AD30TC tube change

littlefred · Post by **littlefred** » Mon Sep 13, 2004 9:47 pm

It's time to change the tubes on my AD30TC. I like the way it sounds with the stock tubes, but I'd like a little more clean headroom on channel 1. Any ideas as to what tubes I should go for? I must admit I'm a tad confused; I've had people tell me that the tubes are vital for a great sound and others say that as long as they're ok you won't hear any difference. Also, will I have to get my head re-biased by an amp tech or not when I change the power-amp tubes?? What did you guys do when you changed tubes? Grateful for any advice!

Joe
holdenmusic.net

motorsquad · Post by **motorsquad** » Mon Sep 13, 2004 9:53 pm

On my ad30tc i put in gt mullard reissues and electro harmonix power tubes which lowers the gain(At least to my ears). Its what i liked about the stock tubes without the things i didnt like. A warning though, the mullard re-issues are about 25 bucks a pop.

Meole · Post by **Meole** » Mon Sep 13, 2004 10:32 pm

The AD series of amps don't need to be biased when changing tubes.

littlefred · Post by **littlefred** » Mon Sep 13, 2004 10:43 pm

Thanks for the replys! I have heard that the ADs don't need to be biased, but then again others have told me that they should be anyway, just to be on the safe side. What I need is someone who owns an AD30TC and has changed the tubes without re-biasing so they can assure me that it works and doesn't mess up the amp...

Then I presume I can just order some ccol tubes online and pop them in myself?

Joe

pedro · Post by **pedro** » Mon Sep 13, 2004 11:14 pm

i've changed both preamp and power amp tubes, no problem, this was last year

irish_admiral · Post by **irish_admiral** » Tue Sep 14, 2004 1:05 am

Yes, we've had this discussion quite a lot. We were assured by the Orange AD30 designer himself that we didn't need to rebias. Put it this way, if it ever so happens that a tube change manages to screw up your amp, you've got a legitimate reason to harrass them. I changed my power tubes - which if it wasn't self-biasing, you'd need to rebias for - to tubes with a different plate voltage, and had no trouble.

You'll be fine. Just remember to get your tubes matched. Dual matched in the case of the power tubes.

Don't tell me the best way, just tell me the cheapest way...

Andy H. · Post by **Andy H.** » Tue Sep 14, 2004 8:24 am

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>It's time to change the tubes on my AD30TC. I like the way it sounds with the stock tubes, but I'd like a little more clean headroom on channel 1.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>You need a preamp tube with a little less gain for that channel then littlefred. Now then folks, which preamp tube position was that again?

The power tubes you use will affect the sound of the whole amp of course. I'm one of those 'semi sceptics' if you like. But what I have always said is that unless you get new power tubes that are radically different in their current draw, yes you'll be fine just swapping out. The cathode biasing system allows a fairly wide variation in tubes to work fine. Ones with extremely high or low draw might just be outside that range, but the vast majority won't cause problems. And as Irish Admiral says, the designer stated that he sees no need to worry about re-biasing.

You could always do what a lot of Vox AC30 owners do. They tend to tell the supplier which type of amp the tubes will be used in. That way they should get ones which shouldn't run too hot, as those amps tend to run pretty hot anyway at the best of times. If you specify the amp, most of the good valve suppliers should provide suitable valves.
(Just talking cathode biased amps here, mind. All others definitely do need the bias checked with new valves!)

Andy.

littlefred · Post by **littlefred** » Tue Sep 14, 2004 10:42 am

Thanks guys! Orange should count themselves lucky to have one of the best forums on the net. Anyway, now I'm off to peruse the Watford Valves site for a week or two...

Joe

irish_admiral · Post by **irish_admiral** » Tue Sep 14, 2004 11:08 am

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote> Now then folks, which preamp tube position was that again?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>The one closest to the short side of the chassis. The valves pairings for the channels run in lines pairs parallel to the edge of the amp chassis. I've got the schematics if you want them...

Don't tell me the best way, just tell me the cheapest way...

littlefred · Post by **littlefred** » Tue Sep 14, 2004 11:54 am

The schematics could really come in handy...

Could you post them here?

Joe

irish_admiral · Post by **irish_admiral** » Tue Sep 14, 2004 1:26 pm

I'll email them to you. I don't have online hosting facilities, nor can I be bothered to find some for free...

Don't tell me the best way, just tell me the cheapest way...

Meole · Post by **Meole** » Tue Sep 14, 2004 1:38 pm

Can you e-mail me them as well?

irish_admiral · Post by **irish_admiral** » Tue Sep 14, 2004 3:14 pm

Done.

Don't tell me the best way, just tell me the cheapest way...

littlefred · Post by **littlefred** » Tue Sep 14, 2004 11:14 pm

Thanks mate, just got them!

Joe

Meole · Post by **Meole** » Tue Sep 14, 2004 11:21 pm

Received them. Thanks as well.

AD30TC tube change

Who is online