAC knob, in comparison, doesn't affect the aggressiveness or response of the amp as much. It's mostly affecting the low end, overall girth of the tone, and the gain. The OR sounds distinctly more raunchy at left settings, and warmer and more polite towards the right. The GRO FAC doesn't alter the amp's character as much. The cap values are different, and the OR FAC is being fed by a lot more input gain.

PLATE CAP:
Another notable difference in the frequency response is the filtering cap on the plate of the last gain stage (before the PI triode). This cap filters out highs. It was likely put there to keep the amps from oscillating, as I've removed it in a few ORs and found that they oscillate at high volumes with high treble and/or presence settings. I ultimately put it back in. The GRO has a different value than the OR amps for this cap. Some people take the cap out, and it makes the amp considerably brighter. It has a dramatic affect on the sound, so even just a different value, like the GRO circuit, will make quite a notable difference.

SOUND:
The warmth of the GRO is probably due to the pre-amp topology being different (FAC early on, tone stack later), and due to the PI circuit. There were a few different PI circuits used, and they seem to yield varying amounts of symmetry in the power amp, when driven hard.

Basically, the OR amps were all the same DNA as the GRO, but with the circuit elements put together in a different order and with different values. Is the same basic idea, but yields a bit of a different flavor. Anyone who likes OR amps but finds them too brash or fuzzy, would love a GRO. If you're looking for the raunchiest most fuzzy stoner rock tone, the OR amps are a better choice (and the later circuit at that). My OR amp is a lot less polite and more aggressive than the GRO. The GRO is more clear, warmer, and less harsh. It has some snarl to it, but it's a bit of a different sound.
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'71 GRO100 || '96 OR-80 || AD30 || '64 AC-50 || AC-30TBX || Hiwatt DR504 || HI-TONE HT30
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mflemmer2
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Re: Differences Between ORS, GRO & OR Models

Post by mflemmer2 » Tue Oct 03, 2017 10:16 pm

Very interesting, that all makes sense. Thanks a lot for that thorough explanation. Anything on the ORS? I know it may have been one of the earliest, if not THE earliest variant. I had thought it might be essentially the same as the OR, given the name similarity, but now I'm guessing it's not. Your thoughts?

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Re: Differences Between ORS, GRO & OR Models

Post by fiveightandten » Wed Oct 04, 2017 1:34 am

mflemmer2 wrote:
Tue Oct 03, 2017 10:16 pm
Very interesting, that all makes sense. Thanks a lot for that thorough explanation. Anything on the ORS? I know it may have been one of the earliest, if not THE earliest variant. I had thought it might be essentially the same as the OR, given the name similarity, but now I'm guessing it's not. Your thoughts?
I don't know much at all about the ORS. A quick google search yields some good info here:

https://ivanrichards.com.au/2013/06/10/ ... 100w-head/

I see the lower value 0.047 mfd coupling caps, like the GRO. This amp has PCB mounted pre-amp tubes, laydown transformers, and a non-adjustable bias circuit. He mentions that the choke is placed before the plates, which is the same as GRO #463 (GRO #842 has the choke after the plates and before the screens). The OR circuits differ in this respect as well with the post '74 choke taking the whole B+, and the earlier amps taking from the screens onward.

The early OR amps I've worked on that had this PCB setup with laydowns and non-adjustable bias were always running very cold...like on the order of 8W per tube. This is part of their sound.

As I've never seen an ORS in the flesh, I can't really comment much on it. But from the pics on this website, I would guess that it's very similar to the GRO circuits and probably sounds pretty similar too. These amps were all wired up a little different though, as there's evidence of a number of different circuit versions. So it almost seems like each should be assessed as unique. There were likely a good number of each circuit iteration produced. But there's really no saying how many are still around.

Do you have any pictures of the insides of your ORS?
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'71 GRO100 || '96 OR-80 || AD30 || '64 AC-50 || AC-30TBX || Hiwatt DR504 || HI-TONE HT30
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mflemmer2
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Re: Differences Between ORS, GRO & OR Models

Post by mflemmer2 » Thu Oct 05, 2017 10:33 pm

I don't have an ORS, I was just wondering about the differences between the 3 models, since they're the earliest. I'm much more in love with their vintage models, as opposed to the variants that have been made since Orange reopened their doors (e.g. the AD, TV, RV and TH series). However, I tend to be nostalgic with the old British amp brands. There is certainly much to love about either the TV or RV. The OR80 or OR120 are still my faves, largely for nostalgic reasons, but the OD's are cool since it's like an OR with a master volume. I'd love to get a Rockerverb if I could afford another amp, but my wife would kill me---she gets mad enough over me getting new pedals. I may have to settle for a Wampler Catapulp (which emulates a RV), and not tell her about it. :D

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Re: Differences Between ORS, GRO & OR Models

Post by fiveightandten » Fri Oct 06, 2017 1:38 am

mflemmer2 wrote:
Thu Oct 05, 2017 10:33 pm
I don't have an ORS, I was just wondering about the differences between the 3 models, since they're the earliest. I'm much more in love with their vintage models, as opposed to the variants that have been made since Orange reopened their doors (e.g. the AD, TV, RV and TH series). However, I tend to be nostalgic with the old British amp brands. There is certainly much to love about either the TV or RV. The OR80 or OR120 are still my faves, largely for nostalgic reasons, but the OD's are cool since it's like an OR with a master volume. I'd love to get a Rockerverb if I could afford another amp, but my wife would kill me---she gets mad enough over me getting new pedals. I may have to settle for a Wampler Catapulp (which emulates a RV), and not tell her about it. :D
I agree. There are a handful of us that prefer the older amps. I've owned a few OR-80/120s, and played through/worked on a lot of them. I'm partial to those amps. For me, that's just "the sound". 8)

