Or120 reliability for new transformer.

[Frank_Jeeves]

http://forum.orangeamps.com/viewtopic.php?f=3&t=50731" onclick="window.open(this.href);return false;
I posted this some months back. Now I have a customer who is will to buy from me (for a lower price) and he's worried about the future reliability due too the not to spec transformer.

[a.hun]

It was a TH100 tranny, right? Why don't you ask Orange (Ade) for their opinion.


Andy.

[Frank_Jeeves]

Where is that at?

[a.hun]

Orange website...
http://www.orangeamps.com/contact/" onclick="window.open(this.href);return false;

If you phone Orange UK you might get Ade Emsley (chief amp designer) if he is back from NAMM. He'll know.


Andy.

[ironlung40]

Wasn't this an output transformer? The power transformer is what gives the amp it's output...wattage, etc....as long as the Output transformer can handle it, then it should be fine....Orange doesn't make a specific transformer for this amp, so any of their 100 watt spec'd output transformers should be perfectly fine in this amp.

Another for instance, is that if you called orange USA today and wanted an OT for a AD140, they would send you the 100 watt demeter that they have put in the RV100's and it would be perfectly O.K. Ask Will Loftin if you don't believe me.


As, far as tone goes, that is where the subjectivity comes in. I have no idea how it sounded with the original vs the new one, maybe better, maybe not, maybe hard to discern?

You can always buy a toneclone from mercury magnetics if inclined...but I think this is a non-issue in regards to reliability. Any transformer could be on it's way out, especially a very old one in a vintage amp. If the amp is serviced regularly and it has the correct fuses in it if something does blow, then the transformer should be perfectly fine.

If this is a power transformer, that is underpowered for the amp, you might have some other issues to speak of.

[fiveightandten]

The 2 specifications that matter with respect to reliability are:
-Power rating
-Primary impedance (Primary Z)

Power rating
Seeing as the TH100 transformer came out of a 100W amp with the same tube compliment as your OR-120, the power ratings should be similar on the 2 units. In any case, the TH100 transformer will surely be able to handle the full output of a 4 EL-34 tube compliment. The OR-120 doesn't put out a ton of power from the EL-34's. It will not overpower any properly designed transformer out of a 100W EL-34 powered amp.

Primary Z
Output transformers do exactly what their name implies. They *transform* the high impedance signal from the tubes into a low impedance signal to drive the speakers. In the case of a 4 EL-34 amp, we're talking about roughly a 2000 ohm primary side, being converted to 4, 8, or 16 ohms on the secondary side. Different types of power tubes will have different Primary Z's, and therefore will have OT's that are designed around the tube compliment. However, when going from 4 EL-34 to 4 EL-34, there's nothing to worry about. The primary Z of both transformers will be nearly identical, if not the same. Therefore, there are no issues that arise.


If your buyer wants a detailed explanation, feel free to point him to this thread and/or this post. I can not speak for the frequency response of the TH100 OT, or how well it bolts into the chassis without the need for drilling or special brackets. But that is all you need to know to address any reliability concerns.

Hope that helps.

-Nick

[a.hun]

Any transformer could be on it's way out, especially a very old one in a vintage amp.

Actually transformers if not abused should go on virtually for ever. They aren't like resistors or (especially) electrolytic capacitors which really can deteriorate with age.


Andy.

[ironlung40]

Any transformer could be on it's way out, especially a very old one in a vintage amp.

Actually transformers if not abused should go on virtually for ever. They aren't like resistors or (especially) electrolytic capacitors which really can deteriorate with age.


Andy.

Yep, and that is reassuring....just so long as they haven't been abused.

Guitar center had a beautiful OR120 70's model pix/text for sale a few months ago. I was interested until I saw it powered on with no cabinet hooked up to it one day....I turned it off and told the store manager....crazy but true...

[a.hun]

Thing is that usually any transformer damage is pretty self evident once you try an amp out. Its not quite always all or nothing, but usually. Only very occasionally will a transformer have a partial burnout and then you can expect that it'd fail pretty fast when pushed hard the next time.

Basically if an amp is working okay then the trannies are okay. Damage by abuse almost always either happens (= amp dead or very occasionally low power + distortion + fast deterioration when pushed) or doesn't happen.

The '70s transformers Orange used were very tough. If the amp performs than it'll be fine. Still undeniably stupid of the shop. All it needed was someone to plug in a guitar and hit a chord with the volume up far enough --> RIP!


Andy.

[Jondog]

Im not an expert by any means, but I think its perfectly fine. The two amps are running basicallythe same power layout. B+ voltages could be different with a atraight swap and no other mods, so that might change the characteristics a bit. Depends what the voltages on the transformer are. Ive contacted Patrick Selfridge at Mercury Magnetics a few times to discuss different options for builds Im thinking about and he'll suggest (example only) amp A transformer with amp B output transformer. All depends on the output section and what the tubes require which is the same in your case.