[HAM] Best 12AU7 now 6550

[David Anderson]

Hi Kon,

Aspen Pittman is a controversial character in the tube audio  
business, so I'll try to give a neutral report.

As you imply in your post, the Groove Tubes label is a marketing  
strategy. The company generally sources vacuum tubes from the same  
factories as everyone else, though there are a few cases where, I  
believe, he has contracted with factories to supply certain versions  
only to Groove Tubes, though, if you know what you're looking for,  
you can get around this.

When I bought my first Leslie, it had completely mismatched tubes in  
it (one Tung Sol and one GE 6550), so, this being 1990 or so, I  
bought a set of Groove Tube labeled tubes for it. The 12AU7, I can  
now recognize, is an American-made GE tube with a Groove Tubes label  
on it. The 6550s are Chinese, and they did work a lot better than  
what came in the amp. The 6550s never blew up or anything like that,  
but I found I liked Svetlana 6550s better when I got a chance to try  
them.

I'd speculate that tube failures under the GT label had to do with  
problems in quality control of Chinese tubes in the 1990s.

So, you pay more for tubes from GT. Maybe GT does better testing,  
maybe not. I don't really think about them that much because I  
neither regard Pittman as the ultimate tube guru, as some do, or as  
an agent of Satan, as others do. On the other hand, I haven't bought  
any GT labeled tubes since 1990, so that may say something in and of  
itself.

David

On Mar 8, 2008, at 7:17 PM, Kon Zissis wrote:

> Hi Scott and everyone.
> I have never used Aspen Pitman's "Groove Tubes" in my Leslie so
> therefore I am not familiar with their sound but I am aware of the  
> hype
> about  Groove Tubes  in the guitar amp world.
>
> Disregarding the hype and presumably the higher prices due to the hype
> and the "matched" tube sets, what are the actual tonal problems or the
> electrical problems with the Groove Tubes  that cause you to avoid the
> Groove Tubes  brand?