Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on November 11, 2010, 06:24:09 am

Title: minimum 12AX7 tube spacing
Post by: tubenit on November 11, 2010, 06:24:09 am
Guys,

I'm still debating whether to go with an onboard active effects loop with my other Tweed Overdrive Special or make an outboard one.  Trying to see if onboard would be an option at all.  The FX tube in my other TOS works excellent.

As you can see from the photo, it would be a VERY tight fit (1.75" spacing)  but perhaps do-able?

Think I can make the FX tube fit in there without noise or oscillation issues?

With respect, Tubenit
Title: Re: minimum 12AX7 tube spacing
Post by: FYL on November 11, 2010, 07:03:04 am
The empirical rule is > 1.5 tube dia. The 12AX7 measures .8" => 1.2" min. 1.75" should be OK.

Title: Re: minimum 12AX7 tube spacing
Post by: tubenit on November 11, 2010, 08:32:45 am
FYL,

Thank you for the response!  It is appreciated.  That allows me a reasonable option then.

With respect, Tubenit
Title: Re: minimum 12AX7 tube spacing
Post by: Fresh_Start on November 11, 2010, 10:15:09 am
Not necessarily applicable in this case because you're shoe-horning an extra tube in, but isn't there a particular orientation 12AX7 type tubes are supposed to be in?  IOW isn't there a certain way they should be lined up to reduce noise/interference?

Cheers,

Chip
Title: Re: minimum 12AX7 tube spacing
Post by: tubenit on November 11, 2010, 10:41:59 am
Quote
isn't there a particular orientation 12AX7 type tubes are supposed to be in

I've never heard that before. I've done quite a few builds & have never paid much attention to using a particular orientation. To the best of my memory, I have not been aware of it making a difference?  Maybe at times, it can matter.

With respect, Tubenit
Title: Re: minimum 12AX7 tube spacing
Post by: echuta13 on November 11, 2010, 11:55:35 am
I've seen some discussions recently on which triode is quieter in a 12ax7 which might affect orientation...  Other than that, I only thought that orientation mattered on tubes with significant radiant heat output.