I gig with my Overdrive 80 quite a bit. FYI, there never was an "OD" model designation, the "Overdrive" amps are OR's with master volumes added. The circuit is exactly the same as the non-MV amps. It just has the post phase inverter master added. IMO, the master volume is nearly useless. The amp just doesn't sound right unless it's up nearly all the way. You *can* get overdrive at any volume you want with it, but the sound just isn't there below 8 or 9 on the master. The amp just sounds like a shell of itself.

That's just my 2 cents. Others are quite happy with the MV on their Overdrive models. For me, the character of the amp is the huge symmetrical clipping that comes from the power amp being driven.

The AD30 is the only modern Orange I've played that I really liked. I have 2 of them (a combo and a head). It doesn't sound like an OR-80/120, but it has a nice vintage style crunch to it. I gig with that amp often as well. It's a great sounding amp, I just find I have to set the controls at extremes to get it to sound the way I want it to. These days, an AD30 is half the price of an OR-80/120. If you want nice vintage crunch from an amp with Orange tolex, it's a bargain.
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'71 GRO100 || '96 OR-80 || AD30 || '64 AC-50 || AC-30TBX || Hiwatt DR504 || HI-TONE HT30
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mflemmer2
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Re: Differences Between ORS, GRO & OR Models

Post by mflemmer2 » Fri Oct 06, 2017 6:20 pm

Yeah, I've read in other places that the MV on the "OD" isn't all it's cracked up to be, which is too bad, especially after reading your assessment of it. I've definitely heard some good things about the AD, and correct me if I'm wrong, but it seems to me as if it was Orange trying to sound more like 70's Marshall with the AD's (not JCM800), and not as unique as their earlier amps. Still darker and more sag than most Marshalls, but less thick low end than other Oranges (?). I seem to keep hearing that the Rockerverb is kinda the best of both worlds, with the great cleans, and the overdrive more in the vein of the older amps in terms of low end, but obviously tighter and with more gain. To reiterate, I really do enjoy the info---thanks.

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Re: Differences Between ORS, GRO & OR Models

Post by fiveightandten » Mon Oct 09, 2017 4:03 pm

mflemmer2 wrote:
Fri Oct 06, 2017 6:20 pm
Yeah, I've read in other places that the MV on the "OD" isn't all it's cracked up to be, which is too bad, especially after reading your assessment of it. I've definitely heard some good things about the AD, and correct me if I'm wrong, but it seems to me as if it was Orange trying to sound more like 70's Marshall with the AD's (not JCM800), and not as unique as their earlier amps. Still darker and more sag than most Marshalls, but less thick low end than other Oranges (?). I seem to keep hearing that the Rockerverb is kinda the best of both worlds, with the great cleans, and the overdrive more in the vein of the older amps in terms of low end, but obviously tighter and with more gain. To reiterate, I really do enjoy the info---thanks.
There were a lot of different 70's Marshalls, all with their own sound. But, IMO, the Orange AD amps don't sound like any of them. It's true that the OR-80/120 have a more unique sonic signature to them than the AD. Personally, I can pick an OR-80/120 out of a record or live mix immediately if it's overdriving naturally. It's instantly recognizable. The AD30, not so much, but they do definitely have their own thing going on, even if it's not as unique as the older ones.

The OR-80/120 have a few design elements that make them sound different from most everything out there. It's mainly the baxandall tone stack and the split load PI circuit. The high value coupling caps and the FAC knob circuit also make them sound unique.

The AD series have none of these things. The tone stack is an FMV type (Fender, Marshall, Vox), and the PI circuit is a long tail (the VAST majority of amps out there have an FMV and long tail). Coupling cap values are lower, and the amp overall is more like a "normal" amp, compared to the witchcraft going on under the hood of an OR-80/120. When looking at the circuit, it's actually surprising that the AD sounds as unique as it does, but it definitely has its own sound going on. I've owned a lot of amps that sound similar to Marshalls (Laney, Sovtek, Peavey, etc.). The AD isn't one of them.

Marshall derivatives have a different midrange presence, and the breakup has a metallic cutting quality to them. The AD is wetter and has a pulpy (yes I'm using that partially because they're Orange), fuzzy harmonic quality to it, which is distinctly different from a Marshall type metallic breakup. I'd say Marshall are more gritty or grainy, Orange are more pulpy, or fuzzy. I actually have fleeting thoughts of picking up another Marshall (I've had some JCM800's, a '71 1959, a '77 50W JMP, 1987x), as I wouldn't mind having that sound at my disposal. My Oranges don't do it.
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mflemmer2
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Re: Differences Between ORS, GRO & OR Models

Post by mflemmer2 » Tue Oct 17, 2017 3:47 am

After my last post, I did read somewhere else about the AD's sounding wetter and more saturated than Marshall. I had previously seen info regarding the AD tone stack and other circuitry being closer to Marshall, and less unique than the OR's, as you pointed out. That's probably why I figured the AD's were more Marshall-esque. Thank you for educating me---keep on rockin'!

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