AD5 combo (PCB model)

bcobby · Post by **bcobby** » Thu Jan 17, 2008 9:03 am

Since buying my AD5 combo several years ago i have been trying to get rid of a nasty rattle after about 4.5 on the volume, so far only a tube screamer could disguise it! Orange were not helpful at all, and nobody on this site could help me.
I recently wrote to Guitarist Magazine (UK) and within a few days i received the following message from the very nice Mick Taylor;
"There is a metal plate between the chassis and the wooden back plate that the chassis mounts on. Remove it!"
I haven't had the opportunity to try it yet, but maybe this info might be of interest to other owners, i know there are a few out there somewhere.

Andy H. · Post by **Andy H.** » Thu Jan 17, 2008 10:17 am

Having never seen an AD5 in the flesh, that could be useful advice.

I don't know whether the process will involve exposing the circuitry inside the chassis at any point in the proceedings.

If so I'd add a little something:
"Remove it - CAREFULLY!"

Don't want to go zapping yourself...

Let us know how it goes. If you could post photos here that would be useful for the future.

Andy.

Bink · Post by **Bink** » Thu Jan 17, 2008 5:11 pm

It sounds like you have a seriously defective amp there - I'll take it off your hands for you! :p

Unfortunately very few of us have seen much of, let alone heard an AD5. Any drooling material or general description of how awesome it is would be appreciated!

Hope it solves your rattle problem for you.

bcobby · Post by **bcobby** » Fri Jan 18, 2008 11:17 am

Hi there, i will post some photos of the amp innards after i get a chance to remove the metal plate. (I'm away from home right now)
According to Orange there were approx 150 original hand wired AD-5's and then approx 75 PCB models made.
After a bit of searching I located mine in one of the shops near Denmark Street and bought it unseen over the telephone, new and boxed.
Unfortunately when it arrived at my house it was not working, so it went directly back Orange to get fixed, they said it was a valve problem.
I had tried the AD-15 and loved the sound, but wanted something more house friendly so hoped the 5 watter would be similar, it is okay but to my ears not as nice as the AD-15.

For me the AD-15 is still the best sounding combo i have heard!

ps. These days I'm mostly playing an (original USA model) Steinberger GL (cricket bat) which is really great and took me a while to track down, it replaced my old heavy, fuzzy sounding 1979 Les Paul Custom, which in a few years i'm gonna no doubt regret selling! Otherwise i can be seen & heard 'playing poorly' a white 1985 Standard Strat or Martin 5-15 mini acoustic.

Bink · Post by **Bink** » Fri Jan 18, 2008 7:45 pm

That's interesting. I absolutely love my AD15, I think it's awesome. I had always assummed that the AD5 would be similar tonally but be able to be driven at more house friendly volumes and would have a sweet overdriven sound.
I guess I had always thought that it might actually sound better than the AD15 at similar volumes.

Andy H. · Post by **Andy H.** » Sat Jan 19, 2008 12:13 pm

Thanks for that info bcobby. Interesting to see those numbers. I remember reading they were only planning about 100 of the PCB ones, but its interesting Orange actually made more of the Custom Shop ones than of the 'production line' variety. Didn't know that.

<hr noshade size="1">
I've always quite fancied an AD5, (PCB or Custom Shop), but purely because I like Oranges and I like low wattage amps, and not because it happens to run in true class A. (Though only having a single output valve means that it definitely does.)

Ironically I think there is a strong chance you prefer the sound of the AD15 because it isn't a true class A amp! [:0]

What most people think of as the 'class A sound' isn't that at all. Partly because what most people describe as 'class A' amps usually technically aren't...

(See this thread: http://forum.orangeamps.com/viewtopic.php?t=13918)

...and partly because what actually gives an amp that alleged 'class A sound' has nothing to do with the amps operational class, but is due to the 'cathode biasing' system those amps tend to use!

In fact it is the reactive 'cathode biasing' circuitry which gives a rich and dynamic sound and compression all of its own. As the signal strength (from your guitar) varies, so does the biasing for the power valves. That gives an especially nice additional type of power amp compression.

