Long plate and short plate tubes

phaqu · 6th December 2006, 07:15 AM

Can someone school me on the difference in long plate ,short plate tubes. Im trying to locate a few Mullard 12ax7 on e-bay for re-tubing a mic-pre,and have a few options. Is one better for a specific application over the other?( pre-amp ,guitar amp, radio?) Also Ive read that some guys prefer ( and seen in a few schematics) a 12au7 on the output stage. Is any re biasing needed to do that? Thanks

Matt Syson · 6th December 2006, 04:27 PM

Strictly speaking the bias should be changed if fitting a 12AU7 rather than AX7 but since the object is to change the sound, most don't bother and as long as the resistors don't mind possible increased dissipation (most don't) then just swap away. The point of the AX is the higher gain and (usually) better balance of the circuit but you want different harmonics and characteristics so the change will provide it.
Matt S

phaqu · 7th December 2006, 05:07 AM

Thanks for the info.

phaqu · 7th December 2006, 11:59 PM

Anybody have any info on the long, short plate tubes?

retrograde · 8th December 2006, 12:10 AM

Quote:

Originally Posted by phaqu

Anybody have any info on the long, short plate tubes?

Ask on the Gearpage - http://www.thegearpage.net/board/

Many people very knowledgable about tubes on that board.

phaqu · 8th December 2006, 12:20 AM

Thanks. Ill give it a shot.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
New Plate Reverbs by Plate-Sonics?	jayridge	New product alert!	10	25th March 2007 02:31 PM
Plate-Sonics plate reverb	beechstudio	High end	5	2nd May 2006 04:27 AM
Looking for a Plate Reverb	WCKnitting	So much gear, so little time!	2	3rd January 2006 08:56 PM
Plate Reverbs	robmix	So much gear, so little time!	6	10th October 2005 08:10 AM
EMT Plate...Who Knows	Konovaliv	Geekslutz forum	6	7th August 2003 03:37 PM

6th December 2006, 07:15 AM	#1
phaqu Gear addict Join Date: Apr 2006 Location: Atl GA Posts: 304	Long plate and short plate tubes Can someone school me on the difference in long plate ,short plate tubes. Im trying to locate a few Mullard 12ax7 on e-bay for re-tubing a mic-pre,and have a few options. Is one better for a specific application over the other?( pre-amp ,guitar amp, radio?) Also Ive read that some guys prefer ( and seen in a few schematics) a 12au7 on the output stage. Is any re biasing needed to do that? Thanks

6th December 2006, 04:27 PM	#2
Matt Syson Lives for gear Join Date: Sep 2004 Location: UK Posts: 1,489	Strictly speaking the bias should be changed if fitting a 12AU7 rather than AX7 but since the object is to change the sound, most don't bother and as long as the resistors don't mind possible increased dissipation (most don't) then just swap away. The point of the AX is the higher gain and (usually) better balance of the circuit but you want different harmonics and characteristics so the change will provide it. Matt S __________________ Matt S www.mseaudio.co.uk

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread:

7th December 2006, 05:07 AM	#3
phaqu Gear addict Join Date: Apr 2006 Location: Atl GA Posts: 304	Thanks for the info.

7th December 2006, 11:59 PM	#4
phaqu Gear addict Join Date: Apr 2006 Location: Atl GA Posts: 304	Anybody have any info on the long, short plate tubes?

8th December 2006, 12:20 AM	#6
phaqu Gear addict Join Date: Apr 2006 Location: Atl GA Posts: 304	Thanks. Ill give it a shot.