Bare Knuckle Pickups Forum

Forum Ringside => Tech => Topic started by: CmdChicken on June 06, 2008, 03:42:08 PM

Title: New tubes for an AC15
Post by: CmdChicken on June 06, 2008, 03:42:08 PM: I've got an old AC15 Twin and I'm looking to replace the tubes but being new to all this tube malarkey I was wondering if anyone had any suggestions?

I think they were originally fitted with: ECC83 (x2), ECC81, EL84 Duet + GZ34 (http://www.voxshowroom.com/uk/amp/ac15t.html), which of course means nothing to me :oops:
Title: New tubes for an AC15
Post by: PhilKing on June 07, 2008, 12:53:18 PM: If you go to Watford Valves web site they will steer you right. For new valves you could look at Mullard's, Groove Tubes or JJ's. The ECC83's are also 12ZX7's (the US catagorisation), ECC81's are 12AT7's, and EL84's are 6BQ5, though you don't see that name as much.

I would think that ECC83's are your preamp stages, the ECC81 the phase inverter. The EL84's are the power tubes and the GZ34 the rectifier valve.

The ones that make the most difference to the sound are the ECC83's and the EL84's.
Title: New tubes for an AC15
Post by: CmdChicken on June 07, 2008, 01:35:44 PM: Top stuff, thanks!
Title: New tubes for an AC15
Post by: hunter on June 07, 2008, 03:25:59 PM: Make sure that you get a balanced tube for the Phase Inverter. (usually this is an option when ordering)

For EL84s I can recommend the TAD EL84 CZ.

I would try a Mullard Reissue 12AX7 in the first slot (V1), they give very nice harmonics.
Title: New tubes for an AC15
Post by: HTH AMPS on June 07, 2008, 11:30:13 PM: this has just a pair of EL84s and uses a GZ34 rectifier? - that seems wierd, a GZ34 is overkill in this situation. I'd expect an EZ81 in there to be honest. You 100% sure its a GZ34?

the two ECC83s are for the first gain stage and the phase inverter. the ECC81 is for the tremolo circuit.
Title: New tubes for an AC15
Post by: CmdChicken on June 08, 2008, 12:50:19 PM: Not sure in the slightest
Title: New tubes for an AC15
Post by: hamfist on June 08, 2008, 12:56:44 PM: Quote from: CmdChicken
Not sure in the slightest

You need to open it up and see what tubes are inside.
Title: New tubes for an AC15
Post by: Elliot on June 08, 2008, 02:13:09 PM: I have a feeling that original Jennings AC15s used EZ81s but that later ones used GZ34s - Did it just use 1/2 of the valve?