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Variations in early to mid 70s OR120 amps

Posted: Thu Aug 31, 2017 1:11 pm
by Cato
Hi . I'm new here and have been looking to purchase a 70s OR120 non overdrive . My friend has a 74 model and I have a purchase option on a 76. Are there any differences worth noting ? Transformers , circuit changes etc. thank you

Re: Variations in early to mid 70s OR120 amps

Posted: Thu Aug 31, 2017 8:27 pm
by fiveightandten
A '74 may not be the same as a '76. You may find some early or mid '74 amps that were still wired with one of the older circuits, but chances are this '76 will be the same as your friend's amp, or at least close.

There are a few things to note:
-Are you sure your friend's amp is actually a '74 and the amp you're looking at is actually a '76? These amps can be hard to date.

-I'm assuming you like the sound of your friend's amp and you want to know if this other one will sound like that. There is some variation in the tone of these amps and each one tends to have its own character (even the ones that are wired the same). They all sound good. Very good.

-Most of the circuit variations are easy to overcome with some slight modifications. See this thread I started for more info on differences: viewtopic.php?f=2&t=55823


Do you have any pictures of the amp in question? With pics of the chassis and internals, we can tell you whether or not it's been modded and what it not original.

-Nick

Re: Variations in early to mid 70s OR120 amps

Posted: Fri Sep 01, 2017 12:08 am
by bclaire
Go to the Orange Amp Field Guide and scroll down on the left to Dating Oranges and see what year his and yours (potentially) are by the serial numbers.

http://www.orangefieldguide.com/

Re: Variations in early to mid 70s OR120 amps

Posted: Fri Sep 01, 2017 1:44 am
by Cato
Thank you both for your advice. The one for sale has a master mod at the back but other than that all original.

Will see if I can get some pics of the internals

Funny thing is I play clean .. and most demos I can find are overdriven ...but my friends 74 has super sweet cleans

Re: Variations in early to mid 70s OR120 amps

Posted: Fri Sep 01, 2017 2:00 am
by fiveightandten
Cato wrote:
Fri Sep 01, 2017 1:44 am
Thank you both for your advice. The one for sale has a master mod at the back but other than that all original.

Will see if I can get some pics of the internals

Funny thing is I play clean .. and most demos I can find are overdriven ...but my friends 74 has super sweet cleans
The amp is capable of gorgeous cleans...just not usually at the same time as really nice overdrive (you have to set the knobs quite different). The FAC control is very powerful and will yield a great clean tone when you click it towards the right. It does a great edge of breakup clean with a little snarl and fuzz to it, and it's very abrupt to break up...you can get a little hair on the sound when you dig in, and keep it squeaky clean by laying back on your picking.

These are extremely loud amps, but the clean headroom isn't high for an amp with a pair or quad of EL-34's, so "clean" is all relative.

The master volume changes the sound a bit even when up full, so you may or may not choose to keep it. I'm of the opinion that master volumes on these amps sound terrible and don't really help in making the amp quieter. It needs to be up past 8 or so with the Overdrive master volume, or it doesn't sound right. A modded master may be a different circuit, there are hundreds of variations out there. You can make it defeatable if you wanted. I did this to my Overdrive 80, and mounted the switch in one of the empty tube sockets (completely reversible, and with no drilling).

-Nick

Re: Variations in early to mid 70s OR120 amps

Posted: Fri Sep 01, 2017 2:09 am
by Cato
Yeah the volume is way more than I need. I am intending on pairing it with a jbl d130f initially so will have to be careful . Though it did come from a vibrosonic 100w amp

Re: Variations in early to mid 70s OR120 amps

Posted: Fri Sep 01, 2017 2:14 am
by fiveightandten
Cato wrote:
Fri Sep 01, 2017 2:09 am
Yeah the volume is way more than I need. I am intending on pairing it with a jbl d130f initially so will have to be careful . Though it did come from a vibrosonic 100w amp
Yeah, an OR-120 will melt that speaker if it's anywhere near full volume. The 70's amps are quite powerful.

-N

Re: Variations in early to mid 70s OR120 amps

Posted: Fri Sep 01, 2017 10:39 am
by bclaire
I know Nick doesn't like the master volume Oranges but I love 'em! I think they make the amp very usable and with the master all the way up, you can use the gain like a volume control and it's pretty close to a non-master amp then....

Re: Variations in early to mid 70s OR120 amps

Posted: Sat Sep 02, 2017 2:21 am
by Cato
Thanks . Will take it ez :-)

Re: Variations in early to mid 70s OR120 amps

Posted: Sat Sep 02, 2017 8:44 am
by a.hun
bclaire wrote:
Fri Sep 01, 2017 10:39 am
I know Nick doesn't like the master volume Oranges but I love 'em! I think they make the amp very usable and with the master all the way up, you can use the gain like a volume control and it's pretty close to a non-master amp then....
With Nick on this one. Yes, with the master up mine sounds great, but with it below about 8-9 out of 10 it doesn't. The MV itself is therefore pretty much useless. You can't get great sounds at much reduced volumes. (An attenuator can help, but not so many out there can actually handle an OR120 properly...)


Andy.

Re: Variations in early to mid 70s OR120 amps

Posted: Sun Sep 03, 2017 12:54 am
by Cato
Thanks Billy
Hope to hear back from him soon.

Re: Variations in early to mid 70s OR120 amps

Posted: Sun Sep 03, 2017 3:10 am
by fiveightandten
a.hun wrote: With Nick on this one. Yes, with the master up mine sounds great, but with it below about 8-9 out of 10 it doesn't. The MV itself is therefore pretty much useless. You can't get great sounds at much reduced volumes. (An attenuator can help, but not so many out there can actually handle an OR120 properly...)


Andy.
It's the asymmetrical clipping in the power amp. You can hear a very distinct transition when you get the master up high enough to bring that in. If the master is below that point, you don't get that sound.

I'm envious of Billy getting the sound he likes at reasonable volumes. I had to buy a Fryette Power station to use my OR-80 with my current band. I use the PS with all my amps now, actually. AD-30 included. It can take an OR-120 running full tilt.

-N