But that only happens when used in a class AB amp (like the AD15 / AD30 / Rocker 30/ Vox AC30) where the overall current in the power valves actually varies with signal. In a true class A amp, as I explained on that other thread, the overall current through the power valves doesn't vary from no signal to full signal*. Therefore even if a cathode biasing system was fitted the bias supply for the power valves also wouldn't vary with the changing guitar signal. Meaning you'd get none of that lovely cathode bias induced compression in a class A amp!

[* What happens with true class A operation is that at no signal, none of the current goes to the output transformer and speakers - it basically just makes the valves very hot. At full signal however up to a maximum of 50% is sent to the OT and speakers. The rest is still just turned into heat. This is why class A amps are less efficient than class A/B amps. And also why their valves actually get hottest when you aren't playing loud!!!] [:0]

Cathode biasing is also less power efficient than 'fixed' biasing, one reason why cathode biasing is rarely seen on higher wattage amps, above say 30 watts or so. For more powerful amps fixed biasing makes more sense efficiency and cost wise.

But anyway, put simply...

A great sounding class A guitar amp is great sounding through great design, and (in my view) despite being a class A amp, not because of that! But hot running cathode biased class AB amps like the AD15 etc etc have a unique advantage, a trick up their sleeves called cathode biasing. Though often confused with it that isn't the same thing as class A at all.

Andy.

PS: Another possible sound factor is that any amp with more than one output valve is likely to have a more harmonically rich sound because the valves can never be exactly matched in performance.
In fact many users of amps like AC30s actually swear by deliberately using less than closely matched valves because it gives richer more complex harmonic distortion. And you can get away with it more easily because the amps are so called 'self biasing'... meaning cathode biased!

You won't of course get that 'unmatched effect' either with an amp which only uses a single power valve!

bcobby · Post by **bcobby** » Sat Jan 19, 2008 1:08 pm

Hello Andy H, many thanks for taking the time to explain that, which sadly mostly went flying over my head, but what i did understand is good to know and i'm just happy that somebody understands it!

bcobby · Post by **bcobby** » Sun Jan 27, 2008 9:19 am

I am happy to report that removing the metal plate has solved the problem and the rattle has thankfully gone.

For the techy people out there, the AD5 valves are EL84 & ECC83.

Can anybody unlock the trick to inserting some photos, i'm sure the answer is here but i can't find it.......

Bink · Post by **Bink** » Sun Jan 27, 2008 9:56 am

To insert a photo you need to have it hosted on the web somewhere. There are free sites such as photobucket which you can set up for this. you then need to paste the url in between img and /img These need to be in square brackets (the img and /img). If you reply using the reply to topic option, then there's a link that inserts this for you if you select the url.
Sorry if that's not very clear!

bcobby · Post by **bcobby** » Sun Jan 27, 2008 10:17 am

Hi Bink, many thanks for that advice, i will give it a try!

bcobby · Post by **bcobby** » Mon Jan 28, 2008 8:28 am

Bink · Post by **Bink** » Fri Feb 01, 2008 9:47 am

Sweet!

I still want one!

Glad removal of the plate solved the rattling issue for you.

bcobby · Post by **bcobby** » Fri Feb 01, 2008 11:12 am

Hi Bink,
Since removing the metal plate the overall sound of the combo has improved significantly so at the end of the day it isn't too far from the AD15 sound i originally wanted, and fully cranked it is still relatively house (detached) friendly.
Cheers, Bruce

Bink · Post by **Bink** » Sat Feb 02, 2008 5:05 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by bcobby
 Hi Bink,
Since removing the metal plate the overall sound of the combo has improved significantly so at the end of the day it isn't too far from the AD15 sound i originally wanted, and fully cranked it is still relatively house (detached) friendly.
Cheers, Bruce
<hr height="1" noshade id="quote"></blockquote id="quote">
Ah man, don't tell me that! :p Now I REALLY badly want one! Don't think it would go down to well in my household if I bought another Orange though! I get glares about the fact I have 2!

Glad your liking it though. It's amazing how quite a simple change can have such an overall effect.

BruceJ · Post by **BruceJ** » Sun Feb 10, 2008 2:12 am

Thanks very much for posting those photos, I have AD5-1002-06-03 but haven't opened the thing up yet. I guess mine's got the PCB board too, I had wondered about that. Anyone know what the serial num means, if anything?

AD5 combo (PCB model)

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