Orange AD30HTC - Valve (EL84) replacement recommendations?

JackGriffiths

Hi all, 

Having owned my AD30HTC for nearly 5 years now and the person I bought it from having owned it a further three years before that, I feel it's due an upgrade in the tube department. Off hand, I can't remember what's in there at the moment, but they'll be whatever was stock in Orange amps 8-or-so years ago. The amp sounds awful, grainy and tinny, until about 10 o' clock on the Master volume but sounds great from there onwards. Have been reading a lot about JJ EL84s due to their balance between tone and reliability, but then other reviews have slated them for not suiting the tonality of the Orange at all and saying that they are much better suited to Vox amps. The Orange is considerably darker than other EL84 based amps, so would I be right in looking for a slightly brighter tube to bring out some more clarity? I'm after less gain, if anything. 

Any recommendations would be appreciated. I'm also considering swapping out the 12AX7s but this is the priority. Plus, I've heard that you don't get much better than EH 12AX7s for vintage-style amps. 

Cheers,

Jack

ICBM

Power valves don't make that much difference to the actual tone - a little, but far less than preamp valves. They do make quite a difference to the dynamics and 'presence', which is not quite the same thing...

If you want less gain and a brighter, clearer tone you could try a 12AT7 as either the phase inverter (nearest the power valves) or V1 (nearest the end of the amp). Or possibly both, but I'd probably try just one first. If you want to try different 12AX7s I would satrt with the Tung-Sol 'reissues', which have a nice bright, clear sound.

I would also be inclined to replace the rectifier valve with a solid-state plug-in like the Sovtek SSR - not a 'valve emulating' one, just a plain solid-state diode pair with no added resistance. This will make the amp brighter and less compressed, and also fix the design fault which causes rectifier valves to blow fairly regularly in these (and some other modern valve-rectified) amps. You or a tech can make one fairly easily from a dead rectifier valve base, a pair of 1N4007s and some potting resin, if you want.

ecc83

Can't find the exact schematic but this one (if it has worked! How do I add attachments please?) uses two PIs!

Dave. (and why does the system not remember me?)

ICBM

ecc83 said:

Can't find the exact schematic but this one (if it has worked! How do I add attachments please?) uses two PIs!

I don't know why your attachment doesn't seem to be showing, but yes, you're correct!

I forgot that the channel-switching one does that. Essentially it's two complete preamps from the standard AD30, and these use a post-PI master volume. The channel switching is just relays to select one preamp or the other.

In which case you may want to try a 12AT7 in both of the positions nearest the power valves if you want both channels cleaner and brighter - or just one if it's only the clean channel you want to change - I can't remember which way round they are, but pulling one of them and running the amp to see which channel isn't working is safe. Likewise with V1 which is also duplicated.

The rectifier change applies to all versions of the AD30.

ecc83

I can't find an icon or symbol that even says "attachment"?

Dave.

ICBM

You just copy the address of the image directly into the post, no formatting or anything. The forum software does the rest somehow...

Puzzled me at first until someone told me!

JackGriffiths

Thanks for the advice, ICBM. I think it would probably be worth replacing the whole set, then. Have you any particular  recommendations on brands? I'm most likely to order from watfordvalves.com. 

Thanks a lot,

Jack

ICBM

You can actually get really nice NOS 12AT7s for quite a low price, they're still relatively common. The JAN Philips (US military spec) is probably the best available.

To be honest I'd really recommend getting just one and trying it in all the valve positions first though, find out what each does and whether you like it before committing to a whole set. 12AT7s do sound brighter and clearer than 12AX7s and with less gain, but in some amps it can be too much, especially in 'gain' positions rather than phase inverters, and they can make the amp sound 'cold' or thin.

I would definitely get a solid-state rectifier as well, even if you don't hear a huge sound change it will be a useful spare for when the valve inevitably blows at some point! (As long as you keep spare fuses too.)